Sparrowhawk

@hoymp existing false ceilings, lucky you! Downstairs I am having to add 2, and flex ducting into one run between parallel joists across the more open plan section to prevent having to lower the lounge/dining room ceiling.

Welcome, it looks good and you have nice slow flow rates on boost. Slower than I'll have on boost at "design speeds" (not to be confused with this forum's idea of actual running speeds). You have a unit problem in column D of the spreadsheet, Volume needs ^3 not ^2. I'm not sure with J2 and J3 what those figures are? Are you planning to mount the MVHR above the stairs or in the loft? Good luck with getting the ducts coming out of it as you've drawn, I am fast coming round to the idea of home-made distribution box (as someone on this forum has done) to get the pipes out in the directions I need! Edit: Looking at your floor plans, which direction do the first floor joists run? Side to side?

And if you didn't want to go Mike's way then I'd look at blocking the 1620mm opening between lounge and kitchen. I know you want openish plan and free flowing, but 5 openings is going to make a comprehensive kitchen difficult. We nearly bought a house with a similar layout and the L-shaped bit bottom left in the kitchen made it workable.

You've not only got a lot of openings, but a lot of wide openings. Can you sacrifice any openings or narrow them down to gain kitchen space? Sticky out bits will help increase worktop area and storage:

Good to know, and nothing ever is. It seems too much water also overexpands the foam leading to a weak mess with large bubbles. I've tried this with the next bit and it's worked better with more foam than my first go. Problem was I was overthinking, as a small bead of foam gives less insulation at the edges than 5cm of PIR so was trying to minimise that amount that was just a dab of expanding foam. But getting it done and airtight ftw. I'll ask my local medium to communicate that to the builder 😁

Readable at https://archive.is/KPa77. Plenty of window-porn to look at. And house porn. There were some brands I hadn't heard of that the architects in the article mentioned. How airtight are they going to get though? I've understood that to be the weakness of all sliding doors.

Thanks those look useful to have. I also found spraying the smaller cracks with water is helping the foam expand and fill them.

The location of the struct is beyond the wall at the top left of this photo (under the floor in the next room's doorway) but this is where I was today. The joists usually run vertical (in relation to this photo) so I was caught out by the extra row of horizontal ones beyond the fire hearth - I thought that would be the last row. At least they don't run under where the drill is; that massive joist is the end of the horizontal stuff. And yes, at the bottom of photo in the entrance to the extension, the builders left it open to the cavity. Which explains some of the draughts.

Good idea, solid noggins would help with strength. I can fit 3 90mm or Flat 51 ducts through (it's actually nearer 33cm wide, but I lowballed here): or even 4 Flat 51: Cut multiple of these out of 1 inch timber and insert them back to back or spaced apart? I should have been clearer that all ducts need to pass through a single joist-joist gap, thanks to a significantly larger trimmer round the chimney breast than expected (there's a trimmer, then a second trimmer or a row of solid noggins 18 inches out).

2m from one wall of the 100 year old ground floor ceiling (3.4m joist span, 7.25m front to back) there's some massive timber herringbone structs, made from chunky timber (like this picture) I need to get 3-4 MVHR ducts through here and that isn't happening with this in place. Am I okay to remove it and replace with multiple timber/metal bars at the top and bottom, not crossed? I had a look for a metal box section to insert, or a meccano style angle girder contraption to build but couldn't find any. I've seen the metal X-bracing which are thinner but prob won't leave enough space, plus without taking out part of the lath and plaster ceiling I don't see a way to fit them to the underside of the joists.

Vitodens 100-W B1HF System 11kW GB. Noisier than expected, but we now reliably have hot water and the promise of gas burned heating the radiators not just going out the flue this winter, so all good.

I'm all for other people's OCD, it makes mine feel less Thanks for that, I'll apply similar logic to mine. We had a Viessmann fitted in June (and a previously undetected 4.8kWh/day internal gas leak sorted) so next year should be significantly better than this year.

