Sparrowhawk Posted January 21, 2023 Author Share Posted January 21, 2023 Another weekend, another hole... Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 5, 2023 Author Share Posted February 5, 2023 (edited) On 18/12/2022 at 21:00, Gus Potter said: Have you had a look under the ground floor.. what kind of solum space do you have, is the solum damp? 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. Edited February 5, 2023 by Sparrowhawk Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 6, 2023 Author Share Posted February 6, 2023 (edited) 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? Edited February 6, 2023 by Sparrowhawk Link to comment Share on other sites More sharing options...
ETC Posted February 6, 2023 Share Posted February 6, 2023 Demolish and start again. Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 6, 2023 Author Share Posted February 6, 2023 (edited) 1 minute ago, ETC said: Demolish and start again. I wish we had the money to! We bought 3 years ago so didn't get to ride the house price increases Edited February 6, 2023 by Sparrowhawk Link to comment Share on other sites More sharing options...
ETC Posted February 6, 2023 Share Posted February 6, 2023 Sell up and move to a more energy efficient house. Link to comment Share on other sites More sharing options...
ETC Posted February 6, 2023 Share Posted February 6, 2023 External insulation. New boiler. New windows and doors. Grants are available. Link to comment Share on other sites More sharing options...
Roger440 Posted February 6, 2023 Share Posted February 6, 2023 1 hour ago, ETC said: Demolish and start again. maybe a touch extreme. But doing it piecemeal is going to be a mightmare. If it was me, id have a caravan outside and gut most of it and do it right. Or move. Otherwise, fill up/seal all gaps, insulate the roof as best possible and call it done. Link to comment Share on other sites More sharing options...
S2D2 Posted February 6, 2023 Share Posted February 6, 2023 You've outlined the priorities well, it's never going to be pretty so chase your biggest issues first: Boiler/rads - new gas boiler and rads will solve the health-affecting 11°C indoor temps, even if it does cost an absolute fortune to run. Make sure the replacement is also suitable for the finished, insulated product. Then, you have until next winter to reduce that cost by improving insulation/airtightness: Loft is easy/cheap, fill your boots Remove cavity draft: ducting air bricks properly and sealing other external penetrations. If you're completely happy the cavity draft is gone, EWI is possible, but rewire and graphene bead fill in the cavities may be a more reliable way to add insulation and reduce any remaining hard-to-fix airflow issues. Ground floor starts to get into the serious disruption but absolutely needs doing, windproof but breathable is most reassuring to me for timber joists. When the drafts disappear and the house starts to feel stuffy you know you're on the right track, PIV is the cheapest ventilation solution or upgrade to MVHR if you're so inclined/like to close internal doors. Forget the house being super cheap to heat unless you want to move out and go for serious levels of disruption. Adding the insulation you can will get you well into comfortable and affordable heating, passive houses are just chasing the diminishing returns after that point. Finally, cost all that up first, include your time if DIYing and check there isn't another house that you could move to that would solve the issue for a lot less hassle. Probably the answer is no, but that will at the very least give you the conviction to crack on. 1 Link to comment Share on other sites More sharing options...
Marvin Posted February 6, 2023 Share Posted February 6, 2023 (edited) 2 hours ago, Sparrowhawk said: Of 35ish sockets in the house, 30 penetrate the cavity How to make these airtight?? Hi @Sparrowhawk At my brother in law's home I turned off the power to the sockets unscrewed the sockets to get to the back box, unscrewed the back box (screws usually screwed in sideways), mixed up some bonding quite thick, cleaned all the dust from the hole, dampened the sides of the hole, carefully filled the back and sides and coated the back and sides of the box and wiggled it into the right position with the wires sticking out the right length and left to dry. Scraped out excess bonding once dry, siliconed any air holes, tidied up the wall finish as required, refixed the socket when all dry and turned the power back on. I used a bag of very old bonding which goes off quick. Sometimes adding bits of block or brick to the hole if required. I think if you use hot water with fresh bonding it will go off quickly. @nod will know. Mix small amounts and practice until it works. Good luck M Edited February 6, 2023 by Marvin Spellingggg 1 Link to comment Share on other sites More sharing options...
Iceverge Posted February 6, 2023 Share Posted February 6, 2023 Closed cell foam in the cavity. 300mm of blown cellulose in the attic. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 7, 2023 Share Posted February 7, 2023 Make a DIY air leakage tester. Basically a fan in a bit of board that fits in a window aperture. It is easier, though not easy, to sort leaks out before they are covered in insulation. Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 19, 2023 Author Share Posted February 19, 2023 (edited) 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. Edited February 19, 2023 by Sparrowhawk Link to comment Share on other sites More sharing options...
SteamyTea Posted February 19, 2023 Share Posted February 19, 2023 32 minutes ago, Sparrowhawk said: U-value 0.27 How many m² and what is the ∆T. Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 19, 2023 Author Share Posted February 19, 2023 14 minutes ago, SteamyTea said: How many m² and what is the ∆T. 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? Link to comment Share on other sites More sharing options...
