Thorfun

sorry to hijack the thread, but out of interest @nod how would you create a service void on those walls? our waterproofing expert company has suggested this form of internal waterproofing (the Delta system) for our basement with a drainage channel to a sump pump but it looks like the only way to create a service void is to build another internal wall with access points for maintenance and then batten on that. They do suggest you can dot and dab plasterboard straight on to the membrane, so could you potentially dot and dab osb and then attach battens to that for a service void and then plasterboard on top?

another that has gone for RAL 7016 here. we're having Shou Sugi Ban larch cladding (aka charred larch) and so feel the black and grey will go together nicely. a lighter or brighter colour would, for us, make the windows too contrasted with the cladding. I'm not worried about it going out of fashion as I'm not building the house for others or to be 'on-trend'. it's being built for us and we love the look of Anthracite grey windows. ? and, just like @canalsiderenovation, we are having white inside but have gone for Norrsken windows instead of Internorm.

GHG is on my research list too. Just one of many subjects on a very long list!

yeah. that's what I gather from the reading I've been doing. I have a neighbour who is a plumber so I'll be popping around to see him and ask about DIY installing the ASHP. as with anything it's only the lack of confidence and not wanting to screw it up that is holding me back from just doing it all myself. that and I want the house to be finished before 2030. ?

understood and agreed. I am already paying for a full thermal modelling report which I'm hoping won't be too far away so I will have those head demand calculations soon. until I get those though I'm working on the results from Jeremy's spreadsheet which all seem to say are pretty darn accurate! I'm still waiting for a couple of companies to quote but at the moment it's looking like RHI just isn't worth it.

thanks @joth. I will read through that document in detail. I also have had a couple of other quotes and neither of those companies have said that all rooms need to be heated so I think these guys are wrong (or simply mistaken), as your research has showed. what I'm also finding is that the MCS/RHI heat loss calculations are shockingly bad! I've used @Jeremy Harris 's spreadsheet and it comes out at worst case scenario an 8kW ASHP @ -10oC. but all the MCS installers have said I need a 14kW ASHP! after speaking to one of the installers we figured out that the RHI heat loss calculations don't take in to account the efficiency of the MVHR. once he added that in my requirements suddenly went down to 5kW @ -2oC. that's a big difference. I'm seriously looking at forgetting RHI for the small amount we'd get and just getting a plumber to install the ASHP. for a highly insulated and air tight building the RHI just doesn't make sense. it would be better for me to aim for a lower SAP rating to get more from RHI rather than spending money to get a high SAP rating. just seems completely balmy and backwards to me.

I had an interesting conversation with a renewables company that said that if I wanted to claim RHI payments then every habitable room in the house needs to be heated by the heat source, ie. ASHP in our case. I asked about Passivhaus properties where heating upstairs might not be required and was told that if a room is not heated by the heat source then the property doesn't qualify for RHI. does anyone who can disseminate the minefield that is RHI let me know if this is correct? sounds like a crock of excrement to me and they're just trying to sell me UFH on the first floor in order to some RHI payments. I still haven't decided if I'm going down the RHI/MCS route yet for ASHP (or Solar PV) but I was generally thinking of not having UFH in the bedrooms and having electric UFH and towel radiators in the en-suites on the first floor. and wet UFH from an ASHP in the basement and ground floor. so if I did go for RHI then the electric heating and lack of heating in the bedrooms was mean we wouldn't be elligble anyway.

thanks @MrMagic I'll take a look. I haven't started researching the different refrigerants yet but it is definitely on my list!

just as a quick update, I found the spec sheet for the Mitsubishi R744 ASHP and it's COP is pretty rubbish. so I'm not bothering to look at this anymore and will focus on a standard R32 ASHP. data sheet attached fyi. Ecodan_QUHZ-W40VA_Monobloc_Air_Source_Heat_Pump_Product_Information_Sheet1.pdf

bumping this topic as I've been informed by a potential installer about the CO2 refrigerant and was wondering if those that know have any more information or updated opinions in the 2 years since this topic was last raised? @Nickfromwales would you still not quote for it? we're going for UFH so don't need the high temps for DHW so should I not even bother considering it? or will it be Uber-efficient when running at UFH temps, even more so than an RC32 ASHP?

@Mako sounds like you need to spend some time reading the blogs of various members here. plenty of Passivhaus examples there. will give you a great understanding of what is involved and how the folks who keep the blogs approached every area of their build. I have found the information invaluable and often refer back to them when researching the various areas of a self-build.

we found cardboard boxes are better as they're stiffer and can be more easily removed during the day. ?

I asked the same question when I first joined but then I realised that it was in the forum guidelines all along! https://forum.buildhub.org.uk/guidelines/ which I'm sure every member has read, right? ?

ha ha....flying by the seat of my pants really! but I'm fortunate that I spend all day sat in front of a computer so a large portion of that is spent on this forum trying to learn from everyone. so if it seems organised then you all are teaching me well. ?

