repair wall plate?

[Cubist]

Hi Gerry,

Sorry but we need to be careful about the terminology. A 'collar tie' is a beam morticed into both truss/rafter members below the apex of the bent. If you look at the cross section diagram of your house that you provided earlier, the collar tie is represented by the top-most horizontal line. At 14 feet x 4 feet I think you are talking about the flat ceiling that someone has installed below the collar ties in two adjacent bents and their trusses.

To establish what repairs are needed, close inspection is vital. Sorry, but all the plaster work currently covering the the two truss members, the collar tie, and the heads of the posts on both sides of the bent must be removed. However, you should not need to remove more than a foot of the plaster into the room from beside these timbers to provide all essential and required access. So no need to take it all down.

Investment of a few pounds for a decent borescope could save you a lot in this and other projects.

I think you may want to consider how best to finish the room after you see the final results of the repair work and how these may appeal or not to your aesthetic tastes.

I'm a little pressed for time right now so I'll come back tomorrow concerning props and straps.

Cheers for now.
Steve

 

[Kearn]

Hi again, thanks for the Flir links ..interesting ... after a couple of sessions looking at and following, I came across the Frankin sensor range ... see https://franklinsensors.com/product-details/prosensor-710-2/ These look a lot lot cheaper than Flir devices which would seem to be great for thermal detection (I'm waiting for my turn on a thermal camera our council lend out to local groups) but i dont see mention of stud/post finding? Any thoughts?
ATB, Gerry Cavander

It may just be my unwillingness to read their entire site, but under the ‘technology’ section there was no mention whatsoever of the actual tech employed to sense studs so wonderfully…

The FLIR isn’t perfect, or maybe my usage isn’t… but it can certainly distinguish where timber is set within a wall as per my image before. I imagine there is a depth at which it struggles though.

 

[Cubist]

Hi Gerry,
Can you advise please that the truss/rafter that is thought to have spread is atop the party wall between your house and your neighbours?

 

[GerryC]

otHi Gerry,
Can you advise please that the truss/rafter that is thought to have spread is atop the party wall between your house and your neighbours?

Hey Steve, not 100% sure i understand the question but the picture below shows the position and the rafter and stud/post which have slipped vis-a-vis the gable end and the party wall sides ? makes sense? BTW one can see the spread across the entire width of the wall inside: its at about 10 degrees next to the party wall and the gable end but a little more in the middle of the wall as indicated below.


Re the collar tie having a ceiling boarded onto it - yes taht's 6just right that's what we have - i could try to put boroscope through that ceiling and inspect the ridge rafter joint ... is that what you advise? .... but should i take that ceiling down anyway to have access to all the ridge / rafter joints?

 

[GerryC]

It may just be my unwillingness to read their entire site, but under the ‘technology’ section there was no mention whatsoever of the actual tech employed to sense studs so wonderfully…

The FLIR isn’t perfect, or maybe my usage isn’t… but it can certainly distinguish where timber is set within a wall as per my image before. I imagine there is a depth at which it struggles though.

Hey, No, you are right, it took a long time to find the explanation and even then its not particularly sound ... but buried way down it says 1) it has numerous 'pads' which emit a 'force' and the interaction with that force and the surface is used to determine if there is s stud or other object + 2) it is not a metal detector. Hmmm ??? Which of the FLIR devices do you use? ATB, Gerry

 

[Cubist]

Hi Gerry,
I'm becoming a little more comfortable now - the fog of my confusion surrounding the layout of the houses timber frame are clearing. I was worried that the post that had slipped was next to the party wall rather than at a midpoint entirely within your house .

Yes, it's vital that you examine the rafter member directly beside the dormer. Its M&T joints to its partner rafter to the rear of the house, the ridge beam, the posts at the front and rear and the M&T joints connecting the rafters to these.

Do you have any idea when that dormer was installed? I'm concerned that someone may have compromised the collar tie thus causing all these problems.

A borescope would be useful but, given its almost certain what the cause(s) of the problems are, then I would be tempted to cut a couple of holes about 1-2 feet apart in the ceiling to allow visual inspection with the aid of a good torch. These would also allow some photographs which would be helpful in evaluating how to proceed. Once you've seen the nature and extent of the problems you can then decided whether to take the entire ceiling down.

Regarding props and straps. Needle props/jacks can be placed under the lateral beams that support the first floor but these need to be positioned next to each of the posts so four in total will be needed. Two on each side of the post that has slipped and the other two next to adjacent posts. It is important that these are not used to lift the beams in any way -- their function is support only. Winch straps will only be of use when the posts and beams of the damaged bent are exposed and made accessible for repair. Winch slings must be passed around the posts just below the first floor and and connected via a winch indoors. a second pair of slings and a winch can later mounted near the head of the posts and their connections to the rafters. Again, these straps must not be used for any purpose other than to prevent these timbers from moving.

Looking at one of your earlier diagrams, the dimensions of the first floor joists are giving some pause for thought. If these are correct at 40x135 they are not safe for a 14 foot span. Are you sure they are not mounted on a summerbeam/bresummer that runs the length of the room between to two outer beams?

