Insulating loft?

paperclap

What a pain in the !!!!!! this all is! 

As the saying goes “If you want something done right, do it yourself”. This house has shown me that more than ever, jeez.

QrizB

paperclap said:

So we recently had someone insulate our loft. But in brief, they screwed it up. They ran it over the joists, rather than between the joists.

For what it's worth, there's nothing wrong with laying insulation over the joists. In many ways it gives a better result than trying to lay it between the joists does (fewer gaps or thin spots).

ThisIsWeird

paperclap said:

What a pain in the !!!!!! this all is! 

As the saying goes “If you want something done right, do it yourself”. This house has shown me that more than ever, jeez.

Lol! This is a minor issue, tho', and easily sortable.

2 planks, one snap-off bladed craft knife.

Lay as much of the existing 400mm LI in the 450mm spaces, leaving the ~50mm gap See if you have any left over. If you do, roll it up to bring it outside for trimming.

Use a large pair of scissors/shears to cut the lengths into manageable sections before rolling them up if needed. Stuff into bin bags to reduce fibres.

If you don't have enough, get on to Fb.

Since you are 'only' going to have ~100mm total thickness (should be effective, although obviously way under recommended levels), then DIP. Do It Properly. Don't leave gaps.

Mask...

paperclap

Of course it’s easily sorted. But when you employ someone to do the job for you… it’s not right to have to rectify it yourself.

ThisIsWeird

paperclap said:

Of course it’s easily sorted. But when you employ someone to do the job for you… it’s not right to have to rectify it yourself.

Absolutely.

sxd901

To achieve the best U value (insulation) glass fibre quilt should be laid 100mm between the ceiling joists and then a further 200mm at right angles across the joists so you cannot see the joists.  This is to eliminate the cold bridging effect of the timber.  If you want to use the loft space without affecting the thermal efficiency then you need to build a floor over the insulation as mentioned earlier.