How do I bathroom / kitchen / extension? etc.

As long as gas prices are cheaper than electricity, wet underfloor should be better and cheaper in the long run.
As floor turns into a giant screed radiator and runs at lower temp, should be more efficient, but not as reactive in temp changes as electric.

Wet

Unless it’s bathroom sized?

Wet, fed from an air source heat pump.

Yeah, think wet it is. I have an electric mat left over from the last place (that chrisbmx never picked up either!) so might stick that in the bathroom

This has been my plan on our new place. However our Architect is trying to put me off and stick to a gas combi.
Why do you suggest it?

Why do you suggest it?

Switch to renewable energy.

Gas today is probably cheaper for you and easier to install but it seems to be a dead end.

From what I understand, an ASHP would cost about £30 less to run per year, hopefully that’d get better over time. To install, gas combi is about £2k, ASHP is about £10k, or £5k if you get the government grant, so the homeowner swallows £3k to go green(er).

Discovered Octopus have their own assessment and installation team so I’m gonna get them round for a survey. Just cutting out the gamble of finding a trustworthy installer makes it way more attractive already.

Ignore me, you've updated it.

And the rest if you have to upgrade radiators and pipe work, putting ASHP in isn't as easy as swapping a boiler.

But we’ll be doing those anyway, so there’s no cost difference.

I'm thinking about doing a similar thing.

Needs 28mm pipe instead of 22mm which are more expensive so will need to factor that expense in.

What ASHP are you looking at? I don't want a noisy one so am looking at the Mitsubishi Ecodan which is quiet enough that you can get round the 1m rule

For some reason i had this thread on ignore and only found out by accident, have just read through 50 pages in case i missed anything. major FOMO.
I wondered why i was unsure about posting questions in the DIY/Homeower threads when they were not DIY or about owning a home...

Report in bad traders thread as a time waster!

(Sorry, got caught up…).

On that topic, is it quite straight forward/cheap to add electric under floor heating to a tiny bathroom if we're having the floor taken up and tiled?

If you were dry lining some insulation (not much probably 35-40mm dot and dab insulated plasterboard to a late 50’s concrete slab floor/ceiling/cavity brick/block walls flat and fitting new rads/piping would you over spec the rads and go bigger bore with one eye on the future?

At the moment a ASHP is out of the question as leaseholder will not allow it, they will not even let you fit aluminium double glazing to replace crittall so it’s secondary glazing only but i think they will have to wake up and allow ugly boxes to be fitted at some point and possibly cavity wall insulation in the whole building.

I still wonder if this is ever going to be enough to ditch the gas boiler given there is only so much you can do to a building from the 50’s/60’s?

Yes

Unsolicited questions instead of answering your question. But. Isn't dot and dab insulation going to cause condensation/damp issues? Unless your vapour barrier line is 100%. Wouldn't a build-up with no cavity/void be better?

Well, i’ll take a steer when we get a quote but from what i have read you seal around the edge of each board/join both with tape and a continuous bead of adhesive. i presume it’s different depending on your wall being solid or cavity and if you have a membrane as part of the board(or not) but would obviously want to avoid interstitial condensation.
would remove skirtings and go right up to the slabs.

.

ideally you'd want hygroscopic material to avoid interstitial condensation and to upgrade the buildings moisture management at the same time - some kind of mechanical ventilation

Do you though? there are air bricks in the corner of each room and while the crittall windows are obviously not air tight, the addition of secondary glazing (decent hardcote LowE) will mean a lower amount of condensation in the bigger air gap as it acts to lower the dew point on the inner surface of the outer pane and move it to the inner pane which being warmer means you do not get the same 0º-22º plus moisture interface on 4mm of glass.
it’s on the 6th floor and cavity wall so as long as the joins between slab and walls are good then damp is only ever going to come from people/cooking/washing so an extractor in the bathroom would be a good idea but lowering the dew point of the internal surfaces is always going help, just don’t see how allowing that to move through the walls is a good idea?
A friend is building a hempcreate house and that’s totally breathable all the way through which is fine when starting from the ground up not trying to improve something 60 years old

fair enough, i'm mostly speaking from my experience of retrofitting a 110 year old solid wall place - sounds like it'd be quite different with a more modern building

but even still - insulating well removes the ability of the building to shed excess moisture. Still maintain that ventiliation beyond a simple bathroom extractor likely a good idea

We’re going for wet underfloor bc radiators are a pita

Really struggling with the micro-cement vs Doug fir choice. Can someone make the decision for me plz

Also we’re not planning on having sink or job on the island - are we savages?