Loft Boarding for storage Help please

[Nozza101]

Hi All


I Have a 1930’s property semi-detached, and we have just had a new roof installed, we had the old tile with torching on the back that was crumbling everywhere.
Currently the ceiling joists span 7.7m and are 70mm x 50mm with a couple of cross braces that span the 5.5m and are 100mm x 50mm.
We will be throwing away all the existing insulation as its covered in the torching and cleaning the space. (Not sure the thickness currently less that 150mm and has been compressed to 70mm in most of the loft.)

What's the best way of tackling this i read you need 270mm of insulation now.

I was going to cross brace the old joist with some c16 120mm x 45mm to add 100mm more insulation but I cant find any 70mm thick roll to go between existing joists.

then just OSB3 T&G over new joist

Any Help much appreciated.

 

[sxturbo]

6x2 on there sides on top of the existing joists you'd have to use some pretty lengthy screws but they are out there, would recommend to use torques headed screws for less can out, you could use coach bolts bit will have to sink the heads into the joist, follow the joists exactly then you can get you insulation in there, it doesn't matter if you install a bit too much as it will compress when you lay the boards over the top

 

[foxhole]

You need equivalent of 270mm , minimum, you can go deeper.Rigid insulation reduces depth required.

 

[Nozza101]

So could I go 4 x 2 on top of existing and then 4x2 cross bracing those? i can 270mm insulation in then 170mm with original joists and 4x2 on top and then 100mm running across between cross bracing 4x2. then loft boards on top of that

Will weight be an issue?

 

[Captain Nemesis]

..70mm x 50mm ..

Blimey thats small for a 1930s house.