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Save Energy with Loft Insulation

September 20th, 2011 |

I recall helping my father fit additional loft insulation to our house when I was a child. The material we used was an orange, fibreglass matting on a roll. It was really nasty stuff to handle. If you got any of it on your skin, it would be very irritating so we wore overalls, long sleeves and gloves. We also took care to wear masks so that we didn’t breathe the fibres.

One thing that I found interesting about it was that it was compressed on the roll, and after laying out, it expanded up to a thickness of about 2″ (50mm). At the time, this was quite normal, and with this additional layer, we had increased the insulation to 4″ (100mm).

Nowadays, the Energy Saving Trust recommends a minimum loft insulation thickness of 10.6″ (270mm) – more than 2.5 times what we had in our house.

As much as 25% of the heat in your house can be lost through the roof. Warm air rises, so it stands to reason that the top of the house is going to be where the warm air is going to be lost. Insulating your loft space to the recommended amount will reduce the amount of heat loss considerably.

The amount of money you save as a result of insulating your home depends on a lot of factors, but you should be able to see a payback time of about 3 years if you upgrade to the recommended thickness of insulation. For home improvement (not new builds) you can get subsidies on loft insulation. For example, Wickes, my local supplier, is currently selling 3 for the price of 2, subsidised by EDF the energy company.

Insulating Blankets

Insulating Blankets are a fibrous blanket on a roll, similar to the fibreglass material I used as a child. Today, it is often made from a spun mineral material which is nowhere near as irritating as the fibre-glass. It is available in various thicknesses and can be used for new insulation or to top-up whatever insulation you have already.

Fitting the blanket is simplicity itself as the rolls split down into narrow strips that fit in the space between the joists in your roof space. Place one end of the roll at the wall in the space between the joists and unroll it. If the roll is not long enough, simply place the beginning of the next roll where the first one ends and continue. If the piece is too long, it can be cut with a sharp knife.

Start at one end of the roof space and progress from one joist to the next until the entire space has been insulated.

Take care!
Take care to step only on the joists when working in the roof space. If you stand on the spaces between the joists, you are likely to end up going through the ceiling of the room below.

I invested in a few packs of loft boards which leave loose up in the loft. I can move them around, placing them across the joists wherever I am working. This allows me to walk around safely without having to balance on the joists themselves.

Something else you might also want to think about is light. Most lofts don’t have a light fitted, so you will need a powerful torch or an inspection lamp on a long lead. Don’t try to work in the dark.

Insulating Slabs
If you want to use the loft space – perhaps you are converting the loft to a room – putting insulation between the joists will keep the rest of your house warm, but will make the loft space colder in winter. Therefore, you will neet to fit insulation between the rafters instead. (rafters are the wooden beams that form the sloping roof and support the tiles – joists are horizontal)

Insulating slabs are made of a similar material to the blanket rolls, but they are compressed into solid slabs. These can be cut to size with a sharp knife and pushed into the spaces between the rafters. Cut them to be a tight fit within the space and they will hold themselves in place.

Also available for the same purpose are expanded polystyrene foam blocks that are made in such a way that they can be squeezed into the space between rafters and they expand once in place to hold themselves in.