Sparrowhawk

Yes, and working out which are worth it and which aren't is a guessing game unless I can find a better way to quantify them and the gains. It's tempting. Floors have to be lifted to deal with the major drafts, but beyond that is a hobby/labour of love. Let's say I take down this sloping ceiling and remove the current PIR. How would I make the replacement airtight at the wall plate and at the top where it enters the cold loft? I have found a lack of technical drawings for those two areas.

Yes, hopefully the extra photos help with understanding the room. Awesome and thanks for the correction. Out of interest if I used Joules per second instead of Watts, would 'Energy' then be the correct term? Indeed! I was surprised at the loss through the wall from keeping the neighbouring, mostly unused room, 4C cooler. Yes, though that is for a deltaT of 10C and with no ventilation heat loss, which at 3ach doubles the loss. I started this model as I found my wife freezing in her office with a 0.5kW oil filled radiator on max and the heating running. The room wasn't getting above 15-16C (unfortunately I don't have the external temperature for that day). On a still day when it's 10C outside she says the room will reach 18-20C with just the oil filled radiator and she has to turn it down. I need to measure the energy input but first need a new energy meter plug, as the kWh recorder on mine has got stuck.

It is draughty but a lot better than when it started! The problem now is that apart from the rafter joist ends (photo below) it's become difficult to track down the rest. Even at the top where the cupboard meets the plasterboard ceiling and there's a cold draught, but none stands out as bad bad. I suspect it's the good old 0.1mm (max) wide gap, but in multiple places and each 2.5m+ long. Here's a rafter/wall plate photo I left out of the previous post. There's 18 rafters at 30-36cm centres, and some are worse than this one. Yes I've had those too! Plus we have that where the central heating pipes come up through the floor, even against internal walls. I have to lift some of this floor before the structural engineer visits in 2 weeks so will be interesting to see what's below.

Photos first then replies! General ones to give a feel for the room. The green painted part is in the 1920s house, the white the 1997 extension. The piece of loose MDF is where I knocked out a built-in cupboard to make space for the desk and open up the room. I have done a lot of taping in the eaves storage to reduce draughts as it was like a colandar when we moved in. I presume the PIR behind the plasterboard ceiling is just as bad. Sealing the draughts at the top of the cupboard - to the windowsill, all along the ceiling edge - has gone poorly. I tried foam with an extension tube, caulk, and most recently Tescon Vana tape. Getting anything tight into the point of a triangle is tricky. On the opposite side to the bit I knocked out is the hot water tank. Note the pipes that disappear into the ceiling and run up - above the insulation - into the loft. WTF are there 4 of them (3 here, 1 from top of hot water tank) and not just 2? The neighbouring room has the same construction and eaves storage. I've emptied it to experiment and take up the flooring, and here are photos: I forgot to annotate that air leaks at the wall straps, because they create a gap around the insulation and it's impossible to seal properly. I'm not clear if I could do better taking out the PIR and replacing it - the wall plate interface is always going to be a weak point with poor contact.

I had little time last month but chased down a few air leaks, and I modelled the 1st floor room my wife uses as an office - model here with comments to explain each sheet. Anything look off in it? I did this thinking I could work out if the room is cold due to fabric or airtightness heat loss (I failed), but it's been helpful to see which bits of fabric are particularly bad and I'm now using it to plan what improvements to make. Some wins are clear - loft insulation (as much as the water tanks in the loft above this room will allow) and CWI (planned but later). Others such as replacing the 50mm of likely-badly-installed PIR in the sloping ceiling seem less clear cut. Due to restricted headroom I can't put more than 10mm insulation below the rafters so 100mm PIR between rafters is most I'd be able to fit. It should help with making sure there's no thermal bridging round the window and radiative comfort as my wife has her desk below it but is also disruptive. What do you think the actual u-value of that sloping roof is vs the theoretical value? And in your view worth doing or the effort better spent elsewhere e.g. IWI on the external walls?

Thanks @gaz_moose and @Spreadsheetman. My situation turns out to be identical to yours @Spreadsheetman. Some kind of contamination on/in the wall and yes I tried bullseye123+ first and it still bubbled. Zinsser cover-stain has sorted it - save I missed two areas and have to redo them! I ended up thinning it by 30-50% with white spirit as it was impossible to spread smoothly otherwise; at a guess because the wall is porous and absorbing liquid.

Thanks, I had another look today and yes it's got the shiny glass fibres in it. Will it have the same insulating properties as the glassfibre rolls in the loft or do I need to remove it and replace with other insulation? It's only in patches of the loft so looks like it's been taken out from the rest.

Buy up all the unsellable houses at a distressed price as a goodwill gesture, fix the drainage and sell them for a tidy profit?

Are joist ends a good place to use passive purple (other brands available)? It seems it'd be much easier than taping round them.

