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+1 to the above, insulate, insulate, insulate (and airtight) then whatever source your heat (preferably ASHP) your running costs will me minimal.

I've worked as a tradesman for 25 years, first as carpenter then Electrician. I've seen, at an ever increasing rate, a higher number of disreputable tradesman than good ones.

You've got a lot of glass in that design, which makes me think you must have some amazing views.. If not. I'd scale back the glass. You'd save a lot in the build, and even more long term in heat loss. Personally, I'd be tempted to build bigger. A 1.7 bathroom isn't that big, you could easily find things get messed up in tolerances, boarding and tiling and you can't fit a bath in there. In terms of project managing with no experience, it will end up costing you a lot more in time and stress. You won't know the terminology of most trades and they will take advantage of you because of this. I'm not saying get someone else to do it, but just be aware that it will happen and you have to factor in that people will lie to make things easier for themselves if they think they can get away with it.

Yes at the moment, as others often point out 1kW of electricity into an ASHP for say 3 -4 kW out.. depending on the outside air temperature but as gas is say 1/3 the cost of your electricity it ends up roughly the same. @Fallowfields you have probably thought all this through but for me if you are rural then I would look at your location and altitude. For example my sister lives on the island of Tiree. Here they benefit from warm seas relatively speaking when say compared with the North sea off the East coast of Scotland or say the sea off Newcastle / Norfolk. They also get a lot of wind. The air temperature never drops that low, say -4 deg C but even then only for a short period of time due to the warm sea all round. They have two ASHPs that really deliver, are economic to run.. they are delighted with them. Reports are that they never hear them having to work that hard, in other words a big drop in efficiency. But as they are rural.. well very the electricity can go off.. no heating and no hot water. The house is well insulated, pretty air tight and they have a gas hob run off bottled LPG and electric ovens. They actually find this cost efective as the hob uses not much gas although catering for a good number of people most days. They also have a wood burning stove. In other words the house has some redundancy built in. Before committing to ASHP I would have a look at your location. If say Wales / North Scotland at 250 - 300m + altitude then you could experience several days where the temperature is below -10 to - 15 deg C.. and regular days when the temperature stays below zero C all day and drops further at night.. what then and what if the electricity goes off? I'm not saying don't put them in... just that your location may influence the overall performance. You other option is oil fired boilers.. but I think their days are numbered (I had one in a self build out in the country and at that time it was great, oil was cheep and it ran a UF stystem over two floors of the house) in the sense that the oil is delivered by companies that don't often play fair and as demand for them drops off then probably the maintenance cost will go up and the oil price will also likely go up. Maybe in ten years time you'll get you oil delivered by an EV tanker? You could maybe set up you system so it can an easily take an ASHP later, use a cheep oil boiler and tank to start with and wait for the price of ASHP's to come down? It will impact on your energy performance calcs so you may need to add more insulation ect to compensate.. but that is no bad thing. Of course if you had a big plot you could have a ground source pump.. ideally a stream / burn with good all year round floor or right next to the sea so you can extract heat from that... but few of us are that lucky.

I suspect each building control officer is going to look at this slightly differently. Decorating, landscaping and flooring would be no problem (though you will need to demonstrate disabled access). If you have multiple bathrooms then I would imagine you only need to fit one out. But I do think you will need to show a working kitchen and bathroom so you can show an electrical completions certificate, water efficiency calculation and adequate ventilation. You may get away with almost all second fix carpentry though if you need fire doors I think they will need to be installed as will stairs and any balustrades. I would do a list of what you intend to do and discuss it with your building control office....

That looks to be a capacitor in the output circuit of a switching power supply. By the time it gets that bad, it has usually blown something else, but if you have a soldering iron and feel lucky you could try replacing the light blue one with the top split open. That £35 one is a "refurbished" used one. It has a 12 month warranty, but if I bought that I would look at the soldering of the electrolytic capacitors and any that had not been replaced already I would replace with good quality replacements.

