G and J

Do you use the fancoils much?

Thank you. That’s a well done for J. I did the polystyrene and the (*&#£*!!! ing) PIR in the floor. J does the walls.

Just looked back at our quotes from our local Jewsons. EPS70 was less than £47/m3 PIR (foil faced) was less than £87/m3 Both for 120mm thick 2.4m x 1.2m sheets held in stock locally at their suppliers.

Is that assuming a BnB floor with the underfloor void being the same temp as outside? One of the reasons I was pleased to go first a solid floor was that the ground under would be a more constant temperature possibly 7C.

If we could do a calculation to determine the total carbon footprint of option a - keep the gas boiler till it dies then replace with latest tech, presumably upgraded heat pump, vs option b - bin the gas boiler and replace immediately with today’s heat pump, I’d be shocked if option a cost the planet less due to the wasted resources out into the boiler. I’m dead keen on renewables. We even paid a daft amount to have gas removed from site. But it’s easy when it’s effectively a blank sheet. Sadly such an analysis would be so affected by multiple assumptions that it would be hard to believe in it. But gut feel says your wasting the planet and your own money replacing newish kit now. But who can really know?

Oh I like these new year confessions as it makes me feel less uniquely dumb. No less dumb, mind, but less alone in my folly. I think I’ve done the same damn stupid thing three times. Carefully put catching bowl under sink trap. Skilfully dismantled said trap with spilling a drop. Then thoughtlessly dumped the nasty water from the catching bowl into the above sink. Sigh.

Allow me, (in my post New Year’s Eve socialising, sleep deprived, just driven 3.5 hours and me adrenaline left the building about 5 miles short of home state), to translate into buildspeak. ”Dunno. Hard innit. Better put enough in to stop anyone moaning, which means too much. But sod it, it’s cheap enough.” :-/

Just for you. Frame insulation: Then VCL and more timber battens and an extra 60mm of mineral wool.:

Thank you. We start the new year with our chilly having a birthday at Christmas. With him and me on site the average site age has just risen to just over 70. You’ve heard of Jerry built. Well ours is geriatric built. lol

I’d strongly agreee, using a piece of wood knelt on as a guide for me really sped it up. Both polystyrene and PIR made mess, but for me only PIR was unpleasant.

We ended up with 335mm to 345mm to fill to get to FFL which includes screed with UFH. I am keen on a good thickness screed so wanted circa 100mm. So for us the insulation thickness was given. We want the biggest living space we can fit in to our narrow plot so our walls haven’t the most fantastic U values so to an extent the floor and ceiling can sort of compensate a bit, so I targeted 0.1 for the floor. Going from the architects suggested 0.13 U value to that felt ok, cost wise. Beyond that felt silly.

Because I’m not on site today I just calculated that had I gone for all PIR instead of 120mm each of polystyrene and PIR the payback (assuming underground temp of 8C, COP of 4, peak time electric cost, etc.) would be in the region of 117 years. Hmmmm. Perhaps a good illustration of the diminishing returns of insulation.

I’ve heard of ash felt floors being laid in old places which as well as being water resistant, apparently made the places warmer than they were (probably was bricks direct on damp earth or the like). It would be interesting to see how homes are built in 50 years time given the pace of change.

How long before some clever wotsit comes up with a self levelling compound, made in a lorry on site and pumped in, that also functions as a DPM. Until then we’re still talking sheets. I accepted a slightly higher wastage (~4%) as I didn’t want small bits and when I planned it out that required a couple of near half sheets spare. Some of that had been used elsewhere like the former for the shower tray to exclude the screed. Unusually for me, the sheets went down almost exactly to plan. I think the only change was to make the PIR layer slightly easier to get as tight a fit as I could.

In the excitement of moving soil from a heap to a hole I forgot. Sorry. Will try harder!

I think you need a certain number of air changes per hour to keep all fresh. With trickle vents it’s a blow through. But with MVHR one still (as I understand it) get a good flow through if fresh air. It at first appears confusing that we have a really low air change score to make MVHR worth having, but that’s a test of the leakiness of the house, not the number of air changes that a good ventilation system will give.

I honestly couldn’t disagree more. But as we’ve not built the house yet my opinion is not based experience, just theory. However I do know from experience that moving air takes a lot less energy than heating it.

