Insulation advice

littlesaint

Hi, I am a bit confused about insulation and wondered if I could get some advice.

We want a warm roof solution so insulation below the rafters rather than over the joists. Our loft is small and want to board it so we don't want to make it more difficult to move around.

My first question is does the minimum recommended thickness (270mm) change if you use compressed insulation ie foil sheets or hard boards? I can't see a definitive recommendation for other width.

My second question is, can you split your insulation between your floor and roof, ie half the recommended amount between the joists. Half over the rafters. Would that be effective?

Am I right in thinking that there is no subsidy / grants for a warm roof solution?

Thanks in advance.

Simon101

Hi Littlesaint

You don't say how much nsulation you currently have.

I you have less Han an average of 60mm then you can potentially get 270mm fitted for free. Some fitters will also give you 5 square metre of boarding on top.

Suppliers are on MSE.

If you currently have more than 60mm then you need to do it yourself. The thickness of insulation has diminishing returns. 270mm does not save you double 100mm. Therefore, since you want boarding, you probably want to fill to the beams (normally 100mm) and forget the rest. Raising boarding seems incredibly expensive. Obviously if you don't need to board all the loft you can have some areas at 270mm and the boarded at 100mm.

I'm sure there's somethinner insulation which is just as effective, however current subsidies are for thicker stuff, therefore it's currently not cost effective IMHO to do anything hat sophisticated.

Simon

littlesaint

Thanks Simon. I will check how much we have already. Would installers be happy doing it just to the beams?

Simon101

Unfortunately not, since they are paid to bring your insulation up to a minimum standard, which is 270mm. If they take just up to the beams then it does not reach this standard.

Whilst there are still grants available you might as well get a free survey done and double check.

After the grants disappear and all these companies which have sprung up to take advantage of them, are looking for work you may be able to get it done more cheaply.

However, on balance, you are likely to have to pay for the install since you, like a lot of people, want to use the loft for storage.

All of the above is why I haven't had my loft done. Although most companies, eg Mark Group, will install 5 sq metres of boarding its not really enough.

I've decided to do my loft myself. Taking all areas up to the beams and then areas I don't need boarding will take up to 270mm. I've looked at various other solutions such as polysterene between the roof beams but they are not cost effective. Unfortunately as my loft is partly insulated the incremental savings don't make this very cost effective.

littlesaint

Had a look in our loft last night. It seems that we have some sort of insulation between the ceiling joists (looks like fibreglass rolls). So I am guessing there is at least 100mm there assuming our joists are that wide - know idea how I can make sure without contending with the fibreglass - don't want to do that!). Don't know whether it is worth booking a survey to find out for sure.