How do you separate out the figures? I sat down to work out our kWh/m2 /yr and only have the 1 gas usage figure, so guestimated and deducted 4kWh/day for HW (cooking is electric here)

A very slightly off white e.g. https://www.tikkurila.co.uk/colours/white-paint/paper-f497 but anything that's not pure brilliant white will be good. And if it fits your aesthetic, wood planking on the vertical walls. (from https://www.scandinaviantrading.co.uk/)

I'm foaming PIR in place as a cavity closer with airtightness as the goal, where one wall is fairly straight and the other isn't. I've got Illbruck FM330 on the gun at present. 1. How small a gap can I foam? On the straight side I cut it fairly snug and cut V shaped notches to put the foam gun in. I thought the foam would squirt in then move vertically to fill the gap. It did that for a cm or two and then came straight back out of the notch 2. Is there a way to get expanding into small spaces? On the non-stright side, between some bricks there's angled gaps and the foam has stopped expanding before they're filled and airtight - preferring to expand along the wall rather than into it. I know that FM330 is low expansion foam so is this a) the wrong foam to use here b) something expanding foam won't do c) user error

It's a practice with (I assume) a good reputation and demonstrable work, and located in Winchester. There's certainly an element of this.

Are downdraft extractors quieter than overhead recirculating extractors? How well do they handle oil and pungent smells from stir frying and curry cooking? Yes but you need 1 pan to heat baked beans to serve with the pasties.

How do you compare their heat recovery to other units, as to me that's the benefit the PH certified MVHR units bring? There's a variation between the SAP and PHI heat exchange efficiency tests (PHI being closer to real world) which makes comparing the numbers between certified and non-certified units tricky - see https://www.heatspaceandlight.com/cheap-mvhr-expensive-heat-exchanger-efficiency/ for a discussion.

Yes that seems about right. If I could do more great, but there's 12.5mm plasterboard below the joist so doing the same 45 degree cut in that gains me another 12.5mm. There is a doorway in the wall above, so is only footfall that comes in over this part. This is looking promising.

30-34cm from this joist to the next (working on screw holes), and then 40cm spacing for the rest. That is where I'll be - a 3m span, and I'm 1-1.5m out from one wall.

I have a joist parallel and 6cm away from the wall I need to get my MVHR ducting through. The joist is approx 7 x 2 inches. Is it permissable to notch the bottom of a joist? In this case taking off a 45 degree bit where each duct goes, say across half the width of the joist. The guides online are all about notching the top. The ceilings this side are lower than the other side of the wall, so I need to go through at an angle and this would give more space to bend the ducting through 45 degress than cutting entirely through brick.

It tells you what you already know, but when you come to sell it tells your buyer something they otherwise have to take on trust. "Well insulated" and "airtight" and "not prone to overheating" - heard all those before from sellers and none were accurate. This is where I dislike certification, and particularly the ideologically-motivated AECB retrofit certifications. I'd rather that certifications for building (or retrofitting) well-performing houses were adjacent to certifying low-carbon houses. Reward people for making low-energy houses without mandating (as AECB do) that they install a heat pump. Many will as time goes on but you can save a lot of energy even with a gas boiler in place.

Welcome! I was new to DIY 2-3 years ago too; it's great fun gaining these skills.

Congratulations! At least it's warmer this time. I do like your stepped glazing in the doors.

Bumping this thread, as I'm considering Tecsound or Mass Loaded Vinyl (MLV) this to finish off my soundproofed floor, which isn't quite there yet (for airborne sound). Words are now indistinct, but would be good to cut the rumble of voices further. Currently have 18mm chipboard, gaps sealed with acoustic sealant 50mm glass fibre soundstop Plasterboard (unknown thickness) Adding something on top before I lay laminate flooring would be significantly less hassle than adding a 2nd layer of plasterboard to the ceiling below.