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Morning fellow masochists, I’ve lurked these forums for a long time reading through posts that have been super informative as I continue with my comprehensive renovation and extension project that, if I was a smarter man, should have been a knock down and rebuild job. Ive decided to finally create an account and start contributing to the discussions. Currently converting a bungalow into a 4 bed detached house by adding an additional floor. Roughly half way complete after nearly two years of weekends and evenings. One door away from being watertight and nearly ready for first fix. Based in the north east.

If you've got a mini digger and you need to use forks occasionally this £55 set off ebay could help. Just need to put your ditching bucket on in reverse and clip them on.

I made a video, but I'm not happy with it. I'll remake later if I can escape my family for 30 mins.

Just wash the heat exchanger in the bath, I’m sure I read somewhere that it has to be fully dry before it’s fitted though? I had to pack my vent axia unit out a touch at the bottom as I had water coming out of the front but only slightly, this helped the issue. I was shocked at how much water the unit produced in the winter as I was catching it in a bucket until I got the drain sorted. Mine was in a cold attic & insulated as good as I could get it.

More or less done these two rooms now, which after finishing the bathroom were basically just flooring and decorating, making a bit of furniture and then moving some other furniture I already had which was always destined for the dining room. I’ve got planned some bench seating for the wall side of the dining table to make it more space efficient, but not any time soon. I think this will be the first time, certainly in the last 10 years, where I have no outstanding ‘filler that just needs sanding down and painting’ kind of jobs, everywhere has skirting board which is painted… the little things in life. Everytime I walk in the bungalow and see the French dresser, it just melts my heart, knowing that my late wife would have loved to see it where it is now, we did buy it while she was still alive as they were stopping making it and was perfect for the look we were going for, managed to bag the dining table off eBay from the same range for around £200 I think brand new, and the chairs were ones we had from ikea which I upholstered and painted white to match. I know the plug sockets need covering, managed to locate them just slightly too high! The bookcase is to be backlit with an LED strip light (awaiting Black Friday being the right bugger I am!) and then will be filled with all my books, photo to follow at some point. The hallway has also been redecorated and the floor sanded and reoiled - out of anywhere this small passageway has suffered the most during the works bringing everything in and out, so was nice to get it back to 100% again