 

[Kearn]

Hey, No, you are right, it took a long time to find the explanation and even then its not particularly sound ... but buried way down it says 1) it has numerous 'pads' which emit a 'force' and the interaction with that force and the surface is used to determine if there is s stud or other object + 2) it is not a metal detector. Hmmm ??? Which of the FLIR devices do you use? ATB, Gerry

Just the cheapest of the bunch…but I’ve only just got it so not quite sussed out the best way to use it yet, beyond point and look. But there are quite a few settings for the way the view is represented.

FLIR ONE Gen 3 Professional Thermal Camera for iOS and Android Smart Phones | Teledyne FLIR

The FLIR ONE Gen 3 is an affordable smartphone attachment thermal imaging camera designed to help professionals find problems faster and get more work done in less time. With MSX® (Multi-Spectral Dynamic Imaging) technology, which enhances thermal images by embossing details from the visual...

www.flir.co.uk

 

[GerryC]

Hi Gerry,
I'm becoming a little more comfortable now - the fog of my confusion surrounding the layout of the houses timber frame are clearing. I was worried that the post that had slipped was next to the party wall rather than at a midpoint entirely within your house .

Yes, it's vital that you examine the rafter member directly beside the dormer. Its M&T joints to its partner rafter to the rear of the house, the ridge beam, the posts at the front and rear and the M&T joints connecting the rafters to these.

Do you have any idea when that dormer was installed? I'm concerned that someone may have compromised the collar tie thus causing all these problems.

A borescope would be useful but, given its almost certain what the cause(s) of the problems are, then I would be tempted to cut a couple of holes about 1-2 feet apart in the ceiling to allow visual inspection with the aid of a good torch. These would also allow some photographs which would be helpful in evaluating how to proceed. Once you've seen the nature and extent of the problems you can then decided whether to take the entire ceiling down.

Regarding props and straps. Needle props/jacks can be placed under the lateral beams that support the first floor but these need to be positioned next to each of the posts so four in total will be needed. Two on each side of the post that has slipped and the other two next to adjacent posts. It is important that these are not used to lift the beams in any way -- their function is support only. Winch straps will only be of use when the posts and beams of the damaged bent are exposed and made accessible for repair. Winch slings must be passed around the posts just below the first floor and and connected via a winch indoors. a second pair of slings and a winch can later mounted near the head of the posts and their connections to the rafters. Again, these straps must not be used for any purpose other than to prevent these timbers from moving.

Looking at one of your earlier diagrams, the dimensions of the first floor joists are giving some pause for thought. If these are correct at 40x135 they are not safe for a 14 foot span. Are you sure they are not mounted on a summerbeam/bresummer that runs the length of the room between to two outer beams?

Thanks Steve, its wonderful to be able to talk about this is detail with someone who knows. Naturally as abeginner i've got questions to 6make sure i really do understand the wisdom, so hope these make sense you can help me get through

Re “first floor joists … at 40x135 not safe for a 14 foot span. Are you sure they are not mounted on a summe6rbeam/bresummer th6at runs the length of the room between6 to two outer beams? I just looked again – the joists are that size (I measure 5.5 x 1.5 inches) and the floor cavity (tongue and groove ceiling on one side and 106 inch floor boards on the other is the same – so although I have not raised all the floor boards to see if there is a bressummer running across the joists it could not fit unless the same size and then tahts would imply joists being tenoned into it which is unlikely I guess?

Re “Winch straps will only be of use when the posts and beams of the damaged bent are exposed and made accessible for repair.” As a beginner I thought that straps should be used as temporary measure to prevent further spread/check the outward thrust of the roof we aren’t unlucky and it moves at some point before we have completed the remedial work (would have moved anyway / tiny reduction in support provided by infills/plaster/ make critical difference …). Can you help me understand your logic … why only of use once timbers exposed. And can you factor in my plan to make it safe for 6 months while I build temp accommodation and then come back to strip all down and effect the repairs?

Re “w6inch straps”: is there any difference between ratchet and winch with straps?

Re “Needle props/jacks can be placed under the lateral beams that support the first floor but these need to be positioned next to each of the posts so four in total will be needed.” The positioning bit clear, thanks. But I’d thought we would have to prop the wall plate rather than the mid/first floor ‘plate’? I’ve propped up the first floor close to the front wall with 2x8’s, one under each joist – they are 16” apart. I’d planned to add similar props on the bedroom immediately above those at a height to just under the wall plate, , arrange acrow props outside and then steel / 2x8 needles. Currently I don’t know for sure yet what the structure of the front wall is – if there are studs that go from sole plate to wall plate or if the studs go from sole plate to mid plate and then another set of studs not necessarily aligned with the lower ones go between mid and wall plate ...

Re When Dormer installed? Not recently - no written data but the pic from the locakl history society shows dirt road and 19th century car

 

[Cubist]

Re “first floor joists … at 40x135 not safe for a 14 foot span. Are you sure they are not mounted on a summe6rbeam/bresummer th6at runs the length of the room between6 to two outer beams? I just looked again – the joists are that size (I measure 5.5 x 1.5 inches) and the floor cavity (tongue and groove ceiling on one side and 106 inch floor boards on the other is the same – so although I have not raised all the floor boards to see if there is a bressummer running across the joists it could not fit unless the same size and then tahts would imply joists being tenoned into it which is unlikely I guess?

