loft floor joists on central wall

[compactpowerhouse]

A builder is proposing to build me a new loft floor using 4"x2" timbers spaning 7'. One end is hanging off an 8"x4" timber and the other is supported on the central wall. This wall is lath and plaster and I beileve it to be hollow with timber uprights. Is this correct or would it have a brick core? So should I be worried? The loft room has been there for over 40 years before I moved in, supported in the same manner without any structural problems but as the ceiling joists are only 2.5"x2" I thought it might be an idea to strengthen them and add a new floor. The other option of course is to go down the building regs route and span the central wall but I lose another 6" head height causing the need for a dormer, which I really don't want to have.

Should I scrap the whole idea? The neighbours use their loft on the ceiling joists and don't seem worried at all!

[John Rumm]

A stud wall can be load bearing - it is not the construction of the wall that matters so much as what it is sitting on. (i.e. if the load of it is correctly transfered to foundations of any sort).

A good clue is often to look at the roof construction. Does anything else sit on this wall at the moment? With older roofs, it is quite common to require a central supporting wall to carry the load transferred from the pulins via stays of some sort.

What are you going to put on the new floor?

What do they use theirs for?

[compactpowerhouse]

The central wall has no purlins sitting on it as these are set into the wall either side. So at the moment is doesn't have much load on it.

The new floor will be 2 layers of 3/4" plywood. As for loading, at the most will be a single bed and chest of drawers.

All they use is timber floorboards 4"x 3/4".

[meow2222]

the 4x2s are ok in the sense that theyre functional, but they wont meet BR which demands very deep woodwork.

As already saud, you need to look at what your stud wall is sitting on. And check it is in fact a framed wall, not a plastered twig wall.

that is pushing it.

indeed

thats way OTT. 3/4" chip or even- 2x 1/2" chip would do. Screwing your floorng every 6" would help with the stiffness.

Adding 1.5" of solid flooring glued and screwed to the existing joists would strengthen them up greatly,. But it woudbe more economical to add wood strips on top of the joistlets then floor as normal.

hope they dont get a waterbed then

NT

[Christian McArdle]

If the structural engineer says it is fine, then it is fine. Obviously, the structural engineer will have to show that the existing stud wall is suitable for the loads that will bear upon it. If they can do so, they it is fine both in practice and to comply with the building regulations.

Christian.

P.S.

I'd go for the dormer anyway, unless it would be problematic from an aesthetic point of view.