Failed beam

[keatsie]

Morning,

We have a failed beam in our hall, it looks like the beam failed sometime back and a crack has been pinned with a large iron nail. The floor above has been raised and is no longer placing any direct weight on the beam although obviously some stress still remains.

The question is, has anyone had any experience of having beams strengthened or braced rathet than replaced. What was involved and how difficult the job was to complete etc. Just gather information before working out what to do next.

Pictures below if they work..

 

[malcolm]

It's the knot to the right of the crack that has caused the failure. The grain will be running radially out from the beam near the knot rather than along the beam and won't be able to take any tension.

The beam will be in compression (pushing together) at the top and tension (pulling apart) at the bottom. Even a broken bit of wood will be fine in compression but It will need something adding to the bottom to take the tension.

If it were me I would screw flat steel bar to the bottom. 100mm * 6mm should be plenty. The bar would need to extend more than 0.5m either side of the crack and be secured with plenty of screws. You can paint it black and make a nice shape at the ends to make it look nice.

Here is a bit of steel with pretty ends for inspiration. It isn't taking much load so just secured by a few stainless screws.

 

[Lime]

I don't think you can repair that fracture, strengthening the beam will be unsightly and probably ineffective.
With a beam that size any sort of metal repair will have to be very substantial and extend over most of the span.

In the old days they'd put a post/column and lintel underneath it to give support in the room space and walk round it.

 

[mims&pip]

The previous owner of our last house applied some serious belt & braces strapping to various beams throughout the Georgian building. I always found them rather unsightly, but they certainly did the job. Will try to dig out some pics when I've a spare moment or three :wink:

Mims x

 

[Lime]

I think there is a big difference between strengthening/stiffening a weak, flexing beam and repairing a broken one.
It isn't impossible to repair the broken beam but it requires substantial steel sections on either side of the beam (rather like fishplates) with large bolts going through the beam in at least four places.

 

[malcolm]

I disagree. The strength of a beam is related to the cube of it's height. Currently the beam is supporting whatever loading it might have with a quarter of it's thickness, so a brace taking tension along the bottom edge should increase the strength by 64 times which ought to be a big enough safety factor given it hasn't fallen down yet.

I've used plates on the sides to extend beams where the ends have rotten and the walls have moved a bit and I need to carry the tension at the bottom and the compression at the top a bit further than the beam manages, but it is something on the bottom that is needed here. Might be worth propping up the beam a little with an acro prop while doing the repair so you get the tension when it settles after removing the prop.

I certainly wouldn't replace the beam. It would make a mess and it doesn't look like there are any beetles in there so it would be a shame. Just a repair to fix the poor selection of wood by whatever numpty fitted it how many hundreds of years ago.

 

[Penners]

The floor above has been raised and is no longer placing any direct weight on the beam

Are you certain that the raised floor above has been constructed and supported in such a way that it is fully independent of this cracked joist and doesn't place any load on it?

If you are, then you might be able to get away with doing what Malcolm suggests, as the joist will probably only be supporting its own weight (plus a fairly insignificant loading from the ceiling structure near it). But if there is any remaining significant load on the beam, then I agree with Lime - trying to strengthen the beam with steel strapping is unlikely to be very effective. You should also satisfy yourself that the joist is not performing any tie-in function between the first floor wall plates, which might place it in tension.

There is a "splicing" system that involves inserting a steel bridge into the beam, secured by resin, but it's not anything of which I have any experience. It is regarded as somewhat controversial, because it hasn't been around long enough to ascertain the life of the bond between the epoxy resin and the timber. I believe it's also pretty costly.

The very best solution, so far as I can tell from your photos, would be to replace the joist. If it's not performing any significant load-carrying function, it should be too difficult* to support the common joists that rest on it, then cut it away. You could use it as a pattern to make a new joist which could then be inserted in its place.

This would, of course, involve a fair bit of cost and mess. After the operation you would have to reconstruct the adjacent ceiling infills and repair any hole(s) in the external rendering that were made in order to allow the new joist's insertion.

