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My only contribution to the discussion is that I usually pilot EVERY hole still except when using plasterboard screws or SPAX flooring screws which are just amazingly designed things IMHO. 6x100 Goldscrews from S'fix - 5mm (long series) pilot. 5mm screws, 4mm pilot and so on. I countersink too. I don't generally hold with all this self cutting / no splitting spiel. In Contiboard or MDF edges I think a pilot is an absolute must to stop swelling/splitting.

I have just been reading this thread in catching up. Some interesting perspectives, and controversial opinions. Some general comments / responses. The audience in this forum is a highly biased one: people interested in self-build development. Moreover, those who want to take an interest in the informed opinion of peers. From my personal research the main risks with MVHR relate to poor maintenance and ignorance of the occupiers. I don't think this is relevant to most visitors to this forum. IMO, the risks in modern well sealed houses are in those without correctly operated MVHR (and closed trickle vents, etc.). @Sensus comments about the risks of condensation due to poor airflow and dead zones in MVHR-fitted houses, seem anecdotal rather than evidence based. They have no underpinning in the physics of gas diffusion. It just doesn't work that way. Heat exchange drops the RH of input air at 0°C and RH 60% to something like 20% at 20°C. The walls in a house like mine are typically within 1°C of room temp. Even the surfaces nearer cold bridges around the windows will only get down to say 15°C under the most extreme conditions. Gas defusion and micro circulation means that the AH in the room will rarely vary a few %. The only material condensation occurs in the MVHR unit itself, and this is designed to discharge it safely. Yes, we will be adding to the moisture levels by inhabitation, but only to comfortable and safe levels. On a different point in some regions decent self-build plots are extremely difficult to come by. We were lucky enough to a have a garden large enough to split, and survived the LPA cat and mouse game to get planning permission. The other alternative here is to buy a rundown property, demolish and rebuild. The local LPA is really only interested in supporting large developments in designated development villages.

Yeh it's called recession. Mate currently building out a site bought around 2010 for less than 10%gdv

Actually I quite like the Screwfix concept where you buy a metal case and keep it topped up. i bought my "Goldscrew" mixed case donky's years ago and I just top it up as and when I need it. its been thrown arround the back of the car, van, site and is pretty bullet proof. Of course i have have countless other boxes of screw n stuff. In fact shelves full of the blooming things.

This may be helpful. http://www.diydoctor.org.uk/projects/screws.htm

I just had a quick scan through the Page 1 results searching 'passive house health risks'. Two things stood out, the first was the use of earth pipes to preheat incoming air for MVHR, and yes absolutely, there are documented problems with that particular 'technology'. From what I remember from previously discussing this, to make it work you needed very expensive pipe which had some sort of (silver?) lining to kill of the harmful bacteria that could accumulate in the pipe. I do remember a rep at one of the building shows giving me a ballpark figure for the pipe, and me falling about laughing until he said he was deadly serious. The second thing that stood out was the many references to insufficient ventilation, caused by either poor design (incorrect ACH specified) or end user mismanagement (not servicing filters, closing vents, reducing airflow to reduce noise). To me the answer to many of these supposed health risks would be to increase the rate of ventilation (ACH). I really can't get my head around why this is such an issue. Noise I can perhaps accept, if a unit was constantly on a boost / its highest setting, but that to me at any rate would indicate an undersized or incorrectly specified MVHR unit. Otherwise, what's wrong with increasing the rate of ventilation? Okay, you maybe then do not fall within the passive house parameters because you have marginally exceeded the threshold heating requirement, but so what? It strikes me that the thing that really needs to change in terms of building regs are the ventilation rates. Do they take into account the realities of modern day living - drying large amounts of laundry inside, lots of showers etc? Both of these things are relatively recent additions to the way we live and probably some of the biggest contributors to the amount of moisture in a house. Skip back 30 years and showers were starting to make serious inroads into our ablutions, but prior to that we relied on baths, which may have been daily, but equally could have been weekly. The amount of laundry we now generate is undoubtedly linked to the ease with which things can now be washed by machine. Again skip back 30 years and twin tubs and washing days were still common.