As some of you may have seen from my introduction post (shameless plug here), we bought a house in the summer of 2023 knowing it had subsidence. We decided it wasn't that bad. It was down as cash buyers only. Surely we know better than the lenders. Read on to find out if we were right... A summary We weren't looking to move house. We did the usual search on rightmove when bored. This house came up; the interior was old, it had subsidence but it came with a great plot of land and we could see it being our forever home. It has remedial work for subsidence done back in 2012, the walls had helifix bars installed and the offending trees were removed. We even had a full structural report written up from a proper MIStructE geezer, and he said the house was alright if a little wonky and the garage was more likely to fall over. What did the report say? Floors are a bit wonky, few cracks here and there. Walls are a bit off but yer roof timbers are alright. Nothing we didn't already know really, but nice to get it from a professional. No bowing in the walls at all so whatever happened was a nice even movement. The professional said some movement could be attributed to the trees at the rear of the property or maybe some damaged drains. (The worst affected area was literally right next to the guttering downpipe😱) What did you do next? I made a post on Buildhub, and contacted a resin injection company to see if we could do some localised repairs. The resin company wanted to inject an expanding resin around the front of the property and also down the sides. This came out at more than we had budgeted for remedial foundation work, and since we were planning to do some structural work (i.e. extension) they said the second we dug near the injected areas it would invalidate any warranty which would have turned it into one big gamble. As part of the resin injection investigation we commissioned some soil samples and drain surveys to understand the state of the ground and also see if we were right in our assumption the drains had failed. Below is a summary from the drain survey. A green X on a run indicates no defects. A yellow X on a run means a minor defect, and a red X means urgent defect. As you can see, there are no green or yellow, only red. 😂 Clearly the old terracotta pipes were knackered. Around the same time as this and thanks to some of the helpful advice on this forum I started a period of monitoring the house. Structural engineers say once a quarter is pretty good for measuring any movement on a house to capture the seasons; I did it every day. Us buildhubbers do like to go overboard... Bought the proper stainless steel measuring discs and a good set of digital calipers. I input all the data every evening into an excel sheet to make it easier to spot trends. I also made sure to do this at a similar time each day to try keep temperatures as consistent as possible. Variations between days were fine; I was looking more to see if we had a trend of cracks widening. I did this for about 5 months - not long enough to get a load of data, but I stopped in winter when the SE told me we'll have to pile the extension which meant my whole theory of monitoring to avoid underpinning was shot. As we have quite a high water table and a lot of clay they reckoned piling out be the most suitable rather than needing excessively deep trench or strip foundations. And because we'd be piling the extension it meant we'd have a rock-solid new part of the house and the old part move at a different pace; leaving us with a real risk of differential movement. Whilst doing the above we also replaced the drains around the house; installing two new soakaways to the front and rear of the property (appropriately sized for our new roof area too. When digging out the old drains this is what we found (no wonder we had some soil washout around the foundations) We decided at this point that we may as well go ahead with the SE's suggestion and pile the underpinning too. Yes, this cost a lot more than we had planned but if I'm honest I'm pretty happy now knowing that the house is fully supported. What was piling like? SE's came back and said pile everything in sight. You can see below the piles for the new extension plus the cantilever underpinning to the front and side of the property. So that's what we did. However trying to find a piling company who would work from someone else's plans AND do their own excavating was a nightmare. We had one company say they wouldn't excavate the ringbeams and would only pile, but also wouldn't tell us what level they wanted the ground at. They then agreed to excavate, and about a month later when someone else visited the site they changed their mind again and said they'd only do the piling. They were swiftly told where to go and we had to go back to RFQ stage to try find another contractor. As it turns out this was good fortune as the company we ended up using was brilliant. They did all the works end to end and also supplied an engineer to mark out the beams and the block profiles so it was ready to go for our builders. They even cleared the oversite down to the required level for the air gap under the block & beam flooring. Piling starts: Very grateful at this point for the large carriageway drive - made it much easier for getting the kit off the lorries. Was rather strange to see so much gear for one house; I definitely wish they'd let me have a go with it. We actually went through two rigs; one had the winch fail but we had a new rig onsite the following day to continue. The weight on them is about 750KG and is dropped from a pre-determined height. For us it was about 1.5 metres. On each drop of the weight they measure how many millimetres the pile slips and using calculations from the SE they can work out when the ground has enough bite to hold the pile. We thought we'd really feel this and we were also concerned for our neighbours, but it turns out aside from a little bit of vibration there wasn't actually that much disruption and we got used to it after a few days. They were on site for about 2-3 weeks (2-3 piles a day depending on the soil conditions) and we had no complaints. Once the weight went below a certain depth the shockwaves from the impact just sailed right under the neighbour's houses. Our nearest neighbours who were about 30 metres away felt very little, but we did have some neighbours about 200 metres away who said they could feel it; but thankfully no damage to their property. The contractors estimated about 6 metres for the pile depth for when we'd get the right bite, based on nearby BGS surveys and boreholes. Things were looking pretty good when we found a solid crust at about 3 metres and we thought it looked like we were in for a saving on the job! In typical fashion though what would have been the last drop forced the pile through the crust and it dropped about 13 millimetres. Once that happened they had to keep going and we ended up at 8 metres for the first pile. Because we found this solid layer at 3 metres but knew underneath was weak we HAD to go through it on every other pile. It got real solid in places but because they knew it wasn't solid underneath it couldn't be used for a fix. The other 35 ended up at between 8-10 metres and we found some very different ground depending on which side of the house they were on. When you got some good depth on the piles you could get a good echo out of them when shouting down though. Was really weird to just see it going down and down into the earth though. Once all the piles were in the excavation team were back to do the ringbeams. Some lovely Lincolnshire clay was waiting for them along with plenty of water. We had pumps running overnight to keep it clear as one trench just kept filling up. As a bonus in the above picture you can see the absolutely top-notch definitely not too thin or too sandy foundation that the original house was sat on. To add to that, the foundation in the house also wasn't level. This one really confused us and the excavation squad. At one point it was 5 bricks between DPC and foundation; at the other it was 8 bricks. You can see in the above where we had to step the beams down to get it to fit; which required some custom Z bars to bind the ringbeam together. You'll also spot the gap this left in the high points where we then had to get a more specialist non-shrinking concrete to meet the foundation. Another nice surprise and request to open the wallet. We still have no idea why they did this; either they decided after digging a certain depth for original foundations that they didn't want to did so deep (or didn't have to), but when you're doing a full set of foundations at once why wouldn't it be level?! Anyway, we persevered (or they did) and at the end we had a nice base to start our extension on: In the end we were in for 35 piles at about 8-10 metres, with 600mm ringbeam all round complete with hefty 16mm rebar sat in it but BCO have signed it off as good and we were on our way. The drone also makes for some interesting photos... footprint of the house is just a bit larger than it was before! Probably missed a few things here and there but hopefully provides a bit of insight into the joys of piling, subsidence, underpinning and just general mess. Absolutely loved spending £££££ for it to be covered in mud and never seen again; should have just filled it with £20 notes, definitely not being sarcastic. 🙄 tl;dr Whatever you are quoted by your contractors, double it. 😂

