Spray foam roof insulation

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  • Spray foam roof insulation
  • gobuchul
    Member

    We have an area at the front of the house that is very cold, single story with a pitched roof.

    The loft space is insulated but I think it needs a bit more.

    Anyone tried that spray foam insulation? Apparently it can be quite expensive and installers can vary a lot. I’m not really looking for a quick payback, more a practicable, comfort thing.

    bensongd
    Member

    Have heard of issues with damp getting trapped and rotting the joists with the spray insulation. Sheets of Kings pan celotex stuff with an air gap possibly? Cheaper and much cleaner.

    Premier Icon thisisnotaspoon
    Subscriber

    If space is tight then celotex, if not then just add another 30cm of rockwool? Rockwool is by far and away the cheapest way to improve things (and easy to do yourself, just buy as many rolls as needed and roll them out over the existing insulation.

    johndoh
    Member

    As above – never heard anything good about spray foam

    nickjb
    Member

    Spray foam is good for getting it air tight and air tight really helps keep heat in, you do need a roof that has been designed for it really, though, or you risk damp and rotting in the timber. As above, stick with the more conventional methods

    Premier Icon bruneep
    Subscriber

    Friend owns/works for https://www.scotfoam.com/ & https://www.facebook.com/scotfoam/

    Drop him a msg he’ll keep you right.

    johndoh
    Member

    OP – do you mean it has a pitched roof with a normal suspended ceiling or is it open with the interior pitched too (so just a small gap between the inside and outside of the roof)? If so, when was it built, what insulation was specified and was it signed off? We had a pitched rood like that and never had an issue with it getting too cold.

    gobuchul
    Member

    OP – do you mean it has a pitched roof with a normal suspended ceiling or is it open with the interior pitched too (so just a small gap between the inside and outside of the roof)?

    Pitched with a normal suspended ceiling.

    when was it built

    About 1840, a think the building regs were a little looser back then. 🙂

    By the sounds of it, I will be keeping away from the foam. Might just try celotex across the timbers. One of the problems is that the loft hatch is tiny.

    johndoh
    Member

    If that’s the case then definitely just put better insulation up there as there is plenty of space for it – just make sure you leave the necessary breathing space and that any light fittings are correctly protected (ie, halogen downlighters having protective covers fitted). Could you make a bigger opening to make your access easier if it really is an issue that needs properly resolving?

    With limited access, what about blown rockwool.

    Premier Icon fenboy
    Subscriber

    go for more rockwool/earthwool rolls over ceiling etc, its the most cost effective for your application and easier to get through a loft hatch. You won’t get celotex boards through the hatch. Avoid the spray stuff its not very good and only suitable for very specific applications not yours.

    gobuchul
    Member

    I have looked at making a bigger opening, however, it will still be very narrow as the joist spacing is only about 300mm.

    singlesman
    Member

    If you’re looking to create a warm loft area you could always use a foil blanket type insulation, something like Tri iso super 10.
    Much nicer to use than rock wool/ celotex, cut it with good scissors and staple it to the underside of your rafters.

    johndoh
    Member

    I have looked at making a bigger opening, however, it will still be very narrow as the joist spacing is only about 300mm.

    You could cut and brace them?

    wrightyson
    Member

    Just be careful on the whole “rockwool” thing. Rockwool is a brand and produces a lot of products some of which are not for thermal insulative purposes.
    Tri iso type stuff is a good shout and I’ve used it to very good effect in my
    summer house/pub/shed combo building. Very very easy to use and can be placed easily with a simple good industrial stapler. Quite a few brands around with a few varying suppliers that I know of.
    As for your loft hatch it would be very easy to take one ceiling joists out to a 600 length and “trim” it out on to the adjacent joists either side.

    wrightyson
    Member

    Oh and as for the spray foam avoid at all costs, good for hot tubs, shit for roofs.

    I looked into it recently and wasn’t convinced. Though to be fair seems to be more popular in Canada so not sure if houses are constructed differently over there and therefore avoid the issues you hear of in the UK, or the installers are just more experienced and better, but despite the horror stories, it is a bit of overkill for the UK. Fine for Canada where it gets properly cold and wintery instead of the mild dreary winters we get – it just doesn’t get cold enough here to justify it and other cheaper options are perfectly adequate, so no point in taking the risk and laying out all the expense.

    I’m sticking with good old fashioned roll out insulation and adding an additional 200mm to get upto the recommended 300mm.

    oreetmon
    Member

    Snake oil,

    Don’t do it unless you want to spend lots of money tackling damp problems.

    Your house/roof needs to breath.

    dirtyrider
    Member

    just sold a house with spray foam in the roof, was there when we bought it 7 years ago, no survey issues, this time the buyers surveyor flagged it as an issue, rot etc from trapped moisture (im 100% sure that if we had decided to live there for the next 20 years there would have been no issues) bank wanted a £10k retainer for a reroof, we haggled by supplying quotes, still had to knock £4.5k off to secure the sale, house was reroofed within 4 weeks of us moving out, so it wasn’t a haggling ploy,

Viewing 19 posts - 1 through 19 (of 19 total)

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