Hi @James Frome how did your meeting with the architects go?

House Planning Help has good episodes and a large back catalogue to delve into.

I pulled back a layer of pink glass fibre to get to a cable and found this stuff. It's pre-1989 I think, when the house was reroofed from slate to tile as there's broken slate in it.

Trickle vents became mandatory (if no alternative ventilation) on 15 June 2022. I'm going to disagree with the two above and say you don't need trickle vents; you've "got the window on the latch most days for the whole day" which will provide adequate ventilation so I don't think that is the problem. I note it's more the silicone at the top of the trim than against the window sill, so I'm thinking it's thermal bridging - in simple language there's a way for cold outside air to get behind the trim. If you want to start with the easiest option I'd remove the silicone and redo with bathroom-grade silicone (i.e. known to be mould resistant). But it'd be worth taking the trim off and looking behind if you're up for doing that. In my experience the supplier/installer will blame any mould on you and do nothing. Good luck but I feel you are on your own to sort this.

Mind sharing which ones you've used as I might need them?

As readers of my introductory thread will know, I live in a draughty house on a cliff top that gets pretty windy at times. I've yet to see anyone in this thread address the variable nature of passive ventilation and how you ensure you get enough ventilation when it's still outside, and don't overventilate when it's windy. I don't see a way to get away from a mechanical system if you want consistent ventilation.

Start a new thread; post the link to it into this thread so people can go there if they want to follow. And the forum moderators here can split out the OT messages from this thread into a new thread, and leave a pointer to where it's found?

Thanks @MJNewton for pulling the discussion back on track 👍 Recent commenters have said they want simple, so no fans/mechanical kit/stuff that can break, so what are the alternatives to MEV/MVHR/PIV for controlled ventilation? My experiences with uncontrolled ventilation says this is not an option as most of the time you're under/over ventilated. Which keeps pointing me back to airtightness + controlled ventilation for indoor comfort. Max Fordham specialise in buildings with natural ventilation, but talk to their office staff for a bit and they'll admit that it's fine until hot still summer days when the office overheats...

Have you had an asbestos survey done and do you have contingency for any "little surprises" that turn up during demolition?

Has your architect done thermal modelling of the property in that fee? Are there heat loss calculations for the property? What difference is the "40mm Ty Mawr Cork Insulation on external walls" making to the thermal efficiency? Once you know that you are in a better position to make that decision based on annual heating costs. Without an ASHP and in an all-electric house you'll be relying on an electric boiler to power the UFH? Personally I'd go gas at this point, in spite of the connection and later disconnection fee.

Wanna-be mid-range for people who want the look without spending the money. Nothing wrong with that but with the prices & fit & finish promised for this renovation they aren't up there. These are more what I'd call medium spec: https://www.astonmatthews.co.uk/axis-3-hole-deck-mounted-basin-mixer-and-pop-up-waste-scuffed-brass

Spec bands are relative so hard to say. You could get cheaper by getting items that'll do the same from Screwfix and upgrade later, but these 3 don't seem medium spec to me. They want to look like medium spec but in 5 years time I doubt they will feel it. Living on the edge of a forest that's New in Hampshire I understand all too well about price inflation! But as others have said your prices are way beyond what I'd expect a medium spec to be in London. Perhaps digging into the costs for Guy Hargreaves' project in Oxford - with restricted access for work plus a bigger house - will give you an idea of what you can get for the money: https://www.houseplanninghelp.com/hph322-an-enerphit-standard-retrofit-of-a-victorian-mid-terrace-home-with-guy-hargreaves/

That's my reading too unless you want to put any insulation between the joists?

What's the impact been on your hay fever? If MVHR means sleeping without issue during hay fever season plus a large reduction on symptoms indoors, that'd be worth a few thousand to me. For those debating running costs, Acrivastine (antihistamine) is £6 for 12 and you can need up to 3 a day. Plus nasal spray, plus... So a reduction in medicine costs plus reduction in lethargy and reduced productivity should be taken into account.

I haven't, I'll look out for them this summer when we're up visiting Skye - Inverness - Cairngorms. On previous trips, Scotland has felt closer to France than England in many good ways, and I should have scoped my rant to England!

I like it. We've got to lose our obsession with houses being beautiful in the UK. And by that I mean lots of brick, quaint-cottagey modern builds, that planning committees love judging by the fights people on this forum have to get designs passed. The continent survives fine with rendered everything (pretty on some but the new estates in Normandy aren't) and heading for the same look would make EWI retrofit - done this way or other ways - cheaper. I am amused when I meet people who are vocal about "buccaneering Britain" but also "preserving our built heritage". If we really wanted to be that country we'd stop holding progress back and get on with knocking stuff down and rebuilding without a second thought, as they did in previous, more "bucaneering" times. Rant over