Sparrowhawk

My house is so draughty that yes I'm planning to depressurise a room at a time to start with. I do have a second fan so if I need more oomph I can mount two in the door. Why a door? This was free and wood's expensive at the moment. Old doors are also cheap on FB Marketplace.

This is my blower door that's awaiting commissioning. My house has 4 5 different doorway sizes so plan is to tape plastic sheet at the sides/tops to seal it in. I am frustrated how oval the hole I cut in the door is. Am thinking of filling the gap or putting the fan in a tunnel (don't know what the technical term is) to guide the airflow.

Which is the other drawback with UFH on a suspended floor I guess (compared to a floor slab) - the cold side has a bigger range of temperatures say 10C more, and the rate of change is faster than the temperature of the ground.

@JohnMo Good timing, I was just searching for a post of yours I'd seen previously which I think will help quantify this. Found it: and also found I thought ∆T was inside air temperature -> outside air temperature, but here the ∆T is the difference between the water going in to the UFH pipes and the temperature of it coming out? If so 6-8C sounds sensible for a hypothetical system where the input temperature is unknown. Taking your calculation from the first linked post, and it looks like delta T here is the temperatures in the pipes/below the floor(?) if it's a suspended floor and the air underneath is a mimum of -2C and indoors is 20C and the water in the pipes an average of 35C, then won't ∆T by 37C? Trying not to butcher it (edits in bold):

Let's say the whole of the downstairs so (excluding internal wall thickness) 10.5m x 5.8 = 61m². I'm guessing at a suitable ∆T as 20 - -2 = 22K?

Since I got buy-in from my wife about lifting floors and disruption she's started coming up with ideas like "we could remove this wall, and that wall, and what about...". We're planning to get a structural engineer round to say which are load bearing and what would be needed to take each out (I think they're the right person to ask?). Her ideas are great but this could all turn into a bigger job than I anticipated 🤑 She also keeps bringing up underfloor heating. I am not convinced I can get enough insulation between (and under?) the joists to make it worthwhile - not without digging 10cm deeper below the joists anyhow. Modelling the floor: 100mm mineral wool with λ 0.038 and 18mm chipboard: U-value 0.27 150mm mineral wool takes it to 0.19 - but ventilation space is likely tight. 100mm PIR with 18mm chipboard over the top gives a U-value of 0.18 assuming perfect fitting between joists (hahahahaha) 150mm PIR takes it to a U-value of 0.12 What do you think? If not feasible this will feed into the 'removing walls' conversation as if the back of the house is opened up there are fewer places to locate radiators.

And the same supplier sells via eBay without the £8 (IIRC) postage charge on a single can of foam. Makes the pennies go further!

They said bills of <£200/month so that could be combined heating and living. Our annual DD is (was) £200/month for gas & elec. 90kWh/day in an older house for heating only isn't unreasonable in cold spells. We have been over that for 8 days in February, and December/January had more days. Averaged over the year... yeah that would be high. We need more info.

Hi Ant, there is a way to meet regulations with mineral wool: build wider cavities. @nod is an expert here and if he says you need more than a 10 mm gap then he'll be right. Though @nod why not just go for full-fill cavity instead of leaving a gap in new construction? No, it's the difference in the materials. Mineral wool can't compete with the U value of PIR boards. So you have to use much thicker mineral wool to get the same effect. Got it in one. If you use Kingspan or other PIR boards, be aware that the quality of installation makes a difference (from the data: seemingly quite a big difference) to the thermal performance. Gaps between the boards let air circulate, negating the benefit. This paper on thermal bypass is well worth a skim through to get the idea of the effect. If you care about how well the insulation works, figure out a way to ensure your builder spends time installing it properly. Then patent and sell your approach, as controlling builders is like herding cats

I saw that Gapogroup tape at NSBRC, one of those "why didn't I think of that?" moments. Feels like a thin latex foam with sticky foil over it. I do wonder how many decades it will last & stay springy.

I've also used Soudal flexifoam (which Toolstation sell) and it's good foam but the blue colour makes it hard to hide stains or spills. 3 hours it took to get an accidental drip off the middle of the wood floor in our lounge...