Rigid rockwool and cement fibre-board, with suitable top, edge and joint detailing?

Thanks Iceverge my proposal was two skins of normal dense concrete blocks, not soft cavity blocks. the battens and counter battens would be 25 x50 not 38 x50 the vertical battens would have to be drilled and plugged the horizontal ones screwed to the others with 50 mm wood screws. ( vertical cladding) I agree extra work is required fixing the internal insulation boards, longer screws etc, but time would be saved on not messing around cutting the boards to fit in the cavity, around wall ties etc. Also no chasing out for cables and pipes, plus making good, as with a wet plaster finish. I still want to go cavity block built, not ICF or timber frame. my builder has just sent me pics of a 15 year old TF building that had a failed rainwater downpipe that had been leaking and splashing up under the cladding ,unseen for quite a while. The rot had gone from the sole plate to two verticals . He was brought in for minor alterations and it has progressed to a major refurb. not his original build by the way.

As we haven't yet decided on the final floor material inside, I've left a (bit arbitary) 18mm ready for it. Then when it's fitted we'll have a fairly level threshold.

Yes to both, it depends on how much you enjoy the tech involvement. I paid extra for a smart thermostat so I can set to auto adapt, which incorporates load compensation, to take care of everything for me in the most efficient way possible, but I have rads, it's an unknown quantity with UFH. Others prefer managing the tech to achieve a "Goldilocks" WC setting. Either system can be made to work well.

RK38 and RK70 are lime/sand mixes, ready to use, with about 6mth shelf life (some say a year but I have had a few lumps lately!).

Yes, I was, on the basis if mineral wool potentially being less moisture-buffering than wood-fibre. I like (expensive!) Intello as it's good for pessimists (tends to become more vapour-open in warmer weather so that *if* any moisture has got in during the winter it may be able to 'breathe' back out).

Absolutely pointless, use the proper braces. you are not holding 2.7m high walls plumb with some 2x1 battens and then pouring wet concrete in them. there is absolutely no need to put the screws into the centre concrete on icf, that’s why the blocks are designed to be screwed into, either woodcrete or eps / xps versions.

It's dead straight on the pro side. On the negative side it is very conductive so ensure that the bottom of it is isolated from the cold. Be careful with wiring too that it doesn't get stripped by the metal. You might need to tie any studs metal or timber to the wall at an intermediate level if it feels wobbly. Get batts slightly thicker than the cavity thickness and wider than the gap between the studs. They'll just stay there then when you put them in. Mineral wool on rolls won't. You'll need batts.

That sounds about correct and is exactly what I see if I let the floor get too cold. Your heat pump controls dT first and slowly working up to target flow temp. So if the floor is cold your return temp by default is also cool. Last year I did an experiment set target flow to 35, never got above 32, after nearly 12 hrs of running. Your floor is a huge mass to heat, they have massive inertia. Simple answer is it isn't a gas boiler, you need to run it almost constantly in cold weather. Add to this you will be defrosting on a regular basis, which fights against short running regime.

