Sparrowhawk

Here you go From the eaves on the en-suite side of the room, it will be 100mm air gap and 50mm PIR, and then plasterboard. But here I would hope there's PIR against the wood forming the window surround. And then more given the depth. I don't want to strip off the plasterboard when other places are far colder but it is on my list for "maybe one day"

I am struggling to get a measure of whether it is or it isn't. I haven't got a blower door made yet so I'm reliant on strong winds in the right direction, and the weather's not been cooperating. It could be a cold spot. The 19th was another cold day and this time I opened the windows. I wanted to see if the condensation stopped at the rubber seal or went up the frame alongside the pivoting bit containing the glass (whatever that is called). At the bottom there was the bigger patch of condensation again. I am satisfied these are cold bridging. Here, the condensation stopped at the line of the rubber seal. All along the rubber seal position was a line of condensation but it didn't extend above the seal. Fair enough. At the top corners the condensation went up further all the way to the external seal (the rubber gasket round the pivoting bit comes at approx 1/3 of the height down the white frame here) There was also frozen condensation further up in the window To me the fact the condensation doesn't stop at the seal says there is an air leak at the top corners. Whether I can make Velux understand that the condensation isn't the problem and what it shows is, I doubt it. It's a cavity walled house. I'm under strict instructions not to post photos of the bedroom in its "lived-in" state, but this room is in the 2001 extension and in cross-section is a triangle with its top point cut off. The roof extends to floor level but they put a little stud wall up to hide the end part (no idea what's behind that). The wall to the left is 2001 cavity, filled with either sheet polystyrene or mineral wool. The wall to the right is the original 1920s external wall, empty cavity. To get the radiator to work properly in this room you have to turn the radiators off downstairs to force more water upstairs. It gets to 13.5C max atm, and then we don't have the heating on in the morning until one of us goes down to turn it on. We will get this sorted when the new heating system goes in. Velux are right that the condensation should disappear with a lower RH, but to my mind the condensation is not the problem but a symptom of another problem: cold spots and maybe air tightness problems.

Another weekend, another hole...

I know, and yet I hesitate because of the cables in the wall. There's enough views on this forum ranging from "it's going to be okay" to "you're an imbicile to even consider it" that... I don't know. So I push on with other measures and delay making a decision fo what would be one of the biggest wins for insulating the house.

It's draughty at foot level in the kitchen so I took the kick boards off. There were a couple of bits of wood piled up in the corner which I hooked out with a hammer. On the outside there is an air brick at this point (single clay brick size) so I was expecting something. But perhaps an airbrick with a grille that I could tape over. This is an all-electric kitchen, no gas appliances. The bottom of the hole has plastic sheet on it (damp proof course?). I tapped the top of the hole with a hammer. The top is thin plaster. It's taller than it looks. How am I going to seal this up? It's behind a corner fitted unit. Lying on the floor it takes my outstretched arm plus a 15" hammer to reach the closest edge of the hole. I can't take the bottom out of the kitchen unit as the fixings holding the carcass together are on the outside butting up to the neighbouring units. Is cutting an access hatch in the bottom/back of the kitchen cupboard the only way? And then the best approach to cut PIR board to fit and tape the edges? Bonus question: is this how the sink waste is meant to be secured into the drain?

Velux have responded. Oh dear. My message to them, photos removed as same as above And their response:

Why's that? Aren't boilers sealed units venting to the outside only?

As scrap car radiators fans on ebay seem to go at a premium at present, would one of these 12" fans or these 16" fans be powerful enough to do the job? They're listed with the same CFM so I'm thinking the smaller one.

I need to stop being a parsimonious ***e and get one of these to try. For that kind of money have you considered a good quality backdraught shutter instead? The Naber THERMOBOX is the only one I've seen and thought "that's well engineered" about (I asked for other recommendations at https://forum.buildhub.org.uk/topic/30851-back-draught-shutter-recommendations/) but with an inline fan it'd be worth an experiment to see what it would do?

I need (okay want) to get an IR camera but I do have an IR thermometer. After wiping the condensation off the bottom part of the frame on both windows, that part measures 7.5C. The rest of the frame up the side of both windows measures 9.5C-10.1C (close to room temperature). These sides are butting up with the roof construction which is 50mm PIR between rafters. My guess for the bottom section is the installer hacked back the PIR too enthusiastically and didn't foam up to the window. Could be the same at the top, but the Velux foam collar should've dealt with this I'd have thought.

On my windows the trim strips are glued and caulked into place. My approach is to use a Stanley knife to cut through the caulk (trying ever so hard not to slip and cut the UPVC window frame) and then get a scraper underneath or even a chisel to loosen an end. After that the whole strip can often be ben upwards and the now-brittle glue breaks. If you need new ones (can you fix it so they're no longer required?), my approach has to been to stick them with caulk or silicone sealent in place. Easier to remove next time!

Re trickle vent that's a really good point. I knew I'd seen this kind of condensation before on a frame, and that reminded me it was when I left a trickle vent open (on other windows in a previous house). Welcome to my story Last night the windows were shut in the bedroom & en-suite, but I married a woman who likes a cold bedroom, so (until today) the heating's been off in there. And the ceiling mounted extractor fan in the en-suite lets a draught in. Mind, by morning the rest of the house was 9-11 degrees so yes there's serious heat loss / air infiltration going on.

The wooden frames we replaced never had condensation either. Though being 20 years old and never revarnished the frame had split and the previous owner had removed the seal between sash and frame so they could still be opened...

I've been unable to track down the makeup, their brochure says: Thermal transmittance window Uw 0.92 - 1.0 Thermal transmittance glazing Ug 0.5 Energy transmittance g 0.47 The other Velux we had replaced in the Study has had ice on it all day long.