Not true. Joists would typically be tenoned into place with a half-dovetail joint with the top face of the joist flush to the top of the beams. But, as yours are only 1.5 inches wide they have either been installed with a straight tenon or joist hangers.

Re “Winch straps will only be of use when the posts and beams of the damaged bent are exposed and made accessible for repair.” As a beginner I thought that straps should be used as temporary measure to prevent further spread/check the outward thrust of the roof we aren’t unlucky and it moves at some point before we have completed the remedial work (would have moved anyway / tiny reduction in support provided by infills/plaster/ make critical difference …). Can you help me understand your logic … why only of use once timbers exposed. And can you factor in my plan to make it safe for 6 months while I build temp accommodation and then come back to strip all down and effect the repairs?

The straps I've referred to are intended to check any further spread by preventing movement of the posts. Once the rafters are exposed a further strap can be added between the members, like a collar tie, to add further reisistance BUT only if the timbers are strong enough to cope with them.

Re “w6inch straps”: is there any difference between ratchet and winch with straps?

Winch and ratchet straps same thing but a separate hand winch may also be needed.

I'm pressed for time again so will cover the rest later.
Cheers

 

[Cubist]

Re “Needle props/jacks can be placed under the lateral beams that support the first floor but these need to be positioned next to each of the posts so four in total will be needed.” The positioning bit clear, thanks. But I’d thought we would have to prop the wall plate rather than the mid/first floor ‘plate’? I’ve propped up the first floor close to the front wall with 2x8’s, one under each joist – they are 16” apart. I’d planned to add similar props on the bedroom immediately above those at a height to just under the wall plate, , arrange acrow props outside and then steel / 2x8 needles. Currently I don’t know for sure yet what the structure of the front wall is – if there are studs that go from sole plate to wall plate or if the studs go from sole plate to mid plate and then another set of studs not necessarily aligned with the lower ones go between mid and wall plate ...

The frame comprising the front elevation of your house should have a sole plate that carries the posts and the beam that carries the first floor would normally be mounted on the posts and directly above the sole plate. Above these would be the remaining beam, also sometimes called a wall plate, and this, most frequently, is joined to the top for the posts with M&Ts. This beam finishes flush with the tops of the posts and below the rafter/truss members. The key beams for support are those at the first floor level as these carry the greatest load and have suffered the largest torsional stresses that may have damaged their joints. I'm not sure there is much benefit to be had from additional props above the first floor.

On occasion additional posts were installed 'inside' the outer frame to carry a first floor used added after the house was first built (like mine). If such an inner frame has been used in your house then the rafter spread is unlikely to have done more than very minor damage to it. The props and jacks must be focused on supporting the outer frame beams and posts.

 

[Cubist]

Hi Gerry,

Its chucking it down outdoors and in an effort to find some relief from drudge tasks I decided to entertain myself with some consideration of your challenges, hence the following.

Despite my being a pedant and perfectionist I've realised that my language when referring to the timber frame and its various components has at times relied on common usage terms that can be misleading, rather than on those offered as the 'standard, but sometimes differing, nomenclature' used in learned tomes available to the old hand and novice alike. With this in mind I thought it helpful that we ensure a mutual, pardon the pun, 'frame of reference' terminology for use in these exchanges to ensure we are on the same page and can avoid needless confusion.

With this in mind I have cobbled together the diagrams below as the basis for mutual understanding of the skeletal structure of your home, labels for the timber components are included and together these can guide any discussion of the original construction process. Hopefully, these will also assist the on-going discussion of the remedial measures needed.

The pondering associated with these have also posed some questions or issues that may require greater consideration. Chief among these is that yours is one part of a 'timber frame building in which one of the bays (the floor spaces between two adjacent 'bents') has been partitioned and a chimney stack, containing two flues, constructed to provide a pair of semi-detached houses. The big issue here is that your and your neighbours homes may be structurally reliant on each other insofar that some of the main timbers may start in your home and terminate somewhere in your neighbours. To illustrate and highlight my point - the rightmost bent in the front elevation view below is quite likely inside your neighbours house. For the purposes of your project it will be vital that you, and perhaps your neighbour too, understand the nature and extent of this mutual dependence and that consideration is given to it when planning any works with the frame.

Please note the above as an important area for investigation before you proceed to any repair works.

