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Fill the side gaps with gravel.

I guess it might help OP to provide a list of key specs (and gotchas) to consider. Here is my starter for 10 (simplest, not necessarily most important, first) Output, specifically Max output at low ambient temperature and your design flow temp – some ‘rated’ outputs are overstated at low ambient Min output at high ambient temps – this matters if you are trying to design with a small or no buffer (but note that system volume for defrost also affects whether a buffer is needed or not) Max flow temp – only matters if you are designing for higher flow temperatures (eg >50), which you shouldn’t be doing. Physical size and placement constraints. All units require space around them and R290 units have some more specific constraints. Have you got somewhere it can go? Also will it meet the permitted development volume constraint if PD is a consideration Appearance – can you tolerate it? Weight – only matters if it is not ground mounted Sound POWER (nb NOT sound pressure which is quoted on an inconsistent basis). Can you meet the noise requirements (eg for permitted development) given the specified sound power? MCS provide a spreadsheet making this easy to calculate. Controls – Weather compensation is a must, certainly for flow temps above 35C. Less important at low flow temps but still highly desirable. Load compensation is desirable unless you have only UFH and/or your house responds very slowly to temperature changes. Night time set back also desirable/essential depending on your control/heating strategy and house time constant. Ideally weather compensation should allow a non-linear/multi point curve to be programmed, very a few do this. However its only worth a % or two in efficiency depending on your specific scenario. Load compensation to some extent negates the need to have non-linear weather comp. As mentioned by @markocosic and if you can find them out (which, mostly, you cant), things like the intelligence in the control strategy when its heating up (as opposed to running in steady state) make a few % difference to efficiency when heating DHW or recovering from setback. Third party controls, eg homely, can mitigate deficiencies but, as others have said, it means being beholden to a third party (or writing some code of your own). Claimed SCOP at your design flow temp - (but possibly treat with a pinch of salt?) Refrigerant - R410a (still around) has a GWP of 2088. With a typical 3kg refrigerant charge thats 6 tonnes of CO2 equivalent if the refrigerant is released(eg on disposal). R32 (very common) has a GWP of 675 (so about 2tonnes CO2 equivalent if 3kg is released) and R290 (the latest available, not universally rolled out) a GWP of 3, ie negligible. By way of comparison heating a typical house with gas emits around 3 tonnes CO2 equivalent per year. I have no idea if refrigerant leak is an actual problem – perhaps others do! Availability and servicing availability – as discussed extensively Quiescent power consumption - some older models (particularly, but not exclusively, Mitsubishi) consume 200W or so when doing nothing, to keep the compressor warm. This problem seems to have been fixed on new models, but there may still be some rogues out there. Expect approx 25W or so. Is it MCS listed if this matters Price None will score top on all of these, but this list will eliminate most for any specific application. Of course that wont stop salespeople trying to convince you that their wholly unsuitable unit is just what you need!

doing mine myself I thought many times that I'd hate to see the sort of job a builder and their labourers would do (not all of them though I'm sure!). the methodical and detailed work we did cutting PIR, membrane and taping I can guarantee that a builder on a price job wouldn't spend the time to do. I'm very glad I did ours ourselves but I wouldn't do it that way again as it was a horrible and slow job.

its hard to sometimes to stick to your guns when the so called professionals push back. I learnt that lesson on our first build. Never again, now i listen to them and make the call. Need a build under the belt to feel confident enough.

They don't have load compensation. Fairly useless for radiator setups. Less of a biggie for domestic hot water. They also don't have sensible control strategies for heating hot water cylinders (they just run balls out against a hysteresis stat) or for coming up from setback (again runs balls out until target flow temp achieved which isn't useful). You can mitigate by bolting on a 3rd party control such as Homely but this would mean being beholden to a startup company and internet connectivity and subscription fees. The second line was supposed so say "all FGas units" but got spelling autocorrected without me noticing. FGas is the high global warming potential legacy rubbish that lazy manufacturers use to delay investment in environmentally friendly refrigerants. Samsung are launching their R290 unit in a bit of a catch up rush late this year. Give it another year or so to iron out the crinkles and it'll be ready to use. I wouldn't touch it until then myself but I'm keen to avoid being guinea pig with cars etc too for the same reason. You might not care. R32 works. It's just crappy of them to be putting more of it on the market in this day and age.

For information....we were advised and can confirm, that our 900 long porcelain tiles all have a curve in the length. Adds to the challenge. Fortunately laying them to 300 staggers reduces this 3mm difference. I hadn't heard of this characteristic. The team are taking to tiling. Superb for the first time. We are also impressed to find 19 different patterns, reversed makes 38, so it won't have visible repeats.