Illbruck FM330. If you want one or two cans, I found eBay is the best place to get it as the major company that sells it direct also sells there, and doesn't charge postage if you buy via eBay.

I wish we had the money to! We bought 3 years ago so didn't get to ride the house price increases

The cold in the last week of January broke us, and my wife has come to accept that disruptive renovations will be needed and that it's okay to do them. As @Roger440 said, we need a whole house strategy. The following are ideas for what we can do. They're uncosted and not prioritised, and I welcome any and all feedback. I've used @Marvin's excellent AIM to break down the tasks. The house Late 1920s extended twice (1998 & 2001) Cavity walls, empty + partial fill in extensions 4 bed detached Cliff top, 500m from sea. Windy! Rendered externally (cement) Suspended floors + concrete floor (ground floor) in 2001 extension The house is cold and draughty. It's started to affect our health - we can't do another winter at 11C with a couple of warmer rooms. Aims To retain heat in the house for longer To provide temperature stability To get rooms to 18C+ and keep them there To stop the (sensation of) air movement Limitations There are 3 floors in the house we are doubtful about lifting: Master bedroom in 2001 side extension Best condition floor in the house Laminate going under the skirting boards Could use ceilings below (garage, utility room & kitchen) to get to heating pipes if needed 20-25yr old engineered wood in lounge & dining room Lounge better condition We are coming round to lifting these as while airtight are not insulated My wife has come round and is eyeing up herringbone replacement flooring already, I have not yet! Airtightness New airtight front door between porch and main house Current is 1950s(?) and no amount of fettling will make it airtight Soft spot for RK doors but UPVC will do and might be more airtight! First floor flooring Remove skirting boards Lift floors Find the missing bricks in the inner cavity leaf and patch up Seal joist ends and penetrations into cavity inner leaf Front bedroom Ceiling is lath & plaster, with small cracks that let air in/out of loft. Put an airtight membrane over sealing, turn it down the walls and tape, and overboard with plasterboard Eaves storage Despite taping the PIR joints and PIR to joists, the eaves storage is still ridiculously draughty. I'm guessing it's the junction at the timber wall plate, half of which within the 1st floor. Hoping this can be done by removing the fascia/soffits outside (9ft off the ground); otherwise needs tightly fitted chipboard flooring or plasterboard ceilings removing to gain access. Will do a blower test first to confirm Under stairs Find where air is penetrating and seal it could be gap into under-floor area, or into cavity via the stair joists? Seal sockets that penetrate into cavity If not rewiring (see below) Of 35ish sockets in the house, 30 penetrate the cavity How to make these airtight?? Front bathroom Seal internally around soil pipes going through cavity. Of course, they're located under chipboard flooring under the bath Airtightness & Insulation Ground floor flooring If possible due to the sleeper walls? Definitely in hallway/toilet/study, as these aren't sealed at the edges letting air in. Potentially also lounge/dining room/hobby room which have engineered wood floors and are sealed at the edges. Remove skirting boards Lift and fill voids into cavity that aren't aligned with external airbricks Sleeve airbricks, so air goes under ground floor suspended timber flooring and doesn't wash the cavity Given the block-sized internal leaf hole in the kitchen aligned with air brick, might be problematic to make airtightish without lifting floors Insulate under them using Ecological Building Systems' method but using Rockwool for cost reasons Or... just seal edges. Won't be that effective as there are gaps between the floorboards under the vinyl. Wooden window reveals The original 1920s window openings have wooden sides rather than plaster(board). The cavity is open behind and where they've been cut back for double glazing, they're draughty. Remove wood and trim round windows, block cavity with 100mm PIR, foam/compriband gaps as appropriate, plaster reveal and fit new window sill New airtight and insulated loft hatch I've weatherstripped the current one but it is 12mm MDF with no insulation on it Windows Replace original sash in downstairs toilet, thin 2G in wooden frame in old back door location, 1970s UPVC in front bathroom [All for insulation only] Replace French doors with a set that are airtight & better thermal value Replace or recondition others? New seals New sealed units CHICKEN AND EGG Cracked concrete sills for 2 upstairs windows, need replacing as letting water in (currently silicone sealant in crack to 'fix' that) Suspect lintels are wood for the original ones due to cracking pattern in the render and should be replaced How to synchronise a builder to do with window installation? The older windows with concrete windowsills are in the inner leaf Would like to move them out to match the windows in the extension, which are in the outer