 

[GerryC]

Hey Steve,

Re “your and your neighbours homes may be structurally reliant on each other” Absolutely! … and guess what… my neighbour is a building contractor!!! I can see the wall plate on the front elevation continues from my side to my neighbours. If we are bay 1, my neighbour has what looks like bays 2 and 3 of the same frame, but in fact only bay 2 is part of the original timber frame structure and the apparent bay 3 is a cob brick structure added on at some point. My neighbour and I have discussed at length the work and I am ensuing they can input and agree on all decisions/work.
.
Re “Winch slings must be passed around the posts just below the first floor and and connected via a winch indoors. a second pair of slings “ this presents one problem id prefer to avoid at least for my ‘waiting-while-safely-propped-and-strap’ phase. The cottage is small, single bay, with kitchen in the lean-to at the back. In the kitchen the cupboards and kitchen units are all mounted on the back wall of the cottage: that wall is completely tiled over on the kitchen side and I suspect/hope that the kitchen installers put up a frame on which the cupboards hang (rather than on the cottage frame) …SEE pic below >>the front room side of that wall is completely covered in a very straight /regimented (compared to the other daubed walls) plywood sheet(s). In order to get a strap around the posts Id have to remove the kitchen cupboards. OK to do so when set about making the repairs but would prefer to keep kitchen relatively undisturbed for full work but in ‘waiting-while-safely-propped-and-strap’ phase while temp accommodation is built in the garden.

At first I thought an alternative would be to strap the posts level with the floorboards on 1st floor rather than top of posts on ground floor (six inches difference) but of course I don’t know and its looking unlikely from the bits we can see that posts are continuous from sole to wall plates and are sole to mid plate (or intermediate plate) and mid/intermediate to wal6l plate only …

Another engineer (a friend) advised using metal brackets to fix the first floor joists to the mid/intermediate plate as a way of using the floor block to resists roof spread? They are easy to access …???

Maybe I have to abandon plan to have a ‘waiting-while-safely-propped-and-strap’ phase and maybe just take risk of letting it stand (as it has done for a long long time) as is but without removing anything, until we can declare the whole building a building iste and we are comfortable in another …

Re “Winch slings must be passed around the posts just below the first floor and and connected via a winch indoors. a second pair of slings and a winch can later mounted near the head of the posts and their connections to the rafters.” I guess part of the thinking here is that strapping only 1 end of a post/beam means it more likely to snap while strapping it in the the middle and near the end mean its less likely to snap … load bearing is spread out some… ?

Re Terminology. Nice work. The bay concept especially useful for this project. I have read / like the term "mid plate" for "intermediate wall plate"



ATB, Gerry Cavander

 

[Cubist]

Hi Gerry,
I've modified my diagram, see below, to reflect my current assumptions regarding the house. These now include representations for the Chimney breast and stack plus a partition wall that separates your house from the neighbours. If that's correct then: -

1. It's likely that the ridge pole for your side was cut to fit into a recess in the brick or stone work of the chimney. The same would have been done for what is now your neighbours part of the building.
2. Its safest to assume that the purlins, if any, are continuous and were not treated in the same way as the ridge pole.

Would you take a look please and let me know if you think this latest is a more reliable representation?

At first I thought an alternative would be to strap the posts level with the floorboards on 1st floor rather than top of posts on ground floor (six inches difference) but of course I don’t know and its looking unlikely from the bits we can see that posts are continuous from sole to wall plates and are sole to mid plate (or intermediate plate) and mid/intermediate to wal6l plate only

You can, I think, get away with using one winch strap just above the first floor level as you have already propped the ground floor. This one is absolutely essential as it will become the only means of preventing any further 'hinging' that may cause further damage to the mid plates and their M&T joints and resisting such damage should there be any more rafter spread.

Bluntly I think you are wrong concerning the posts, certainly as far as any that form part of the bents. No framer would make unnecessary work for himself and introduce such a weakness in to the frame. I suspect you are mistaking intermediate posts sited on the mid plate that were used to provide additional support for the top plate

Another engineer (a friend) advised using metal brackets to fix the first floor joists to the mid/intermediate plate as a way of using the floor block to resists roof spread? They are easy to access …???

There is some merit to that idea but in my view this approach risks greater damage to the mid plate timbers and/or the joist and floors/ceilings as a consequence of any further raft spread.

Re “Winch slings must be passed around the posts just below the first floor and and connected via a winch indoors. a second pair of slings and a winch can later mounted near the head of the posts and their connections to the rafters.” I guess part of the thinking here is that strapping only 1 end of a post/beam means it more likely to snap while strapping it in the the middle and near the end mean its less likely to snap … load bearing is spread out some… ?

That's right, the key function of the straps at the head of the posts is to protect them from damage when the post is brought back to vertical.

If I may Gerry I'm a little puzzled by your planning priorities. Have you considered the possibility that you could make all the required repairs to your house 'before' embarking on a operate project to build some temporary accomodation/holiday let?

 

[GerryC]

Hey Steve, lots to think about ...

Re “ possibility make all the required repairs to your house 'before' embarking on project to build temporary accomadation/holiday let?
I certainly have , but the core issue is where to live while the work is being done. It’s a one up one down room cottage with a lean-to on the back for kitchen and bathroom. So with straps across the bedroom and dust from needle holes et al, we would be rather uncomfortable. Renting in the Cambridge area isn’t just very expensive, here is a long queue and short lets rare. Other considerations include we want to replaster most of the walls, having to go quickly on all the work to get the living accommodation back would mean having to use/wait for very-difficult-to-get contractors while if I do it myself, and have other accommodation, it will be much cheaper and sustainable when inevitably something else needs doing (floors) in future … we need guest accommodation anyway as grandchildren on the horizon. And there are other complications which make it very desirable to stabalise the cottage, build the studio and then enjoy the restoration of the cottage doing as much of it as is safe for me to do …. with the help of experienced people like yourself to help me make good decisions re that last point as well as tech

​

Re “You can, I think, get away with using one winch strap just above the first floor level as you have already propped the ground floor.” Thanks that will save a lot of difficult work on the kitchen.