I may be misunderstanding, but I do get to essentially 0 imports on some days, eg when we are away or have no large loads outside sunny times. Look at the data under here for example: https://www.earth.org.uk/energy-series-dataset.html#V-imp Partly I picked the Enphase ACB system to have very low import/export threshold before stepping in. Rgds Damon

So just a bit of feedback. As I think I mentioned, the Building Control guy would not countenance anything in metal or wood stating that "only concrete was suitable for a new build" He also insisted on 1:10 at least which is what its' meant to be, but was a bit tricky to achieve on a path that already been sloped. Here's what my builder came up with. TBH I'm not delighted with it (though the fossilised plant on the bottom slab is quite nice 🙂) Wondering whether to put some plants down the sides for the time being. Anyway, thanks for all your feedback, suggestions and encouragement. 👍

Looked back at this thread and remembered the sheer panic I felt when I wrote the original post! Thank you all who contributed, whatever you contributed. Such a comfort to know there's others out there who've trodden this path. 👍

theres 3 separate entries for the battery, updates on the progress i made I too was disappointed at first but I did make good in the end with many tweaks from the manufacturer of the inverter, but it can never be zero, I went into it thinking that was how it would be, but totally understand now why it can’t be achieved, at least on a system like this with CT clamp

Have a read of my blog, I covered this exact subject when I got my battery system installed, hopefully it’ll help you too. My import on a day with no requirement to import is around 0.3kwh, I’ve explained the reasons why you will never get to zero in the piece.

Thank you, yes, it did in the end. I got the paperwork from LABC and, I'm pleased to say that in the last week. I've finally got building control sign off 🍾, so I can now try to rearrange the mortgage a bit to get a better rate and apply for my VAT clawback. 🤞

Not really. There are SI base units, kg, m, s and a few others. From those, you can make recognised units like newtons, joules and watts And from those, with a bit of mixing up, you get recognised units like kWh, So kg.m2.s-2 = J kg.m2.s-2 / s = kg.m2.s-3 = W kg.m2.s-3.3600 s = 3600 kg.m2.s-2 = kWh as there is 3600 seconds in an hour. In an ideal world, we would use joules for energy and watts for power, but somewhere along the line, someone thought it was a good idea to use the kWh. That in itself is not too bad. But, then it gets corrupted into nonsense units like Killa wots per our, which does not even make sense in English, let alone phyisics. Try the historical records on Weatherunderground. You can usually find a weather station within a mile. Some are better than others i.e. solar meter.

I would be chuffed if I got that low. So I would say well done.

Ours has a humidity sensor in the extract pipe so it's automatic. I also have a sensor on the shower that I use home automation to force boost mode but that's just to help get ahead of the steam cloud.

No offence but this simplified picture may be better. An imbalance, caused by leakage to earth, gets picked up by the search coil: Pushing the test button brings the resistor in and creates an imbalance. It is critical that the in/out wiring is correct. (Same as with current transformers).

https://heatpumpmonitor.org/

It's water based acrylic and can be cleaned off surfaces easily enough. Holes upto 12mm can be filled or larger if the hole is meshed first. I think this has a real potential to improve old housing stock but I expect it is an expensive service currently. One to watch.

Coolio. Makes life easier as the firrings across that direction are a lot shorter than the other way. Will make meeting the return a bit more difficult as the fall then goes the other way... Will cross that bridge later. Will have loads of offcuts so noggins not an issue.

Those cupboards into the eaves under the window ring alarm bells. Anything similar I have seen is poorly insulated if at all and leaks like a sieve. Get your blower door on that room and I bet you will find howling cold gales coming in there. That looks like an access trap into a crawl space to the right of the cupboards, again likely to be poorly insulated and draughty. But put your head in there with a torch and you will get a good idea of the quality or otherwise of insulation and detailing there. Take some pictures and post them. The other common detail I often come across is you take a socket or switch off the wall on a windy day and get a cold icy draught coming out of the hole, meaning detailing is poor and cold air is able to get where it should not, and I am talking about switches on internal walls here. What should be simple tings like sealing cable holes from a cold loft down into an internal stud wall.

Not sure, but I think the idea is that it precipitates out of the air when the suspension experiences a pressure drop - ie when there’s a route to outside air, the fluid flows through the gap and deposits its load of sealant as it does so. So it’s targeted at gaps rather than just coating every surface. Since not every sealant drop is going to flow through a gap (especially once the house is now sealed) you have to cover any finished horizontal surface that the sealant could land on (floors, windowsills etc) but not completely cover every wall in plastic. Not sure I’d want to do this on a finished house though. And I don’t know how big gaps it can do (one demo had half inch and a bigger one with gauze across it: think it would take a very long time to seal an open 50mm.