leaf PROBLEM: new requirement to fit trickle vents... I don't want to do that!!! Bay windows As well as sealing the window surounds, try fitting some insulation below the window in the cavity (lounge) or IWI (front bedroom) and adjust the windowsill to fit The lounge bay window has an air brick into the cavity at above floor level (I think) For the lounge bay window, raise window sill to right level using Marmox boards under it, so 3 sets of trim aren't needed to hide the gaps Need to see if cost effective to recondition the bay windows with new 2G units And hard to measure the impact it'll have 3G bay windows would be expensive but provide radiant comfort indoors Also, heavy and goodness knows how well the bay is constructed Chimney in lounge Currently has 4 inches of insulation shoved up it. If not used for wood stove (see below) then block it properly Local roofers have no idea about this, only "You can't, must vent it" Bedroom & en-suite in 2001 extension Much of the floor is over the integral garage. The floor is plasterboard (garage ceiling) then 100mm yellow glass fibre insulation then 50/100mm air gap, then chipboard and laminate/tiles Take down garage ceiling Remove glass fibre insulation Fill with insulation batts Add airtight membrane and tape to garage walls Plasterboard over the top Not sure if this is worth the effort at this point as when the heating to the extension is improved the room should be warm enough. Insulation Increase all loft insulation to 300mm Use Rockwool for new stuff - more expensive than Knauf glassfibre but more pleasant to work with, so I'm more likely to get on and do the job It's a vented, gabled roof so I will try to put hardboard down the edges, then tape a windproof, vapour permeable membrane to it and cover the insulation to stop wind washing per this guide That is going to be much slower than just laying loft insulation! Walls... Either... rewire to remove PVC cables from cavities and then get the cavities filled Big job to rewire, expensive and disruptive Last rewire looks to be circa 1998. It's grey, modern cable Most architectural technicians I've spoken to are working with someone where the retrofitted cavity fill is gappy and causing problems We are clifftop by the sea and while the house is rendered, for caution I lean to keeping the cavity Or... selective internal wall insulation (IWI) in the older parts of the house as currently functioning thermally as single-skin brick walls And optionally cavity fill the now internal cavity walls - insert divider & fill only them. In cold weather we notice the lack of radiative comfort from the cavity wall between the lounge and garage, vs the internal wall between lounge and hallway. 1-2C lower surface temperature makes a difference when sitting next to it Heating Replace 25yr+ old gas boiler with... another gas boiler Without adding underfloor heating, don't see how we can oversize radiators enough for low-temperature flow in the depths of winter Will change depending on insulation choices Replace radiators Keep 2 modern ones, replace the other 10 as rusting and not emitting heat If lifting the lounge/dining room floors, should we consider UFH? Long response times put me off While the floors are up, get the daisy-chained heating pipes (extended with each extension) sorted if the heating engineer says the flow through them is the problem with the upstairs radiators. The radiator in the main bedroom in the 2001 extension is slow to get lukewarm Sort heating for our unheated kitchen Currently has electric panel heater that does bugger all Options are Somehow extend the central heating into it without disrupting the master bedroom floor Needs plasterboard ceilings below taking down = mess Better electric heating A2A heatpump to do kitchen, utility room (16m2) Wood burning stove? We have a chimney in lounge Don't like the air pollution so not keen, but would provide extra heat I like staring at flames. But muggins here always has to clean it Mechanical Ventilation Replace extractor fans with Iris ones Not convinced they will withstand the backdraught here, have approached them for info New kitchen extractor Ours doesn't extract, just makes a lot of noise Externally mounted fan preferred to make the kitchen quiet Needs good backdraught shuttering MVHR? I was at the NBSRC show in Swindon on the 27th January (fabulous day out!) and none of the MVHR vendors were interested in talking once they knew it was a retrofit with solid joists I know how I'd do the 1st floor, but the ground floor I cannot work out how to get ducting around without cutting holes in the joists Especially the kitchen MVHR alternatives? Pressurised Input Ventilation? Other Raise sockets from 1 inch above flooring on skirtingboard to higher so moulded-on plugs will fit the sockets Replace wood gable at front as the timber is starting to rot (as is one barge board). By the time we get scaffolding up there to paint it (and a builder to replace the cracked bathroom window sill) might as well make it last for the next 25 years Where next? I am feeling daunted by the scale of the work and deciding which bits are worth doing. What would you pick out from the list?

