Cavity Wall Insulation. Cost for EPC Improvement ?

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  • royw
    replied
    Has anyone tried insulating a stone house with either internal or external insulation? Not only are the walls designed to breathe but as there's no damp proof course there's guaranteed to be a certain amount of moisture in them.

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  • flyingfreehold
    replied
    Someone in the low carbon industry told me to expect massive changes to EPCs within the next ten months. MHCOG realises its flawed as it stands. The system cannot as it stands discriminate between the lowest grade insulation and the best stuff which is triple the price. There is just one tickbox as it were, is it 50mms thick. I know about AEROGEL it is massively expensive, been around a while. Another interesting product Ive come across is a spray on cork insulation which is climate negative rather than glass wool and mineral wool products that are made by heating product up to 1000C and of themselves have huge embedded energy. Cork is infinitely renewable and the trees actually absorb CO2 as they grow new cork bark every nine years. Amazingly the cork insulation is made from the left overs of making "bottle stoppers" ie wot you and I know as corks!

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  • SW1 ghetto
    replied
    That's interesting about the breathable waterproofer, though I am yet to be convinced that spalling should be an issue in many cases of uninsulated walls e. g. I don't think of garden walls spalling heavily for not being heated, though I may be wrong.

    I gather assessors may take different approaches - I met a strict one who said he insists on being able to see the insulation, and won't accept photos or invoices, but I don't think they're all like that!

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  • Codger
    replied
    My own home had urea foam wall insulation in 1982. But no photos! And the pattern of brickwork does not suggest a cavity wall even though there is one.
    Epcs are a disaster!

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  • ifallelsefails
    replied
    I appreciate your scepticism, as I was at first worried about this too, however, I just want to say that good quality water repellent masonry creams such as Stormdry have been tested and let water vapour out of the masonry (ie, they are breathable). So they still allow the brickwork to dry out, if they are still wet or get wet. It has been tested to be many times better than masonry paint (report on their website) so would not behave in the same way. A quote from Stormdry's website says "Because it works by lining the pores rather than blocking them the masonry is allowed to breathe and does not suffer from increased frost damage (spalling)."

    I understood from my conversation from the EPC assessor that I spoke with and from this article that insulation makes a significant difference to EPC points.
    The reason for providing photographic evidence of eg. internal or flat roof insulation was so that they have it to upload as proof with the report. Furthermore if you can show it with a tape measure for the thickness, the reason for this is again for proof because I think it is much more difficult for them to measure this type of insulation themselves than eg. loft insulation.
    In my opinion, if you have spent all of the money on insulating, don't leave it to chance with the EPC assessor - provide the photos if you can.

    I note from what you have said about requiring a target U-value of 0.3 that it rules out the Stormdry EP Board - thank you very much for mentioning this.

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  • SW1 ghetto
    replied
    On damp in solid walls, retrofit is a non-ideal fudge that isn't necessarily compatible with the mechanism of the wall as it was originally built, which in the case of solid walls is often porous bricks and lime mortar that are supposed to allow the wall to breath (though often pointed with sand /cement which undermines that). I tend to be sceptical of trying to waterproof such walls, because sooner or later water will get in somewhere, and maybe the waterproofer can then itself cause spalling - ie the same issue that masonry paint can cause.

    I seem to think there aren't many EPC points to be gained from insulation anyway, but the assessor will measure the thickness of it, which goes into the calculations. Anything will make a difference, but ideal form is to target a U-value of 0.3 as Building Regs mandates, which needs 100mm of PIR board or some such. This is my aim on my current refurb, as insurance in case some tyrant cuts off the gas supply, but even that may not be enough to make a heat pump work!

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  • ifallelsefails
    replied
    I am glad that it was helpful to you Codger.
    Originally posted by Codger View Post
    I have lined some cold ceilings and walls with 30mm thermaline and it did improve comfort a lot. But how would the epc surveyor recognise this?
    Yes, I asked an EPC surveyor this as I wanted to prove indefinitely that I had cavity wall insulation. He explained that so long as you have photos to show as evidence that you have installed said insulation, then they can have those photos to upload as evidence with the report. So he went on to explain that if you put in internal insulation or flat roof insulation, take photos of it, preferably along with a tape measure to show the depth of the insulation so that they can have it as evidence.
    Hope that helps!

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  • Codger
    replied
    Thank for sharing that research ifallelse. Looking at the maths of foam insulation i felt that the first 25 mm was the most important and that internal lining of the cold walls was feasable if expensive and disruptive.
    but the epc regime is inflexible and could lead landlo rds to give up trying.

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  • Codger
    replied
    I have lined some cold ceilings and walls with 30mm thermaline and it did improve comfort a lot. But how would the epc surveyor recognise this?