I thought so! Velux said (direct quote) "The seals look fine" when I raised this.

We had two new Velux UPVC windows fitted in November 2022 and went with the 62 glazing as top of the range. Codes: GGU PK10 0062 with BDX PK10 2000 When -1C/-2C outside we've had condensation on parts of the frame, and I thought they had slight air leaks at the top. So I got the installer back who said "nothing to do with me" and raised with Velux Technical support. Velux technical support have said that "Condensation is an environmental issue, there is too much moisture within the room. You have used BDX collars so we know the window has been insulated properly." Photos from today The room was at 61% RH at 10.2C this morning. -1C outside according to the Met office, feeling like -6C. In the top 4 corners, we get corner condensation on the frame. This is where I thought/think there were air leaks, assuming that was cooling them down: At the bottom on both sides of both windows, for 8 inches up from the corner we get condensation: The glazing gets some condensation round the edges of the entire window, but I was expecting that (triple glazing isn't a miracle, right) So... Is this normal/expected? If it was too much moisture within the room as Velux say I'd expect condensation around more of the frame, not specific areas. As a comparator we had a third Velux replaced at the same time in a different room in the same aspect. It's a cheaper GGU PK10 0068 with EW PK10 6000 and has no condensation issues (but is in a room we don't sleep in). RH in that room this morning was 54% at 11.1C.

Thanks all! The trims and quadrants being the "strips of shame" between the window and the wall? I removed a section in the autumn. Behind it was... the open cavity. With slivers of daylight visible around between the outer brickwork and window. Instead of plastered window reveals we have the original half inch timber which was cut back when they installed the windows. My plan is to rip it off this year, close the cavity, seal the window to the new closing, and get a plasterer in to make good. As you can see, 3 trims stacked on each other between the window sill and window! Would this go along the edge of the outer wedge gasket? Thanks, jit seems such a waste (as well as unnecessary expense) when the UPVC is okay. And thanks for the link to replacement glazing, exactly what I wanted to see what it'd cost. How would I find out which paths are required so as not to muck it up? I drilled and filled the joint between a UPVC door frame and the abutted window with foam last winter as the extension had settled since it was built and the mastic pulled aprt, so (again) cold air came in through a half-mm gap up the join. Foaming that made a massive difference. I was wondering how to get the beading out, so many thanks. Now to find a few YouTube videos and see this in action. These windows regularly get hit by 40mph+ gusts throughout the winter months and these rooms are "breezy" - if I close the door out of them and put my hand under it, there's a stream of air. I can't wait to have to worry about ventilation

I keep coming back to this idea, it appeals because it would solve the airtightness issue alright. However it's a one way shot with no comeback if there's any problems. As I found a half-brick missing in the inner-leaf of the cavity in the first floor void where they'd dropped wiring through, I think I need to find and seal these up first before thinking further about cavity insulation, to stop the house being filled with foam/beads/insulation! If there's one of those in every room that's a heck of a lot of holes that are letting air in.

Thinking about the bay windows:

Our house has south facing UPVC double-glazed bay windows in one room upstairs and downstairs. I'm looking for advice for what to do with them. We don't know the age of the windows but maybe 25 years old? The frames are in fair condition, we had a locking mechanism replaced as it had rusted solid (coastal location) and bits are rusty but otherwise okay. However, airtight they are not. The bubble gaskets on the opening windows no longer seal and I'm replacing those, which makes a noticeable difference. And has made the air leaks around the glass panes more noticeable (marked by post-it notes above) The windows face the prevailing wind and the mould in this one should've been a giveaway that air and moisture is coming through, even before I went round with a candle finding draughts. Looking at the rubber seals around the glazing units they look worn down (for want a of a better phrase) and aren't angled up the glazing like they are on other, 20-year-old UPVC windows. I suppose these draughts can be sorted by taking out the panes and replacing the rubber seals around them. But then if removing the glazing, what about replacing it with new glazing units? They'll have better U-values and losing less heat out through the windows in winter would be good. I haven't got quotes so not sure what the costs are like. And then the option that gets every double glazing company salivating. Full replacement. I know that's not going to be cheap but don't know the price jump from replacing units to replacing it all. As brief background we're doing what we can to stop draughts and insulate, but it's never going to be passivhaus and as we live in it we can't strip it to a shell and rebuild. There is a cost balancing issue here e.g triple glazing would not make sense given the thermal inefficiency of the rest of the house, and replacing these windows probably wouldn't either. The north facing ones on the other side of the house, maybe have a better case. What difference would replacing the glazing units make? Anyone done that and sourced them themselves?

I've been thinking about this and a few possibilities are: to get a power station built there may be contractual purchase amounts. So always going to be some as would be more expensive to tell that power station to "shut down" ability to ramp up quickly means the power station has to be already running, so must keep it generating at a low level Be interesting to hear from someone in the know about gas power stations.

I found this 2020 PDF: https://www.gyproc.ie/sites/default/files/The White Book Oct 2020.pdf For the 2022 version it looks like you have to download it in chunks rather than as a single PDF, starting from https://www.british-gypsum.com/specification/white-book-specification-selector/white-book-overview

That's a good idea, I've done it for eaves cupboards and it works very well. The step is a bit of a problem as my dear wife is not the most coordinated person and I can see her catching her foot on it and going flying... I'll mock one up and see how quickly she injures herself Thanks, TIL those existed. It looks like I'd need to cut more off the bottom of the door to make it fit and/or cut it at an angle (an excuse to buy a track saw?)

Started my first side-thread on the door into the garage: