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Uplifting existing 60mm cavity insulation & 50mm cosy board & 100mm attic floor

  • 07-02-2023 4:58pm
    Registered Users Posts: 804 ✭✭✭

    My goal is to bring down the large heat-pump-driven (up to 15,000 Kw p.a.) electricity bill in a non-airtight house, so keep as much heat in V upgrade cost.

    The house was built in 2006, roof on, doors and windows but no MPRN until 2014. Has anyone got a grant in this case? I am getting mixed messages from the scheme

    I am hoping to find someone who started with the same as me:

    • 6cm kingspan in our cavity blocks (visible in meter box)
    • 5cm cozy board internally
    • windows double glazed
    • 100mm attic roof insulation

    I want to get an idea what % of extra heat will be retained depending on what I upgrade.

    I used a home energy saving kit from the library which indicated that there was some thermal leaking under the front and back door (3-degree difference)

    Options currently on the table:

    1. Pump the 4cm gap in the cavity walls with WallTite CV-100
    2. Uplift attic floor insulation from 100mm to 300m
    3. OR instead of 2, spray foam the attic floor with 80mm

    How best is my money spent to keep the heat in and bring down our electric consumption?

    Any advice is appreciated!


  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    Pump the 4cm gap in the cavity walls with WallTite CV-100

    Uplift attic floor insulation from 100mm to 300m

    OR instead of 2, spray foam the attic floor with 80mm

    How best is my money spent to keep the heat in and bring down our electric consumption?

    On none of the above I'm afraid because your primary method of heat loss currently is likely air leakage and none of the measures listed will address this.

    On paper, your house is actually reasonably well insulated and should not be costing you what it's costing for heating. However, there is likely no air tight barrier in your external walls so you are losing your heat by air leakage (convection losses) rather than by conduction (which insulation addresses generally). Getting a handle on your air tight weaknesses would likely be money well spent to drop your heating costs,

  • Registered Users Posts: 804 ✭✭✭boardtc

    Thanks. Ok, makes sense to find out where air is getting out before investing. I need to learn more about how air is getting out if none of the above will help.

    Is my first step to pay for thermal imaging? Maybe someone could ping me with a recommendation, please.

  • Registered Users Posts: 23,083 ✭✭✭✭mickdw

    Were the insulated slabs fixed straight into block wall or were the walls plastered first?

    Unplastered walls let air walk through them.

  • Registered Users Posts: 804 ✭✭✭boardtc

    Everyday is a school day. No plaster on walls. 🥺 So the WallTite CV-100 in the cavity gap won't stop the air escaping? Is that because there will be air pockets between the Kingspan and inside wall?

  • Registered Users Posts: 355 ✭✭Biker1

    WallTite CV100 is an airtight product therefore no need to plaster walls first.

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  • Registered Users Posts: 3,380 ✭✭✭chooseusername

    Only 40% of the cavity is going to be pumped, assuming the other 60% is done properly will it still be airtight?

  • Registered Users Posts: 355 ✭✭Biker1

    Yes, that stuff will get into every cook and cranny.

  • Registered Users Posts: 804 ✭✭✭boardtc

    Thanks! I am retroing. @MicktheMan, based on your comment you don't agree WallTite CV-100 will help?

    Does anyone have other info for me on how air is leaking please? Thanks!!

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    While walltite may well do a decent job on airtightness of the block work, my concern with using it would be the very real risk of cracking in the structure due to the pressure exerted by the expanding product on the cavity wall leafs.

    Imo, solving one issue while introducing a real risk of creating a bigger issue is never a good idea.

  • Registered Users Posts: 804 ✭✭✭boardtc

    I hear you @MicktheMan of course it would be great if my walls has been plastered first in 2015 but these are the cards I have now!! Waiting on Walltite quote anyway.

    In the context of paying a bunch of money for thermal imaging has anyone bought a Thermal Imager Camera with LCD Screen? I see some on the market for €300. Are they foolproof to use? Maybe a better investment would be to buy one and then sell it on...

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  • Registered Users Posts: 355 ✭✭Biker1

    There is no point in buying a thermal camera unless you are trained to interpret the images taken under the required conditions.

  • Registered Users Posts: 23,083 ✭✭✭✭mickdw

    I don't know. I'd imagine anyone could learn a fair bit if just handed a fairly generic thermal camera

  • Registered Users Posts: 355 ✭✭Biker1

    Good article from an industry expert.

    "That's too expensive, just send me the images without analysis".

    We have heard that statement 2-3 times a year for the last 21 years and I'd like to take two minutes to explain why we never just send raw thermal images to anyone, ever.

    Thermal imaging is a tricky, weird service & science that requires two very important steps.

    Firstly, you have to take the images in the correct conditions. If you are receiving cheap quotations from providers guaranteeing survey dates, you ought to be very suspicious. Your Spidey Sense should start to tingle. If it rains, is too windy, too warm, foggy, misty etc - you cannot survey. The laws of physics dictate this process and it cannot be side stepped or underestimated. The golden rules are 2-3 hours after sun down. Dark, dry, low wind conditions and heating on in the building.

    So, assuming your images were taken in the right conditions, what's the second step? Well, analysis is the answer to that question. Have you set the level and span properly, the emissivity, humidity, distance to object? Do you understand the thermodynamics at play? The construction details that cause cold bridging? Again, Spidey senses should tingle if your chosen provider doesn't understand how buildings are built or is willing to send you raw images and an invoice..

    21 years ago thermal cameras were £40K. Today, they are around £6-7K for a similar spec camera. That fall in price has lead to more and more start ups entering the market, which is fantastic - it validates the technology and helps people raise finance to grow their companies - but it also means people are entering the market without the experience needed to do it properly. £40K means you think about it quite a bit before investing it. (The drone market is very similar).

    That aside, please don't ask anyone for images without analysis. It is far too easy to misinterpret an image and make an expensive mistake. eg take an image on a hot day, your building will look like it's badly insulated. If you can't see when the image was taken you could conceivably spend thousands of pounds scaffolding a building to extract perfectly good insulation and put a tenant into fuel poverty.

    If a surveyor is willing to send you un-analysed images - you should run a mile.

  • Registered Users Posts: 23,083 ✭✭✭✭mickdw

    Well that's all well and good but written by a service provider.

    No doubt, there are skills involved in that business but the given a thermal camera, I'd certainly have a good go at finding an obvious area of leakage.

  • Registered Users Posts: 804 ✭✭✭boardtc

    I wonder if anyone will come at 8 o'clock at night!

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    Have done some midnight / early a.m. surveys in the past when required and no other option available. But these are very unusual cases and most surveys of this nature can be done very successfully during the heating season.

  • Registered Users Posts: 11 larrymc123

    @boardtc any update on Walltite, did you get quote / proceed?

  • Registered Users Posts: 804 ✭✭✭boardtc

    The guy giving the quote got sick so no... looking at getting a thermal image of the house first to see where eat being lost...