Well, it won't surprise many of you to hear that some of this thread has whistled well over my head, but I've read it all and I'm actually quite encouraged by that which I have understood. It seems likely to me, as so often is the case when opposing opinions are articulated, that the truth (in this case best practice) lies somewhere between the two, and that (hopefully) is just about where my build should end up. The ambition for me was to create a house that delivers the best possible environment for my wife, rather than the most energy efficient possible. Her health problems include chronic asthma, eczema, severe allergies and bronchiectasis (a degenerative lung condition). Due to a very rare 'syndrome' she has no sweat glands, so rapid temperature/humidity swings play havoc (and not just with her asthma), and just to add insult to injury she is T2 Diabetic (despite weighing little over 6 stone) and has high blood pressure, reflux and osteoarthritis. As I set about researching the home I should build, air quality was, unsurprisingly, my main concern. Ebuild certainly informed my opinion, but I decided quite early that PH levels of air-tightness, insulation and energy efficiency were not for us. Yes we'll have a well insulated home; yes we'll have MVHR with F9 filtering (oversized so hopefully capable of more ACH than may be prescribed as we REALLY don't want to be opening windows); and yes we'll have it reasonably airtight (I'm aiming for around 2 and if we achieve better I may well engineer some 'leaks'). I don't expect the house will demand too much heat input from the UFH (driven by ASHP) but I'm quite happy to force a need for more by bypassing the MVHR unit's heat exchanger in winter (using the summer bypass, not by opening windows!) if that proves to help air circulation (due to the additional convection) and management of humidity levels. As for solar gain, I wait to see whether the SageGlass (electrochromic) glazing on the southern elevation proves to be as good as the manufacturer claims at regulating unwanted SG at warmer times of the year, whilst allowing us to benefit from it on sunny winter days. Finally, as we're building a chalet bungalow, it was a no-brainer to go with a warm roof throughout, even in the non-habitable spaces. Time will tell whether the 'gut feeling' that has largely steered my decisions will provide the home that can give my wife the best environment for her wellbeing, but this thread has at least convinced me that I have a fighting chance.

They are used for a lot of civils contracts but tend to be very deep - they are used more for temporary retaining and then have a significant concrete or steel ring beam attached to them to stabilise the tops. From recollection they have to be 2/3rds / 1/3rd below and above ground, so a 4m wall needs a 12m pile. Bizarrely saw a Movax unit from these guys earlier today !! Beast of a machine holding up the traffic on a low loader !! http://www.stuartpiling.co.uk/

I know I will appear boring and yet : every single house I lived in so far had mould and smell and RH levels above 60%. And I can quite clearly see for myself that the house with (old) cavity insulation is better for us than the one without it which was in turn better than two with solid walls. So my point is somehow I am pretty certain I will be better of in the house with good insulation, good air-tightness and MVHR because on top of everything some people are indeed from Venus :-) and unfortunately my wife is not a big fun of open windows in October. And even open window does not help much on cold rainy day.

Highly unlikely given the two outer walls are insulated - and internal - with 100mm rock wool and the loft sits above with over 400mm above an unventilated false ceiling. Computational fluid dynamics can show the flow in a box is not even and has significant "cold spots" where flow reduces - this is exacerbated at low flow rates so MVHR doesn't really stand much chance when it comes to ensuring a clean extract. I think there is a lot more science to this than the manufacturers and the "designers" of some of the systems want to admit to and they just don't understand it - or more likely can't make it understandable for Joe Public in a simple and effective way.