Agreed. Please continue in the original thread, as linked by @ProDave folks! Thread now locked to new / further comments here.

It is also relevant to note that Thermafleece used to (I don't know if they still do, but I guess so) require that a breathable membrane was used to separate the sheep's wool from the wall itself, for exactly the reason which @SimonD is suggesting - that the outer (currently cement-based) render *may* fail at some point in the future, in which case the sheep's wool does not want to become a sponge. I second the ventilated (and I mean properly cross-ventilated) void. See for example Stirley Barn, done by the Green Building Company (Green Building Store's building arm).

Absolutely. Yes, but for safety sake. Indeed, as you wouldn't want to get zapped when working on something that had defective / incorrect cabling downstream of the CU, and you come to then work on it as a 3rd party. Switching 'off' the front of house RCD or main switch should give double-pole isolation of the entire electrical installation from both sides of the incoming supply.

Yup. But its all about pushing back and standing your ground for a better "tomorrow". The BCO's I am meeting on my PH ( or thereabouts ) builds have not got the slightest clue of what they are looking at. Most are very curious though, and usually spend most of the visit marvelling at this new 'phenomenon' vs doing any BC content. They do a few laps, smile and nod, and then leave. And then we all look at each other and say, "nice chap, why was he here?".

I wouldn't put it in cavity walls tbh. Blown in, bonded beads for that AFAIC.

For me, not until surveyors have got over their fear of it. I have just been organising the home report for our old house, and one of the very first questions the surveyor asked was "is there any spray foam insulation in the house" the implication being it would be a problem if there was.

my concern would be if it gets damp or clumps on wall ties etc reducing its U value. Much of an issue ?

whats the u value and m2 price of the cellulose ?

Posi's and a bit of additional timber to get you up / around 350-400mm depth, and blown-in cellulose wins the day for me. Just one days work for one guy, chilled out, and staggeringly good performance for both insulation AND sound-deadening. For the OP, I'd seriously consider getting spray foam in, but only if there's a robust interstitial condensation mitigation plan in place. Did you cap the open cell layer with a layer of closed cell, or did you go for an internal membrane instead? In talks with one client atm to go down this route ( vs membrane for AT plus obligatory's ) as the roof space is nigh-on impossible to get a man into, let alone cut and fit insulation AND ten cut and tape an AT / vapour membrane. A very bust attic trussed roof indeed, and just looking at the planning for insulating it "manually" was making my brain bleed. Worse than that was the assurance that a builder would just put a 'decent labourer or two' on it, and the results would be dire at best.

@markocosic can you elaborate on both of these points? What do you mean by "all days units"? These were on my shortlist, but now you have me concerned.

Singles would need containment- way more work than swa. Meter tails could be buried in a wall deeper than 50mm or covered with thick steel plate. I wouldn’t do it though. 3C SWA won’t work, as there are 3 phases and a neutral. 4C and a separate earth is the way to go.

In relation to the line conductor, yes.

The house may well have had timber windows there before the PVC was installed, and then the "cracks appeared". A lot of shit window companies mistakenly removed timber windows with central mullions which were load-bearing and incorporated into the load for the spans. Yes, a cause for concern and may be tricky to fix retrospectively. Try and negotiate a discount for this work, at least £5k, and also ask for the building regs paperwork for the room in roof, or the house needs to be valued minus that room ( so it would then only be classed as a ( valueless ) attic / storage space and not habitable space ).

I would suggest the OP do as @ProDave has suggested with a cut roof. having been through the process of filling our attic trusses with 195mm glass wool and adding 100mm PIR underneath I can tell you it is a pain on attic trusses! in our vaulted ceiling entrance hall we had a cut roof and it was a doddle not having to cut around trusses. but might I also add the suggestion of using very deep trusses as filling will blown cellulose instead of mineral wool and rigid insulation combo. if I had my time again I would do a cut roof with blown cellulose for sure!

In principle we don't like materials pretending to be something else. Wood would have been appropriate but over budget and dog damageable. UFH will work better too. Still, most tiles have only 6 patterns and strong features and 'knots' that would be in line...no real knots look the same. These tiles look so real. Topps contrived to have repeats even in their 1m2 display. But in real life we can lose the strong patterns in cuts and are happy. Good discount too.

Have you got a little confused there? My alterations in bold.