Re I've modified my diagram, ….It's likely that the ridge pole for your side was cut to fit into a recess in the brick or stone work of the chimney. Just to add that it is a corbelled chimney stack … I don’t know yet if that means the chimney carries any beams or not …

Re propping dormer: the rafters on which the dormer sits are easy to access of course. to prop them I propose to use 2”x8” posts like the props for the 1st floor. I’m wondering how to connect the prop with the rafter. I haven’t exposed the rafter yet but I guess they will be 3” wide max ? So it’s a slim touch. Should I put a birdsmouth notch in the rafter that the prop can sit in and position the prop so its 8” width is at right angles to the 2” / 3” width of the rafter? Or maybe gets some metal straps to screw them together on each side? Any thoughts?



Strong enough for straps?. I hope to finish exposing the wall plate on the back wall this week to see if it will take straps. Like the front wall plate its only a 4”x”4 piece. I would be able to tell if it was rotten completely but otherwise I can only do the screwdriver test to make sure its hard apart from a little give on the surface … is there any trick to know surer?

 

[Cubist]

Hi Gerry,
I appreciate the quandary, we were considering a similar strategy for one of the properties we were looking at before finding this place. That said, uppermost in my mind was the knowledge that yours is a G2 listed building and, having a too intimate a knowledge of the difficulties, time lost and expense involved in merely getting approval, never mind executing, a fairly straight forward project within the curtilage of such a home, I felt that the repairs to the house could be completed much faster and with less fuss.

Frankly I'm convinced that with all the preparations you are making now, that the repairs to straighten and strengthen the frame could be completed in as little as a weekend.

Corbling of the chimneys brick-work is the most common approach and provides the ledges and shelves that often carry or support roof timbers. There must be a section of ridge pole from the peak of the neighbouring bent to the mid-line of the chimney. The ridge cannot be floating in space unless the pole itself has been damaged or dislodged.

Re propping dormer: the rafters on which the dormer sits are easy to access of course. to prop them I propose to use 2”x8” posts like the props for the 1st floor. I’m wondering how to connect the prop with the rafter. I haven’t exposed the rafter yet but I guess they will be 3” wide max ? So it’s a slim touch. Should I put a birdsmouth notch in the rafter that the prop can sit in and position the prop so its 8” width is at right angles to the 2” / 3” width of the rafter? Or maybe gets some metal straps to screw them together on each side? Any thoughts?

Do not under any circumstances cut into the rafter timber! It is already under stress and any saw cuts for an additional birds mouth may weaken it to the point of total failure.

I'm assuming that your objective for propping the dormer is to combat the possibility of further 'rafter spread'? If that's correct then I would advise against the proposed approach and suggest two alternatives. Both of these depend on your exposing the collar tie for access and inspection - I would urge you to do this soon - and the nature of the collar ties connections to the rafters. Assuming the collar tie is in good condition and if it is fixed to the rafters by means of M&T joints, then two needle jacks positioned beneath the juncture of the collar tie and each of the rafters will do the job. Again if the collar ties is in good condition but is fixed by pegs/nails/screws to the visible face of the rafters then a winch strap positioned behind each rafter and below the collar tie could alternatively be used to resist further spread.

Strong enough for straps?. I hope to finish exposing the wall plate on the back wall this week to see if it will take straps. Like the front wall plate its only a 4”x”4 piece. I would be able to tell if it was rotten completely but otherwise I can only do the screwdriver test to make sure its hard apart from a little give on the surface … is there any trick to know surer?

Why are you considering using straps on the wall plate? I have already said this is a high risk and potentially damaging approach. With the exception of the rafters near the apex and collar tie all other straps should be routed around the posts only.

I'm a little concerned about the dimensions of the wall plate, at 4X4 these seem too small, what are the dimensions of the main posts?

Theres an old carpenters trick, rather like that used by the famous railway 'wheel-tappers'. The sound made when hitting a timber with a hammer can, to a practiced ear, indicate if the timber is sound - but it takes a lot of practice. That said you may be able to get a 'feel' by striking a heavier blow and seeing what damage is done to the surface - but do rest the urge to try for a batsman's boundary shot.

 

[GerryC]

Hi Gerry,
I appreciate the quandary, we were considering a similar strategy for one of the properties we were looking at before finding this place. That said, uppermost in my mind was the knowledge that yours is a G2 listed building and, having a too intimate a knowledge of the difficulties, time lost and expense involved in merely getting approval, never mind executing, a fairly straight forward project within the curtilage of such a home, I felt that the repairs to the house could be completed much faster and with less fuss.

Frankly I'm convinced that with all the preparations you are making now, that the repairs to straighten and strengthen the frame could be completed in as little as a weekend.

Corbling of the chimneys brick-work is the most common approach and provides the ledges and shelves that often carry or support roof timbers. There must be a section of ridge pole from the peak of the neighbouring bent to the mid-line of the chimney. The ridge cannot be floating in space unless the pole itself has been damaged or dislodged.