I found a 2" hole under the vinyl in the hallway so put a ruler and camera down there. From underfloor ground level to top of the original floorboards is approx 11 inches. Pictures are poor but looks like 1 brick + damp course (?) plus timber along top of sleeper walls, and then the joists on top. The sleeper walls run from front to back of the house (S->N) and the joists side to side (E->W) I saw no gaps in the sleeper wall so could one install underfloor insulation, as it would block sideways airflow? No dampness in sight.

Hard plastered - some form of breeze block and then hard plaster on top. Onto a maybe-insulated concrete floor but judging by the rest of the build, the min BRs needed in 2001.

Hard to measure the impact as it's warmer outside this morning than yesterday so is the 2C difference due to that or no hole in the wall, but the lack of air movement in the kitchen is noticeable.

The deed is done I had to wait until the weather warmed up to be above the "min 5C" temperature for the foam, and used a disposable Soudal can as the straw it came with was small enough to fit through the air brick holes without drilling them out. It took the whole can to get it to seal this plus back to the airbrick so I imagine the cavity has a bit of fill too.

Hi @Alan Ambrose Do you know why they're failing? Is it water being blown in between the frame and sealed unit that's reacting with the glue? Air pressure making the glass flex and breaking down the seal? Given the size I'm thinking the latter is most likely, but photos of the edges of the next one that fails would be helpful. Not answering your question, but when I asked on this forum about sealed units someone gave me https://www.sealedunitsonline.co.uk/ I also found https://www.glasstops.co.uk/ which has a bigger range of glass.

Hi @pyros and welcome to the forum. Congratulations on the impending arrival - you've got a well-positioned new office planned to ensure the noise won't disturb you! I am surprised no one has picked your post up as you've provided good detail. I suspect because of the forum you've asked in, but let's see if this 'bump' to the top gets you some feedback. I am very amateur and still working through my udnerstanding of what BC require for retrofits. My only comment is about your planned layout. Why put the bathroom at the far end of your office, rather than the end where you have planned french doors? My thinking is that having it there, with a corridor past the bathroom and then an entrance into your office makes the bathroom more accessible from the rest of the house. Yes it messes around with where the garage door replacement needs to go, but in terms of living with the finished house it seems more practical.

The width is 890mm. Measuring up the side of the window reveal is 14cm to the edge of the Velux frame / 18cm to the pivoting window. I am curious what's in there, might have to drill an inspection hole and have a look.

Our kitchen with the hole in the wall has 2 very cold north-facing windows about 20 years old. While outside looking at the airbrick I also had a look at these windows for the first time since we moved in and spotted a few gaps. Window A The one below isn't bad at least there's plastic at the back of it (unlike window B) Window B The gaps at the top should be foamed/caulked I think, but the one at the bottom where the window doesn't sit on the sill? Is this a drainage path and so shouldn't be blocked? Under the sills of windows A & B Under the sill there's some gaps in the render. Hard to photograph but again something I could fill & seal or is it a place water will drain away?

Did you get anywhere? I am pretty sure I have air leaks too but Velux technical services are impossible to make see reason.

That's my experience when using a 30cm extension tube with Soudal Flexible Expanding Foam Gun Grade. It changes the texture of the foam and it doesn't skin over in the same way. I think this way which you and @ProDave have suggested is the most practical approach and most likely to succeed. The outside of the house is rendered so the air brick can be rendered over eventually. Though I must take the tape off the air brick tomorrow and check the two line up!

The expanding foam cans I've used (gun-grade & not) have to be held near-vertical to work. Is there one that will work on its side under the units?