For Building Regs, you can get a completion certificate once you are at shell stage and complied with all the regs. Floor and wall finishes don't matter, but electrics need to be complete and signed off, as does gas and drainage, heating and ventilation. All insulation in place, doors and windows fitted, airtightness signed off, entrance access in place. You will need your as built SAP. External works not an issue for Building Regs, but probably over 90% of the spend will need to happen. Don't risk running short of money in the current lending climate or you could go skint.

Different banks have different requirements. Ours, was architects completion certificate and building control signoff. But ultimately, it'll come down to the banks valuation surveyor's opinion. We recently went back to our bank for additional money but the valuer rated the house as "zero" due to unfinished landscaping and a few other things.

The battens and 25mm airflow path means that it is not essential to have the VCL. The insulation is not bridged by timbers so all looks good. 150mm insulation would have been better, but what you have looks OK.

Yes just add a vcl below the rafters and before plasterboarding. Perhaps seal any gaps between roof and walls before fitting the VCL.

I’ve found the PMing quite hard at times and I’m an experienced PM. It’s not to be under estimated how hard it can be managing all the individual trades especially when you run into problems. What’s made it hard is I know nothing about building so it’s been a baptism of fire.

In a nutshell: the argument for finding an excellent - not necessarily expensive - PM. Key 'interview ' question for a potential manager : Have you any suggestions about local builders and trades folk that you would like to make? Who's a reputable plumber round here? How long have you known him / her? Do you know of any local chippie / brickie partnerships (team) Do you know any concrete dispatchers? : ( listen to the answer) what's the chance of getting a part load from that company? - and where do they do their slump tests? What are the local window fitters like here: do they deal with imported window companies like Velfac of Gaulhofer ? How much is concrete a cube yard from company [...x...] ? Ring to check. How long has [ company x ] been trading ? Which is the best pub for local tradies ( Local to us its The Patten Arms) Go and waste time there. Then triangulate the answers.

Just taken a look at your plans and I would, even at this late stage, consider how you could improve the design, especially in respect of the insulation and airtightness.

Yes, lots more info and pics, please. How deep a reveal are they on? Is the leak all round? Is it concentrated at the top/sides/... where? Have you established that the leak is at the window-frame - timber frame joint? Could it be the opening lights somehow not sealing? Lots more please!

No, I am not aware of any domestic accessories that need ferules. That is mainly for terminating stranded cable.

Fit MORE insulation under the ground floor slab, a lot more. 300mm is probably a good target to aim for. And wider cavity with more insulation in them. You build a house once and get one chance to do it right. You will never get the chance to improve it later and will probably regret not doing it right. You are aiming to get the heat input down as low as possible. UFH should then work fine. If you do it really well like many of us have the house ends up so well insulated you don't need any heating at all upstairs, but fit upstairs UFH unless you are really certain of that and really determined to detail it properly. Do it properly and many of us are heating a house that size with a 5kW ASHP. If you are doing this properly, you get a Design SAP done which will tell you all that. It is a requirement for building regs in Scotland, but so few people seem to get it done down south that I suspect it is optional? It is not so much the design on paper that lets a building down, but unless you are detailing everything yourself, or have a really trusted contractor who actually understands low energy houses, then a typical house gets let down by poor details, e.g badly fitted insulation so cold air can bypass some of the insulation, and poor details at junctions. If you are having a cold loft then the details of how to insulate and air tight seal the upstairs ceiling is one of the major details that is often done poorly. And I know you are only asking about heating, but don't block your downstairs hallway. You WILL get fed up having to go through the kitchem / diner to get to the back. Scrap those cupboards and have a hall you can walk through front to back.

Wow, thank you all so much for the answers and discussion, incredibly helpful. In terms of use, the plan is to have a working bathroom and kitchenette, however it will not be a permanent sleeping space (though I may occasionally house guests on a sofa bed in there). I suppose from the above, I would just need to ensure that this would be deemed to be the case when if a building inspector shows up unannounced? My understanding would be that I would not need to request an inspection as long as it fell within permitted development rights? Many thanks for all the help!

