Bitpipe

Before you figure out your spec, the key question is what do you want to achieve? Do you want to be able to play different sources in each room? Where is the source coming from? Do you want a wired or wireless speaker system? Is it just radio / music or do you want to tie it into AV (i.e. your TV). How do you want to control it (app on phone etc..). Figure this out and you'll then have a better idea of how to deliver it.

Services can be very expensive and sometimes not logical, i.e. even if next-door have mains power and water, you may still need to bring your connection in from a distance. Even though you don't own the plot, you can get free quotes now for power and water. Off grid is a nice idea but you have to be realistic on cost and space for batteries etc. plus your quality of life. What do you do if you have zero power at night in winter and can't operate your sewage system, heating etc. You don't say if £200k is your whole budget i.e. inc plot purchase or if it needs to cover professional services or is just the build budget itself.

Completely agree with this approach, exactly what we did. For a start, you'll be zero rated VAT for the build vs 20% for renovations. Even with a traditional renovation, you'll quickly reduce that to a shell and will need to replace a lot of it regardless. The pain of renovation is tying new in with old, as you strip back you just keep discovering more problems. Also you get a house that performs consistently vs a poorly insulated, draughty downstairs and a well insulated airtight second floor.

Welcome - very interesting post. I've been looking at garden buildings for a while and agree that they can get very expensive very quickly! I guess the main advantage of the log kits is that they are designed and manufactured to go together tightly and then stay stable as the wood expands and contracts naturally. No reason you can't replicate this but depends on your joinery skills and the strategy you use to join timbers (mechanical fixings, timber joints or mix of both). Or commission a joiner to make it for you (or even get you started) and perhaps the savings in materials offset their labour. Did you watch that woodworking show on C4 last year? The final project they did was garden buildings. https://www.channel4.com/programmes/handmade-britains-best-woodworker

Effectively what we did (with zero experience) - the structure is key but once in place you can sub out all the first and second fix, or DIY to your competence level. Home builder's bible (an essential read) has a good explanation of how house design can minimise or increase costs - some is plot related (slope, access, services, etc) and some is the house shape and size itself (square, L shape, gable ends, roof complexity etc etc). You will also become familiar with the time/quality/cost triangle - wisdom is you can have two at the expense of the third. In your case this may be time or quality. You may decide that you can live with a budget bathroom and kitchen for a few years with a view to upgrading later. Prioritise spending money where it it is difficult to revisit e.g. fabric - insulation & airtightness, good windows etc. There are many strategies to work to a limited budget and to enable an extended timescale. One is to live on site (if possible, caravan etc) to reduce ongoing accommodation costs. Second is to partially complete and leave some bits until more funds available - however this needs consideration as, for example, getting trades back to plaster one room may be less economic to getting them to do it as part of a bigger job. Third is to buy and resell vs hire (things like caravan, site storage, scaffolding, a digger etc..). You need to watch the VAT situation as while new build is zero rated for materials and labour (NOT professional services or hire - lots of details on the HMRC website), you get one shot to claim VAT refund on materials you have bought but only at the end* of the build and some very extended builds can cause complications with the claim. Trades must always zero rate their services to you and any materials they provide as part of their services, you can't ever reclaim VAT charged by a trade, even in error. *a number of different ways to determine this event, some in your favour and some against. Going 100% off grid may need to be a longer term objective when economic to do so, does your plot have any services at present? How will you get water? Have you got a quote for power? Local sewerage should be straightforward but will need appropriate ground conditions to discharge effluent etc. Good news is you've come to the best place to get as much information as possible from people who have been there and done that!

Well all that kit will use more energy so they will pay more regardless as they will consume more. Also, given their obviously wealth, it would likely not deter them one iota.

Welcome, take your budget and divide by £2000 or £2500 to be conservative (and to allow for contingency) this is for a decent spec, you can maybe come in less if you do a lot of work yourself and are very focused on value engineering / design and aggressive searching for materials. Does not allow for any professional services (architect, SE etc..). That is your approx square meterage (all floors) gives you best case 100m2, 60m2 worst case. While PV is affordable, storage batteries etc are still quite expensive. Best to get a power quote also from your local DNO.

Resin bound is strong but will heave / sink and crack if the substrate moves - it is not that thick itself, maybe 30mm. Ours sits on 70mm porous tarmac which itself sits on a generous layer of compacted shingles and type 1. After 5 years we have a few small cracks, all from the corners of a drain which must have settled over time.

