Loft Conversions Question

Loft boarding over 4m spans of 2x4

Right... in the process of boarding my loft to provide extra storage in a traditional 1930's semi. Front to back is 7.5m and party wall to gable is 6m. A load bearing wall spilts the 7.5m span into two bedrooms or nearly 4m span each. The existing joists are 2x4 at 350 centres (not quite 400) and run from front to back in 4m spans staggered over the load bearing wall. There are already 4 or 5 cross joists (6m 2x4) running from party wall (not touching) to the gable wall. Again these are original and nailed at each cross over to the joists below. Probably to tie things together?

I hope the above makes sense, if not please ask.

My original plan was to cross batten with 2x4 timbers at 600 centres (in line with the cross joists already in place). I can get 4m lengths into the loft easily. 600 centres as the previous owners left 27 sheets of 22mm T&G chip board in the garage.

My concern is... is it safe to cross batten with 2x4 at 600 centres and then board with 22mm chipboard when the original joists span nearly 4m? To be used for storage and not a habitable room.

Thanks for reading.

Reinforce how? by running 2x6 timbers next to the 2x4? but what about the existing cross battens, how would I get around them do I just remove them?

Thanks for taking the time to give your advice A&A! It sounds like a big job. What if I have cross battens at 400 centers will that be any better and the floorboards less bouncy? Remember it is just for storage so no regular foot traffic.

2 Answers

Best Answer

You have to consider the weight that could potentially be stored in the loft. The cross battens cannot just be removed, they are there for a reason. They are called binders and they are an integral part of the strength of the ceiling, effectively shortening the span of the ceiling joists and stiffening them. I think screwing larger joists to the side of the existing is a good plan, but you have to calculate the size of the joists you will need. You can then remove the binders if the calculations allow for that. Dont be put off by the fact that you need calculations. They are not that expensive. I do them myself. There is another alternative using steel plates screwed to the existing joists, called flitch plates. They can work out expensive though.

Phil Routledge

Answered 25th Nov 2011

Right Surveyors North Midlands Limited

Member since 19 Sep 2011

In my opinion having cross battens at 600 centers will make the floorboards quite bouncy.
My suggestion will be to reinforce the existing joists that go from front to back of the house.
Good luck with your project.
Yes, running and screwing 2x6 timbers next to the existing timbers, this is a good chance to level the floor as well.
You can remove the old cross battens, the floorboards will do their job,cheers
If its just for storage purpose and you have cross battens at 400mm would be just fine.
You're welcome.

Answered 6th Nov 2011

A&A Plastering and general Building

Member since 4 Sep 2008

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