Don't waste money on 1.5mm, totally unnecessary. Use 1mm 3 core & earth and the terminals are large enough for three of those.

EPS beads every time over blown in wool.

You can read this. https://www.sciencedirect.com/science/article/pii/S0378778817323101

Our build was ICF so basically no upstand needed. The screed company insisted on the foam perimeter strip as said EPS wasn't compressible enough. I'd assume same applies to PIR.

This was on a cold night and we’ve gone from waterfall windows to mist! So mvhr does help with condenstion in an old leaky house!

Only thing I would worry about is the kitchen does not seem to be covered by ventilation? Is the bedroom also having dMVHR? If it is, really confirm noise levels, anything above 30 to 35 may sound noisy in the middle of the night. But I would really concider a simple condition based dMEV setup. Put humidity activated vents near patio doors and in bedroom, these are silent in operation and need no power. Then a dMEV in kitchen and bathroom that runs at all times at a very low background ventilation rate and is automated with humidity sensor to boost only when needed. Greenwood dMEV is silent in operation while doing background ventilation and have a humidity sensor built in.

I’m not sure that’s accurate. Although it is best practice to comply with the PWA, it is not compulsory. It’s power lies in the fact that if you ignore the PWA requirements, then in any subsequent dispute, if it was caught by the PWA then the Courts can make negative inferences (ie without evidence) against the person who ignored it.

>>> I picked up some heatmiser/grant stuff for the ASHP. Be nice if there was something similar but for electrics... There is - and we use that to control towel rails etc.

Slide a length of 180mm twinwall drain pipe over it and be done.

If the insulation absorbs sound waves, then the more you install the better the results. Air does not arrest sound waves "fill 'er up!!"

Oh Lord not my strong point!! Both are fairly easy, at the level needed here. Think of Physics as what you already know, intuitively. There are only 3 'units' to remember, the kilogram (kg), the metre (m) and time (s). Just about everything comes from those 3. So you know, from experience, that catching a small ball, gently thrown towards you is easy, Say that ball has a velocity of 2 metres per second and a mass of 0.1 kg as you catch it (this is momentum and has the unit p, for pellere, which means push, or drive). The momentum is p = kg.v, so p = 0.1 x 2, p = 0.2 kg.m.s-1. When you catch it, the equation changes to the energy equation, 1/2 mass times velocity squared, E = 1/2.kg.(m.s)2, E = 0.1 x (2)2, E = 0.1 x 4, E = 0.4. Energy what is called a derived unit, the joule (J), this is important as ANY energy, be it a moving mass, electrical energy, thermal energy stored energy, gravitational energy, can me expressed in joules. The main thing is to remember that a joule is very small, the force needed to move a mass. This force is known as a newton (N) and is equal, in everyday life a mass (kg) x acceleration (m.s2). As you can see, those basic units of kg, m and s, keep appearing. As a J is a very small unit, we tend to multiply them by 1,000,000 and talk in mega joules (MJ). An MJ is still quite small, and in the domestic setting, we talk about kilo watt hour (kWh). The kWh is a dreadful unit and causes lots of problems, but can easily be broken down into the base International System of Units (SI). So let's try it. k = 1000 W = J.s-1 (joule per second) h = hour, which is 3,600 s. Multiply that lot together 1000 x 1 x 3,600 = 3,600,000 J So there are 3.6 MJ in a kWh. Say you buy 2 kWh of electricity. That will be, 1000 x 2 x 3600 = 7,200,000 J, or 7.2 MJ. As a J is mass times acceleration, and if we assume, for simple arithmetic that we start with that ball of mass 0.1 kg, then to get to 7,200,000 we have to throw it quite fast. E = 7,200,000 (J) 7,200,000 = 0.1 (kg) x ?2 (m.s-1) (we normally use x where I have used ? to save confusion with the multiply sign, which is normally a period, .). Let us rearrange so that ? becomes the subject (as they say in arithmetic lessons). 7,200,000 / 0.1 = ?2 72,000,000 = ?2 72,000,0000.5 = ?, which is 8485.28 m.s-1, which is really fast, about 19,000 MPH. If you are wondering how I went from ?2 to 72,000,0000.5, 0.5 is the same a taking the square root. The Economics bit is really just accountancy, if your 2 kWh of energy cost you 30p/kWh (electricity price), then that is 60p, but if 'passed though' a heat pump, you should on average, get 3 times the amount of thermal energy out, at the temperature that you want, so 6 kWh of hot water or warm air in your house. If it is gas, and it cost 10p/kWh, you will only get, on average, about 0.9 kWh out (this does depend on the efficiency and usage of the boiler, you can get close to 1.1 kWh out on a condensing boiler). So a heat pump would work out at 60 (p) / 6 (kWh) = 10p/kWh. Gas 10 (p) / 0.9 (kWh) = 11.1p/kWh and 10 (p) / 1.1 (kWh) = 9.1p/kWh. The real Economics bit is double guessing where the electricity and gas prices will be in a few years times, and how they are impacted by not only supply and demand (we have good historic data on that side) and government intervention (currently electricity is priced by the gas price). If there is one thing that is certain, it is that government intervention is unreliable and inconsistent. I hope that helps explain what Energy actually is, and from it you can quite easily work out the energy to heat things up, move things, change things etc. Just think of it as a mass moving and going from moving to rest, quickly. (disclaimer, it is late and I have had a busy day, and it is strange for me to work during the day and do the fun stuff on here in the evening, had 15 years of having the day free and working the evenings, so may have made an arithmetic error.)