Re propping dormer: the rafters on which the dormer sits are easy to access of course. to prop them I propose to use 2”x8” posts like the props for the 1st floor. I’m wondering how to connect the prop with the rafter. I haven’t exposed the rafter yet but I guess they will be 3” wide max ? So it’s a slim touch. Should I put a birdsmouth notch in the rafter that the prop can sit in and position the prop so its 8” width is at right angles to the 2” / 3” width of the rafter? Or maybe gets some metal straps to screw them together on each side? Any thoughts?

Do not under any circumstances cut into the rafter timber! It is already under stress and any saw cuts for an additional birds mouth may weaken it to the point of total failure.

I'm assuming that your objective for propping the dormer is to combat the possibility of further 'rafter spread'? If that's correct then I would advise against the proposed approach and suggest two alternatives. Both of these depend on your exposing the collar tie for access and inspection - I would urge you to do this soon - and the nature of the collar ties connections to the rafters. Assuming the collar tie is in good condition and if it is fixed to the rafters by means of M&T joints, then two needle jacks positioned beneath the juncture of the collar tie and each of the rafters will do the job. Again if the collar ties is in good condition but is fixed by pegs/nails/screws to the visible face of the rafters then a winch strap positioned behind each rafter and below the collar tie could alternatively be used to resist further spread.

Strong enough for straps?. I hope to finish exposing the wall plate on the back wall this week to see if it will take straps. Like the front wall plate its only a 4”x”4 piece. I would be able to tell if it was rotten completely but otherwise I can only do the screwdriver test to make sure its hard apart from a little give on the surface … is there any trick to know surer?

Why are you considering using straps on the wall plate? I have already said this is a high risk and potentially damaging approach. With the exception of the rafters near the apex and collar tie all other straps should be routed around the posts only.

I'm a little concerned about the dimensions of the wall plate, at 4X4 these seem too small, what are the dimensions of the main posts?

Theres an old carpenters trick, rather like that used by the famous railway 'wheel-tappers'. The sound made when hitting a timber with a hammer can, to a practiced ear, indicate if the timber is sound - but it takes a lot of practice. That said you may be able to get a 'feel' by striking a heavier blow and seeing what damage is done to the surface - but do rest the urge to try for a batsman's boundary shot.

Thanks for the time and patience Steve, i am going to try and write up finalised prop and strap plan once we've got through these questions.

Re “all done one weekend”. Ah that would be nice! This is one of the hardest thing when one is new to type of work / not in routine doing it frequently. Not estimating but having to think carefully before every step rather than knowing from habit and just executing. I can imagine the work to access and winch rafter, access and push up floating stud might take 2 or 3 guys one weekend … but are you factoring in the work on the rest of the wall. The photos are not that easy to interpret because is all white surface … but between the failed/floating stud and the front door the wall recedes into the building in a line 30% away from the front edge of the plinth – if you looks at the tow photos below you may be able to make out that at the far left of the cottage the studs meet the plinth only a little back from the front of the plinth while near the door they are much further back on the plinth? So apart from the stud that is floating / slipped / jammed we would want to get those other studs into the correct alignment and that will involve removing all the infills which are wattle and daub and will have to be reused. To do the whole wall so sole plate and studs can be moved into correct alignment. I find it hard to estimate but lets say 5 days to remove and then to reconstitute / prep daub, re-fit infill lathes/withies etc … 10 days? 25% contingency 20 days. And a lot of dust about. What do you think?



Re “why …strapping wall plate”. Sorry yes I’m with you, just a wording error … I’m working along the wall plate to find the studs and had been thinking to strap wall plate before you suggested posts … so just habitual. But on this subject again, am I right in thinking you would not strap the top of several posts as well as at first floor level?

Re “dimensions of the wall plate, at 4X4 these seem too small, what are the dimensions of the main posts?” Sorry the wall plate is 5x5 not 4x4. The post I can see (only 1 at the moment is only 3” across and if my finger work is correct 3” deep! This part of the world is known for flimsy builds like that isn’t it.

Re “Do not under any circumstances cut into the rafter timber! …. propping Dormer to prevent more roof spread.” Thanks! I was thinking it will need supporting for when I remove the decayed piece of wall plate immediately underneath it (and on which the rafters on which its built rest too. In fact its perhaps not odd that the wall plate has a discernible crack in it just in the position where the rafter is and the decay is on the window side and the other side looks OK ). It looks like the dormer rests on that bit of wall plate but if its just the windowsill resting on it then the weight of the dormer is on the rafters and they rest of piece of plate that has to be replaced. The tiles are relatively heavy. ….

I guess I will have to support any rafters that rest on the piece of wall plate to be removed … and will have to carefully remove any fixtures holding them to the wall plate if not just birdsmouth in rafter. ?

Re Winch dislodged rafter. I guess you would use the ridge as support .. pass rope over ridge attach to rafter end and winch/guide it back into position?

