I was wondering if you could help me.... We have had a brick shed built with a flat roof. The rafters (8"x2") sit on a wall plate and are approx 4.6m long. The roof is made of ply (3/4" I believe) and has 2 rows of 8x2 noggings between the rafters.
I was looking to store a load of things between the rafters (e.g. the mountain of spare timber from the house renovation!) but the noggings are now in the way.
Given this is a shed roof with no plasterboard etc. I was wondering what purpose the noggings was and whether I can remove some/ all of them?
Noggings have two purposes, once the roof is up (they also help as formwork when building). One is to stop the joists moving from side to side, the other is to stop them tipping over diagonally. Both of these would usually be triggered by a sideways shear force on the roof (often from wind load) relative to the walls, and at right angles to the joists.
You need this. You still need this, you need to keep this. However you might not need as much of it as you currently have.
If the roof is plywood and well-screwed to the joists, then there's no scope for sideways movement, once the roof is decked out - although at least temporary nogging would have been needed during construction. However there's still scope for a toppling of them.
Do you have noggings at the ends of the joists too? Those will also help. They're not unusual if the joists are on a wallplate, although they'd be rare if the joists are on metal hangers.
It's unusual to see so much timber nogging these days. Most of it is now done with diagonal steel strips, either pre-formed, or off the roll. The pre-formed are neat, but force a particular joist spacing. These diagonal strips are also considerably stronger against a toppling collapse than free-floating timber nogging - although 8" deep is pretty strong either way (if nogged full-depth, with good attachments). Shallow timber can wrench itself off the nails holding the nogging. A timber nogging added afterwards is pretty much useless for this anyway, as it's hard to attach the components well enough.
The following is almost certainly a breach of building regs and the Geneva Convention. However....
If you have the plywood deck attached well enough, it will brace the joists against sideways shifts. If you nogg joists from at least one side, so as to make boxes, you are still supporting each joist against topple - even better if three joists and two noggings are joined. If there are good end noggings too,even better.
So in this case, I would personally consider (and remember I've not seen the building) removing _some_ of the noggings to make extra space for long storage. However I wouldn't de-nog both sides of a joist. I wouldn't even de-nog two adjacent joists. If I needed storage for 2.5m lengths, I'd also only remove one of the noggings from a gap, not both. I would only remove what I needed, but I would be happy to remove some of them.
I'm a bit out of my depth here, so I would now be looking at the standard textbooks etc. to see what the rules & recommendations were on sizes and spacing. It's one thing to bend these, but ignoring them completely isn't a good idea.
I'd be hesitant to rely on end noggings alone, as the span would then be quite large. I'd probably try to remove one instead, if that would give me long enough storage for my timber. Otherwise it's a good idea.
It's also quite awkward to attach noggings to joists, once they're in situ - easier to add them as you go along. So think this out first and come up with some decent attachment. After all, they're only as good as their attachment.
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