Strengthening ceiling joists

[teddysnips]

I'm in the process of moving into a new house (well, old house, but you kno= w what I mean, I hope!). I've had a structural engineer's visit and he sai= d that if I want to board the attic and use it for storing anything heavier= than bags of feathers I need to upgrade the existing 4x2 ceiling joists. = Initially I thought of taking down the ceilings and replacing with 6x2 jois= ts, but my brother suggested strengthening the existing joists by screwing = (and/or glueing) 2x2 lengths; in effect, laminating. This would be conside= rably quicker, cheaper, and less messy.

Now, I _could_ ask the structural engineer if he thinks this is a satisfact= ory solution, but a) he's forgotten to send his bill, and I'm reluctant to = remind him, and b) he seemed quite blase about the ceilings (he said they w= ouldn't collapse, just that they might bow or deform a bit) so I don't thin= k I'm putting myself at risk by going down this route.

Thoughts, anyone?

Thanks

Edward

[The Natural Philosopher]

what I mean, I hope!). I've had a structural engineer's visit and he said that if I want to board the attic and use it for storing anything heavier than bags of feathers I need to upgrade the existing 4x2 ceiling joists. Initially I thought of taking down the ceilings and replacing with 6x2 joists, but my brother suggested strengthening the existing joists by screwing (and/or glueing)

2x2 lengths; in effect, laminating. This would be considerably quicker, cheaper, and less messy.

solution, but a) he's forgotten to send his bill, and I'm reluctant to remind him, and b) he seemed quite blase about the ceilings (he said they wouldn't collapse, just that they might bow or deform a bit) so I don't think I'm putting myself at risk by going down this route.

As long as the bits cant slide over the other bits a laminated beam should work.

[Tim Watts]

How long are the joist spans? 4x2" is pretty string over shorter spans.

[Dave Liquorice]

Ugh, very messy. One assumes you are living in this house or will be whilst this work happens.

How about putting more 4x2's cross ways to the existing ceiling joists? That would spread the load and give you an 8" gap to fill with insulation... I suspect that each crossing point really ought to be fixed to prevent movement and make a more rigid structure.

[harry]

now what I mean, I hope!). =A0I've had a structural engineer's visit and he= said that if I want to board the attic and use it for storing anything hea= vier than bags of feathers I need to upgrade the existing 4x2 ceiling joist= s. =A0Initially I thought of taking down the ceilings and replacing with 6x=

2 joists, but my brother suggested strengthening the existing joists by scr= ewing (and/or glueing) 2x2 lengths; in effect, laminating. =A0This would be= considerably quicker, cheaper, and less messy.

ctory solution, but a) he's forgotten to send his bill, and I'm reluctant t= o remind him, and b) he seemed quite blase about the ceilings (he said they= wouldn't collapse, just that they might bow or deform a bit) so I don't th= ink I'm putting myself at risk by going down this route.

If your roof has purlins.

You nail/screw a bit of 4x2 across the ceiling joists at 90 deg,immediately beneath the purlins. Then you put vertical ties/ hangers between this bit of wood and the purlins. This supports the ceiling off the purlins. In a proper roof, this should have been done already. If it has,you can put in additional ties/hangers. Most ceilings have additional support off partition walls below.

Your inspector may just be covering his arse. Most are complete tossers anyway. A proper carpenter who works in the building trade can tell you far more

[polygonum]

harry,

Which "inspector"? None mentioned by OP.

An excuse for trotting out your bile on BIs?

[charles]

you will need to make sure your additional piece is supported at the ends by the walls - otherwise it's just an extra load.

[harry]

Subject to above, screwing gluing extra bits on is a good plan. Just make sure you can wangle long enough pieces through the loft trapdoor. And don't forget to incorporate insulation into your plan.

[The Natural Philosopher]

That doesn't net the same stiffening.

[Lobster]

But what are you actually wanting to use the area for? Living accomodation or just storage of stuff; and if so, what stuff (how heavy?) Depends on the unsupported length, but 4x2 is still reasonably meaty: I imagine for converting to living accomodation building control would insist on upgrading them, but for just boarding out and stashing junk, unless it's really heavy stuff I'd have thought you'd probably be OK.

Over my lifetime I've certainly scampered around plenty of roofspaces, with old, much shallower joists than that (often without even crawling boards, let alone full, fixed boarding) and have never come to grief.

The guy's going to be professionally qualified - does it not occur to you that maybe he knows what he's talking about? Imagine putting a 4x2 out in the garden laid out across two supports, like a joist - then you and a mate climb on and start jumping up and down in the middle. Do you seriously reckon you'll snap it? That's a far worse scenario than in your roof space, where the joists will be connected via boards and the load will be much more spread out.

David

[David WE Roberts]

During the course of our refurb we found that our ground floor is on 2*4 at (IIRC) 350mm centres. So in principle no great problem in supporting a loft floor as long as the length of the joist between supports is not excessive and the spacing between joists is likewise not excessive. There are calculators around online to tell you what minimum joists you need for a given length and spacing.

Our loft is on 4*2s at (IIRC) about 400mm spacing. I've floored it in with chipboard which is screwed to the joists so that should give a little more strength. Loads of crap up there and the ceilings haven't come down yet.

AFAICS the main benefit of increasing the joist height is to allow you to get more insulation down between the joists before flooring over. Alternatively you could lay Celotex across the joists then chipboard on top of that and screw through. This gives more structural rigidity and more insulation.

