How do I replace a rotten timber lintel?

[michael]

Any ideas on how to remove and replace a rotten timber lintel without the brickwork above falling down?

The lintel in question is above an outside door at one end of a 9”thick gable wall.
There is an arched brickwork lintel above the door on the outside face of the wall but just a straight piece of 4X4 timber on the inside face which is rotten to the core. I’ve pulled away some of the rotten timber only to find that the brickwork above (at least one or two courses) is loose allowing pieces of mortar to fall away.
Due to the fact that the door is located at one end of the gable wall, there is not a huge amount of brickwork above, probably a maximum of about 10 courses before reaching the pitch of the roof.
I have discovered this problem having just removed a section of water damaged lath plaster ceiling. The ceiling joists all appear to very sound however they run parallel to the gable wall, the first joist being only 3 or 4 inches away from the wall which would make it very difficult to incorporate acro props etc.
Any suggestions on how to rectify this problem without too much disruption would be appreciated

 

[MdB]

An acro prop + attachment maybe want you want.

These were used above to hold the brickwork in place whilst the RSJ was fitted.

 

[michael]

Thanks Mdb. Yes I had considered using these cantilever plate type attachments to the top of the acro props but I wouldn’t be able to accommodate them due to the ceiling joists running parallel to the wall and obscuring the first course of brickwork above the door frame. The first ceiling joist is no more than 4 inches out from the wall so it would cause an obstruction to the plates. I suppose I could place the acro props up between the first and second ceiling joists and then fix the cantilever plates into the wall above the joists but this would probably mean loosing 3 or 4 courses of un supported brickwork below. What’s the maximum distance the acro prop can be positioned out from the wall when using these plates?

 

[skier-hughes]

Can you remove the first ceiling joist relatively easily?

 

[chuckey]

If the wood is that rotten, then de-facto its not carrying much of a load. There will be a loose triangle of bricks above it as you have discovered. If too much of the loose stuff is removed you might have an embarassingly large hole. What I would do is to use a car jack and a piece of wood to jack up the centre of the lintel (it will crush and generally disintegrate) until you see the bottom brick course heave upwards (just slightly) then get hold of a thin bolster chisel and knock it into a vertical joint in the centre of the span. Aim to get it in to top bit of the vertical, if it is narrower then the joint is high. At this stage the bottom course of bricks should be locked in place. Slowly undo the jack and fingers crosssed, the bricks will remain in place, they might drop a bit (say 1/16"?).
Another technique that could be used if the levels are OK is to drill a 1/2" right through the mortar joint over the wooden lintel into the back of the brick arch( 1" into the brick), go for say 3 holes under the centre of three bricks. Bash in 1/2" re-bar and with a 2" X 4" piece of wood and 5" long screws, clamp the re-bars up to your ceiling joist. Put in your lintel, push in mortar in the slightly over 1/2" gap over it to hold the bottom course of bricks, when cured, remove re-bar, or cut off flush.
Its a job I have to do in limestone walls - :roll:
Frank

 

[Flyfisher]

If the wooden lintel really is rotted through then it won't be providing much, or any, support to the wall above. Plus, from your description of the brick arch above the door, it sounds like the lintel was never intended to be load bearing in the first place. It probably just supported the first course of the brick arch when it was first built; thereafter the arch was the load-bearing structure for the remaining (few) courses of the wall.

On that basis, it might well be possible to just remove the rotted lintel complletely together with the in-fill material between the lintel and the arch. Then replace the lintel and the in-fill.

I'm not suggesting this is definitely the method to use, because it's difficult/impossible to be sure based on a written description only, but it might be worth considering before going to the trouble of removing floorboards, joists etc.

A picture might help.

Edit: Frank hadn't posted when I started writing this post.

 

[michael]

Thanks everybody. I think I would like to have a look at removing the obstructing ceiling joist as Skier suggests. The ceiling in question is not that large as it’s just an entrance lobby and it’s already exposed in part from the lath plaster that I had to take down (dusty messy business that was.)

The ceiling joist is a 4 x 2 timber probably no more than 6ft long. One end of it is built into the corner of a brick pillar by about half a brick, the other end is nailed to a roof rafter and is chamfered off to suit the pitch. I am presuming that this has no structural significance? Removing this ceiling joist would allow me to use acro props with the cantilever attachment plates on top as previously discussed.

