Our loft has loose fibres between the joists - I don't know how effective it is, but it is messy!
I am thinking about improvements - should I
a) remove the loose fill and replace with fibre glass or similar b) lay fibreglass over the top (it is not boarded and only used for minimal storage) c) fix solid insulation between the roof rafters (leaving an air gap below the tiles)
Any recommendations?
Not sure why you'd bother doing that (you got lots of spare time?)
I'd do that: the deeper the better. We recently had our 6" made up to a foot by one of those there insulation firms who are doing so well at the moment, courtesy of Govt initiatives (I think we paid a couple of hundred quid, for cavity wall insulation too.) All they did was roll out new blankets over the old ones, at right angles. As stated, it's all now about a foot thick.
Goodness knows if it will have any effect: presumably, it will, but it bloody well didn't feel like this morning when I got out of bed at 6!
John
...or you want to get a bigger insulation grant! I had about 50mm of loose fill insulation in my loft and I applied for a loft insulation grant to bump the thickness up to 300mm. When I spoke to the surveyor on the phone he told me that if I had any insulation in the loft already, I would have to pay about =A3350 and if I had no insulation at all, I would have to pay only =A390! By the time he visited, I'd removed up all the loose fill stuff (two hours work for 60m^2 - not too bad), and so was eligible for the bigger grant, and I used the loose fill elsewhere.
Our house is dramatically warmer than it used to be, so yes, it does work.
dan.
I had to turn my radiators down 24 hours after my top-up was done.
I wonder if there is any kind of insulation one can put down the part of the roof sloping down to the eaves? As I understand it, one should not close up this space with fibreglass, because it will prevent necessary ventilation. But is there some kind of insulation which will allow some ventilation - or maybe that is a contradiction?
AIUI the usual way is to use fibreglass slabs or foam between the rafters, leaving a 25mm gap between the insulation and the roof tiles. If you have a breathable membrane rather than the old type of roof felt, they say you can go right up to the tiles. I wasn't sure, so I didn't
Actually, the roof of my cottage is not felted, so I guess I can go right up to the eaves.
Incidentally, how bad is it not to have felt under the tiles? I notice in another building that felting the roof has certainly made the loft much warmer in winter. So I guess the felt must save energy, I don't know how much.
No you can't. You need to make sure that there is enough space for the membrane to drape over the rafters, unless the membrane is laid taut over the rafters with counter-battens over.
For the depths of most rafters in existing buildings, the thickness of mineral fibre batts that would fit wouldn't give a lot of insulation (although some is better than none). The other problem is getting it into the gap. Even though MF batts are stiffer than normal loft insulation, they will still bend and snag as you try and push them down the gap.
Far better to use polyisocyanurate boards (Kingspan, Celotex, etc.). Even better is an insulated plasterboard under the ceiling.
A few of the rafters in my house have some plastic bits designed to keep a gap there, but many don't. Photo:
To complicate things, the roof comes down to the first floor floor level in places, so the first floor rooms have sloping walls/ceilings except at the gables and dormer windows.
So the cross section looks a bit like this:
(I've more or less given up on the idea of replacing the fibreglass with Cellotex or similar - while being rigid would make keeping an air gap easier, if it fits tightly between the rafters I'll never push it down that far, and it it doesn't fit tightly I'll never seal working that far down a 50mm gap (again, short of taking all the tiles and felt off), so fitting more insulation (and a vapour barrier) inside the rooms makes more sense. Unless anyone can suggest something else. But that doesn't fix the missing ventilation.)
My situation is similar; the cottage only has one-storey, but the ground floor rooms have sloping ceilings (with a flat portion in the centre).
The roof is not felted at present. I am thinking of getting a big job done (not by me!), felting, re-laying the tiles and putting in some insulation on the sloping part over the ceiling.
I've been given a price of 8,500 euro - say, £6,000 - for this. The cottage is about 5m x 20m, and was built in 1860. It was completely re-furbished about 40 years ago by the previous owner, a trawler owner who kept his mistress in the house.
If this is just for the sake of insulation, it would probably be much cheaper just to replace the sloping ceiling areas and fit insulation behind them. OTOH, if the roof needs attention for other reasons, then so be it.
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