There isn't one answer. It depends on what you are including in you economic comparison. Just day-to-day costs? Including installation? Including maintenance? Lifetime costs? As a broad fuel cost comparison per kWh: Fuel Energy price per kWh (p) Efficiency % Heat price per kWH (p) Natural Gas 8.0 85 9.4 Oil 9.0 85 10.6 LPG 8.7 85 10.2 Wood Pellet 13.8 85 16.2 Coal 8.9 80 11.1 Direct Electricity 30.0 100 30.0 Low efficiency ASHP 30.0 250 12.0 High efficiency ASHP 30.0 400 7.5 I took the energy prices off Energy Savings Trust national average on 1st July 2023 - https://energysavingtrust.org.uk/about-us/our-data/ There's not much to separate Gas, Oil, LPG and ASHP (I'm ignoring coal) With the benefit of a £7.5K BUS grant for the ASHP, I'd expect installation costs to be similar (assuming same heat emitters), with ASHP possibly being the cheapest. If it's a forever home, maybe you should consider the ease of a replacement boiler after 2035, when FF boilers will not be available. ie. whatever you go with now should be ready for a low temperature system and at least space for a UVC, positioned close to where you would site the ASHP. When it comes to the other side of the economic calculation, the amount of energy used, there you can make a much bigger difference. Building to current building regs you'd likely be in the order of 50-60kWh/m² per year energy use for your space heating. It's quite easy with some care and attention and not too much additional expense to halve that.

So a new build, embrace the chance to fit a LOT of insulation, properly designed, make it air tight, fit MVHR and UFH and you will have a house that needs very little heat input. Then a small ASHP will be all you need. It will be cheap to run, and no oil or gas tanks to bother about and no boiler servicing. While you are at it, fit some solar PV on your roof and your running costs go down even further.

Physics and Economics books.

