I have some 4 inch ceiling joists in an attic which form the existing floor.As I use this room as a bedrom I would like to strengthen but due to crude construction of the wall plate I cannot run deeper joists parallel.I read that you can screw and glue on top of the existing joists in 2 x 2 OR do the same at 90 degrees to form a grid.I lean to the latter as I can fit joist hangers to the gable wall to form extra support.Any views welcome thanks!
Best way to reinforce joists
- Thread starter gnvqsos
- Start date
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Putting the new pieces at right-angles to the existing ceiling joists, although frequently done as a diy job. adds hardly anything to the stiffness of the floor.
If you want to improve stiffness, glue and screw them along the tops of the existing ceiling joists. You don't have to take the additional pieces right up to the wall plate - they can be stopped short a foot or so, Use 4" x 12s screws at 12 inch centres, with plenty of PVA. It won't give the equivalent strength of 6x2, but will be far better than putting the pieces across at right-angles
If you want to improve stiffness, glue and screw them along the tops of the existing ceiling joists. You don't have to take the additional pieces right up to the wall plate - they can be stopped short a foot or so, Use 4" x 12s screws at 12 inch centres, with plenty of PVA. It won't give the equivalent strength of 6x2, but will be far better than putting the pieces across at right-angles
With respect to Tony, all your proposal would be doing is adding a little stiffness and a load of extra weight to an already inadequte for purpose 4x floor. It could give a dangerous sense of stability to a later house owner who might overload a fragile carcassing. Not to mention sagging and cracking the ceiling below.
OP i should go with your right angled, adequately sized joists suspended on hangers just above the in-situ 4x joisting.
4x sections should not even be walked on without using walking boards, never mind extra loading.
I'm sorry if i sound severe, but we are advising inexperienced DIY'ers and we have no hands on knowledge of what exists on site, so to my mind, the conservative, cautious approach is the best.
OP i should go with your right angled, adequately sized joists suspended on hangers just above the in-situ 4x joisting.
4x sections should not even be walked on without using walking boards, never mind extra loading.
I'm sorry if i sound severe, but we are advising inexperienced DIY'ers and we have no hands on knowledge of what exists on site, so to my mind, the conservative, cautious approach is the best.
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I know what he will say, it will involve taking your roof off, lowering your ceilings, and a lot of steel. He will prove, on paper no less, that your house should already have fallen down. He will tell you not to use your attic as a bedroom. And this advice will cost you several hundred quid.
You are better off listening to a few people on here, the hard part is working out which ones....
You are better off listening to a few people on here, the hard part is working out which ones....
With respect, tim00, the OP first considered stengthening his existing 4x joists. Glueing and firmly screwing additional 2" pieces along the top will contribute to strength and stiffness regardless of the marginal increase in weight. Each joist will have considerably increased I and Z values which will reduce bending stress and deflection. When allowing for the countersinking, it wouldn't be the equivalent of 6x, but it wouldn't be far off.
Yes, in an ideal world, he would put new joists above the existing, but he might have headroom problems. If he is using it as a bedroom already, it will almost certainly not have a certificate, and the OP probably doesn't want to go down that route. All he wants to do is improve the situation structurally, and 2x2 fixed as suggested would do that at minimal cost.
He has no obligation, legal or moral, to any future occupier of the property.
Any new occupier would take it as it is and if in doubt, should get a survey done.
I agree with you Tony, except that from what the OP says (thinking about putting 2x2 over the top) it doesn't appear there are any headroom issues, just an issue with bearing new joists onto the wall plate.
4x2s sistered to the existing may be sufficient as the stiffness and capacity will be doubled, but should he require something more robust, then it would appear there is room to sister 6x2s to the existing.
Without spans and spacings we can only guess.
but is it relevant to the question?
Which is:
Should I strengthen the existing structure using timbers parallel or perpendicular to the existing joists?
He's not asking whether the final solution will satisfy some arbitrary structural building code, just which one will give the better solution.
And right now it's 2-1 to parallel. You could cast the crushing vote !
Because I'd be really interested in knowing.
Which is:
Should I strengthen the existing structure using timbers parallel or perpendicular to the existing joists?
He's not asking whether the final solution will satisfy some arbitrary structural building code, just which one will give the better solution.
And right now it's 2-1 to parallel. You could cast the crushing vote !
Because I'd be really interested in knowing.
I have had a chat with a retired JDLaing site foreman and he has confirmed that glueing and screwing to existing joists is a good option especially around the centre of the span,near the moment.I will try this and it should not add much to the weight.
Thanks again for all comments.
Thanks again for all comments.
J
joinerjohn
Do let us know how you get on though gnvqsos. If your house collapses, or stays up. We're always interested in outcomes on here.
brilliant! vindicated at last!!
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