Roof fix ideas - converted loft too hot

[MRex]

The previous owners had the loft converted, so we don't know exactly what insulation is in the roof. It is superficially ok in winter; we're probably losing more heat than we should, but mostly it's only noticeable if we open up the eaves cupboards. In summer though we bake. Even with the blinds down and windows open later on it's still 26 degrees up there. The rest of the house is fine. The converted room is big, it has one slopy roof and the rest is a big box, a flat roof on top. Apart from the eaves there's nowhere obvious where we can get at the insulation inside.

Any ideas what we can do? The eaves are low, so is insulating them any use at all for heat?

Did it have building regs ? It might mean pulling the plasterboard off re insulating and then reboard and plaster .

I'm hoping for a solution that doesn't involve pulling it apart. There is clearly insulation in the bits of the eaves, maybe just could do with being thicker. Replastering would be the last resort and then we would get radiant barriers.

The question about Building Regulations approval is important. I'm sure your solicitor would have checked this when you bought it.

If you have an indemnity policy but no Approval it is likely to be substandard.

Is there a staircase? Do you have fire doors?

Formers and lost conversions do generally tend to be cooler in winter and hot in summer. It may not be a flaw in the construction but just how it is because you are in the roof essentially.
I've lived in 3 or 4 houses like this and it's what loft conversions and formers are like for the most part.
Your solicitor should have checked building regs were in place when you purchased the property.

Aarrgghh auto correct!! Dormers and Loft ....

How many windows do you have and where are they? Could you add a Velux at the front if you don’t have one? How about on the top? Ours is very new and is lovely and warm in the winter and beautifully cool in the summer. I know the insulation isn’t quite what it should be. I think it’s cool because we have windows front and back and on the top.

Yes it has building regs. I can't see what's under the plaster for insulation and tonight it's 23 degrees for example.

The fire door is just the bedroom door, I don't think that will make any difference to the heat.

We have 2 Velux at the front, 3 standard windows at the back.

if you can access the BRs plans (they may be on the council website, or you may have to apply for a copy) you can see what insulation was specified. Modern standards are quite high, so it should be well insulated, unless it was done many years ago. This should help puzzle out what's happened.

For my previous house, old plans were still on file from the 1960's.

Bit of a left field suggestion but how about solar panels on your loft flat roof? They would absorb/reflect heat so it doesn’t go into the loft and of course would also generate electricity for you.

Quite a bad investment now the subsidy has been reduced.

Do you open all the windows to get a through flow of air in the summer?

I lived in a dormer bungalow for years, it was hell in the summer

@PigletJohn - ok, but I'm not sure what good that does? So then we know how thick the insulation is, but we know it's hot and we'd therefore prefer more and/or a radiant barrier. Either of which means taking apart the ceiling, so we don't want to do that. I must be missing something about why you keep saying about building regs?

@BlueSkiesLies - we can't open the front much because there's direct sun through the heat of the afternoon (west / north west but the tilt of the roof means it gets the direct westerly sun), so we just open the velux a little with blinds closed and open the back wide (the back faces east / south east, so it only gets early morning sun).

@minipie - that's not a bad idea, there's a large flat portion where they wouldn't be visible. How do I find a good firm to quote on that, what am I looking for?

Sorry I have no knowledge of solar panels beyond the initial thought! Do an MN search for anyone who’s had them?

Or alternatively if solar panels are too expensive, any kind of reflective material on the top of the roof might help. Just be careful not to blind your neighbours with reflected sun...

if it is an old conversion and has poor or no insulation, then you won't get acceptable performance unless you either pull down the plasterboard, or apply an internal layer over the whole ceiling.

If it is recent and properly insulated, there may be something else you can do. Maybe ventilation will be enough, or maybe the knee walls are allowing hot air to flow in from the eaves section. Maybe you need a thermal imaging camera to discover the hot spots.

It will help to know what the cause is.

. It could just be gappy insulation and when the tiles heat up the heat gets through the gaps and into the room. Covering the roof with foil would be very noisy and it wouldn't last long. A radiant barrier only gives a relatively small improvement in u-value.
If you don't want to take things apart, first look for gaps with draughts and deal with them, and then start considering things like internal insulation although they require a lot of making good and would impact on the headroom quite a lot. At that point opening it up would be more economical.

Thanks. I'm excited by the idea of a thermal imaging camera to check for problem areas, though they seem to range from £120 to £500, so I'll need to find one to borrow or second hand because that seems a bit much just to try it out. (Or discuss it with gadget-mad FIL in the hope that he decides he wants one for his house so we can borrow it!)

The conversion was about 4 years ago, if we find an issue with the insulation should it be covered by warranty or would it be considered just one of those things? We have all the paperwork relating to it downstairs somewhere.

Also, what are knee walls please? Are they the bits at the edge of the roof in the eaves? (Because that area definitely gets more hot or cold in different weather.)

knee-walls are the short vertical walls usually put round the edges of a loft conversion, going up to the sloping roof, so that you don't have headroom tapering down to nothing. Usually there are doors or hatches from the room into this space so you can crawl into the eaves. There is often no floor in this space. Cats like to go in and get stuck, and covered with dust, and fibres from insulation which may be the old yellow irritant type.

Some smartphone cameras can be set to infra-red, but I don't know how.

@PigletJohn - we have exactly that set-up with one of our eaves cupboards, it has some flooring and insulation though the flooring doesn't extend all the way to the roof. I assumed it needs to ventilate, should we be putting insulation and wood floor down in there?

I've looked up the thermal imaging apps, but they all seem to be a con, just colouring a normal picture. I have an idea of a neighbour who might know a man who has a thermal imaging camera (or the neighbour himself is also gadget freak and might have one), so I'll ask him in the week and see if I can get hold of one.

yes that sounds like our dear cat!

knee walls should be insulated. If, from the other side, you can see the plasterboard and the wooden studs, you can put fibreglass loft insulation between the studs, then roll another layer along to cover that.

you can probably find a depth near enough to the depth of the wooden studs.

I prefer mineral wool inside a house, rather that foamed plastic slabs, because it is incombustible and does not emit fumes in a fire.

I only use the brown stuff, treated with Ecose, which does not shed irritant dust and fibres. It is made by Knauf but also sold as an own-brand, the packaging will have the "Ecose" flash on it.

At this time of year the sheds will be trying to shift their stock cheap. Nobody buys heaters or insulation in summer.

There is a kind of fixing nail with a big disk on the head. Some people hold it in place with netting. this might possibly do but I haven't tried. You can also clad the wall with plasterboard if you want. It is easy to cut and nail in place, and quite cheap.

If you can find any gaps or cracks around walls or floors, seal them with expanding foam. i use the pink fire grade which expands and resists flame. It is marginally dearer than the pink. you can get a Fischer applicator gun, and the gun-grade foam cartridges, from builders merchants or ebay. You will need just one canister of gun-cleaner solvent.

As Monsignor Chauvet would agree, there is a lot of wood in a roof, so any opportunity to use fire-resistant materials should be taken.

You are probably getting too much 'heat gain' from the velux windows in the afternoon.

You could cut tight fit thick celotex or similar insulation into the recesses of the velux to stop the heat coming in. there will be a noticeable difference in temperature.

I did this with a friend's velux and she was really pleased with the difference. Although not particularly nice to look at but she wasn't bothered as she just wanted the room to be cooler.