Loft insulation & floorboards - the basics

[cutml33]

Hi All,

Our 1900s loft has original floorboards (which is a little odd) but no insulation beneath as per photos. The depth between joists is about 170mm.

Assuming our requirements are simply to insulate the loft to modern standards while retaining storage space, are these our options?

1) Lift up floorboards, install 170mm insulation, replace floorboards

2) Remove all floorboards, install 270mm loft insulation, fix loft stilts and reuse floorboards (or use chipboard) on top to retain storage

The second option would be more expensive and time-consuming.

I don’t understand why none of the previous owners insulated the loft. There are pieces of thick cardboard between the rafters but that’s it. Anyway, time to put things right!

These may be fairly basic questions but I would appreciate any thoughts on the best approach. Cheers.

 

[Paintguy]

I don’t understand why none of the previous owners insulated the loft.

Is it possibly insulated overhead? Below the rafters? Thus making it a warm loft, part of the heated area of the house?

That might explain why they've never insulated where you plan to.

 

[stealthwolf]

If the depth of joists is 170mm, you need some ventilation above any insulation you install. Either go for 100mm insulation if using traditional loft insulation, or look at the likes of celotex. Alternatively, loft stilts or loftzone to raise the floor but you do lose some storage space as the floor is raised.

I can't comment on the roof as to whether it's been insulated or not but worth looking at.

 

[Ian H]

It looks s good space, I'd be PIR'ing the roof.