Generally, for 8 months of the year, PV can supply a normal 2 person household with all its DHW. Possibly for 5 or 6 months of the year, the PV will export as well. One has to ask if it is really worth the time, effort and complexity to save a few quid of imported energy. You could just look at a PVGIS hourly report and take the integral, 40% either side of the mean (around noon for most people with south facing PV). Then run things in that window. That window will vary about an hour a month, so you are adding or subtracting 30 minutes to each 'tail', but only during March, April, September and October, the summer can look after itself. I have cheap timers on my DHW and storage heaters. Think they cost less than 20 quid each, they are set up to lock out connection when it is unnecessary. A simple solution to a complicated and variable problem.

if i cant make it using a hammer then its beyond me im afraid.

Octopus have a tiny share of the ASHP market. While this will increase it will remain a tiny share. Most ASHP installs are by smaller independent companies and that isn’t going to change. They don’t insist on connecting the ASHP directly to the meter cupboard. It just sounds like a conspiracy theory to me. I really can’t see Octopus switching off power to your ASHP willy nilly when it suits them. Octopus seem to be one of the better companies.

Did it work out OK?

For me overnight electricity is cheaper than midday solar (7.5p cheap rate import vs 15p to export excess) so it's a no brainer to get the tank ASHP hot overnight, then top up from ASHP at midday (or as soon as the battery is full). The only question is whether to then use the immersion diverter for >55°C top off or just export the rest.

With using the HP, unless you have some sort of direct and intelligent link between solar generation, house consumption and the HP, you will almost always end up consuming some grid electricity. This argument has been had on another thread recently and I get the proponents saying for the 'greater good' we should be exporting whatever we can, paid or otherwise. However to keep it simple, you have a solution whereby you can charge your HW tank using excess solar whenever it is available, from the moment the solar generation becomes greater than the total consumption. From that point on, all HW is free until you get a piping hot tank at 75/80 degrees. If you run your HP, you'll get whatever it's DHW setpoint is (50degrees?) but also run the risk of import an cost to do so. each time the sun goes behind a cloud or turn something else on or ((HP consumption + House) > Solar Generation) then you will be importing the difference. Personally I'd be sticking with the Solic until the PV can't cover your DHW load and then the HP comes back on. This way you also run the moving and serviceable parts of your expensive HP half as much and prolong it's life as well. Edited to say ^ ProDave's approach is ideal and could even by automated using forecasting software, but requires a fair bit of continuous input from you (him).

Ours is also only a couple of mm at most, very similar to @Russdl. Any more than this with a handleless kitchen and finger access becomes a problem IMO. So, unless 20mm was explicitly discussed and/or drawn and signed off I'd be going back to them. Aesthetically I agree with others it's only a minor detail in the grand scheme of things, but if using the kitchen is going to be a pain for years to come, or if you are going to need to add handles to a handleless kitchen to make it usable.. that is a significant issue.

I am now in the uncomfortable position of needing £70k to finish with £50k in the bank to spend. The more I do myself to try a save money the longer it will take while price inflation continues eating away Do I need flooring on the ground floor? Do i need a en-suite? Do i need a stove? Do i buy materials now to use later? What is the bare minimum i can do to get it signed off? These are the question i am asking myself. Next year i may be able to by a cup of tea for £10k! What would you do? Currently having it boarded out which I estimated would cost £6k but now looks its going to be £8K+ Plus twisted my knee last week and can currently do very little, feeling frustrated and exposed.

I understand your pain / enjoyment. At the end of a self build day I find drinking wine and eating steak solve all my issues …

This forum is full of people like me that had a unforeseen situation meaning we were short of expected funds. We all found a way to resolve it. Flexibility is the key. Our solution was lay off the trades and do it all myself, thus began a 5 year "build as you earn" completion of our self build. You don't need flooring for completion sign off, bare chipboard is fine, fit the proper flooring later. Likewise curtains etc not needed. You will need a functioning kitchen that could be second hand or the very cheapest flat pack units that you can upgrade later. You don't need much in the way of garden completed, usually just a parking space and a hard path from there to the front door, usually with a ramp for wheelchair access. We chose to do our VAT reclaim a little before the house was actually finished just to get the injection of capital for the last few items and to pay off some 0% borrowing that would have been due soon.

Blower door in action for the first time. I was pleasantly surprised by how airtight the main rooms downstairs were (I sealed the dining room door into the hall, and mounted the blower door into the lounge doorway into the hall). Even on the slowest setting the fan created enough pressure difference to find the major leaks, with the next speed up used for the smaller ones. Now to start sealing the 40ish leaks we identified!

Remember the level entry requirements stipulate a flat area in front of the door, so a wooden ramp on top of that, would have to have that flat are first before it starts to slope. That is NOT a "level entry" door. If it was it would not have an external cill like that, just a threshold strip that floor inside and ramp outside tuck under.

Yes, absolutely and I will take that into consideration when fitting a pipe etc. The thin pipe shown is actually a drainage rod used for demonstration purposes, but thanks anyway.?