You can get thermally broken fixings: essentially a screw with a plastic collar. The screw goes deep into the collar which might protrude 30mm above the head of the screw. The plastic doesn't conduct heat very well.
eg
The foil backed stuff tends to delaminate from the foil fairly easily, so I wouldn't rely on glue alone. The battens however will be screwed into whatever's behind and spread the load across the insulation so it doesn't droop.
Theo
JOOI I asked the architect at an Open House weekend 10 years ago what it had cost to bring his modest Victorian mid-terrace up to close-to-Passivhaus. Around £200,000. And that was with internal insulation at the front as he couldn't get planning permission for external.
I wonder where the costs went. Assuming you're starting with a shell (ie empty and due for full redecoration anyway) I don't see it being that expensive to thoroughly insulate and seal everything. Quite a bit of labour involved but not intrinisically complicated. I'm thinking tens-of-k not hundreds-of-k.
Maybe there was a lot of fancy windows involved, or maybe they were doing an extension as well? Or if they were trying to live there at the same time?
Theo
This was not DIY. And it was in London.
IIRC some of the biggish items were:
- replace suspended wooden floors by solid (else risk of rot and hard to get good UFH)
- new windows (triple glazed) moved outwards ('cos of the extl insulation) and some also sideways (as a result of adding extl insulation to rear extension wall)
- external insulation & render
- new roof [wd at v least need to extend roof & upgrade roof insulation]
- new CH with UFH
- rewire
- new ceilings
- plaster & decorate throughout
Of course a lot wd be needed for any full refurb. But most people don't do the floors and wall insulation or go for such good windows.
As I said, you can buy plasterboard with foil then 50mm of celotex behind it that can be dob-glued onto raw single brick. Or glued to studwork attached to the blockwork
Fast and very effective
Well it depends on size, but of course you are looking at stripping out the interior completely, probably lifting the floors, replacing all the windows, lining all te walls, replastering, re decorating etc etc.
I think from a shell to a completed livable space is usually about half the total cost. And you would re wire and replumb and redo all the bathrooms and kitchens as a matter of course.
As I said in an earlier post, if its not a terrace, I'd be looking at knocking it down and starting again. Or the neatrest equivalent - gut the inside totally and replace it
I think £200k sounds cheap.
John Prescott did that to many streets of big, old drafty, moth-eaten terraced houses in the North West but failed to replace them.
That's what I did to the North-facing front of my house. I dug out the ground floor screed, removed the sand/cement plaster from inside of the front wall (to strengthen the fractured joints in the blockwork - 1976 built where the mortar dried too fast in THE heatwave) then applied
50mm full length Celotex sheets fixed to the wall using 30mm battens cut down from 95mm CLS treated framing, so three battens per original timber. Battens fitted horizontally and fixed with stainless steel frame anchors into the original blockwork, and used 30mm Quinntherm (much more accurately made than Celotex) to infill between the battens, followed by 9mm PB and skim.I also ripped all the plaster off the window reveal and pulled off the galvanised mesh from the lintel. I made up my own foil-backed PB using spray adhesive and Turkey wrap and boarded out the reveal using Foaming PU adhesive intended for fixing PB to effectively make my own insulation backed PB to the exact thickness.
Doing the window reveal was most of the work.
This gives 80mm PIR inside, plus a 65mm cavity filled with rockwool, plus 70mm on the floor in between 75x25 battens screwed into the slab with a 2nd 1200 gauge dpc
Flooring battens fitted with 250mm spacing so that I could use Wickes 18mm T&G flooring (2009), glued to create
360mm wide planks the length of the room. Each plank then attached to the battens with Spax screws through the tongue. I predrilled and countersunk the hole. Laborious but my time is free. There were many short bits in those packs of Wickes flooring hence the need to glue several to create big structural planks (that don't creak and wobble).If I had done more research I could have bought decent hardwood flooring in longer lengths for not much more.
I might get some quotes to have the end gable wall externally insulated and rendered. Faces east, and only has 65mm rockwool filled cavity but the brickies threw all the 'snots' down inside the cavity so that I had a solid wall for the 3 courses above the dpc (now removed from the inside) but I expect every wall tie will be encased in a big glob of mortar snots which creates lots of cold bridges.
Ah yes, thanks. They've come on a bit since I last looked. I used 25mm battens with 25mm celotex in between, then 25mm lapped over the top. Not ideal but easy to do.
At £100+ per 25mm 4x6 sheet . . . that's going to add up.
Rigid insulation board, batten over, drill a hole though the batten, insulation and into the wall. Then insert a long screw with a wall plus started on the end of it. Tap it in until the plug is seated in the wall, and then drive the screw home.
You still have a tiny cold bridge on the screw itself, but the plastic plug gives a small thermal break at the far end of the screw and ultimately the head will be under plasterboard.
Once the battens are on, they hold the insulation.
You don't have to use glue at all - you can get nylon "hammer in" fixings for insulation boards - you drill a hole through the board and into the wall, then inset the fixing, and hammer home its nylon "nail". E.g. (one of many):
All combination insulation products cost extra. Plain pb, pva & turkey foil are cheapest if you want that. Add insulation offcuts & you can do it very cheap and very slow. Just know your options.
But you need screws with heads that are larger in diameter than the size of the hole needed to push the ?plasplug through the batten or plywood, surely ?.
Frame anchors would achieve the same.
hardly a challenge.
at several times the price.
Yup... I think you will find they are called screws!
i.e. most screws of adequate size will also have a significantly larger head than a brown plug (which normally requires a 7mm hole).
For many times the cost, yes.
Ah, London. Where a modest Victorian mid-terrace can be several million quid.
That sounds like there was nothing left but the walls - they've essentially rebuilt it inside the facade and the internal walls. I'm not surprised that came in at 200k, since it's essentially a new house.
I could imagine that's a pretty good return in certain parts of London, if you turned it from something clapped out into an attractive family home.
Not sure why they went for UFH in a passivehaus though - the point of a PH is you need almost no heating.
Theo
+1
+1
Well it depends on the size of the house. And how many people are in it and what electrical kit
Even with HRV, there is a limit to how passive a house can be and still be warm, AND ventilated.
I suppose the site constrained it to some degree - one feature of a PH is orientation to make best use of solar gain. I imagine this site was neither oriented well nor had window openings optimised for that. So that would reduce your scope somewhat.
But I'd have thought a bit of electrical heating would be sufficient in a place so well insulated. I suppose if you went with electric UFH you might not want to put that on top of wooden floorboards, but solid floors upstairs sounds like a recipe for complications (not least you may have to reinforce all the walls downstairs to take the load, and you have nowhere to run services).
Theo
No, you put it underneath. It goes ceiling->celotex mouldings for hot pipes or resistance wires -> air gap ->upstairs flooring.
but solid floors upstairs
If you do use screed - and Ive seen new houses done that way - there is usually plenty of insulation underneath to put wires and pipes in or in
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