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How to insulate a loft conversion

How to Insulate a Loft Conversion

Last Updated on December 12, 2020Are you wondering how to insulate a loft conversion?

With so many families needing extra space, it is not surprising that many are turning to loft conversions to add a little extra space. Loft conversions are an excellent way to add floor space as well as increase the value of the house, when you come to sell it.

Most people know that heat escapes through the roof, which explains why our homes need good roof insulation. Just as when humans go outside in the very cold weather, it is the head through which the body warmth first escapes. Most of us can remember being dressed in a woolly hat to keep our heads warm – it is just the same with your house.

Taking this a step further, if you add a loft conversion you need to be thinking about insulating the roof while the conversion is in progress. If it is not insulated, or even poorly insulated, the heat will escape, and the house will never be as warm as it could be.

Regulations on Loft Conversion Insulation

As loft conversions have become more popular, so have the regulations become more stringent. Unfortunately, the conversions done more than ten years ago were not subject to the same regulations and are not likely to meet the standards these days. If your conversion was done before 2003 it is probably offering very little insulation.

Regulations state that the u-value of the roof needs to be 0.18W/m2 or less. To a layman this means that the layer of insulation (either fibre or wool) should be 270mm thick, with a rigid board of 175mm, or a spray foam filling of about 125mm thick.

If you plan to re-insulate your old loft conversion, then you need to adhere to these standards. Fortunately, of you re-roof your house, this can be done at the same time.

Can I retrofit loft insulation?

Yes, you can do this. It can unfortunately be expensive but will make your house warmer in the winter and keep it cooler in the summer.

There are three things that you can do to retrofit insulation.

1. Fill the residual space.

This is the small area of space which does not actually form a part of the roof room. Rather it is the area of space that is often just used to store things. It is usually easy to get to and just by laying insulation between the joists will give you some insulation. This method is cheap and quick to do, in fact it is an easy DIY project.

2. Stud walls.

You will find these at the ends of the sloping ceiling. Again, this is an ideal project for a handyman to do, it is cheap and can be done quickly. Simply staple the insulation to the wood joists and place a rigid board in front of the insulation.

3. The roof.

This is normally an expensive job because it is the largest area to insulate and the most difficult. Read more about roofing costs.

Unless you are skilled at loft insulation, it may be quicker to hire someone to do this for you.

Ideally, you should start with your retrofit insulation by doing the smaller areas and those which are easy to reach, then have a qualified person take over the rest.

So, when you consider your loft insulation there are two things you should ask yourself before you start.

Is the loft going to be used as a cold room or a warm room?

A cold loft is only suitable for storage. This is where you throw up the Christmas tree and all the decorations, the old chair you plan to recover, the extra blankets and sleeping bags with the tent for that camping trip…you get the picture. The cold loft is not where you want to send your guests because you have run out of beds!

A warm loft is suitable for converting into an office, an extra bedroom, the gym you plan to use, the playroom for when the kids get too noisy, and any other reason you can think of to live in it. Because it is a warm room, it will provide insulation needed to keep it either warm or cool.

Cold lofts

If your loft is going to be used as a cold loft, i.e. it will just be used to store things in, you may still think about laying a flat surface, so the joists are covered up and walking there to get things is safe.

You should consider laying insulation between the roof of the house and the floor of the loft. Insulating the floor in this way will keep the heat in your downstairs rooms and thus save you money on your energy bills.

Warm lofts

Because you are crating a liveable place you need to keep it properly insulated during both summer and winter months. You should insulate between the roof of the loft and the new ceiling which you would install up there. This is the most cost-effective type of loft insulation – read more about loft conversion cost here, and it is also one of the simplest to do. It will mean that your loft is as warm as all the other rooms in the house.

One thing to remember if you do this yourself is that you should leave a gap between the insulation and the roof slats. This is to ensure that there is enough ventilation to prevent any build-up of condensation and moisture. If any moisture settles in the insulation fabric it will eventually rot.

To sum up on how to insulate a loft conversion

If you have added your loft conversion to the house, then it makes sense to insulate it before you use it.

Decide what the purpose of the loft is going to be because this will indicate the method of insulation you choose.

There are some types of insulation that a DIY person can carry out themselves and thus save some money. Other larger projects may be better handed over to a professional who will complete them for you. He may also offer you a guarantee of no moisture build-up and no condensation in the loft, so bear that in mind when you come to insulate your loft.

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