Condensation is an odd thing - RH is another. If you boil a kettle or use a shower you get a very dramatic rise in RH to the point of saturation UNLESS you are extracting the moisture at a rate that RH cannot be maintained. What normally occurs is that water vapour condenses on the first available surface and by capillary action - unless it is a sealed/tiled surface - the water is drawn into the material. Once in the material, the condensate has to evaporate which requires the latent heat to be sufficient to cause the vapourisation to happen - this is where your issues will lie as the temperature differential is not enough. As the material stays damp for a sufficient period and is usually moistened on a cyclical basis then you start to see why mould forms. Taking the points about airflow, unless you want to do a full 3D model of room and understand it's fluid dynamics then most MVHR placement is just shy of borderline guesswork ... Extracts are regularly placed over or very near to hot spots for vapour generation, and yet this may not be the most suitable place for fully extracting from the room. I have a shower that has an extractor directly above it yet due to the shape of the cubicle we still get tiny patches of black mould appear on the silicone in the top corners - the extract is doing its job but fluid dynamics tells me there is a significant slow down in air flow from extraction, and this cannot compete with the secondary air flow caused by heat rising from the hot shower - I could increase the airflow but this would still only have an effect if I had a perfectly circular shower with an extract that was the same size and the tray was perforated to allow a linear airflow from below me - I would hazard a guess that 99% of showers are actually sealed at the base so in a practical situation the laws of fluid dynamics go out of the window ..!

Its raining and its dark so no pictures or video yet But Iv finally finished the front wall!! Yay Me

A1 to A3 is exactly 50% its easier if you mark key values on a plan anyway as then there is no ambiguity when a plan is scaled and printed.

Sap means diddly squat. Just something you have to do to get your house passed by building control. As long it's a pass then that's all that matters.

With no Pv, I'd try and get away with a Combi. If you deffo go LPG, id recommend a heat store Combi like the Vaillant 938 which is as close to an UVC as you can get without having a cylinder. Heating can be via a buffer in the airing cupboard, and that'll allow your low grade heat to feed off the boiler with ease. How many bathrooms, and what's your DHW requirement? Couple on your own or 3 teenagers?

The Screwfix case is great. I've topped it up on occasion with the Goldscrew Plus stuff when they've run out of the "normal" ones. Left the catches off a couple of times and dropped the lot! First time I managed to convince the youngest it was a game to sort them back into sizes but she's wise to it now! This is that Lidl set.....comes in a case. See how the drill bit flutes are weird: I tend to leave a PZ2 bit and holder along with a countersink bit in my Screwfix case. Also got a few of these type scattered around: http://www.toolsandfishing.co.uk/4-pce-pilot-drill-countersink--screwsink-drill-bit-set-792085-8562-p.asp

I've been using this countersinker http://www.screwfix.com/p/erbauer-plug-cutter-countersink-set-4-pieces/86253 it's a plug cutter as well but it's a good design because if the drill bit breaks you can just replace it. Twin thread screws are pretty expensive and like most everyone I can't see the point We've got one of those boxes from screwfix too, they work pretty well, though we do have quite a lot of the smaller screws left. Still you can always tip them out and replace with more sensible sizes.

We have now had or Haeker kitchen delivered and installed (awaiting worktops). Attention to detail in cabinetry is very good - e.g. rear panels are screwed in with tight spacing between screws and glued around all edges and all joints have been well glued - no movement in the assembled cabinet. Fitter also expressed how solid they are. Here's hoping that this detailing results in a long-lasting kitchen - I have no desire to replace it in my lifetime.

Whoosh....

Couldn't disagree more.

Right, Once you've got them, how do you store the sodding things.......? Eh? Answer me that!

We paid £3k to our architect to discharge our planning conditions and liaise with our chosen Timber frame company to finalise the design, we didn't have a clue and it was money well spent in our eyes.

Got one of these and I think it's great for pilot / countersink http://www.axminster.co.uk/axminster-turbo-drill-countersink-set-of-3-717964

Rip off. Ive paid sub 2k for what you describe. A technician should do all that for way less than what you've been quoted. Move on