We’re self builders. Faffing is what we do. Why do the obvious when one can avoid doing anything for weeks while researching? 😕

I’m not sure I agree that it’s impossible to calculate a payback for the cost of MVHR because using Jeremy’s spreadsheet our heating requirement is a lot less than half of what it would be with sub one air changes per hour compared to say five air changes per hour that you’d need with a non-heat recovery system. However, the extra spend to get airtight would be quite difficult to calculate and indeed we’ve not done a cost benefit calculation in payback terms, we’ve gone for it just as an act of faith for comfort. So despite it being theoretically possible, I think calculating payback for MVHR for us at least is rather pointless.

Me too. Big time. I’ll take and post some pics tomorrow but you really should get out more lol She has served, and hopefully will continue to serve, with distinction. Bless her. I’ve become quite attached.

PS. Regardless of economy polystyrene is so nice and easy to work with - the spring in it means you can easily get it really tight - for me that makes it worth serious consideration. PIR May have a better lambda but the better fit of polystyrene must compensate a bit methinks.

I was dead set on 250mm of polystyrene with the DPM effectively sandwiched in the middle. Our slab however came up higher than planned so we ended up with 240mm of space so we converted to a PIR layer atop the polystyrene. I sort of priced various options using online prices and almost ended up designing by spreadsheet. Then I talked to my favourite building supplies bunch. A few mildly confused emails led to a clarifying phone call and it being pointed out that if I used 120mm of both then stocks are held locally and a good price could be had. Suddenly it got easier. We got prices matching or beating the best I could find online. So given my experience I’d have a coffee with the most helpful local dudes and see what they suggest. I would not contemplate a step in the DPM. I’d put a flat layer of polystyrene down then the DPM then vary the above later. I found to get good straight cuts in PIR I had to saw and 120mm is not much more nasty than 50mm. Both I found horrible. But I did notice that when the foil face became detached the sheets were much weaker and had to be handled more carefully. I suspect one gets less horrid dust with foil faces too.