It's been a while since we obtained planning permission and my last blog entry but we've not been idle. it seems that the last 3 months or so have been a constant stream of decisions that need to be made to get this project started. It's also been a period where money seems to be going out but we don't have much to show for it! The majority of the decisions have stemmed from the architects needing to get the detailed BC drawings finished. here's a nice summary of our decisions so far (although I've probably missed and forgotten a few) Timber Frame Company This was a one of the biggest decisions for us (windows and doors was the other) and was the one that had to happen as soon as possible after getting planning permission so that we could get the timber frame designed and the BC drawings created. We previously had quotes from 9 on the original plans before we had to make changes to get through planning. Of these one was discounted as they never got back to me about changing their set specifications, one because they wouldn't use metal web joists insisting that they only used I-joists, another due to extortionate costs and one more because of costs although not as excessive the ones that made the shortlist but just enough for us to make an easy decision not to include them. That left 5 for us to get updated quotes on the approved planning documents. We are going for an open panel system and I will be fitting the insulation to help reduce costs; even though this will extend the build time the savings are substantial enough to justify it. With those quotes we discounted another due to their location and narrowed it down to 3 local companies and MBC. MBC were by far the most expensive for an open-panel TF but they get such good reviews on here and we have friends that are using them we couldn't discount them out of hand, but in the end we couldn't justify the extra cost when we weren't getting from them what they excel at, i.e. factory fitted insulation and promised air tightness levels. to give them credit they were completely upfront about it and completely understood the decision. So that left just 3 local-ish companies to choose from. We visited sites from each company to see their work and after that, although it wasn't easy, there was one clear winner and that was Flight Timber (https://flighttimber.com) based in Essex. We were very impressed with the quality of the build we visited and are very happy with how they've conducted themselves during the negotiations. So we signed the contract and paid a deposit. Since then they've been doing great work in getting the TF design done and liaising with the architects to finalise everything. That has now been completed and it's all with the structural engineer to do the basement/foundation calculations and drawings. Structural Engineer For the structural engineer we had 3 quotes from firms that the architects use, one from a friend of a friend and 2 from recommendations from the buildhub hive mind. We are having a basement and so this was a consideration and needed someone who could provide us what we needed. One of those requirements was an insulated slab foundation under the basement and the arms of the house. There was quite a discrepancy on costs between the 6 quotes and a couple were easy to discount as they were so much more than the others. So from the remaining 4 and after much consideration and communication we decided to go with TSD as they have a great reputation for insulated slabs, are highly recommended by many on here and their price was very competitive! So far, they've only been working on the design since the start of the week, I've been very impressed with the communications and their open-mindedness to my ideas and requirements. I made a decision (doesn't really require it's own heading) to ditch the idea of using block and beam for the lid of the basement and will be using hollow core precast slabs. Sadly though, after the SE spoke to a supplier it was obvious that they wouldn't span our basement at a reasonable thickness without internal structural walls (which we were trying to do without) and so we've resigned ourselves to having load bearing walls in the basement, otherwise costs could easily have gotten out of hand by going for thicker precast slabs, thicker foundations and thicker external basement walls to all accommodate the extra weight of the thicker slabs. so be it, I'm sure it's not the last concession we'll need to make to save money. Civil Engineer we are creating a new entrance to our plot from the road that will go over a ditch and so requires a culvert. so we decided to hire a civil engineer to plan and manage that, the drainage, driveway levels and water course discharge. we only got 3 quotes (it's my magic number for quotes) all from companies that the architects deal with and simply chose the one that wrote the best proposal and the costs were reasonable trusting that the architect's recommendation for each company was good enough for us. Windows and Doors This was a huge decision for us and caused a lot of brain power to try and work out who best to go for with spreadsheets being created to compare the various companies. We have a lot of glazing (about 120m2) and we want triple glazed alu-clad units. We approached 7 companies initially, visited lots of self-build shows to get a feel of the windows to help us to decide. We did consider IdealCombi for full alu windows but in the end our desire to have timber internally won and we didn't proceed with them. We discounted a few others due to costs and in the end it came down to Internorm and Norrsken. Internorm windows are so nice but they are so expensive; despite this we thought we could potentially justify the extra cost but the reviews of the supplier on here put a dampener on them as the last thing we wanted was to pay a load of extra money for windows that we didn't get any sort of support for when things go wrong. We visited the Norrsken showroom in Poole and were very impressed with the windows, doors and sliders and I couldn't find any bad reviews on here for them. The price was very good and so we signed on the dotted line and paid our deposit. We are very happy with our decision and the money we saved over going with Internorm will pretty much pay for our kitchen! External Blinds With all the windows we are having I was worried about overheating, especially after reading some of the issues other forum members have had with solar gain. We needed to make a decision on these before the TF design was completed so that they could be built in to the frame and are then hidden from view. So, external blinds were on the cards and needed to be researched and a decision made posthaste. I've posted elsewhere about my experiences with Roma blinds so I won't repeat that here. In the end I came across Warema blinds which look good and seem to do what we would need them to and found 2 London based Warema suppliers to get quotes from. Both were so similar in price it was hard to choose between them. In the end, after my company house checks (which I do on all people I wish to do business with) it looked like one of the companies had grown their business really well over the last 5 years when looking at their accounts that I decided to take a punt on the smaller guy and went with Corner Star Aluminium. Only time will tell if I made the right decision on that one. MVHR This is a subject that I have done a ton of reading on here in the forums and also posted a few times on the subject. the whole 1 or 2 unit debate is real but I really would like a single unit solution. I got 5 quotes (one through the architect and 4 off my own research). BPC wouldn't do a single unit saying that the largest unit they do is for a 350m2 house but our house is 450m2 and so we need 2 units. I felt that they're just sizing on Part F calculations and the manufacturers own statements regarding house size for unit size and didn't take running at Passivhaus levels that most on here feel that running their MVHR units at is fine. Also, they do sell bigger units, e.g. the Airflow DV245, so they could do a single unit but I just got the feeling that they couldn't be bothered to consider another option. so they're not getting my business. CVC were just too expensive and I didn't trust the company the architects asked to quote as they didn't give any details as to the ducting etc that they'd use (and also were selling a 2 unit solution). so it came down to PAUL Scotland and Enhabit, both of which were offering a single unit solution (Zehnder Q600 with 90mm ducting). Pricing was very similar so in the end it came down to location again (although a price reduction did help!) and Enhabit won. the deposit will be going over today and then they can crack on with the design. Others I'm sure there are loads of other smaller decisions we've made, like external finishes for the discharge of planning conditions etc, and I know there will be hundreds more to come as we move forward with the build including ASHP, Solar PV, UFH, DHW, RWH, floor coverings, tiles, lighting, home automation and so on. The next big decision will be the groundworks company to do the culvert, driveway, foundations and basement. Once I have the SE plans and designs I can approach the companies I've shortlisted to get detailed quotes and can carry on with the decision making. I have ended up having to make a list of decisions to be made there are so many. that way I can tick them off when they get done as it was getting to the point that it seemed they were never ending. at least this way I can see what has already been done and can see the list getting smaller as we progress. thanks for reading. ?

