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@Redoctober @Jude1234 @Christine Walker @CC45 Hi, The broker I used is called Mayfair Performance Insurance, 11 Lurke Street, Bedford. Tel 01234 242900 (no connection with them other than as a customer) My reason that i went through a broker is that my self-build is a holiday home which is timber frame and timber clad so a little unusual but the insurance is not too bad - £200 a year for the building & usual 3rd party liability (but no contents cover) I've been using them for a couple of years now and started a few months before I got my building regs completion (but after the highest risk work had been completed). Loss as a result of construction work prior to full completion was an exclusion on the policy. Ian

Sorry, but let me get this right. You want to buy a plot, with planning permission, and build a 3-bed dwelling (presumably detached) for a total of £200k. You say you are unable even to project manage such a build, so i'm guessing you won't be doing too much of the building yourself either? That's not tight, I'd say it's damned nigh impossible, unless I've misunderstood your original post and that's a budget for the build alone (ie not including the plot cost).

I'm pretty happy with the result. I'd recommend this technique to anyone that wants a cheapish way to get an interesting finish to a concrete floor. It was fairly easy - the most time consuming part was getting the floor really clean to start with. A pressure washer with surface cleaning attachment and a wet vac was very useful for this. - reddal

I think the lesson here is don't just believe the instructions, actually LOOK at the thing and see if it really behaves as it should.

PassivHaus has never been about having no heating, for several very good reasons, not least of which is that if you built to a "no heat input ever required" standard then the house would almost certainly need a fair bit of cooling in warm weather. We don't like the house to be warmer than about 24 deg C, and with the level of insulation and airtightness we have (similar to @PeterStarck, although not certified as a PassivHaus) we have found that cooling can be an issue at times. Over the past couple of years we've had days when the outside air temperature has been higher than we'd like the house to be, so opening windows just makes the house warmer. The choice of heating system is really down to personal preference. We have an MVHR that has a built-in air-to-air heat pump, and that has enough heating capacity to keep the house warm in winter, but I don't much like the "feel" of warm air heating, so we don't use the MVHR in heating mode, only in cooling mode in hot weather (the heat pump is reversible so will cool the air as well as heating it). We had UFH pipes cast into our passive slab as a part of the package, so we heat and cool the slab with a small ASHP. We find that the very small heat output from the UFH gives a comfortable feel that we both prefer, but that is just a personal preference. The heat input needed even in really cold weather is tiny, so the UFH never makes the floor warmer than about 23 deg C, if that. We also have heated towel rails in the bathrooms, and they have to be on a timer I've found, as otherwise they tend to make the bathrooms too warm. Local climate makes a very significant difference to the heating and cooling requirements of a house that's built to passive standards, and I found that we accidentally created a significantly warmer micro-climate around our house as we had to cut back deeply into a hillside at the bottom of a valley to get a level plot, and that's had the effect of providing a lot of shelter from the wind, so we have an air temperature around the house that's normally 1 or 2 degrees warmer than the local weather data suggests. The effect of this was to seriously screw up the PHPP over heating risk prediction, which then meant having to add external solar reflective film to help keep the sun's heat out in Spring and Autumn (we have overhanging shading to deal with the summer sun, but that doesn't work for low sun angles). The most important factor when looking at construction methods for a low energy house is, IMHO, making sure that the wall and roof construction method provides a high decrement delay, so that the house has a long thermal time constant. Once the decrement delay exceeds the time that the sun is likely to shine on a surface, say 6 to 8 hours, then the risk that radiant heat will be conducted through the walls and roof to the interior reduces a great deal. Decrement delay is a function of both the thermal resistance and the heat capacity of the structure. Having a low U value structure with a low heat capacity will give a short decrement delay, so it's important to consider this carefully. Finally, wind has a pretty large impact on heat loss, and this becomes more noticeable as you decrease the overall heating requirement, to the point where wind speed around the house may be as important as the air temperature in determining the heat input required during the heating season.

https://velfac.co.uk/domestic/technical/download-centre/10424/interface-drawings here is the link

I seem to remember from when we were looking that Velfac had different requirements. I think their fitting guide is available to download from the website if not I might have it somewhere.

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we had Internorm windows and they went in before the render...also an MBC frame. I think Velfac may have their own particular requirements but its odd to render first and then try and get the windows in

You can do them afterwards Then pick up the unredered reveals when the frames are fitted But much better to get all the window frames in prior to refer

@Dreadnaught Ian checked on his way in this evening and reports that a glow can be seen coming from the glass domes. It is a dim glow but quite visible probably more so in our location where we have little to disturb the dark skies. Probably more muted in an urban environment with more lighting around.