Once upon a time a deluded wrinkly, his much less wrinkly wife and their noisy little dog left their almost fairy tale rural retreat to live in a freezing rented bungalow while they buggered about trying to build a new semi-urban retreat nearby. (How clever am I avoiding the word suburban!). Everything would have gone swimmingly but for the fact that the head of the wrinkly was just too full. It sort of still is I think. In the four months since the last post (stop thinking of a bugler at sunset even though some days that feels appropriate) much has been done: We’ve built a garage and the front of site is much less of a moonscape. All our blockwork is in, much of it rendered. We’ve now got one flat roof and two slated rooves, one with loads of solar panels. All our windows and some of our doors are in. We’ve got 240mm of underfloor insulation and a circa 100mm sand and cement screed with lots of buried pipes, of both the heating and soil varieties. The screed alone changed things to more house than warehouse - fabulous. Almost all the internal wall skeletons are back up - so now we get a much better feel for the layout which is a very good thing. (We built some downstairs walls earlier but took them down to make the DPM and insulation easier.) Most of the frame insulation is in. There’s even loft insulation in the loft - ok it’s still in its rolls ready to be fitted but it’s still there, patiently waiting. And there’s some VCL in place and we’ve made a start on the inner skin - some battens and yet more mineral wool to form what is really an insulated service void to give us a half decent wall U value. The man cave has its insulated metal panel roof and is usefully storing tons of stuff. All the service pipes and wires are buried in a trench ready for connection to said man cave which meant yet more depressing hours on a digger, and now the back garden is a moonscape. A humongous insulated twin pipe monster conger eel of a thing is buried, surfacing at the concrete plinth for the heat pump at one end and in the under stairs cupboard at the other. We have surface water drainage pipes installed at the back. Phew. No wonder we are worn out. And I’ve probably left lots of things out too - when you are on site every day it’s so easy to forget what has been done and focus instead on the rather elongated to do list that keeps me awake at night. Not every night mind, some nights are a lot better than others and I am getting a vaguely sensible amount of sleep more nights than not now, thanks to constantly talking stuff through with J. But there is an essential difference in the build. Before we sold Bramble we knew we were running out of money so we weren’t going at full hurtle. I had a twenty minute drive to and fro and a soak in the bath, all of which helped me keep my head in the game. It felt like there was time to think. Now I have a twenty second walk (if I dawdle) to and from site. Despite the ice box (aka rented bungalow) having a really powerful gas combi boiler it has a low power electric shower that dribbles just enough water to get clean but not get warm. And we’ve the money we need to complete, so it’s warp factor 8 Mr Sulu. Now if I was doing this on my own I’d have no choice but to slow right down, and try and get my head together, and feel in control again. Thankfully we are totally in this together, so we aren’t slowing down. Not that it’s without tensions. J and I talk everything through and she keeps track of tons of things that I can’t (hopefully everything that I can’t, which is an unfair burden but that’s how it is). We identify short term priorities and I focus on them, with me tacitly accepting that I am not personally in control of everything as for me to be so would mean a lot slower progress: neither of us want to stay in the ice box a day longer than strictly necessary. So the tightrope act is to balance keeping the pedal down as hard as possible without us actually losing control or allowing any major cock ups to occur. Simples. It gets harder when there is anyone else on site but ourselves and Rolly, our chippy. Peeps are incredibly (and I believe unconsciously) attention hungry especially when their needs are coupled with my need to monitor all work and limit disturbance to the neighbourhood. It’s so frustrating that when a contractor is on site my own productivity declines enormously. And then there’s the gargantuan mess, especially in one particular case - the thoughtless dumping of spare stuff; the treading of material up and down the road without a care for the frozen moron still sweeping and hosing down the road in the dark hours after they’ve finished their second pint; the drifting flocks of discarded paper bags mixed in with fast food packaging. Sigh. At least everyone we’ve had on site so far has done excellent work, so that does compensate. The feeling of a lack of control is not helped by the fact that I’m completely useless at estimating the time needed for tasks - though as J frequently mentions we’ve not done lots of this stuff before so we should accept that we can’t know. The DPM and underfloor insulation took me many, many times what I imagined and I’ve a black belt in beating myself up. I enjoyed doing the lower polystyrene layer, so nice to work with, but hated the PIR layer. The polystyrene has spring in it and one can cut pieces a little oversize, lever them in and get a really nice, tight fit. It’s messy in that little baubles of white stuff get everywhere but they don’t get down your throat. PIR however is sooooo different. The dust it creates is truly horrible, it lingers in the throat many hours later even if a mask is worn, which it mostly was. It almost appears to shrink away from it’s neighbours - when cut to precise size and shape, wrestled into place shooting showers of nasty dust up as the air trapped underneath is expelled through the tiny gaps at the side - it still sits there showing a small but definite gap between the sheets. Not at all satisfying. Thank heavens we ignored the architect and chose not to put PIR in the walls. So it turns out that there is a job worse than moving tons and tons of crush. But thats now done, thank heavens. As an aside I’d planned just polystyrene, but the reinforced slab came up a bit more than planned so I switched to part PIR to get the insulation level I’d targetted. Note to self: get quotes for different thicknesses of stuff before deciding. Buying stuff that local suppliers have on hand saves tons, which accidentally benefitted us on the underfloor insulation - had things gone to plan it would have cost us rather more for the same insulation performance due to me designing in theoretically available sizes. Odd world, innit. The need to book contractors is a real source of pressure. An example: We have been recommended a plasterer who everyone says is brill and so is v busy and we don’t want to lose him, but that means guessing a timescale and thence sticking to it. I’m an ex-project manager. I know that to manage the project requires knowledge of the timescales for each task in the train, and as above - I really don’t have a scooby. Well, I do, but Skooby the Skoda probably doesn’t count in that regard. So, in summary we’ve got tons done, but tons still to do. Xmas has annoyingly punctuated the project but that’s probably a mental godsend - at least I’ve a popped ballon to enjoy putting in my empty honey jar. We’re working really well and closely together as a couple and I will get used to the feeling of panic just below the surface that not feeling personally in control causes; the foreboding that I cannot be confident that I haven’t missed something important; the relying on J that will deliver much faster progress. You never know, my next post might even be a bit about the build…

You probably know this, but just in case, the first lot we grabbed didn't have the adhesive skirt, so would have needed to be manually taped to the visqeen barrier. We swapped it and the stuff with the skirt went down in no time and did the job of containing the screed perfectly.

Presumably the stripping is in the quote? And scaffold? Our solar is only on one side and in one block, but it took longer than the other side to do, and the roofer came before the solar was installed to help the solar guy set out to make sure he could do best job of setting out the slates. In the end for the same m2 the roof with the solar in was 50% more cost in labour than the roof without.. does your quote take into account working around the solar? If so I can see that adding significantly to the work. We also do not have any roof windows, or valleys. All that said your quote does seem high......however others may chime in.