Loft Insulation

[Gazz]

Anyone know anything about insulation lofts?

A couple of years ago I put down the woolly stuff on the floor and laid a floor on top of it but there are still some serious drafts coming in and making their way into other areas of the house somehow.

I was recently up my parents loft over Christmas and they have a foamy silver foil covering the underside of the roof. Their house is a council house so was fitted by the council.

I was under the impression that you were not supposed to cover the insides of roof because the roof apparently 'sweats' and can lead to dampness and if the roof were to get a leak you would not be able to spot this.

However, this option seems like a very good solution to keep out the drafts.

I have some light coming through into the loft that I am keeping a close eye on for leaking (it doesn't leak at the moment). Just the thickness of a nail. But if I was to fit something like stated above, I would not be able to see if anymore holes were to appear in the forthcoming years.

Any suggestions on how to improve the insulation in the loft?

P.S. - Parents loft is like a sauna, my loft feels like you are actually outside.

[mudcow007]

My parents have just had their loft insulated an its basically now out of bounds due to how much insulation has been fitted

house is massively more warmer, but they have lost their roof space, it must be at least 300mm thick

[Islander]

Sounds like yours is a cold roof and your parents' is a warm roof:

https://blog.kingspaninsulation.co.uk/what-is-the-difference-between-a-warm-pitched-roof-and-a-cold-pitched-roof/

The recommendation is two layers of loft insulation with the top layer laid 90 degrees to the bottom. That'll give you almost 300mm of insulation and increase the efficiency massively. There are plenty of 'how to' guides online.

[Rogerborg]

Agreed, the amount that you can get between the joists if you floor over them isn't really sufficient. I laid insulation, floored, then laid more insulation on top of the flooring in the areas that I'm not using for storage. If you do need more storage room, you can just pile the insulation up higher.
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[J4mes]

Insulation relies on the air trapped within it, so if you squish it down to put flooring over it, it's not as effective as when it's plumped up and full of air.

Did you squish it?

You can buy legs to build floors up on so that you don't squish it down but still retain the storage. I just floored the bare minimum above the landing for storage and left it 450mm thick over the bedrooms.

[weasley]

I'm halfway through doing ours. I have removed the 50mm of straggly dust that was we before and laid 100mm between all the rafters. Next I will add a further 160mm at right angles over the outermost area of the space, then ion the middle area lay some joists at right-angles to the existing, put insulation between these and floor on top.

The roof space needs to circulate air, which usually comes in between where the slope down meets the walls, so if you lay more, don't stuff it into this area. This means that the loft space is essentially 'outside' and thermally insulated from the rest of the house. If you have drafts coming through from above then it suggests a breach in the ceiling somewhere, or it is through the loft hatch. Or it could be through light fittings, especially if you have recessed downlighters fitted. Or an extractor fan.
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[doggone]

The rigid foam panels between joists is usually called Kingspan but that's a trade name and most of it nowadays is from other companies.
When they fit it they should have left an air gap above so condensation is minimised.
You can have both kinds fitted and the roof space will still be much warmer - not unusual to have water tanks up there.
It's quite good at reducing noise from traffic or wind too.

[GSTEEL32]

300mm is what British Gas etc fill as standard.

We've had it done, its the bollox to be fair. 300 mm and cavity wall takes an 80's house pretty much up to modern spec.

Only down side is that its impossible to put flooring in the loft with the existing joists and keep it efficient ......

The house now takes 8 hours to warm after a week away, rather than 2 full days ..... once warm, it takes 2 hours to stay tip top .... cheap as the proverbial chips ......

[Raffles]

[GSTEEL32]

[Diggs]

The condensation issue really is important. I go into a lot of lofts for work and the worst offenders tend to be houses built in the 1970s. Lofts aren't designed for the amount of insulation we put in them nowadays so you have to make sure plenty of air can still circulate once the insulation is down. Bear in mind that many houses were only designed for insulation between the joists and no higher than the top of the joists.

Thinking about it, pre Building Regs houses weren't designed to have any loft insulation at all, but these tend to have draughty roof-spaces by virtue of age so less likely to be a problem here if yours is an old one.

Condensation kills roof structures over time and knackers anything you store up there....
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[GSTEEL32]

[Diggs]

Read this...

https://www.telegraph.co.uk/finance/property/advice/propertyclinic/5186754/Property-advice-loft-condensation.html

This bloke makes sense.
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[Wonko The Sane]

[GSTEEL32]

Nice, very helpful. TVM.

[stinkwheel]

Draughts are one thing. Insulation is another.

There shouldn't be draughts running between your room and the loft, that would mean there are gaps in the plaster/ceiling. Seal those up with the plaster/sticky goo/foam/sealant of your choice.

Draughts IN the loft are fine. A cold loft means your insulation is doing its job.

The insualtion should be deep and even across the whole ceiling area. If put a layer down, added a second layer of joists on top, put in a second layer of insulation then floored over the top. First I made the hatch big enough to fit full size floorboards through for much cheapness and simplicity.

I got a local guy from an energy efficiency charity in to do a thermal survey of my house with a thermal imaging camera. This will find any draughts and will also highlight any gaps in your insulation. If you tell them its for your own information for advice on how to make your home more energy efficient rather than for an official certificate for a sale/purchase, it'll be both cheaper and more useful.

If they start pointing their camera at the outside of the house and pointing out heat escaping, they are cowboys, sack them off. A thermal survey is done from the inside and looks at temperature gradients along the wall and ceiling surfaces and around gaps (like windows)

Main problem with my house was draughtly windows rather than insulation. A cheap fix.

He even reassured me that the bit of mould in the kitchen was due to condensation/poor ventillation, not damp coming in. And confirmed I'd killed all the rats in the shed.
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