ATB, Gerry

 

[Cubist]

Gerry, you're going to have to forgive me but I think you are getting too far ahead of yourself trying to devise the plan of action without having all the facts to hand. At the present, and based on the information you have supplied thus far, the root causes and nature and extent of the damage to the buildings frame is in large nothing better than speculation. That speculation may be well informed and, in time, prove accurate but you must first secure a clear and thorough understanding of the true nature of the problems before attempting to devise detailed plans of how to fix them.

With the above in mind;

• Have you made any progress with my earlier recommendation to open holes in the ceiling so that you can examine the rafter apex?
• Have you exposed the suspected collar tie so that it too can be examined for damage?
• Have you exposed and identified the post it is believed has been pushed out of vertical by the roof spread?

If the answers to any of these questions is 'No' then the outstanding tasks must go to the top of your ToDo list. Photographs of the rafter apex, the collar tie and its joints to the rafters, and the head of the post will be extremely helpful in determining the final plan of action.

Regarding the questions in your latest post: -

But on this subject again, am I right in thinking you would not strap the top of several posts as well as at first floor level?

Not sure what you mean here. For the purpose of stabilising the frame, one strap only is needed and this must be connected to the front and rear posts of the bent that has slipped. More straps may be needed when it its time to straighten the repair the frame.

Sorry the wall plate is 5x5 not 4x4. The post I can see (only 1 at the moment is only 3” across and if my finger work is correct 3” deep! This part of the world is known for flimsy builds like that isn’t it.

5x5 is a little small for the job but I would expect any posts used with plates are beams of that size to be at least 6x6 and probably 8x8. I think the 3x3 timbers you've found are studs that merely connect the mid and top plates; they would be far too flimsy to carry the building.

Re “Do not under any circumstances cut into the rafter timber! …. propping Dormer to prevent more roof spread.” Thanks! I was thinking it will need supporting for when I remove the decayed piece of wall plate immediately underneath it (and on which the rafters on which its built rest too. In fact its perhaps not odd that the wall plate has a discernible crack in it just in the position where the rafter is and the decay is on the window side and the other side looks OK ). It looks like the dormer rests on that bit of wall plate but if its just the windowsill resting on it then the weight of the dormer is on the rafters and they rest of piece of plate that has to be replaced. The tiles are relatively heavy. ….

Do not attempt any surgery on that timber until after the frame is straightened and secured! I believe it is tenoned into posts in both your and your neighbours homes and as such those tenons are currently subject to torsional stresses/pressures due to the hinging of the post. If you cut it before the frame is straightened you may not be able to splice a new section of timber into place. The crack you are seeing could be a symptom of this.

What tiles?

I guess I will have to support any rafters that rest on the piece of wall plate to be removed … and will have to carefully remove any fixtures holding them to the wall plate if not just birdsmouth in rafter. ?

Yes. And as per my earlier suggestion before learning the house had more serious issues.

Re Winch dislodged rafter. I guess you would use the ridge as support .. pass rope over ridge attach to rafter end and winch/guide it back into position?

No need for a decision yet, lets see what you find when you open up the area around the collar tie and apex.

And another job for your ToDo list. One of the last tasks before the frame can be straightened will be the removal of the fillet of concrete(?) I can see on top of the plinth. If that is not removed the sill plate, post and walls cannot move back into their correct positions.

 

[Cubist]

I forgot to mention; the post that has been pushed off vertical in your frame is right next to your front door, its on the left when looked at from outside, so about 3-4 feet from the inside of the dormer window upstairs.

That measure will also inform where you cut the access holes in the bedroom ceiling to view the principal rafter, collar tie and the head of the post in question.

 

[GerryC]

Hey Steve hope you had a good holiday weekend. Bank holidays always take me by surprise which I find rather adds to the feats and rest.

Re “Hold on …speculation “ !!! I’m right with you … not proposing to document full action/repair plan because as you say some investigation still to do and hance repair plan as such not possible ... only proposing to get the strapping and propping plan ironed out now so I can get on and defend the building temporarily while I get on with the temporary accommodation. So no, I have not cut the wholes in the ceiling yet to look at the ridge/rafter joints and collar but certainly intend too. We currently sleep in that room and the roof void has not been open for centuries so the black dust is going to be significant/we won’t be able to sleep in there. So even 6if the cause of the roofspread is rafter/ridge joint issue or failed stud/brace/sole plate putting straps and props in to resist the push down and out would be first step weather we do the work asap or wait till I build the temp accommodation no? And there are bound to be details in the strap and prop plan I’ll do well to get yr’ view on (like the placement of the straps we’ve already elaborated for example) No?

Re ”For the purpose of stabilising the frame, one strap only is needed and this must be connected to the front and rear posts of the bent that has slipped. More straps may be needed when it its time to straighten the repair the frame.” Really want to make sure I get this. A) so you don’t think a couple of additional straps from other posts would help ensure stability? B) Wont putting a strap on the failed post/stud mean the stap is ineffective? If placed level with 1st floorboards the post will be pulled against the floor so I guess that means it wont move … but originally you said to place this at ceiling level on ground floor .. wouldn’t that mean the post would be pulled inside as it has no footing. Not suggesting you’ve got it wrong, rather something I’m not getting in my head?