That is only 7 degrees change for 12 deg change in OAT so a slope of 0.6, maybe you should up it a bit. The time constants involved in UFH are so long that you cannot realistically expect an immediate response after an off period. If your HP size was well matched to the heat loss then it would need to run nearly the entire time in cold weather. That seems very cold for Northamption even in the recent cold snap. Either your WC settings are still wrong or you should not be trying to run the HP intermittently or it is simply not big enough. What does your installer's Heat Loss Calculation say and how does yr HP capacity compare with this?

I managed to pack it off the wall at the base . So it tips a bit more backwards . At this point in time as it’s run flawlessly for 4 yrs - I can only assume it’s moved slightly causing water to pool forwards and to the right ( bit with no drain ) . Or maybe dirt/ dust in the heat exchanger changing water flow direction ??? . How best clean that ? . Just sit in the bath and run hot water and detergent through it ?? All back together now . Want too see that water out the front has been solved . Then it’s in the lap of the gods if it flows left ( hurrah ) or right ( boo )

It's easy to do something like draw a layer of PIR taped correctly but another thing altogether to try to do it in reality. I built a passive house, really understood my junctions and airtighness layer, and did the necessary work to get it airtight. Having seen the level of detailing and labour required I think that attempting to do so in an old house with internal boards is absolutely futile. You will have leaks, you will have gaps behind the boards and you will get interstitial condensation. The impermeable nature of the PIR will prevent the wall from drying apart from the miniscule cracks where the vapour got in in the first place. My main preference for a parge coat and mineral wool is that good real world performance is actually achievable. Parge and airtighess paint is very forgiving on wonky surfaces and corners around timber etc. The parge is vapour permeable so all the wall can dry. The mineral wool can flex to old wonky walls so there's no gaps for condensation to occur.

In a split its quite possible that the indoor unit is adjacent to (or integrated with) the DHW tank and point where the primaries to the heating system split off, and thus also possible that little or no 28mm is needed (the connections between the ODU and IDU in this case are refrigerant not water) and you would get away with a short length of 22mm at 9kW. However he should know the difference!

I’ve had a couple of pre-app responses that were both misleading and slow. Maybe ask what the consultant would deliver for the money and also check out other consultants? Does he have an example report (redacted maybe) to share?

This is something heat geek put out there for pipe sizing, you will be looking at a dT of 5. So as you thought you need 28mm. The pipe your plumber is specifying is thick wall so closer to 22mm. I would have alarm bells ringing as he isn't doing the basics.

At the start it was their payment terms triggering a look. If they ask for >50% upfront, payment in cash or amounts in excess of the materials costs. I now use it for every company we’re giving more than a few thousand £s to. I think it’s a good habit, easy to do and the guide @Susie mentioned is a good ‘how to’. It does indeed show who is going bust, shows if they are in liquidation. Also as mentioned above shows how often companies change their trading name, or base location, or directors. One company moved office and changed name almost annually. A quick internet search for reviews on the previous company names showed a whole load of issues and we didn’t use them.

Hope this helps a bit.. but when we want to create a void above the wall head level the forces in the roof members change a lot . The following is very simplistic but intended to give folks an insight into some of the things we design for and hopefully give you all some ideas. Below is a standard fink truss. This fink truss is triagulated, very economic an importantly the loads at the supports are downwards.. and upwards when you get wind uplift. A lot of roofs can be "uplifted".. Below is what we call a raised tie truss. Here we have an extended leg. The ceiling tie and wall support create a lever arm... like having a long spanner to take off a wheel nut on your car. This type of truss depending on the length between the ceiling tie and the wall support causes other forces / sideways movement which can grow exponentially with a small increase in length. An important one is that this kind of truss can push the wall outwards (sideways movement).. so you often need to have "special" sliding truss clips at the wall head or a very strong wall.. and if you have a very strong wall then there are other options! Now the above truss generates some nasty forces at the connection between the ceiling tie and the sloping rafter. Timber connections can be quite weak and they are hard to design economically / buildability wise once you reach a tipping point.. which can be quite early on.. this can be a hard lesson for a Graduate Engineer / self builder. Below is a scissor truss Here you can see that the sloping ceiling tie stops the forces that want to spread the walls outwards as the bottom of the scissor is conneceted to the wall head. Often when we design timber roofs one of the problems is not the size of the timber but having enough timber to make the connections work ok. If you have an old house with a traditionally cut roof you'll see that the ceiling ties and soldiers (the short upright bits) are 1/3 to 1/4 checked. Below is a screenshot of one of my drawings that shows this. The dark green bit is the rafter, light green the soldier/ ceiling tie framing in. But there are only three nails! The one shown here is later detailed as having only 3 no 90x 3.1 mm dia Passlode ring shank galv nails. The three nails are there just to hold the soldier in place when there is say snow / access and roof self weight on the roof. The check in the timber allows for direct bearing.. timber to timber contact... much "stronger" than a few nails! Also we need to watch out for nail spacing and edge distance.. to many nails / to close to the timber edge and we weaken the timber so folks bear that in mind. The three nails are enough to hold the connection together when the wind is trying to suck the roof outwards. To sum up. Timber roof design is a bit of an art.. but hope the above gives some insight into what it is all about. The key thing is that often its the connections that govern the design rather than raw timber size. A good starting point is to go into some old buildings/ terraced houses and see how the roof is put together. @ProDave If you want to chew the fat then would be delighted to hear from you, mind you I'll want to pick your brains too so no free lunch!