* This suggestion presupposes that the cracked joist rests on the first floor wall plates and is not housed into them.

 

[chuckey]

I think the first thing to do is to see if the joist can be jacked back into place. A couple of 4" X 2" props with wedges hammered in would do. If the joist can be straightened up , I would use a piece of 4" wide by 3/8" thick black iron and long enough to overlap "good" wood by at least 12" as a strap under the joist. Chamfer the lower corners/edges and drill for 10 or 12mm metric tapping size in four places. Hold it into position and then drill through the holes into the wood by 3" or more. Run a tap through metal into the wood. Screw in studding with a bit of epoxy resin to lock threads into wood. Cut of studs flush, run over the surface with a angle grinder. Mask of surrounding wood and paint with primer and three coats of gloss black.
Frank

 

[88v8]

Mmm, you might look for a camera with a flashgun, I believe they are widely available.

That 'nail' looks like a big coach screw.

I'm rather with Malcolm on this one. If it were in the middle of a king-post roof, or transmitting load from a floor post above which was carrying the roof, that would be a different matter. Perhaps.
As he says, strength of a beam = square of the depth x the width. Having restored the bottom chord, you'll have effectively restored the depth.

So, get a plate made, quarter inch x the full width [less an inch for aesthetics] x errrm, 2ft long. It's a tension plate, so quarter inch should be ample, don't forget it has to bend to conform to the shape of the beam.
A blacksmith job.
If you have any fancy ironwork in the house - hinges? - they might give inspiration as to end curlicues. Get the ends beaten out into a taper so it looks old.
Attach it with coach screws with square heads, not hex heads. Washers. Long screws in the centre, what is that beam, 6" deep? if so, then 5" screws x 3/8" at the centre, graduating to 3" x 5/16" at the ends.
Screw it underneath.

I really wouldn't bother jacking it up.

If you're able to do a job like this I need not suggest where the holes should be nor caution you to avoid drilling too near the edge of the beam, nor need I remark that the screws should avoid knots and existing splits.

Worst case, you have to do something more extensive later. But I doubt it. If it's still up there with that rather minimal existing reinforcement, it will see you out.

Ivor

 

[Flyfisher]

I'd be careful about jacking up the beam. It and all it supports will have settled into position over many years and if moved significantly will likely disturb a lot of other things. Otherwise I'm in broad agreement with the suggestions about fitting a tension plate to the underside, though I wouldn't bother to make the repair look old and see nothing wrong with using hex-headed stainless coach bolts for an 'honest repair'. Personal choice I suppose.

We had a similar beam, though not quite as bad, in an old cloakroom, and our surveyor's advice was to repair with a tension plate. However, I eventually used Lime's suggested approach and propped up the beam as part of building a dividing wall to create a small cloakroom and the failing beam was conveniently placed for the dividing wall - two birds with one stone as it were.

I tried to jack up the beam with an acro-prop before inserting the supporting post but after applying considerable force to no visible effect I gave up for fear of causing more damage upstairs. So the ceiling/floor remains wonky but I'm now very confident about its stability.

 

[chuckey]

I was thinking about jacking the beam up only to the extent of tidying up the underneath so the plate fits tightly.
Frank

 

[mims&pip]

Hi Keatsie,

I've just trawled through in excess of 14,000 photos on my mac but unfortunately don't appear to have many 'good' ones showing the tension straps the previous owner of our last house fitted In particular one of the two attic bedrooms had a very impressive array, not least where a beam had totally disintegrated at one end. In another bedroom on the middle floor one beam had a huge (4" diam?) hole slap bang in the centre :shock: I guess we chose not to photograph these as they were less than pretty!

Anyway, it won't be of much use in your situation, but I promised to add some pics so here are those I could find - these were in the snug (first pic - smaller sheath-like straps) and master bedroom (second & third pics - longer, more significant straps). Had we been carrying out this job we'd have certainly opted for something more decorative along the lines of that posted by Malcolm - especially as we have somewhat Arts & Crafts tastes!