Oh, and I am assuming that to glue the new wood down you would have to make sure that the tops of the old joists are reasonably clean :-)

Cheers

Dave R

[Dave Plowman (News)]

A structural engineer isn't an 'inspector'.

Fine (maybe) if your house is the same as others he's seen. But it's very unlikely he will be able to do the calculations required. Nor will he have the insurance a pro does.

[teddysnips]

Many thanks to all posters. There are a number of solutions that I'll cost= out and discuss with the carpenter. I think the main difficulty would be = getting the lengths of timber into the roof space - I'm currently thinking = that when I put in the recommended air bricks into the gable ends will prov= ide the opportunity to feed in the timber.

[John Williamson]

out and discuss with the carpenter. I think the main difficulty would be getting the lengths of timber into the roof space - I'm currently thinking that when I put in the recommended air bricks into the gable ends will provide the opportunity to feed in the timber.

Just one other thought. If you're upgrading the timber anyway, then it might pay you to upgrade it as if you were going to use the loft for living space. The extra timber cost now will be less than the labour and materials to do it again if ever you or a future occupier decides to convert the loft space, and it may increase the value on resale if the loft is "conversion ready".

[michael adams]

- I'm in the process of moving into a new house (well, old house, but

- you know what I mean, I hope!). I've had a structural engineer's

- visit and he said that if I want to board the attic and use it for

- storing anything heavier than bags of feathers I need to upgrade

- the existing 4x2 ceiling joists. Initially I thought of taking

- down the ceilings and replacing with 6x2 joists, but my brother

- suggested strengthening the existing joists by screwing

-(and/or glueing) 2x2 lengths; in effect, laminating. This would

- be considerably quicker, cheaper, and less messy.

- Now, I _could_ ask the structural engineer if he thinks this is

- a satisfactory solution, but a) he's forgotten to send his bill,

- and I'm reluctant to remind him, and b) he seemed quite blase

- about the ceilings (he said they wouldn't collapse, just that

- they might bow or deform a bit) so I don't think I'm putting

- myself at risk by going down this route.

- Thoughts, anyone?

- Thanks

- Edward

You don't actually say what you intend to store in the attic or how heavy its likely to be. But unless you also intend to widen the loft hatch in the old house, then there's a limit to the size, and presumably the number of really heavy things you'll be able to get up there. So that all you need do is mark out your joists as go along as you board up your loft and once its finished measure out from below and mark up on the loft floor above exactly where your supporting walls are underneath. And then make sure, if you're worried about it that you only put really heavy things directly above where a joist crosses a supporting wall. I've got 4x2's and the heaviest thing I've put up in my loft is a radial arm saw in bits which I winched up on a pulley directly above the hatch. Though the loft was already partly boarded up I didn't bother with the marking at the time but simply measured up below to identify the best spot over a supporting wall.

Then in 50 years time the person you sold your house to will be posting on here (some hopes) asking if anyone can explain all the strange marks on his loft floor

michael adams

...

[meow2222]

On Wednesday, October 24, 2012 8:49:21 AM UTC+1, [e-mail] wrote= :

now what I mean, I hope!). I've had a structural engineer's visit and he s= aid that if I want to board the attic and use it for storing anything heavi= er than bags of feathers I need to upgrade the existing 4x2 ceiling joists.= Initially I thought of taking down the ceilings and replacing with 6x2 jo= ists, but my brother suggested strengthening the existing joists by screwin= g (and/or glueing) 2x2 lengths; in effect, laminating. This would be consi= derably quicker, cheaper, and less messy.

ctory solution, but a) he's forgotten to send his bill, and I'm reluctant t= o remind him, and b) he seemed quite blase about the ceilings (he said they= wouldn't collapse, just that they might bow or deform a bit) so I don't th= ink I'm putting myself at risk by going down this route.

You forgot to tell us the span and spacing of the 4x2s. Those figures chang= e everything.

NT

[PeterC]

what I mean, I hope!). I've had a structural engineer's visit and he said that if I want to board the attic and use it for storing anything heavier than bags of feathers I need to upgrade the existing 4x2 ceiling joists. Initially I thought of taking down the ceilings and replacing with 6x2 joists, but my brother suggested strengthening the existing joists by screwing (and/or glueing)

2x2 lengths; in effect, laminating. This would be considerably quicker, cheaper, and less messy.

satisfactory solution, but a) he's forgotten to send his bill, and I'm reluctant to remind him, and b) he seemed quite blase about the ceilings (he said they wouldn't collapse, just that they might bow or deform a bit) so I don't think I'm putting myself at risk by going down this route.

That's what I was looking for. My loft is boarded on 3x2 and there's no sign of any new damage to the ceiling boards (only the cracks that were there anyway). My spans are about 4m and 3m, with quite big timbers at right-angles and the double-pointy-nail-thingies in each joist, so this might not be a guide.

[harry]

Calculations can be got wrong. Someone experienced in building construction is far more reliable than some twerp who has only read books.

I have never had a prospective house purchase surveyed. Determining domestic house faults is not rocket science as some would have you believe.

[Dave Plowman (News)]

You think a structural engineer only reads books?

BTW, how do you find this mythical experienced carpenter? Take his word for it?

You could start by finding out the difference between a surveyor and a structural engineer.

And this topic is about 'house faults'?

Perhaps, Harry, you should go back to books and learn now to read properly.