Loft boarding screw question

[mankymanning]

Sorry if this has been answered but I can't find the answer by searching.

I am about to attempt to board (T&G from B&Q) out my loft (not really done much DIY before) and it is a 1900 mid terrace house.

Each board needs cutting slightly if the ends of adjacant boards are to meet in the middle of a joist. The joists look like 4" deep and 1" across.

That doesn't leave much room to screw each board down at the end on the joist - only 1/2" or so and according to the instructions which come with the boards the screw should be 15mm from the edge.

Am I going to have a problem screwing them down so close to the edge? Should I leave the edges and just screw down on the joists which are spanned by the board?

[David Hearn]

If you're using T&G then you probably only need to screw them down where a whole board spans the joist. Where they butt together, they should have another board which fits into their toungle/grove. This board will span a joist and be screwed down. Once everything is completed, the butt joints should be held down by the T&G's of the neighbouring boards which are screwed down properly.

That's what I would do - whether its the 'correct' thing I don't know.

One word of warning - if your joists are 1" wide, then you're going to have to be accurate with the screwing on the spanned boards, as you won't be able to see exactly where you're screwing in. So best mark the position of the joists onto the top edge of each board as you go, allowing you to draw a line between the marks on the new and previous board, showing where the joist goes, allowing accurate drilling/screwing.

David

[mrcheerful]

if your joists are that narrow then the weight of the boards may be too much anyway!

mrcheerful

[Dave Plowman (News)]

If they really are 4x1 I'd be a bit worried about the weight of the new floor, let alone anything you're likely to put up there.

However, you shouldn't arrange things so all the boards join over the same joist. It will mean more cutting, but not necessarily more waste, to stagger the joins.

[chris French]

These are most likely just standard T&G boards with side T&G's not end ones as well.

If they really are 1 inch wide then I'd forget the whole idea as I'd doubt the strength of the joists but that sounds very narrow, I'd expect more like 3x2 or 4x2. Have you actually measured them David?

If you did do it then I'd screw a bit of batten to the side of the relevant joist to get a better thickness of wood to fix into.

[David Hearn]

If the butt joint is fully supported by a joist, there's no need for a T&G on the end is there? I was meaning that where they butt together, there's no T&G on the joint, but the neighbouring boards would fit into their side T&G's. Hard do describe with words.

I'm not the OP... ;)

David

[chris French]

Ah, I understand what you meant now. It's not the 'right' way to do it though, relying on the T&G to support the end of the board

Ah, whoops :-) mis read the attributions

[David Hearn]

Nearly there - I was suggesting that the joist supported the end of the board (un fixed), rather than the butt joing floating in air relying on the T&G to keep it in place. The neighbouring boards which spanned the joist would be screwed to the joist, meaning the T&G would have to stop and major upward movement caused by weight put between joists, but I think this would be far less of a problem than relying on it to stop downward movement. Of course, this requires that each row is staggered by 1/2 (like a standard brickwork pattern).

[MankyManning]

Well now I am worried then, I have re-measured them and they are definitely only 1" thick and spaced around 17" apart.

I don't want my ceilings to cave in.

[Dave Plowman (News)]

The smallest joists in my house are 4x2" and only span about 4 ft. And that's decent Victorian timber.

4x1 are merely ceiling supporters - and only just.

I'd say they would if you add any appreciable load. I'd be worried enough about just my body weight up there.

[Chris Bacon]

You can still put down boards, but be careful about where. If you can arrange to board a couple of feet either side of a supporting wall, for instance, or somewhere that the span as small, such as over a stair, it could be OK. I wouldn't store great blocks of lead or similar up there, nor board off anything more than a foot or two close to a support. You might have a vague possibility of adding new joists above the existing ceiling, between and higher than the existing ones, and boarding those.