Please excuse the appalling condition of our then home - this was just a few weeks after moving in/taking on the project :roll:

Mims x

 

[Penners]

Please excuse the appalling condition of our then home - this was just a few weeks after moving in/taking on the project

I'm sorry but I cannot bring myself to excuse the fact that, shortly after you moved in, your home was tidier than ours has ever been.

 

[Flyfisher]

:lol: :lol: :lol:

I was thinking much the same thing about our house!

 

[Flyfisher]

I was thinking about jacking the beam up only to the extent of tidying up the underneath so the plate fits tightly.
Frank

Fair point. If the beam moves with relatively little force then it might be a good idea, especially in terms of getting the steel brace into tension immediately. I was surprised that our beam wouldn't budge despite what I considered as more than enough pressure. I suppose the details of each case are unique.

 

[mims&pip]

Please excuse the appalling condition of our then home - this was just a few weeks after moving in/taking on the project

I'm sorry but I cannot bring myself to excuse the fact that, shortly after you moved in, your home was tidier than ours has ever been.

Lol, Penners :lol: :lol: :lol:

Well, I have to confess I am rather obsessive compulsive when it comes to tidying.........just not cleaning :lol: I'm also a firm believer in unpacking and getting on with your life - even if the house is falling down around you - which if you're going to be living on site whilst DIYing the project at least makes the place feel more homely for the [insert however many years it takes, but in that case three] duration :wink:

That said, a) Did you not spot the glaring area of stripped plaster adjacent to the bed in the second pic? Alongside that horrific eyesore was a radiator literally falling off the wall as well as a couple of seriously nasty cracks in the external wall - we lived with it like this for most of the three years we were there, only resolving the issue a few weeks before we sold :roll: It was also the only room out of fifteen that was never fully decorated during our tenure - at this house I jolly well made sure our bedroom was among the first to be tackled! b) You obviously haven't seen the before pics of our kitchen extension at that house?!?

 

[Penners]

Did you not spot the glaring area of stripped plaster adjacent to the bed in the second pic? Alongside that horrific eyesore was a radiator literally falling off the wall as well as a couple of seriously nasty cracks in the external wall

Seems like normal life to me!

 

[keatsie]

As always, thanks to everyone for the feedback and advice it really is appreciated.

We are going to get the local blacksmith to shape an iron strap and coach screw this to the beam, with regard lifting with an acroprop we are going to just take the strain out of the beam while we place the iron strap into place, and see how this goes.

Cheers J

 

[stephenh]

Hidden inserted metal flitch beam for timber repair

I have done the following when I was active in the building trades :

You need the advice of a Structural Engineer who has previous experience of this technique.
You need a builder who is likewise experienced.

1.Jack up the beam to desired and advised level.
2.The bottom of the beam is in extension and this is where the stengthening is necessary.
From this the S/E will state that, say, a 900mm x 75mm x 6mm steel plate is needed.
3. An 8mm wide by 105 deep slot is centrally cut into the timber from underneath, predrilling and using a chain saw. Much accuracy is needed.
4. Horizontal bolt holes are drilled through the beam and slot and then equivalent holes in the steel plate. By countersinking these holes and the use of a box spanner both bolt ends can be recessed and then plugged.
5. The slot is filled with thick epoxy resin (very messy !), the plate smeared with resin, inserted and located. At this point a 10mm x 8mm cover strip is put under the whole lot and the resin left to cure. Then ( and not before) the bolts are tightened and plugged.


Good luck !

 

[mims&pip]

Did you not spot the glaring area of stripped plaster adjacent to the bed in the second pic? Alongside that horrific eyesore was a radiator literally falling off the wall as well as a couple of seriously nasty cracks in the external wall

Seems like normal life to me!

Oh yes, most definitely normal life for us! As I sit here surrounded by piles of rubble & various associated tools, I can't remember a time when we weren't living on a building site :lol: Actually I can, it was in 2007.......for about six months :roll: