Green Building Forum - House refurbishment / extension Tue, 19 Dec 2023 08:27:49 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303240#Comment_303240 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303240#Comment_303240 Wed, 13 Sep 2023 07:44:43 +0100 englishjohn
Built around 1970, brick, block and apppox 50mm filled cavity.

Initially my money is going on squaring the property off with dome some extensions.

Externally insulation applied to the property.

The BI has said i can build a cavity as we have currently and then external insulate to meet reg as i wish to do the whole house, or single skin block 190mm block and insulate — any thoughts on the preferred?

I was also looking at Marmox thermoblocks as a whole retrofit -crazy? Would these need to be added to the internal and external skin, it doesn't look like the do a block wide enough to bridge the cavity? This bring me onto the next question.

The other big/massive job I’m considering is smashing the solid concrete floor and installing insulation, which would tie into the Marmox.

If anyone has any initial guidance it would be appreciated.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303247#Comment_303247 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303247#Comment_303247 Wed, 13 Sep 2023 11:52:28 +0100 djh Posted By: englishjohnThe BI has said i can build a cavity as we have currently and then external insulate to meet reg as i wish to do the whole house, or single skin block 190mm block and insulate — any thoughts on the preferred?I'd have thought a single skin with EWI would be a whole lot simpler (and cheaper?) to build.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303249#Comment_303249 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303249#Comment_303249 Wed, 13 Sep 2023 13:51:06 +0100 fostertom
Posted By: englishjohnsmashing the solid concrete floor and installing insulation
Or leave it untouched: instead carry your EWI in trench down to the bottom of the founds (incl out and over the toe of the strip found), put in a french drain, backfill with Leca aggregate for extra insulation at a price, or sharp clean aggregate as rainwater-permeable fill, wrapped in geotextile optional. As a coffer-dam of insulation, continuous unbroken with the wall EWI, the heat-conduction path distance down thro the subsoil under the house, outward under the bottom of the found, and back up to the garden surface (the main destination of floor heat loss) is greatly lengthened and provides a pretty good standard of floor insulation, without internal dispruption. And the subsoil block forms a massive heat store helping to stablise house internal temperature.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303251#Comment_303251 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303251#Comment_303251 Wed, 13 Sep 2023 15:09:13 +0100 englishjohn
Building inspector said the min was 190mm which he showed me from a gov document. Maybe worth investigating the cost of structural calculations for a two story extension? Does anyone have any specs done i could show to the BI initially? Been quoted about £35m2 for 215mm deep blocks.

The wife hates cold feet, and in our previous house I had overlaid insulation, this isn’t achievable in this house, hence the drastic idea of lifting all the floor.

Running eps all the way down as all ready thought about is certainly easier. Maybe I’m overthinking the heat loss through the floor as it will be ‘warmer’ once the external eps work is undertaken?]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303252#Comment_303252 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303252#Comment_303252 Wed, 13 Sep 2023 15:22:21 +0100 fostertom
Posted By: englishjohnBuilding inspector said the min was 190mm which he showed me from a gov document
That'll be the Building Regs; 190mm is the thickness which is 'deemed to satisfy' the Regs i.e. gets automatic approval without calcs to prove structural stability (i.e. to remain flat/straight etc between butressing corners/block partitions etc). Where such butresses are close-ish together, then thinner (140 or 100) blockwork may remain flat/straight but an Engineer needs to do calcs to prove the case.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303253#Comment_303253 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303253#Comment_303253 Wed, 13 Sep 2023 15:33:04 +0100 GreenPaddy
very quickly... I'm not sure the 215mm thick wall requirement is a structural issue. It's about rain penetration. See Approved Doc C Section 5.9

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/431943/BR_PDF_AD_C_2013.pdf

In Scotland its Section 3.10.2 (which indicates 200mm)

I know there's insulation on the outside, and very waterproof no doubt - just giving the links.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303256#Comment_303256 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303256#Comment_303256 Wed, 13 Sep 2023 16:31:46 +0100 djh Posted By: fostertomO'course 190mm block doesn't existI know nothing about the subject, but a quick search for 190 mm wall block shows lots of products?]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303259#Comment_303259 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303259#Comment_303259 Wed, 13 Sep 2023 19:00:31 +0100 englishjohn
If i was to install UFH in the future do you that would swing a decision on if I should smash the floor up and insulate? Now excuse my lack of knowledge, but why to i/we need so much concrete as a floor slab, does the load o walking around on and placing chairs and tables have such an effect that say 50mm or less wouldn’t work?]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303260#Comment_303260 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303260#Comment_303260 Wed, 13 Sep 2023 20:02:20 +0100 Peter_in_Hungary
Retro fitting UFH is a really big job and I for one wouldn't contemplate it. But if you do want it then digging out the concrete floor to insulate in preparation is the way to go because you don't want to do the job twice i.e. do it now.

I have made big improvements to the thermal properties of solid floors by putting 20 mm of XPS covered by click fit flooring of what ever quality that suits your budget and SWMBO's demands but it adds 30mm or so to the floor height which may be a threshold issue but easier to alter the threshold than dig up the floor.