this bodes well as it looks like I'm going to be approaching Milbank (along with others for comparison of course) for supply of hollow core precast slabs for our basement 'lid'! fingers crossed for a good price on that. ?

ok. thanks. I was just trying to get a feel as to how long a pump 'should' last in a direct fed system. if it's every couple of years then a gravity fed system might make more financial sense in the long run as the extra cost will be mitigated by a less frequent pump replacement. but if the pump lasts for 10 or 15 years then 2 of them will probably outlive me!

that's great to know @JamesP as I've been looking at those F-line systems (as well as the Rain Sava systems). how is the F-line system? you've gone for the same sizing I'd be looking at in the F-line series. why did you choose the F-line over a.n.other system?

interesting. how long did the pump last?

cool, so yours is sized so that it will overflow occasionally?

ps. was told that the RWH tank needs to overflow occasionally to 'wash away' any pollen that could cause a sulphurous smell that has gotten through the filter.

I've been recommended a 4500 - 5000 litre tank when taking in our roof size and average rainfall. we will have 6 toilets in the house (obviously not all of them will be used at once!) with a regular occupancy of 4 humans (the dog and cats don't often drink from the toilets so that will save us some water). will also be used for washing the car, watering the veggies etc and thinking of potentially using it for the washing machine but will need to do more research on the potential pitfalls of that one. thanks for your opinion on not needing a header tank. I'm leaning that way, especially as it's about £500 extra for the gravity system and that's before the extra plumbing required. and for the money saved I could replace the pump later on down the line if required and still be quids in.

got another question about RWH and thought I'd keep it here rather than start a new thread. Direct vs Gravity? I can see pros and cons for both, here's a basic list that I can think of although I've probably missed some obvious ones. Direct fed Pros: 1. no header tank 2. cheaper 3. reduced risk of Legionalla 4. reduced plumbing complexity needing to run extra pipework to a tank in the loft Direct fed Cons: 1. pump runs every time a toilet is flushed 2. slow drip leak from a toilet will cause the pump to keep cycling to compensate for that small leak 3. a low RWH tank level will result in mains water filling the RWH tank rather than a header tank in a gravity system (at least I assume that's how it works) I guess the Gravity fed Pros and Cons are pretty much the opposite of the direct fed ones. Now, I know on here folk don't seem to think that RWH doesn't make sense financially but we really like the concept and reducing our reliability on the main utilities where possible. we also think that we can incorporate the cost into the total build budget. so with that in mind, would you go direct or gravity fed RWH and why?

well done! you managed to get her to buy you a shed. she sounds like a keeper. ? as long as she doesn't change the locks to the house while you're 'working' in the shed that is.

can't the wife be put outdoors instead?