A parge coat is used to make the wall airtight, for three reasons. First, it stops stop cold outside air from reaching the insulation, which would degrade the effectiveness of the insulation and potentially lower the temperature within the insulation to the point where condensation forms - which is why it needs to be on the outside of the insulation. Second, it stops the wind from blowing outside air in and drawing inside air out. Thirdly, it stops air escaping due to the 'stack effect' - that is, even on a day without wind, warm moist internal air is more buoyant than the outside air, so will rise and escape through any gaps, drawing outside air in as it does so. If the building is airtight, the air pressure inside the house and inside the insulation will be more-or-less identical, so there's nothing to drive that warm moisture laden into the insulation. So, in answer to your question, no, it won't. That leaves only differentials in relative humidity as the means by which moisture (moisture vapour) can move through the materials and into / out of the insulation. Which is why, if one has been specified, a vapour control layer will always be on the the warm side of the insulation (or at least not more than 1/3 of the way into the insulation, according to a well-known rule of thumb).

Please do :) It's good to have an update and to see what you've been up to!

If your Water Law (WC) with no adjustment was, for example, set as:- Outside 15>>>>>>>>>>>>>>>>> -2 deg C Flow 35>>>>>>>>>>>>>>>>>50 deg C your adjustment of +5 to the flow temp takes effect across the whole range, so the Water Law becomes:- Outside 15>>>>>>>>>>>>>>>>> -2 deg C Flow 40>>>>>>>>>>>>>>>>>55 deg C so either you should be feeling a lot warmer, or your room stat cuts the heating sooner, or both.

We are in the process of going for a Dan-wood house on a plot in our current back garden. Great to read this feedback on the process. We are about to submit our stage-2 technical planning application having got planning in principle approval for a self-build. I was inspired by @kandgmitchell to get in touch with Greenraft today for a raft foundation and they came back straightaway with an outline quote. Would be interested to know about the spec that Dan-wood were happy with (eg is 150mm concrete sufficient). And whether it is worth exploring AACM as a more environmentally-friendly alternative to Portland cement as we won’t need a construction warranty for mortgage purposes.

