It's been asked before, but cutting a new loft hatch...

[justanotherguy]

... just want to be sure, because a structural surveyor suggested something different (it was an incidental question, he came to check if a wall was supporting).

I have an old-style non-trussed roof (with only about 4 diagonal roof supports across the whole 12m), so 90% of the joists only support the ceiling. Having taken down the lathe+plaster, and replacing with plasterboard, it'll be supporting even less weight.

The rafters are 2 x 4's, at 30cm centres. Just cutting one joist would therefore not be quite enough, so am planning on cutting two, for a 90cm opening.

The surveyor suggested simply moving two of the existing joists either side, and bolting them together with M12 grade 8.8 bolts at 40cm centres. That would mean a 1m gap all the way across the ceiling, which seems wrong, particularly if I want to be boarding it and walking around, storing medium weight stuff.

The classic/normal method I've seen here is to:

1) Put in noggins between the joists you're going to cut
2) Cut the joists inside the new hatch area, along the nogins
3) Add extra side pieces alongside the nogins/cut joist ends
4) That's pretty much it for the hole itself.

Have I missed anything?

Thanks

Marcos

 

[rou]

You need to double or tripple the joists next to the opening and then add smaller joists bewteen them to support the ones you want cutted.
Have a look at picture bellow...

Untitled

• rou
• 3 Nov 2009
• 1