For the conventional definition of time constants used in mathematics, physics, electronics, etc, it comes out as simply the temperature difference between inside and outside divided by the rate of change of inside temperature. E.g., if the inside of the house is at 20 °C and the outside is at 10 °C and the inside temperature drops initially (when, say, the heating is turned off) at 0.2 °C/hour then the time constant is (20 - 10)/0.2 = 50 hours. That's the length of time the temperature would take to drop to the outside temperature if it continued downwards at the same rate as it started. Actually, of course, as the temperature difference decreases the rate of cooling will also decrease so it will curve out (following an exponential curve) getting closer and closer to the outside temperature but never (in a theoretical steady-state) quite reaching it. When the temperature has dropped to 15 °C the rate of cooling should have halved so the time constant is now (15 - 10)/0.1 = 50 hours. Yipee, the time constant is constant. After the time constant it should reach 1/e ~= 0.368 times the original difference. So, after 50 hours our example house should be at 13.68 °C.

Hmmm. You might like to do some research on this board about Thermal Mass. The idea is much misunderstood. At least read this

So there should be a tundish in the output pipe from the PReV (tank one) within 500mm of the valve. If the relief pipes are combined from the inlet group (big thing with a red and grey cap) and the tank then they should be increased to a minimum of 22mm as close as practical to the joint of the pipes. This also depends on the length of the relief pipe and the number of bends too... But someone with a G3 ticket would know all that.......

Ha ha! Given that (apparently) only around 50% of the guys wash their hands after going to the loo and the gents is always simply disgusting to the extent that you wonder if they actually know how to use a loo (according to some of the blokes I work with) I’m not sure IT professionals are necessarily decent tenant material. They do probably have money to pay for a cleaner however ...

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Years ago we rented a maisonette out. We used a letting agency to supposedly make life straightforward and for that service they took a decent chunk of the rental money but they dealt with the tenant, and made regular inspections (supposedly). Until that is the tenant stopped paying. They contacted us and told us and asked what we expected them to do about it when we asked them to deal with it. We turned up at the maisonette to find that the tenants had done a bunk. The maisonette was a new build with new carpets, magnolia walls etc. I emphasise the word ‘was’. The tenants had wrecked the place. They’d had cats in there that had shit / squits literally anywhere you can imagine; kitchen worktop, carpets, hob, everywhere! They had left bags of decomposing stuff in there (god knows what, we didn’t look), that had turned to maggots and swarms of flies. There was vomit all over the bedroom carpets that had been left to dry and the stomach acid had bleached the pale grey carpets in vomit spatter patterns. There were used condoms and syringes everywhere. I don’t need to explain what the bathroom looked like other than it was brown rather than white, and they had ‘redecorated’. They must have been to the pound shop and bought endless single rolls of wallpaper and borders, and literally put them up one by one. Endless different patterns and colours. Rather than trim the wallpaper they had pasted it up over the ceiling and over the skirting to avoid cutting it. The border was put up with drawing pins. There were letters from debt collectors, the police, benefit fraud investigators. Stuff of nightmares. My one and only foot in the rental camp, we sold up and got out as soon as we had spent money (more than they ever paid in rent) tidying the place up. Makes me laugh when people talk about landlords in such disparaging tones ...

Happens under much the same conditions!

Wondered why I always end up with hardwood!

Are you preserving the wood or teasing it!! ?

Wow.... how the other half live........

Thanks mate, I am chuffed like you after our problems, see my other new thread!!!!

Regarding DHW, be careful of over complicating it. I am heating HW to 48 degrees with the heat pump. Most of the time the HP does not need to defrost. However we had a 1 week cold spell recently with an average temperature of 0 and about -6 overnight. For the first time during that cold snap I did see the HP defrost when heating HW (I can confirm even at -6 it did not need to defrost when heating 37 degree water for UFH) the consequence of that is the HW for that week consumed 30KWh compared to a normal week of 22KWh. So it was using roughly 1KWh more per day either to defrost, or through a lower COP (probably a bit of both) I am shortly to be implementing a "boost" system using a modulating instant in line hot water heater. This is being installed mainly to cover those "oops ran out of hot water" moments, but it will allow the HW tank to run at a lower temperature with the electric heater boosting it as it is used. If you are going to use resistance heating then doing so real time heating just what you use will be more economical than heating the whole tank that last bit with the immersion heater. Once this is installed I will experiment with reducing the tank temperature during very cold weather to reduce or eradicate HP defrosting.

Back up is one thing, so that was not aimed at you, it’s for those who have underestimated the ‘need’ for heat and how to best deliver it, both comfortably and conveniently. Having to employ auxiliary heating should be the exception not the rule at best.

I used the cavity therm boards in mine. But I was building it myself so took my time and cut each board correctly with a hand saw as I had the time. I also scraped the walls smooth filled in any gaps in the motar beds and then put the insulation in. Doubt any brickie will go to that much trouble without you crossing his hand with lots of £50 notes.