Wot Tom said about taking the EWI down to the base of the foundations +1

Re the walls - I would go for single block and EWI, as said above easier and cheaper and easy to get any U value you want by increasing the thickness of EWI. If you go down the cavity route you will need wider than normal cavity to get really good U value and if you are not doing the work your self you will need to watch the builders like a hawk to ensure the cavity insulation is installed properly because once the wall is up you can't see any bad workmanship. Over here it is all single skin block and EWI. Even walls of Ytong blocks (a type of Thermalite block) used here have added EWI to improve the U value.
The only caveat is that if the PP demand a brick finish, whilst you can get brick slips for EWI realisticly it would probably be a cavity wall-]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303261#Comment_303261 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303261#Comment_303261 Wed, 13 Sep 2023 20:11:42 +0100 djh Posted By: englishjohnIf i was to install UFH in the future do you that would swing a decision on if I should smash the floor up and insulate?In most cases whatever the UFH is embedded in needs to be above insulation, so you don't lose too much heat into the ground. If you wanted to put UFH into a floor slab, then it needs to be done when the slab is laid, though it is possible to put UFH in a screed above the insulated slab at a later date.

Building regs set minimum thicknesses for slabs. Thickness (and maybe reinforcement) is needed to prevent subsequent cracking. A structural engineer will advise what is required in any particular circumstance.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303262#Comment_303262 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303262#Comment_303262 Wed, 13 Sep 2023 20:56:06 +0100 englishjohn
Extension single skin + ewi. I shall wait to see what the se says about block size.
Existing house with pre-filled cavity + ewi
My existing floor - ceiling is 2340mm so maybe just overlay with 20-40mm and then enjoy life (for a while)

The more I think about it removing the concrete floor seems too much, i could still use overlay UFH.

Ultimately compared with what i have it will be a big difference, hopefully.

On another note, my wife has said my username is akin to someone who sits on the far right, lol. I had never thought of it like that I assume I cant change it?]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303268#Comment_303268 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303268#Comment_303268 Thu, 14 Sep 2023 08:43:54 +0100 GreenPaddy
my thoughts on your scenario are:

laudable ideas that never get carried to fruition don't help anyone, so sometimes we just need to get on and do something that is not perfection. I suspect digging the floor would not ever happen (cost and disruption) so you'll continue with cold feet (metaphorically too??). I sometimes dig out floors for property refurbs, so I've a good idea about the costs and mess, going down more than 300mm, and then putting it all back.

Go for the over-floor insulation (as above), and some new floor covering, which will look and feel so much better. Very quick win for all the occupants. Spend the time and money adjusting skirtings, doors etc, and enjoy the results. Do it room by room, so you can still live in the house, and manage the cash flow.

Then, having shown the benefits of your approach, hit the EWI, and consider Tom's advice re. sub ground level EWI continuation. That will have very little impact on family life inside the home - more impact on the bank account, but that's just how it is.

Extension with single block and EWI. May be, you can't get as much depth of EWI on the existing house as the new extension (for whatever reason), so adjust the single skin block face position, to enable good depth on the extension.]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303269#Comment_303269 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303269#Comment_303269 Thu, 14 Sep 2023 09:24:23 +0100 WillInAberdeen
Actually a lot of the benefits of the new floor came from stopping up draughts where the floor meets the walls, the bottom few inches behind the skirting were not plastered. And getting a warm-to-the-touch floor covering such as wood or thick carpet, instead of our previous thin carpet, which let the solid floor suck the heat out of bare feet! Could be quick wins there? UFH helps with the bare-feet problem but only in the hours of the year when the central heating is running.

*For the same reason, have you considered doing the extension as an insulated timber frame? Much less carbon emissions than conc blocks covered with plastic insulation.

I'm no longer in Aberdeen but haven't changed my user name!]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303274#Comment_303274 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303274#Comment_303274 Thu, 14 Sep 2023 17:17:23 +0100 englishjohn
Ripping up the concrete floor is now forgotten about.

EWI thickness on existing house is limited by rear house access route.

The cost of the SE cals are making the difference in using a 215mm block vs an a 140mm block ‘only’ about £300. Because of that I’m thinking that it may just be easier to forgo the se calcs and the BI will be happy. The house will feel solid! I might be wrong but it looks like 215mm aerated block and 200mm eps comes in at approx 0.13 on the extension. I expect the existing walls will be similar.

It’s genuinely a shame the people aren’t rewarded if the wish to make significant thermal improvements to their houses, mine currently sits as an E i think on the epc reprt. 0% vat would be start!]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303278#Comment_303278 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303278#Comment_303278 Thu, 14 Sep 2023 22:29:29 +0100 WillInAberdeen
http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17827]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303279#Comment_303279 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303279#Comment_303279 Fri, 15 Sep 2023 07:24:16 +0100 fostertom House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303303#Comment_303303 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303303#Comment_303303 Sat, 16 Sep 2023 12:08:32 +0100 englishjohn
Work has to be done by a contractor so I can not submit a claim from HMRC thereafter myself.

The builder (who is also a friend) is sole trader and i don't think is vat registered though that could me be misunderstanding the difference between how companies are set up ect. Historically he just charges the cost of materials by giving the invoice from his jewsons account or whoever and then chargers labour on top.

It would be so much nicer if all these materials were just zero rated at purchase, it appears to be a whole lot of extra bureaucracy and paperwork.

Moving onto windows and placement. I have read and looked at lots of ways you all do it like, plywood box pushed out into ewi, larger frame attached to external wall by ordering a larger window ect. As I’m creating new openings is the idea of creating these holes bigger, running the ewi back into the window reveals and sitting the new windows in place a terrible idea?]]> House refurbishment / extension http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303310#Comment_303310 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17950&Focus=303310#Comment_303310 Sat, 16 Sep 2023 15:27:49 +0100 djh