Re slates The dormer has a clay pantile roof around which the thatch is closely cut. The weight of the dormer is mainly the slates and the collar tie is not a rafter tie, its in the top 3rd of the rafter so I wonder if leaving the front edge of the dormer (which looks like its resting on the wall plate) without more direct support could risk it folding in?

Re “the post that has been pushed off vertical in your frame is right next to your front door”. This made me realise that the explanation of the bowing I gave previously was misleading. The centre of the inward lean is at the immediate right of the main window (looking at house fm outside). The deflection from the centre to the rear of the plinth starts from the immediate left of the main window (looking at house fm outside) and is deepest immediately right of the window (and this is where the inside of the wall in broken in at the base) and then travels back onto line at the left door post. Where the deflection is deepest is also where the wall immediately on top of the plinth is broken on the inside). So this position did worry me as two first floor joists are very close to the main line of failure and the thought of putting me and ladder on those joists which are resting on wall very close to the failed stud … but since ive propped under every joist on the ground floor I should be OK to put some weight on. At the start of all this my pwn guess was that the failure might be caused by the heaviness of the downstair window casement which seems like a heavy beast which the wall has to carry in addition to the radiators (and which I will have to handle carefully when removing to renovate as a likely leg or arm breaker!)





Re “fillet of concrete” – cheers will do

 

[Cubist]

Hi Gerry,
Thanks, given the constant reminders from family I seldom get the chance to be surprised by the holidays - my greatest risk is that I'll be cajoled (read blackmailed) into being sociable. Bah humbug.

Seems I've fallen foul of my Euro heritage by making dangerous assumptions based on a lifetime of conditioning to read, and also therefore to measure, from left to right. Flipping my thinking, I can see that the zero line for the house was at the extreme right of the construction, not the left. As a consequence, and based on the rule of thumb measure of 12 feet for the width of each bay in a timber frame build, I suspect that Bay 2 in the diagram I provided earlier is bounded by the post immediately to the right of your living room window and to the immediate left of your neighbours window. Measuring that gap between those reference points may help to confirm that supposition.

That said, there is another assumption here that the house is a traditional timber frame design. Its unlikely, I think, but there is a possibility that it could be what our American cousins refer to a 'Stick Built Frame' that uses smaller section timbers to construct each of the walls and fixing these together to form the rooms and exterior walls of the building. For the purpose of this discussion however it's important that you properly identify the principal timbers that have a bearing on the structural integrity of the building. However, for the purposes of clarity and in the hope of avoiding future confusion, the 'posts' in each bent are identified as single continuous vertical timbers that sit immediately on the sill and directly under, in the case of your house, the foot of the principal rafters.

We currently sleep in that room and the roof void has not been open for centuries so the black dust is going to be significant/we won’t be able to sleep in there.
I appreciate that opening holes in the ceiling would be messy and certainly leaving them open for any appreciable time would be far from ideal. However, these need not be very large and could be covered after the inspection with some suitably sized pieces of plasterboard fixed in place say with some instant grab adhesive like NoNails.

So even 6if the cause of the roofspread is rafter/ridge joint issue or failed stud/brace/sole plate putting straps and props in to resist the push down and out would be first step weather we do the work asap or wait till I build the temp accommodation no? And there are bound to be details in the strap and prop plan I’ll do well to get yr’ view on (like the placement of the straps we’ve already elaborated for example) No?
My original thinking for the strapping was based on how to best defend the house 'while' the frame was returned to vertical and all the repairs made. The strap below the ceiling level on the ground floor was intended to resist the possibility of the posts pulling away from its joints to the floor above when the foot of the post was pulled away from the house to return it to vertical. The second strap, originally at the head of the posts where they meet the rafters, was to assist and stabilise its potential movement as the post returned to vertical and therefore asset the 'liftoff the rafters back to their original position. Your kitchen cabinets obviate the use of the first and your desire to continue using the bedroom makes the second a potentially dangerous trip hazard; so that too becomes redundant.

Frankly, given what I presently know of the internal design of the frame and the layout of the bedroom I cannot see a way in which to add extra support for the roof that would not, in effect, prevent any further use of the room for its intended purpose.

Re ”For the purpose of stabilising the frame, one strap only is needed and this must be connected to the front and rear posts of the bent that has slipped. More straps may be needed when it its time to straighten the repair the frame.” Really want to make sure I get this. A) so you don’t think a couple of additional straps from other posts would help ensure stability? No. Unless its a 'Stick Built Frame' as mentioned above.
B) Wont putting a strap on the failed post/stud mean the stap is ineffective? The intent was to 'stabilise the frame not move it. If placed level with 1st floorboards the post will be pulled against the floor so I guess that means it wont move … but originally you said to place this at ceiling level on ground floor .. wouldn’t that mean the post would be pulled inside as it has no footing.No. The intent for that strap was to prevent the post from pulling away from its joints to the floor above while the post was brought back to vertical - the tension on that strap would be slowly released as the post shifted back to vertical. Not suggesting you’ve got it wrong, rather something I’m not getting in my head?

Bluntly put, I think you are between a rock and hard place and the decision is to either put the house to rights now or to delay it until you've built some temporary accommodation. How advanced is your planning and approvals for the the latter?