I now have 20, 20 hindsight , I also have ordered a computherm room stat (that @JSHarris recommended as I can’t be arsed to wire in a relay to deal with the Wunda stat that blew my main ASHP board ?

Click - God it took me ages to get that. Must be fifty years or more since I was taught that......

I cost me the price of the ufh pipe (around£600) and a day of my time to install it. I zip tied it to the steel mesh prior to pouring the concrete. I used a free ufh layout package to work out the optimum pipe layout and length required.

The only thing to watch out for is if you aren't connecting all the pipes up to a manifold and have the pipes sitting under a few bar of pressure you run a greater risk of the pipe being damaged during the pour. People here have done it both ways so it's up to you. Not sure how your plumbing skills are with regards connecting all the pipework up to a manifold but even if it's only a few hrs work for a plumber it might be money well spent.

The price will depend on how much pipe you need and if your doing or a trade. More pipe more expensive. You can get 500m rolls for £300 or less so work out if you need 1,2,3 rolls and then after that it's only clips. You won't need manifolds and pumps when you are doing the slab. There is a pipe decolier in the tool hire section which if you are doing it yourself will be a lifesaver.

Are you doing the work? If so you can work out the pipe spacings and how much pipe you will need if you use Loopcad which I believe is free for a month. We did all this and then fitted the pipes to the steel mesh one Saturday morning so it only cost us materials. Each build will be different as the square meter cost will differ for each house but it is definitely very easy to do and is well worth having it in the slab as a fallback if you decide you need UFH later. I would say on average it costs between £500 to £1000 for materials which includes pipe,manifold,pump etc and cable ties depending on the size of the property.

All mine are under the slab its not a problem. They were a bit out on position after the walls went up so slab had to be hacked out and they were moved a bit.....I would not recommend that so as was said measure and measure again. Our problem occured because architect plotted them as if they were floor standing pans not wall hung with cisterns in the stud......no one noticed on the drawing and so every one was wrong.

I for one just wish that volume house builders would build the majority of new housing stock to a decent standard.

Yes. You put the 100mm waste pipe in when you are doing the foundations. It will come up through the concrete in what ever position you want to have the toilet. Just measure and measure and then measure again before any concrete is poured. The pipe will then go under your floor and out to join up with the rest of your sewage system.

I'm not so sure. If he's like the many I've met then he will genuinely have no comprehension that he is doing anything wrong.

If you’re going to the efforts of building your home to such a good standard, what a bag-o-crap it must be to litter it with £30 heaters you ran out to get from Argos when your wife told you “I told you ‘“ UFH is the number one way to heat imo, and in conjunction with a decent slab ( as opposed to a thin screed ) you can realistically plan for fine tuning your heat input to the nearest 0.5 degree. Heating by duct ( given it also commands a much higher airflow rate ) would be the last option for me to look at tbh as a generic MVHR should be near inaudible and unnoticeable in operation, and to use it for heating in anything other than a ‘small’ dwelling would take you away from that target. Accepting that higher flow rates are necessary, when cooling is utilised, is easy when you compare it to the rather unsympathetic alternatives ( split aircon ) etc.

But @lizzie, wimmin are always '... freezing... ' ........

This thread -so far- is a good precis of UFH and PH ideas. I wish that a few years ago we'd had a thread that summarised issues so well. I suggest we pin it.

What makes it harder for me is he's a family friend. I'm going to have a word with him when he's back on Tuesday and of he won't do it the right way then it's the highway. Aka mag to grid

No vested interest here whatsoever but I can confirm, having visited @PeterStarck's house that UFH is not really required. Might have something to do with his meticulous attention to detail on the build where it counts and the fact his air tightness beats the regs by a factor of something like x4. The sprayed icynene insulation too.

Just fiddling today! Thought I'd play with the tiles that line the pockets: Onto then these pocket lights using the cheapo LAPP deck lights (stainless steel, £4.99 /10). I need to drill a 22mm hole in the soffit tile (then up thru the Aqua Panel and timber beneath). No problems there. Considering the spread of light within the pocket as I have two different pocket depths, 78 & 100mm. I reckon the centre of the light fitting should be a constant from the mosaics, so 78/2 = 39mm. It'll therefore be central on the 78mm pocket but offset, 39/61 on the two deeper pockets. The arc from the lamps should appear equal on all three: Here's them in loose a while back pre mosaics etc. Interesting that within the fitting are 3 LEDs arranged 120o apart so they all have to be aligned the same way!

TBH an extra 150mm both ways would be not noticeable and would allow for a 175mm blown bead cavity that would meet regs and be very quick and easy to build.

