Rotten rafter ends

[Anonymous]

Many thanks for your suggestions, and especially for also saying that you don't have direct experience. On reading through this forum I have a suspicion that some other contributors are not quite so candid!?!?

Do you think a Strong Boy is the right tool? I've never used one, but this site (http://www.higear.co.uk/hire/products/buid.htm) says that it is used for inserting into a mortar course so that masonry beneath can be removed. Or am I missing the point of your suggestion?

I think the issue is that in a single pitched roof the downward force of the weight of the roof exerts an outward force on the rafter ends, which the joist between them ties together (i.e. in tension) as well as providing the structure for fixing a ceiling and/or floor to. If you cut through the joist or rafter this strong triangular structure is no longer complete. So the question is how to support it until the repair is complete. As far as I can understand supporting the joist is a matter of using a vertical prop beneath, but what are the accepted methods for stopping the outward force on the rafter? Or does it not matter if you only repair one at a time?

If #51 is reading this, I would be very grateful if you could give me the benefit of your experience. I would like to hear all the ideas and then decide how to proceed. If it is of interest I will let the forum know how it went in the end, including a photo of the hopefully successful repair.

 

[Anonymous]

Well since you asked so nicely ...

I'm only a DIY'er, you know, who knows if I'm competent to answer - but my roof is still sitting atop my house walls !

Right - my ten penneth:

You don't say what's on your roof. If it's stone slabs double lapped (ie laid in 3 thicknesses mostly) then I'd be tread very carefully - nevertheless - if you want to cut the foot off a common rafter one at a time you should be able to prop up the rafter straight off the floor or several joists with a timber spreader. Fix the prop vertically, a metre or more away from the wall, and clamp it securely to the side of the rafter. If you're not entirely happy with this, and you're gonna have to judge it, no-one else here can, then put coach screws right through so the rafter can't slide down the prop. Skew-screw the prop to the floor in case you kick it accidentally. I'm not an engineer but I really would not be concerned about breaking your triangle of bracing for just one rafter. To be honest, with the timber sarking that you seem to have, if the nails are good (don't know, do we?) the rafter probably wouldn't move anyway.

Another way would be to coach screw a short but substantial noggin across the two adjacent rafters as long as they're sound.

Have you got purlins ? The rafter could be supported on the purlin anyway. So many questions, variables !

Even if the rafter does want to move, it will simply pivot downwards a bit from the ridge, until the laths or sarking hold it, it won't slide down to fill the piece you cut out.

Cutting the foot off a valley rafter is a different matter. The jacks (rafters meeting the valley) are all bearing on it. I'd still do it, though, just put some beefier supports in. I don't know how you could do this without dismantling the valley from outside, though, hence the comment about being a plumber (nowadays plumbers just do cosy indoor jobs and leave leadwork to roofers).

As to repairing them, I've mended most of mine with bits of oak bolted right through like a sandwich. I can saw a bit of wood, but wouldn't fancy hacksawing a bit of 10mm steel and then drilling it. If your rafters are 3" x 4", then a bit of oak say 1 1/2" thick x 3" deep fixed over a length of about 3 feet or so would hold the rafter. Twice bolted to each piece of rafter (4 in total per repair).

Maybe I wouldn't do a whole run of rafters like this though, that would possibly require a different approach.

I'm reminded of that story where a client of architect FLLW couldn't live with the massive concrete cantilevers he designed into his new house - and he had a wall built underneath it whilst work was in progress. FLLW had the top course secretly removed, and when the house was fully built, said to his client, 'the concrete hasn't collapsed, may we take the rest of the wall down now?'. Not really relevant, but I like the story anyway.

Do take care, but I think you'll be able to judge for yourself whether you are prepared to give it a go (the roof, not the concrete patio)

I expect to be ostracised for mentioning con......

 

[Anonymous]

If your ceiling joists / loft floor joists are weedy you might have to continue the support through to the floor below

 

[Anonymous]

Hi #51

Absolutely brilliant!!!! Thank you so much for taking the time to post such a comprehensive reply. It has reassured me that I was thinking along the right lines. I now need to sit back and work out exactly where best to put the props. I did also have the thought that I could put a long timber tie from above the repair point in the rafter to the rafter on other side of the roof. This would involve cutting a couple of holes in plasterboard walls (which are easily made good afterwards) but maybe this is overkill.

The rafters and joists are 6" x 2", so for the more easily accessible repair points I was thinking of making the sandwich with about 1m of 6" x 2" on each side and 6X M12 coach bolts and double-sided timber connectors. The awkward one is pretty close to a wall, so I may have to use steel on at least one side, so I’d better buy some new hacksaw blades and drill bits!

Fortunately the valley rafter is sound, so I don't need to repair that.

By the way, did you use stainless steel bolts or is this an unnecessary expense?

