The Self Build Self Help Site Insulating the Loft
o o
Sub header photo of a window
Insulating the attic is not one of the best jobs in the world! It's not rocket science either, so there's not a lot to say except make sure that you take up everything you need from the start. Its bad enough getting hot, permanently crouching, denting your knees, bashing your head and getting stuffy in a mask (if you can wear goggles as well and not get steamed up then you're in luck), but to keep going up and down to get things you have forgotten just piles on the agony!

What you will need is:

The detailed plans will tell you to what depth you should insulate.

It is now good practice to install manufactured fire proof electrical fittings in all areas required. The manufacturers instructions are to be followed at all times - your electrician should be installing such fittings as routine. In this case, make sure that there is clearance around any downlighters (also called recessed luminaires) fitted into the plasterboard - cut the insulation away to within 6 inches of the downlighter body. Your electrician may fit intumescent covers (also called fire hoods). If possible, move electrical cables above the insulation to stop any overheating. ,

Getting the insulation into the space above a gable extension is a nightmare!!! Best done by someone who can contort themselves and make good use of sticks for positioning the insulation.

It is best to insulate the loft before the plasterers skim the upstairs ceilings to minimise the risk of 'popping' the nails or screws (screws are preferred) used to fix the plasterboard.

Your electrician won't thank you if you've insulated before he's done his stuff in the attic, so contact him first.

Make sure you leave a gap of 50mm at the eaves to provide adequate ventilation of the roof space.

Boarding it Out

Unless you are using a very shallow pitch, there may be quite a bit of space in the attic that you could use for storage - in which case you will need to board it out. A typical 10" depth of glass fibre insulation will not allow floorboarding to go in unless you squash it down, which will ruin its insulation properties - and will get picked up by Building Control. Instead, you will need to use a cavity insulation between the joists. Ask your architect what thickness insulation you will require. You will need to increase the depth available by nailing wood (something like 2" x 2") onto the joists to give the required depth. Then saw the cavity board into strips, put in between the joists and screw the boards down.

It is preferable to screw the boards down in case they need to come up to get to the wiring underneath (not a likely eventuality), and avoiding hammering is less likely to pop the screws holding the plasterboard up.

You may need to cut out some small pieces of the board around the downlighters and screw these down, so you can get to the downlghters easily.