It doesn't really matter whose name is on the beads they will be the same type of eps beads. If you won't increase the cavity then you will have to go for a fullfill type cavity board. The problem here is that how good its put in will mean it either works or doesn't. Badly cut boards at corners and door and window reveals leave gaps which leave cold spots. All the cavity boards have much better u values than eps beads in a nice science lab but if they are installed badly they end up much worse. Eps beads are blown in and fill every single gap leaving no holes. Are you tied to 65sqm by planning?? Could not not build as you intend and keep all the internal dimensions the same and increase the cavity to 150mm so you are only increasing the outside by 50mm all round the house.

At the moment I am having quotes for my roof 220mm I joists the prices are on average double the cost of a standard 225x50 structural grade timber. But its not just the cost of the timber to look into if you stick build it in normal timber you may use something that could be anything from 140mm to 180mm any bigger and your getting silly, so you need to look at how much insulation you can get in between the joists. Not enough. So now you need to look at insulation across the face of the studs either inside or outside, so more work and more cost. a lot to think about not just the cost of the joists. Im not clever enough to start talking about u values and all that junk, I just like knocking it all together, I will let somebody else tell you how to get it up to spec with regards insulation.

This is what we have done - so it is scaremongering. The BCO has no problem with me building it neither does the structural warranty company.

A rice steamer? ALWAYS ask for this???

It looks like an expensive one to build to me - lots of 'interesting' angles and change in elevations etc Bet that chews through £400K fairly quickly.

I've been chewing on this since yesterday, and I don't think I am convinced that you are getting as much for your floorspace and budget as I would expect. Whilst I agree with the previous comments that it is an attractive and pleasant house, I think that it is not yet a great or very flexible house. I think the outside is probably a more attractive design than the inside to me. But how to feed back without sounding hostile, and still be provocative but contructive? Rather than list details yet, let me start by asking you to think about "use cases". ISTM that for 300sqm and the best part of a million ukp including plot, you could reasonably expect everything you could ever want, and then some more. How will this house be practical if eg 1 - A parent has to come and live with you? 2 - One or both of you need to work from home? 3 - You have another child, and it turns out to be twins? For a large house like that, I think that all of those should be easily accommodated, and I am not sure they can be on the current design. Switching to rooms and spaces, as I see it you have 3 very generous beds with baths including a master suite, one more generous bed, family bath, a nice big kitchen-diner-sitting, and 2 more reception rooms set up as a playroom and a lounge. The "wow" features are the 'bridge' on entry and some interesting profiles / details on the roof and rear facade. For an extra 100 sqm and 200k on the build budget over a 350-400k 200sqm house, I think that more could be expected. The impression I get is that the extra space and cash budget has gone in part to the bridge and void (and even more space beyond the 303sqm has gone into the insets in the rear facade), but that most has gone to adding space to the same selection of rooms that I would find in a 20-25% smaller self-build house, rather than doing things a little differently to relfect the larger dwelling. I have all of the above or equivalents in my 2100 sqft house, and it feels generous so I am not sure that all that space needs to go towards making the rooms huge rather than merely very generous indeed. What would I change on the current design to go in the direction I suggest? 4 - As mentioned, the stairs do not seem resolved. That stub corridor to a bedroom door and window seems incongruous. Move the door, make the stairs full width with half landing, and put an even larger stair window and window seat on it to give another wow, which will also dramatise the route in for visitors. Put an interesting feature tree or bush at the back fence where it will be seen as people walk in. Make the stairs 35 degrees of slope or even less. 5 - Am I right that Bed 3 is entirely north-facing, and never actually gets any sunlight? I could have misread the plans. 6 - In a 35-40 sqm master suite, istm that it should be possible to find room for a relaxing-bath in addition to a conventional shower. I would also look at turning that Master Bed window into doors onto a balcony in the recess - inward or outward opening should fit. If neighbours overlook, then it could be angled south. 7 - I would make provision to easily divide up the Jack-and-Jill into 2 should it be needed. 8 - I would look to adjust the downstairs to give an easily adaptable grannex. 9 - I would try and create an extra room upstairs as Bed 5, for flexibility and a hobby room or office. 10 - I might try and create a study / reception 3 downstairs for similar reasons. And that is without getting into things like gyms and cinema rooms. 11 - I wonder if storage space is too slight, and you will end up with a large traditional shed. Personally I would want a double garage, or at least make some use of the gable void above the existing. I think that one feature of great designs for normal houses is how they organise space for ancillaries (eg garden store, workshop etc) into the original concept. 12 - I do not understand the passageway between the garage and house. Why is that space not inside the garage? How to approach it - I would perhaps suggest giving your architect some extra constraints if you want to pursue these lines, and see what emerges. Best regards. You did ask for alternative views ! Ferdinand

When I first joined the site's predecessor I couldn't for the life of me figure why people were using passive infra red detectors in conjunction with insulation! "pir"