Raise loft floor & strengthen joists

24 Jan 2019
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United Kingdom
Currently in the process of a full renovation, and the loft is the next job on the list!

There was very little insulation previously, so I'm taking that out and raising the joists so I can get 270mm in. The joists are only 3x2, so my plan is to raise these by gluing and screwing 4x2 along the length of them which would then give me 170mm and strengthen them so I don't need to worry as much about weight. I'll then put some 4x2 going perpendicular to take me to 270mm, and then board on top.

Problem I have is the binders (A) and hangers (B) are in the way so I can't go all the way across. Would I be alright starting at the far wall, and then trimming the binders back one joist at a time as I glue and screw the 4x2 on top? The binders aren't supported on a wall at either end, just nailed to each joist and hanger.

I'd also like to move the loft hatch as it is currently awkwardly placed in the bathroom. Am I ok to put a 4x2 across the length of the joist which has been cut, and then cut it a bit further along (as marked) and brace it on the joists either side?



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Are you converting the loft space, creating a floor for storage or just putting in thicker insulation?
Just creating a solid floor for storage and thicker insulation.
So in effect you are relying on creating 170 x 50mm joists at 600mm centres if the screwing of timber to timber is strong enough, is that right ? Anybody would need to know the span to advise on the size of joists.
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Yep except at 400mm centres, and will be Gorilla glued the whole length as well. Front to back is about 8m, but there is a brick wall about half way.

If cutting the hangers/binders isn't a wise idea, then I'll just do three lengths of 4x2 instead (either side of the binders and in between them). If I do it that way, do you think it would be ok cutting the binder across the three joists where the loft hatch is (last pic) so that the hatch can be moved, and then attaching some 4x2 across those three joists either side of the new loft hatch?
So the span is about 4m if there is a loadbearing wall near mid span. The maximum span for 200 x 50mm floor joists at 400mm crs is about 4m !
Don't really understand the hangers /hatch query without giving it a lot more thought.

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