Agree, we have external blinds on east and south windows (on roof also) - super effective. I expect internal blinds limit the volume of air that can be heated and also stops the sun warming the floor and other objects. Anyway, works

If the UFH pipe is already purchased and you need screed anyway to make up the levels then your approach makes perfect sense, especially if you can use a bit of EPS to save some screed! I think you'll be amazed at how little you will need to heat your house but, having built at the same time of year, understand how hard that is to realise until you're in. Good to see you're giving the same attention to cooling as you're giving to heating as guarantee that will be your number one comfort issue. One of my regrets is not making provision for air con. I just spent £1000 at Ikea on their wireless battery operated blinds which by pure luck are exactly the right length such that three perfectly cover the large west facing sliders on the ground floor. All connected to their smart hub so controllable by Alexa - will make a big difference in summer as the afternoon sun can significantly overheat the GF. We have cheap linen panels for now which help a little but the blinds should be much more effective. Now, crack on to your next dilemma

Running pipes and not using is not a bad strategy if it gives you peace of mind for nominal cost. However you're seeing the dilemma that we faced. Like us, you have a thick layer of load bearing EPS (we went for 300mm) under the concrete slab. I assume that the external wall insulation ties in to this so the basement is 'wrapped' externally in insulation (ours is 200mm EPS 70). This means the basement structure will warm to an ambient temperature (ours is about 19-20) and stay there year round. Remember also that the ground stays at a nominal temperature of around 6-7 degrees year round irrespective of surface temperature so it's a fairly stable system. So all that said, if you add a heated layer to the surface of the basement slab then you either need to isolate it from the rest of the slab (to avoid the storage heater effect) or go for the opposite approach. Another 'peace of mind strategy' that you may consider is to put isolated electrical spurs in the walls to allow for small space heaters in future (what we did for our bedrooms, never used after 6 years). Or lay 150w UFH wire in the area if you're worried about cold ceramic tiles underfoot (what we did in our bathrooms, although that would have been unwarranted in basement as our bare slab is comfortable underfoot, we then laid Karndean over it). Or even just plug in an air fans if the basement ever feels cool and it will warm up very quickly. Regarding traditional screed, we did not use any. The cast floor was tamped flat (not perfectly) and the flooring guy used a self levelling compound ranging from 10mm max to 2-3 mm min to give a stable surface to work with. Why don't you do this, save on screed and have slightly taller rooms? Our basement contains two fridges in the hallway plus TVs and other gadgets in the den rooms. The gym has an occasionally used running machine. All are perfectly comfortable temp. The plant room has the MVHR, gas boiler and UVC so they also contribite heat into the envelope. Just keep in mind that however you do it, any additional heat you introduce into the basement will propagate into the upper structure so may make the house much warmer than intended. It is very easy to overheat a passive standard house, even in winter. We had one additional family down for Christmas and were opening windows to get some cooler air in after making the xmas dinner.

Our BC waived the need for an external SVP as the houses either side had them and they are to vent the sewer system and provide little benefit to the house itself. He said the requirement is really 1 in 10 properties needing one. AAVs inside the house at end of runs will provide the necessary system ventilation for flushing loos etc. Was a relief as we were this close -> <- to cutting a hole in one of the flat roofs, plumber had left his big holes aw at home that day so we had time to get a second opinion from BC.

Don't feel bad, every self builder has a similar story, if not ten. I spent a weekend removing and replacing board to get last minute UFH trunking in for the bathrooms but similarly forgot to do some things that would have made my life so much easier. The lesson we all learn is, put the duct in when it is easy and worry about what will get pulled through it later... In relation to 'home cinema audio' we put in cable for 4 wall speakers in the living room and hooked up a cheap LG home cinema / DVD unit which was ok but is now a bit flakey (volume randomly increases and decreases). Stopped using it and got a cheap Sony sound bar as the late TV audio is not great and it's fine for the vast majority of viewing. Now have 4 unused speakers on the wall and a vague plan to upgrade to a proper 5:1 av amp some day in the future. I've always felt that a lot of audiophile 'science' is just marketing nonsense (I remember the fad for 'oxygen free cables') and to persuade people to part with £££. By the time you're in your late 40s/early 50s I would suspect that your hearing range is suitably diminished so as not to be able to tell the difference - even though you 'know' it's better. Similar to those blind tests where the experts can't differentiate between £100 and £10 wine etc..

It was more frustrating than anything and we were kicking ourselves for being a bit naive but it worked out in the end. I can PM you details of a very good broker who we have used on every re-mortgage since the build if you like?

Completely agree - when faced with a challenge, I always opened with 'how would you do it if it was your house?'. I was lucky in having an amazing electrician who had prior experience with MBC passive houses and had free rein on our house for design etc. Also had a very decent plumbing firm who were open minded on passive requirements and a talented joiner who came up with some thoughtful designs. Rest of the trades (outside of MBC) were alright but they had a clearly defined job to do and did it to the spec.

+1 on approaching an experienced mortgage broker - it's a fluid environment and lenders have different and changing criteria. Also +1 on talking to your current lender. Even if you choose not to, be very, very wary of doing anything 'clever' as if they find out (small but not zero likelihood) they can ask for immediate redemption of loan which will force you to sell. We naively took out a 5 year fixed rate residential mortgage on the property we purchased to demolish while living in it and in PP limbo. When we got PP and a buyer for our BTL house we realised that we should probably tell the mortgage provider that we planned to demo and rebuild. We considered maybe not telling them but we'd had a few strong objections from neighbours during planning and would not have put such mischief beyond them. After 16 weeks contemplation they said no, you need to redeem (plus the early repayment fee) if you want to build. So we made the allowable 10% overpayment to minimise the pain. Then then a week later they said, oh, maybe we can let you do it under strict conditions (i.e sole contractor etc). Then they said no, again. At that point we just asked for the redemption fee to be waived in lieu of the delay and changes of mind and they said ok, even though it was against policy etc etc. Remortaged with Ecology and was plain sailing from there on in.