I return... nearly 18 months later. The project is still ongoing, but I thought it was worth updating everyone on our experiences so far. I admit we've probably made a few mistakes but as a first attempt at a big project I'm pretty happy how we've dealt with issues and moved on; every day is a school day! If any of this helps anyone else then it's worth it even if I look a bit daft during it! So - onto the project. We started by demolishing the old extensions since the foundations for them wouldn't be up to supporting a floor above them, plus they were built inadequately for our needs (solid walls, weird floor buildups, even weirder roofs). There was plenty of advice on this site around the existing foundations and how to proceed with them which we really appreciated, but in the end we were led by the structural engineers and underpinned the property for peace of mind to avoid any differential movement. The extension foundations are piled down to about 8-9m and the existing property was cantilever underpinned using piles too. Overall we're pretty confident the house won't be going anywhere (we now have 36 piles!) We've then wrapped a fair chunk of the house in a new extension to better use the space, and put the poorer performing old external walls further into the property. Cavity is 200mm with 190mm PIR made up in two layers incl interlocking boards and tape, and the flooring is 240mm EPS insulation in the new areas, whilst we've just finished digging the old flooring out of the house which should be insulated to 170mm. I'd like more here but we're restricted by the depth of existing foundations which is a shame. The old electricity supply has gone from overhead to a nice new underground supply, complete with 3ph up to the DNO supply head so we're future-proofed (still only 1ph currently) and I'm waiting for a response to my request for a new water supply. Wet UFH is throughout, with the oil boiler gone and an ASHP to replace it (When I can get an installer on the BUS grant that won't rinse me). Spent a fair bit of time playing with Heatpunk and Jeremy's spreadsheet for heat loss predictions which is fun when half the property is 200mm cavity and the other is 50mm. I really wish here that we'd stepped the walls outwards and then EWI'd the older walls but I didn't think about this until it was too late - a good reminder to plan ahead here. I'm also scheming for 10kWp of PV to go on since we're having a new roof fitted. The savings in tiles & labour lets me man-maths my way into some GSE trays and panels 😁 My current focus is looking at the air tightness, not as much of an issue in the new section but the older part of the house is good fun, so I guess there will be updates on this part from time to time as I'd love to get MVHR fitted as well. Words can be boring sometimes, so the tl;dr is: should we have listened to you all knocked it all down and started from scratch? In hindsight, Yes 😂 Did we? No... (Be gentle 😳) time to learn from it and make the best of it! And the pictures: Steel reinforcement for ringbeams in place after piling at the back Starting the build to DPC Second lift and on the way to wall plate. Will maybe dump a few more before & after shots in the coming days or a specific focus on parts if anyone is interested. Poor house has been battered about a bit - for the greater good I hope!

I think we all know how much we can trust Kingspan datasheets. 🔥

It was a while ago but I think about 2 weeks.

Understand the wall issues, and with render, then all the more important. There are, afterall, only types of render, render thats cracked, and render thats going to crack! Which is why i cringe everytime i see EWI covered in render. The long term outcome can surely only go one way. But your roof build up is exactly the same as a modern house, so breathable products here are just spending money for no benefit.

For example by default Vaillant HPs modulate the compressor, fan and pump to maintain a dT of 5C. This requires a flow rate of 170 l/hr per kW of output. It is possible to define the building circulation rate separately for both HW and CH but I don't know of anyone who has done this or why they would. I recommend reading the detailed analysis by Michael Podesta of how their weather compensation works. It is complicated, and spread over this and the three succeeding articles. Not helped by some errors in the Vaillant manuals in particular the basic graph illustrating how WC works(!).

Just reread Meant to write And as way of example - mine does modulate the circulation pump and I cannot change that. Others will have external pump(s) or some like Grant have an internal pump that runs at a fixed speed, the speed is adjustable, but remains fixed after that.

The bigger companies will also have a Profit & Loss statement or P&L. The smaller ones won’t. If there is one, just observe (in the last line of the statement) whether the company is making a profit or loss and whether it is increasing or decreasing. Losses (usually shown with brackets round them e.f. (X,XXX) ) and to a lesser extent decreasing profits are a warning sign. So, to recap, we should have built up an overall picture. We might have major warnings e.g. company in liquidation, general warnings (low cash, decreasing profits, losses) or queries (e.g. doesn’t seem to be based where we thought they were). We might be comforted e.g. old family business, with plenty of cash and a consistent record of profits. At least you will have gained some information to help your judgement, in negotiating terms, or knowing who to deal with if there’s a problem. You’ll also come across as informed when dealing with the salespeople, which might set the right tone for your relationship. There are people who make careers out of this analysis, so there’s more depth which we probably don’t need. Please feel free to add your thoughts, comments, questions, tips, experiences etc.

I beg your pardon, @JohnMo? I think he means "not necessarily". Heat pumps have a target flow temperature. But it may take them a while to reach that target. They will indeed shut down if the target is exceeded (by some pre-set margin) at their minimum electrical input. You would try to establish the the minimum flow temperature needed for your desired interior temperature at each particular outside temperature. Once you have done that, you use weather compensation to render it automatic so you can stop playing around.