Thanks again.

P.S. Do you have a real name? It doesn’t seem right to address you as a number!

 

[Anonymous]

Yeah, I just don't think it's necessary to put temporary collars or ties in if you're just going to fix one at a time.

6" x 2", they're moderately big, but if you add the same again each side and fix it with all those bolts, well, that's my kind of overkill ... the important thing is just to make sure any temporary loads are spread as far and wide as possible, and as I said, braced up so you don't kick it out.

I used 10mm x 100 and 150mm plated coach screws ex Screwfix, and sometimes bolts right through with a nut each side. Smaller ones would invariably shear in half before they were tight. I got some of those star thingies but they won't make a mark on old oak, with softwood they would be helping I'm sure. You'll need some big penny or square washers as well or you'll pull the heads right through the timber.

You can call me hash . . . . or Geoffrey

 

[Anonymous]

Thanks again Geoffrey. I was wrong that this forum is not the right place to get detailed advice. It just seems that you need to find someone who has done the job before and is so generous with his or her time as to explain it in detail to a novice like me. Thanks also to Schoolmarm, Mike and Jake for their advice.

One problem with getting a professional in to do the job (and this probably applies to almost all trades) is that the good ones are so busy you can't even get them to come and give an estimate. This significantly increases the chances of you getting a cowboy. I have enough experience and basic practical skills that I can usually tell a cowboy by asking them some questions about how they propose to do the job. I'm sure many people really don't have enough basic grounding to do this. What chance do they have getting the job done properly?

Is there anything that could be done on this forum to help people pick a good builder, roofer or whatever?

 

[Anonymous]

Let me explained something to you Roland
I have over 30 years experience in constuction
And I am still learning
I don't know one, not one job that i have ever been too, has ever been the same as the other jobs I have done over the years
Yes the basics are there but the type of construction/renovation etc is allways different.
Now doing repairs and renovations is a bit like detective work i.e trying to find the villan.
Mike me or anyone else cannot find out how to do the job unless we visit, assess it and work out a way how to approach, cover eventualities etc.
i.e one job I finished some days back involved new guttering. simple enough job you might think.
But Ooh no! there was nothing to fix the gutter brackets too. I had to figure away around how to do it. It was a nightmare, caused mainly by the previous pr*ick who did the work incorrectly.
My point is we can all say to you, 'do it this way, or that, cut this out, and you'll need one of those, and Ooh dont forget that support. verbaly on a forum in a letter, but there's no better way to give an opinion or show you what to do than to be there "hands On"
You just don't know what is around the corner when
doing repair or renovations.
So I'll say it again get someone in to look at the job,
If you do the job yourself with out help, your asking for trouble, especialy when it comes to structure and load bearing conditions.
Seek "on the job advice"

 

[Anonymous]

If what you say is correct then the answer to every single question on this forum is "get a professional". I can see that option for myself without posting any messages.

Alternatively you can do what #51 did and try to explain the principles and suggest (and I emphasise the word suggest) some possible solutions. It is helpful to be told that there is a risk, but that risk is mine to take.

Do you have any opinions about the problem I mentioned of finding quality professionals in the current market? Or are you just interested in protecting your business?

Before you explode, please be aware that I am being deliberately provocative in my language, but I think the point is valid.

 

[Anonymous]

*If what you say is correct then the answer to every single question on this forum is "get a professional". I can see that option for myself without posting any messages.*

I refer to the last part of my previous post..
"Seek "on the job advice"
Not someone to do the job ..............
But someone to advise you..

*Do you have any opinions about the problem I mentioned of finding quality professionals in the current market?*

You have just got to keep trying and besides you only want an opinion.

*Or are you just interested in protecting your business?*

I suppose my post did sound like I was touting for business. But I was not.....

Look! What I am saying is if you where near enough I would have a look at the work**** "YOU"**** wish to do.
Give you some adivce and pointers, that's all.
i'e support this, remove that, cut that out, you need so many of them, be careful this don't happen.... Yes!

And If I did not know the correct way to do the job, I would tell you and would most likely try to find someone who did know.
If I'm not sure about something I may ask BC
Or the college, or on the web. or the nearest
construction site, or the other builder's etc etc, etc

 

[Anonymous]

I think you must be on a different planet from the rest of us. If I called up a builder (including you) and said "I've got a job that needs doing. I'm going to do it myself, but I want you to come here and tell me how to do it" the answer would be two words (four letters and three!!!).

Your previous suggestion of going down the pub and paying the first person who says they are an expert is the surest way of getting a cowboy that I can think of.

I think you are seriously misleading the people who ask questions on this forum and I think you should stop. I was trying to be polite before because you took the time to reply, but I've given up now. This is also my last post in reply to you, partly because the thread is going to disappear off the edge of my screen <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT="">

 

[Anonymous]

Whatever