Remind me if this is a new build? A house you already own? old or new? In a self build new house with no mains gas I would say without a doubt UFH and ASHP. With a new build you have one chance to get the insulation right and make the heat demand low. Whatever system you fit, you will need UFH or radiators, so ignore that cost, that is constant regardless of heat source. So it literally boils down to the cost between an ASHP and an oil or LPG gas boiler. An ASHP is probably slightly more expensive but not a lot. The running costs will be about the same at the moment.

So after a month or so in the house, the time has provided us with an opportunity to reflect on what we have achieved and what if anything, we would change or could have done differently. In truth there is very little if anything that we would change. The rooms flow, the doors open in the right direction and the lights can be switched on and off in the appropriate places. Even the WBS has proven to be a worry that wasn't worth worrying about, as it's position within the hearth is no longer an issue due to it being vented through the back as opposed to the top. Some jobs have been completed such as the down pipes and a few jobs remain outstanding but nothing that has an impact upon our daily lives. One such job is the porch that needs to be slated. Thankfully I still have some financial leverage over those various trades so I know they will return. Our satisfaction I suppose, has to be routed in the preparation work, the research and being a member of this superb forum. None of these elements should be underestimated. Therefore I would like to sign off this blog with a heartfelt thanks to all those who have contributed, not only to my issues over the past couple of years, but to all the other threads, as they too are just as relevant / enlightening. I have also attached some images which complete the project, namely the WBS chimney installation and the erection of the much mentioned porch. For a final time, thanks for reading, and given the date, seasons greetings to you all. Paul.