Gill Posted February 19, 2023 Share Posted February 19, 2023 1 hour ago, Sparrowhawk said: back of the house is opened up there are fewer places to locate radiators We've just started researching A2A as an option. I'm very much leaning towards this. We're electric only so this saves the disruption of plumbing /ASHP. Not quite the same use case as you but I like 'no rads' idea. If you stick with rads then A2A might be an option for the back. Would have loved ufh but with concerns about heat loss and suspended floor coupled with huge outlay put that idea in the bin early on. Link to comment Share on other sites More sharing options...
JohnMo Posted February 19, 2023 Share Posted February 19, 2023 1 hour ago, Sparrowhawk said: suitable ∆T as 20 Your delta T will need to much lower than that, 6 to 8 comes to mind. Your floor will be hot and cold spots with a delta that high. Also the floor heat output is calculated by the mean flow temp, the bigger the delta the lower the output for a given flow temp. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 19, 2023 Share Posted February 19, 2023 I worked out if the flow temperature, in an UFH system, was 32°C and ground was 8°C, the with a U-Value of 0.27 W/m2K, then it is about 400 W lost to the ground, and at 0.12 W/m2K, then 175 W will be lost to the ground. So about half the losses with better insulation. That is probably a worse case, so maybe halve it. But if you have less insulation, the mean flow temperature will probably be higher, so even greater losses. Insulation is not an exciting product, but it works all the time and consistently. While it might be easier to say that the losses are relatively small in the scheme of things, having UFH in the house will probably make it a nicer place to be. Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 19, 2023 Author Share Posted February 19, 2023 (edited) 30 minutes ago, JohnMo said: Your delta T will need to much lower than that, 6 to 8 comes to mind. Your floor will be hot and cold spots with a delta that high. Also the floor heat output is calculated by the mean flow temp, the bigger the delta the lower the output for a given flow temp. @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): Quote So if you have a 35 degree mean flow temp, the ground is -2, you have a delta T of 37. If your U value was 1.0 your downwards heat loss from your UFH water flow will be. 37x1=37W per m2, so over a 8hrs a 60m2 area would loose. 37x8x60= 17760Wh or 17.6kWh The same area with radiators and a room temp of 20degrees would loose [Edit ARRGH got the difference!] 20--2=22 delta T room to floor. 22x1=22 22x8x60=10560Wh or 10.6kWh Edited February 19, 2023 by Sparrowhawk Corrected nonsensical numbers Link to comment Share on other sites More sharing options...
JohnMo Posted February 19, 2023 Share Posted February 19, 2023 Sorry I may have jumped in without reading all the previous parts of the thread. When working out the heat losses from the floor with ufh you are using the mean flow temperature instead of the room temperature. Just to complicate things. The worse the U value the higher the flow temp has to be, to compensate for the downward losses, etc.. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 19, 2023 Share Posted February 19, 2023 (edited) 12 minutes ago, JohnMo said: When working out the heat losses from the floor with ufh you are using the mean flow temperature instead of the room temperature. Just to complicate things. The worse the U value the higher the flow temp has to be, to compensate for the downward losses, etc.. Almost. It does depend on what the losses of the building/room is as well. A floor slab is no different to a wall, except the angle it is at. There is a hot side and a cold side. The hot side is the mean flow temperature (give or take a little bit because it will have some concrete above it). The cold side is the ground, which varies with external temperature, but with a quite long delay/response time. The easy way to get an idea of what the ground temperature is, is to run the kitchen cold tap for a minute or two, then measure the temperature. Underfloor heating is generally considered to use more energy that radiators (which are really convection heaters), the amount extra used is generally considered 20%, but that is dependant on so many other things it is only a rule of thumb, just as easy to work it out more reliably with a thermometer and ten minutes with a spreadsheet. Edited February 19, 2023 by SteamyTea 1 Link to comment Share on other sites More sharing options...
JohnMo Posted February 19, 2023 Share Posted February 19, 2023 Sorry should have been more explicit, that I was just talking the floor, but you also need to take in to account perimeter, area ratio also. Link to comment Share on other sites More sharing options...
Sparrowhawk Posted February 19, 2023 Author Share Posted February 19, 2023 5 minutes ago, SteamyTea said: A floor slab is no different to a wall, except the angle it is at. There is a hot side and a cold side. The hot side is the mean flow temperature (give or take a little bit because it will have some concrete above it). The cold side is the ground, which varies with external temperature, but with a quite long delay/response time. 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. Link to comment Share on other sites More sharing options...
ProDave Posted February 19, 2023 Share Posted February 19, 2023 I think it was Jeremy that worked out with his super insulated passive raft foundation, that 8% of the heat into the UFH was "wasted" heating the ground under the house. But when the total heating into the house is not a lot, then 8% of not a lot is even less. We have a heated floor area of about 40 square metres at a U value of 0.14, so say 30 degree floor temperature and -10 under the floor worst case, that's 224 watts lost through the floor heating the air under it (suspended floor) With a total whole house heat loss of about 2.2kW at +20 inside and and -10 outside that is about 10% lost through the floor in our case. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 19, 2023 Share Posted February 19, 2023 2 minutes ago, Sparrowhawk said: 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. Might be. Outside Air Temperature (OAT) can be modelled quite accurately using a Normal Distribution. Plug in the mean air temperature for your area, adjust the standard deviation until he coldest temperature you have every known there is reached i.e.-10°C (or in my case -2°C), then multiply by 8760, which is the hours in a year. Link to comment Share on other sites More sharing options...
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