We (wife and I) are both from an electronic engineering background, In that domain there is an expectation that everything is designed & specified before moving to production as retrospective changes are not trivial (if even possible) - very much a waterfall method of development. I'd liken self build to agile s/w development - sprints of activity where you then take stock at the end of each phase and course correct. Takes the pressure of needing to 'know everything' at commencement but you're still working to a fairly well defined framework. If you require absolutely fiscal certainty then you will pay a significant premium for that as your contractor will just price in all the risk. Also, as the build takes place and you actually see it 'in the flesh' you may well change previous decisions, even ones that were firmly held. For that reason a degree of flexibility, however uncomfortable that makes you feel, is required. What is also important is that you find contractors who you trust in their field of expertise and do your best to specify the outcome you want but leave the implementation detail to them. Experienced trades don't often like being told how to do something by an inexperienced client, but they are happy to facilitate the what. What worked well for me was having high certainty for works that were ongoing (with still some wriggle room), and deceasing certainty for works further out with some being just vague ideas (e.g. we will need the walls painted in 6 months, don't know who will be doing it or what colour they will be).

You can definitely get away with it in a passive standard house - we only have low temp UFH on ground floor and towel rads / electric UFH in upstairs bathrooms. We like the bedrooms cooler but they warm up quite quickly when occupied. However in a retro fit it will all depend on how close you get to the passive values for insulation and airtightness, plus quality of your windows (triple glazed, passive standard seals, tapes to frame etc...) Ultimately you will need to do some modelling and see what the numbers tell you. Will you have a MVHR system?

I'd just put a sheet of perspex in front of it - feature enough. Bit like those exposed sections of roman wall / mosaic that you see.

You need to hire a couple of teenagers for sound checking, especially the nocturnal variety who decide to do their hair at 1am. More seriously, if you're having MVHR then you need to allow 7600mm2 under each door (i.e. a 10mm gap on a standard 760mm door) for air movement. This will also allow transmission of noise...

Yes, the combination of the deep filled cavity, triple glazing and airtightness has that effect on outside noise, ours is similar. Greg made extra provision for internal soundproofing between rooms with rubber matting, resilient bars, sound block board etc but it seemed to make little difference.

A previous stalwart of eBuild built one of the first MBC houses in Oxford, similar time to Jeremy Harris. He spent a fortune on acoustic materials and was very disappointed with the end result, for exactly the reasons stated above.

Depends on what you're buying. If it's bulk, general building materials etc then yes, I agree. But I found that for things like skirting, ironmongery, upmarket sanitary ware etc then I was always better off doing my own research & buying.

Unless you're an experienced builder then everyone is in the same boat. You either take the step by step approach that we did or throw your lot in with a main contractor and accept that you may tweak the specification (and cost) as you go and as you learn. Provided you're making decisions in a timely manner then it should not be too disruptive - the closest call we had was a last min decision to put electric UFH in the bathrooms, made just after the tackers had boarded over the first fix. Luckily electrician was accommodating and we popped off a few boards to get the necessary cabling and trunking down over the weekend before the plastering started the following week. You can also spec things to the Nth degree and get into diminishing returns. Unless you have very deep pockets, you will need to accept some things could be done better after the fact, take a breath and move on. You will make mistakes, you will forget things but in the grand scheme of building a large house from scratch.

I was given my person's details by one of the groundworkers - they basically do the shopping around, source best price, arrange delivery etc and invoice you for commission on the sale, still works out cheaper than tying to buy it yourself. However for most things, good old internet shopping is the best approach. If you're not looking for a single contractor tender, then you don't need all the detail up front, in fact as its almost a certainty that things will change it may not be a good idea. What you do need is a ballpark cost to pivot off for each significant part of the build. We used a QS to take our planning drawings and do such an exercise. The quantities they calc off the plans should be fairly accurate but their prices will be SPONs or equivalent so reality may be higher or lower. We got a relatively detailed cost plan in Excel which we used and tweaked as the build progressed. To give you an idea of how it went... we got firm quotes for major elements such as demolition, groundworks, basement and the timber frame and locked in those contractors. I was then able to shop around contractors for windows, roofing, render scaff etc and if was a question of if they were available in my timeframe and then getting a quote and refining it based on particular materials etc, then locking them in to follow the frame erection. Focus then moved to first fix - again first task was ball park quotations and availability and then with a selected contractor, firming up the spec, usually by walking around the shell and making final decisions. Once they were locked in, I moved to first fix joinery and plastering, tiling etc. Then ordering second fix items (mostly sanitary ware), decoration, kitchen, internal doors, skirting etc etc. At each stage the build became more 'real' and final decisions could be made in context. We also picked up inspiration as we went and were able to flex the budget and spec.