Some will modulate flow don't. Basics are Target flow temp, dT, max and min flow temp (hysterisis). So compressor starts, at min flow temperature, once started tries to establish dT at minimal flow temp, as dT decreases, more flow temp is added, up to target flow temp. Once there different manufacturer do different things, but it's all about power input, to maintain dT and flow temp. WC is just a variable flow target temp based on outside temp.

No, unless it is completely choked just clean it out, reassemble and re-open the service valves. Do the same all over again after a day, a week, a month depending on the rate it collects grot until it eventually slows down. This doesn't sound like a blocked filter though. You may have an entirely different problem, like the HW diverter valve which seem very prone to fail.

Adding wet UFH to the first floor is an unnecessary expense that adds a degree of complication to your floor build up. A lot of us on here don’t have any heating upstairs apart from heated towel rails and/or electric UFH in the bathroom(s) which is what I’ve done. In addition I fitted sockets at points where we could fit electric wall panel heaters in the upstairs rooms should it ever be necessary. If you build the house well enough you’ll not need UFH upstairs and for the odd day you might want extra heat input there are other ways to achieve that. We’re in Perthshire and the heating has barely come on at all since the weather turned over the last few weeks and the upstairs rooms are still around 21°C.

dig it out. working back from top. 65mm screed 150mm insulation 150mm hardcore nice and toasty.

This was 8 weeks from slab to hand over, with all services done and bathrooms tiled. We wanted our stair for space purposes and decided to fit our doors and skirtings. It's taken almost as long using local labour to do that as the poles took to put the thing up!

with this as the rear

Well this is entirely our original design but adapted for the DW system so they can do it (if you alter any of their standard designs by say moving a window it becomes "bespoke"). We omitted additional cladding due to cost and didn't do the glazed gable and fancy aluminium glazing as their system couldn't handle it. The interior is however exactly as we wanted. Sure there were compromises to make but we should be in, carpets laid and sitting on the sofa watching TV within 12 months of clearing the site and bringing on the static. We are both in our later 60's so didn't want a prolonged build on site, been there, done that. Garden to sort but can enjoy a warm modern house this winter after the last couple of renovations of old, cold "characterful" houses.

It's not a particularly specialised slab, it's just a little awkward (and has to be "right" dimensionally and level). They want a min. 150mm thick slab to lay their dpm over and then stand the frame on and fix down to. They then dress another dpm skirt off the bottom of the frame onto the vertical face of the slab. In a local DW build they used traditional foundations, built up to level with blockwork and cast their slab across the whole lot. That meant they needed formwork around the perimeter to contain the slab (normally the slab would be within the blockwork on a traditional build). Add to that their internal floor insulation used to comply with BRegs by itself but the last changes meant that some additional underslab insulation is needed as well. We therefore used an insulated raft design. The formwork and under slab insulation is then covered all in one. The only frustration was that they wanted the upstand insulation removed so that their dpm skirt could be fixed to the vertical concrete. I removed that, stored it and will fix it back after completion. If you go that route then make sure the upstand is removable. We used Greenraft who use a plastic "fin" on a strip to join the horizontal and vertical, so removal was easy. I've covered the foundation cost elswehere but it was about £20K (100m2) inc some drainage and a bit of cutting into a slope . One quote for the DW suggestion was £65K. I get the impression that DW are aware of the foundation issue and the rise of insulated rafts following the reg changes, but being based in Poland and feeding the German market it's not had the highest priority. That lack of awareness is illustrated by them not offering a half glazed door option. This is due apparently to the Germans not normally having "back doors". After a concerted push by the UK sales people, they have now added such a door to the options for the UK market.....

Same! It really feels like we're searching for the same solution here - at least we'll have some safety in numbers!

4 weeks is fast. I was 6 months from request to working electricity. Also Octopus

What exactly are you hoping to achieve/learn here? If you ever feel the need to come to wales, ill happily show you a real life example of lime V cement on a wall with no DPC. I was sceptical, i have to admit. But 2 houses later, real world experience tells me what i need to know. None of it is helped by the "hardcore" lime-ists though, who would have you believe its the answer to every problem. There was one on a group im in fitting a kitchen work top wanting to know what breathable sealant he should use where it meets the wall, as though a 5mm bead of silicone was going to make any difference to anything.