The next stage of the setup of the site took place over the last 3 weeks. with some good progress. The trip up North, 433mile from our current rental in the NW of England. I set off on Wednesday morning in the 7.5T truck, and the 2 dogs for company. I took some materials with me, and had a gut feeling I was overloaded. I had worked out the approx. weight of what I was taking, but was unsure of the TARE weight of the truck. so I didn't take all I was planning. Luckily the nice guys from VOSA, At Carlisle (Todhills check site), confirmed my suspicions when the invited me in for a check. I was over weight, but the truck and my paperwork were all in good order, and they give the truck a thorough looking at. The upshot of this was me renting another 7.5T truck for storage, offloading the excess weight, driving the remaining 333 miles, unloading, returning the next day with the empty truck, re loading and driving back to site. 1100 miles in 38 hours. not what was planned, but you live and learn.... I arrived back on site on early Friday morning, 02.30am. and slept in the cab of the truck, until I was woke up at 05.10, by the guy delivering the Static, he was at the end of the road... Here's a screen grab of our new home arriving to site, this was 05.25 am... I hired a contractor to carry out the highway works for the site entrance, basically as he had the correct insurance and RAMS it was easier to get this stage subbed out. The idea was he would open up the site, with a 5 T digger, start the initial road and stone this up with around 60T of type 1. I would then meet on site and hire his man for a few days to assist with the pecking of the treatment plant. This didn't go to plan, they had to use a 13T machine, as it was available, so when I eventually get to site on the Thursday, due to the size of machine, the operator has completed the initial works, then pulled out approx. 60M of the road, and pecked the treatment plant hole, and I got this for free... 😁 Having a 13t machine on site, with operator for the Friday, I needed to make the most of it, as I was only paying for the rental of a 5T machine. Mikey the operator, made short work of pulling out the remainder of the road up to the location of the house, in total this road is around 90M. Next I had him strip the area for the house. The house is around 13M x 7M, so I wanted to strip back a working area around the house, my thought was we would hit the bed rock so this was the plan, we marked out a 16M x 11M rectangle, and he set to it, it took him about 2 hours to strip the land and scrape it clean. The above is the bedrock where the house will be, and the road coming up the side of the house. (I used a geotextile as a separation layer for the road, although in sections the road is on bedrock anyway,) You can make out that there is a fall from the top left falling to bottom right, this will be made up with type 1 stone, raising SW corner of the house around 700mm, I will raise the road in this section and use some of the top soil to level this out a bit and soften the impact. The last Job for Mikey was to dig me the trench for the services, he dug a 600mm wide trench about 8M short of the Treatment plant (to allow me access to move the spoil, and a similar distance short at the other end for me to connect to the water. just shy of 60M. Friday was a busy day on 3 hrs sleep. The treatment plant also arrived as can be seen above, I went for a Tricel unit, this was based on cost, treatment, dimensions and availability. Last job for the day was to move the caravan, Mikey helped me with this and we stripped a bit more land and located here temporarily for the night North / South. Saturday I decided to get the water connected to the caravan, for this I needed to complete the trench from the standpipe to the large service trench. I never dug this on the first trip as I was concerned about the electrical supply to my neighbours property. Cables seemed to run across my field at around 300/ 400 mm depth. I used my contact at SSE and he arrange to get the cable moved / deepened. This was carried out a few weeks prior and we discussed the position of the new road, and he made a site visit and we talked about me extending the water pipe trench in both directions so that I could also lay a utilities duct to the road for broadband. So to say I was a bit surprised, and p***ed off when I cut through the neighbours supply cable. The cable was as I was worried about 400mm deep, and the marker tape was next to the cable.... How to upset your new neighbours by having their electricity supply stopped two times (1 for the initial connection, 1 for the remedial works), only for me to cut the cable for a third time.... At least they were very prompt, they arrived after about 40mins, and it took him around an hour to re-joint the cable. I then removed the water standpipe and ran my new water main up to the caravan. It will tee off for the pods at some point, and then continue up to the house. SO now I had running water in the van, and gas for the water heater and hob / oven. Sunday was glorious, so I caught up on my sleep, and had a restful day. Scottish Power were due to fit the meter on the Wednesday, so I needed to get my service cables from the meter box into the service trench and up to the caravan and to the pods. I dug a trench across the road and through to the service trench. I used a 125mm Duct, and inside here I ran some 6mm SWA to supply the pods and some 50mm Duct to run a service cable to the caravan and ultimately up to the house. I pulled the cables through, and I have put a caravan hook up point next to the static. Tuesday / Wednesday, I had 80T of Type 1 MOT delivered in stages, I spread this out using the Back hoe, and vibrating roller. so by the end of Wednesday I have the base in for the road. which will give me good access for deliveries. Scottish power were a no show..... Discussing the caravan with the neighbour they advised turning the caravan 90deg, so it was end on East / West as the stronger winter winds tend to blow from the West, and being side on would ultimately be unstable. I dug out another section of land next to the caravan with the idea of swinging the van around at weekend when Mandy Joined me for the last week. It took me and Mandy all Saturday to move the van, using the backhoe to pull it around. and most of Sunday to get it jacked up off the ground and levelled. We dug 4 pits later on in the week and concreted some anchors in to chain the van down. The van in position with Mandy getting the best job of the week to squeeze under the van and start to insulate the water pipes... Scottish Power let us down again with a missed appointment on the Tuesday with a promise of Friday.... They actually turned up late Thursday and fitted the meter, so we had power on the Thursday night. We spent a couple of days moving spoil around the site to create a mound of earth to shelter and soften the impact of the pods, this was also a planning requirement for the neighbours amenity. Still work in progress and there's 10's of tonnes more to move. Last job before packing up on the Friday was to level the base of the treatment tank pit. At this point we were still waiting for the building warrant. so couldn't actually install the plant. We end the week by getting the Building warrant approved, and the certificate for discharge for the treatment plant both on Friday. Thanks for reading..

Progress has slowed down a fair bit frustratingly. I’m getting odd days here are there from the plasterers but they’ve been back this week so I now have about 40% of the plastering done but it’s taken a month. I’ve also started painting which feels like a big step. Sparky also went off sick for two weeks and hasn’t been around this week either so no progress there. Groundswork team eventually came back to continue drainage work and install treatment plant. However they have a staffing problem at a bigger job that has penalties attached to have had to go back there for two weeks. I doubt I’ll see them again for 4 weeks though.