Just to try and reclarify, the brickwork arch on the ‘outside’ face of the wall is all very sound. Each brick in the arch is set vertically i.e. 9” high with only the 4” depth of the brick back into the wall so in other words, when you walk through the door from the street you can look up to the underside of the arch. Beyond the arch, (4” into the building) is the fan light above the door replicating the curve of the arch. The fan light is all part of the sturdy door frame. The top of the door frame therefore, which is straight and flat and above the fanlight, together with the rotten internal timber lintel which sits on the top of the door frame and the first course of internal brickwork (all stretchers) are all located behind the external arch.
Header bricks in the internal brickwork only start coming into play from the second course up once the external arch has been cleared.

The situation is that the rotten timber lintel (4 x 4) is only a doors width wide plus the extra sitting in the wall at each end. Half of the lintel is relatively ok and would probably survive with a bit of chemical treatment and wood hardener, the other half is totally rotten. I think the sturdy door frame (on which the lintel sits) is probably helping to keep everything up in place so I’m not sure if Chuckey’s methods can be applied. The brick work above the lintel (above the ceiling) was never meant to be on show and so consequently there is virtually no pointing, just the “muck” that the bricks were laid together with. Lumps of this mortar which splurged out when the bricks were laid 190 years ago can now be pulled out in chunks with the fingers whilst the outside fair face side of the wall including the brick arch is relatively sound.

Just a thought, do you think it might be worth strengthening the internal face of the brick work above the timber lintel before disturbing anything below it perhaps by thoroughly pointing it with say a relatively quick setting 3.5 NHL hydraulic lime. I know it should be hydrated lime but it’s only a small area on the internal face of the wall (10 courses high by a doors width wide) If this was forced between the vertical and horizontal mortar joints it might provide sufficient compression once set, to hold the bricks together whilst the joist is repaired?

All very confusing I know but your help and suggestions are much appreciated

 

[chuckey]

Reading your seconnd post reminded me, brick courses have "headers" every now and then, these are bricks set in at right angles to the length of the wall, they are to hold the inner and outer courses of "stretchers" together. They are look like 1/2 bricks. these would hold up the inner skin bricks if there are any at a suitable posiition. What you say about re-pointing the inside will work. make sure the joints are really cleaned out of dust and soaking wet. For this application I would use OPC and sharp sand, beause it will develop 10 X the strength of lime in 2 days rather then 3 weeks. I doubt that this area of OPC in your house will cause differential settlement and cracks. What sort of new lintel will you be using?
Frank

 

[Gervase]

OPC will also develop 10x the strength of the bricks, which is exactlly what you do not want. The mortar beds should always be weaker than the material they are tying together.

 

[michael]

I’m planning to replace the rotten timber lintel with a new piece of 4 x 4 PT timber. I would prefer to point the brickwork above with lime mortar rather than OPC but I don’t really want to wait months for hydrated lime to carbonate and provide the necessary strength and bonding. Do you think 3.5 NHL hydraulic lime would be an acceptable solution in this case? It dose at least set hard in about 5 hours and would probably provide an acceptable level of strength in about a week to allow me to get on with the job.

 

[michael]

My builder is going to set about replacing this rotten lintel in about three weeks time but prior to that he will firstly cut out the obstructing ceiling joist which will allow me to get up there and point up the brickwork above the lintel to provide extra strength to the structure before the lintel is removed. I would however very much appreciate advice from the lime experts on whether it would be ok in this instance to use 3.5 NHL hydraulic lime? There will only be about a two week period between my pointing work and his removal of the offending lintel and I’m sure you will appreciate that I can’t really wait the months required for a hydrated lime mortar to carbonate sufficiently to provide the necessary strength and bonding.

 

[skier-hughes]

I'd use it.

 

[Nemesis]

Yes so would I!

 

[michael]

Many thanks

 

[charlie-ia]

we have to replace some of our timber lintels. our walls are rubble with earth mortar, and maybe not too good in some places, thou i dont think theres anything dreadfully wrong with the wall.
.would it be a similar procedure? i dont need details at the mo, cos we are still learning and just arnt ready for something so major.

also the wood was very soft when we moved in, and seems to be drying out and becoming firmer. is it likely to reharden to any significant amount? could excessive amounts of wood hardener be a possible solution? or is it not worth risking it on such an important thing?

some of the lintels can be pushed upwards a little, so there clearly isnt any weight on them, i assume these will be straight forward, or is the rubble infill likely to pour out?