gambo

1) Any good software I could use to calculate it? MRXBOXAB-ECO2B - probably slightly too small but I got it almost for free so want to test it first before going for something expensive. Also the house is leaking (old double glazed windows and no cavity insulation). 2) Do i need specific insulated mainfolds or just insulate it myself?

I'm finally getting closer to my diy retrofit but (again) stuck on ordering what I need. Assumptions: late 80s house, 4 people, 4 bedrooms, 3 toilets/bathrooms (once renovation completed), location in cold roof. 1) terminal vents are on the roof and the size of the pipe is adjustable. MVHR unit has spigots 125mm but it's a cheap unit and I may upgrade it in the future if needed. Shall I use 150/160 galv ducting from terminals to mvhr and reduce it at the unit? It will be 3-4m run with 2-3 90degree bends. 2) mainfolds - any particular difference between fancy looking ones like zehnder/ubbink and stainless steel from lidab/quiet-vent? 3) mainfolds - is there any reason why some of them say they are not compatible with comfotube? I'm doing pick-n-mix so am worried about something not working when I start installing it. 4) Noise Attenuation - where shall I install them and how many ideally? Only between unit and mainfold? I understand the need for one in supply but what is the benefit of having one on extract side?

That's a photo of bricks under window of the garage conversion

Just a random thought, could it be that there is no insulation in my concrete in either of rooms (late 80s house) but the reason it feels cold in the garage conversion is due to cold bridging from either the other garage or driveway?

That's what I was worried about. Lots of YTs and articles are from 5-10years ago, perhaps they tried to enter the market and it failed.

I'm in a similar boat and trying to decide how to insulate the ducting from the unit. Is there any best practice as to what to use? I can see different products ranging from flexible sleeves to some rigid insulation.

Why is VIP not practical? I have one quote for retrofit and it's £8k. So VIP would be just 1-2k and no mess. I may go for thin engineered wood or LVT but need to do the math on U values.

There is PB inside but I would be surprised if it was 2 layers or FR. So, is there any for-dummies description how such conversions should be done? I get that fire resistance is important so that's something I would rectify. What about floor? If it's just concrete on top of concrete shall I try to skim it and/or put VIP insulation +6mm cement board/plywood + engineered wood? What can LA say if I go for retrospective permission given it's 30yo?

Yes, thats how the wall of that room looks like inside the garage.

Apart from the cold floor, how can I fix this room? There will be a lot of mess done in that room so I don't mind redoing some of the work but have no idea what the actual issues are. Regarding the floor, what am I looking for when drilling?

We don't keep cars/motorcycles vehicles in the garage so fuel spills should not be a problem. The issue was flagged by surveyors but we accepted it. Question is what should we do now about it? Retrospective application for 30yo garage conversion?

I know it's not worth when comparing to energy savings but there are a few factors: We have to remove carpets and do something like engineered wood, I don't want to loose more than 10-20mm height, the cold feeling of the floor in colder days is really unpleasant. I've already have a small corner of the room don using 25mm PIR + engineered wood on top (nothing in between) and it already feels a bit claustrophobic.

No idea, we bought the house a few years ago. Neighbours say the conversion was done during the build but LA has no record of it. By the look of how it's done (eg.heating pipe running around sockets) it must have been done very unofficially.

Floor of the room converted from garage is level with the rest of the house. The difference between floor of the house (and that room) and garage floor (it used to be double garage so still one garage left) is around 200mm (+/-50mm). Hope that makes sense.

Mix up, I thought XPS was better but I've just checked that PIR has better parameters. I measured and the floor in the room is at least 150-200mm higher than garage floor and level with rest of the house.