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  • ifallelsefails
    replied
    Regarding the potential for damp in solid wall properties; in the last few days I've been doing a lot of research in this area (for a slightly different issue) and it would appear that if you are doing internal insulation, then you run the very real problem of preventing internal heat from warming up the solid wall like it originally did. So whilst your rooms are warm as desired, the solid walls are cold. Therefore, when it rains, the bricks/masonry potentially do not dry out properly and in winter it can freeze and may lead to brick spalling.
    To prevent this issue, my own analysis would be to apply a masonry water repellent protection cream (which is where my research started!). There are loads out there under own-name brands and leading brands (some are tested in science labs, some are not), but the market leader and BBA certified is "Stormdry masonry protection cream". The water repellent protection cream would prevent the rain from penetrating the masonry and stop it from getting wet in the first place, thereby keeping it dry. By keeping the wall dry, it has the knock on effect of keeping the wall warmer. This is my thinking of how you could get around the problem, but I'm no expert!

    If you can't install insulated plasterboard (with a foil backing to prevent warm moist air from being trapped behind the insulation and the cold solid wall) because the insulation board is too thick, you can use Stormdry's EP Board, which is thin but still very energy efficient. It is designed for properties with limited space for internal insulation. Stormdry state that the EP Board is designed to be used in conjunction with Stormdry masonry protection cream externally (they are thinking of old properties with limited space and solid walls).
    You can only buy Stormdry EP Board directly from Stormdry, but you can also get the same product from "A Proctor Group", who produce "Spacetherm", which appears exactly the same as Stormdry's EP Board, utilising the same Aerogel backing. However, A Proctor Group also produce Spacetherm with thicker plasterboard surfaces and in larger sheets and for different applications. My concern is that the EP board doesn't have a particularly thick surface (only 3mm magnesium oxide and once you have your 3-4mm plaster finish coat on top you only have a total of 6-7mm + the 10mm aerogel insulation backing) so I fear that it is potentially vulnerable to hard knocks in a rental property (A Proctor's Spacetherm 13mm board brochure says that it is robust but it can be damaged with sharp objects and force - damaged areas would require a proprietary filler). Therefore, a thicker plasterboard surface from A Proctor Group would fair better in a rental in my opinion, if you had no option but to use Aerogel.

    Incidentally, I also discovered that you may require building control when internally insulating. See here for details: https://www.labc.co.uk/news/when-do-...hermal-element

    I cannot post lots of links to the products and to articles/youtube vidoes to my research, otherwise my post is marked as spam. So instead, I'll put it all into this Privatebin instead: https://support-tools.com/?b515ca752...1V34RLS/Ndaoo=

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  • SW1 ghetto
    replied
    Originally posted by jpucng62 View Post

    This is the time to insulate - when you do a major refurb. As you say for anyone trying to retro fit the costs are so much more than just the insulation. Not sure any of the policy makers understand this.
    This is now my approach on refurbs (at least for solid walls) - going DIY on the the current solid walled terrace, and will discuss with the assessor if that can be acceptable (noting also he needs to be able to see the insulation). This street is mostly landlords, and none are C or better!

    Sorry I can't comment on cavity walls - will be crossing that bridge on my next project.

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  • jpucng62
    replied
    AlexR,

    This is the time to insulate - when you do a major refurb. As you say for anyone trying to retro fit the costs are so much more than just the insulation. Not sure any of the policy makers understand this.

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  • AlexR
    replied
    I updated an end terrace which was originally built around 1900 and I went straight for insulated plaster board on internal walls. The house is now an EPC C.

    The cost of this will be prohibitive to most as I spent over the government recommended £10,000 on the property. The costs rise because you have to refit inside, new bathroom , decoration etc.

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  • jpucng62
    replied
    Originally posted by flyingfreehold View Post
    Nobody seems to be all that interested in EPCs despite the huge efforts landlords are making to raise their grades........
    What makes you say that? Scotland have just brought in legislation requiring EPC C from 2025/8 so I think we can assume the same will be applied elsewhere once the MEES bill goes through.

    I believe it will precipitate a housing crisis as swathes of properties become unlettable overnight. The Govt seems to believe LLs are going to pay the tens of thousands required to upgrade their properties in the same way that they believed only a few University courses would charge the £9k max when that came in!! Unfortunately, they and their advisers do not live in the real world!

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  • flyingfreehold
    replied
    Dont use fluff (blown glass) as it will slump if it gets wet. Better to use ecobead which is free draining. If the house has lime mortar leave it be. Nobody seems to be all that interested in EPCs despite the huge efforts landlords are making to raise their grades........

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