I would quite like to explore the relationship between increased ventilation and increased heating cost. Relevant to passive but also relevant to the new environment created when old houses are double glazed and treated for draughts - even as crudely as door sealing etc. My experence of older (pre-1950) houses is that insulating well plus double glazing and upvc doors with seals is still a very significant improvement even if there is still a lot of ventilation. I can point to one where we only got as far as half double glazing, which had condensation issue with the remaining single glazed bays. That was fixed with trickle vents to those rooms with the "close the vent" shutters removed on fitting. But it was still a warm, relatively inexpensive house compared to others those Ts had lived in. It is due to become a road now. Another we have reduced the energy bills by about 60-65% by insulate / double glaze / board out as convenient doing other work. The T has an indoors/outdoors lifestyle due to a statistically significant qty of dogs (8-10 depending). It also has a loft-fan fitted which was in before we double glazed etc; that may now be unnecessary. Typically the statement seems to be that leakage account for perhaps 30% of lost heat. How much of that leakage do we actually need to keep, and is there a method to find out for a particular property other than by suck-it-and-see? Can we fix a stuffy passive house by fitting a couple of HR trickle extractor fans, a leaky cat flap and a non-sealed loft hatch :-) ? Ferdinand

It is also where the plots are, and I think that the current self-build community is very fussy and perhaps still looking to make a profit as well as a home in some cases. I can point you to plots starting at about 35k, all within an hour of Sheffield, Derby and Nottingham, or half an hour followed by 1:45 hours to London on the train. Mansfield District Council is struggling to sell land in good areas with Outline PP for £200k an acre. The train journey to the regional centre - Nottingham - is under half an hour with trains from about 6am to late evening. As if by magic, here is a small 258sqm plot in a cul de sac near here which has just sold for £35k (advertised at £45k) after several months. Probably suitable for a compact 3 bed detached or 2 bed bungalow. I think I could have a 1000sqft 2 bed nearly passive bungalow built on that for around £100k plus the plot - but little or no profit in it as a sale. http://www.rightmove.co.uk/property-for-sale/property-37649083.html Original ad: http://www.zoopla.co.uk/for-sale/details/41781573?search_identifier=c7db1d80e8e63c0757967fedfbf15181#4kv4Apdvw6t72aTw.97 For a comparator this 3 bed 2 recep garage house on a larger plot 3 or 4 doors down is on at £160k http://www.zoopla.co.uk/for-sale/details/41175270?search_identifier=c7db1d80e8e63c0757967fedfbf15181#BbmgvCMUcH5kcYj3.97 Ferdinand

While my house ain't at pH standard its close enough for me. In my last pad, a 1960 council townhouse, the air quality was terrible. It was stuffy and generally in winter had damp patches due to the high amount of condensation. The change to what my new house is like now is night and day. No condensation and no stuffy air. My wife always opens the windows to let fresh air in even though I explained that is what the mhrv is doing. Now I just let her work away. People get too wrapped up in trying to make sure your house has no cold bridges and has thick insulation everywhere and airtightness tape on everything. Me I have a large wrap around window that is as big a cold bridge as you could get. Does it bother me, not a bit. It lets an unreal amount of light in and is nice to look out at. I even have two stoves, one pellet and one wbs. I love sitting in front of them on a cold day looking out the big window watching the world go by. Remember that at the end of the day you have to live in the house when it's done so have nice big windows and even let the wife open them. Enjoy the time you spend in the house instead of obsessing over the minute details that pH requires.

Loving this thread! I'm just waiting for the passive house police to come along (and to be frank I've seen a few posts from current and past forum members along these lines). So don't forget some of the important rules: 1. Kill the cat, cat flaps will not be tolerated. 2. Remove or reduce all windows. I know you've bought a plot with a view but seriously saving on your energy bills is way more important than a view. 3. Make sure you go paperless for ALL bills etc. There is no way you are having a postbox. 4. Bury your partner under the patio. Far too risky that they may open a window. 5. Kill the dog. Can't think of a reason why other than enjoying yourself cannot be tolerated. OK, I'm having a bit of fun BUT you are going to drive yourself to the edge of insanity doing this self build lark, nothing is more stressful. SO BUILD YOURSELF A HOME NOT A HAUSE!

We've been living in our (non certified) passive house for a month now and I've only got round to completing the MVHR installation today due to other works in the plant room. So for the last few weeks we've been randomly leaving the windows, velux and big sliding doors open for ventilation and it's been fine - no need to have the heating on either even on the recent cold nights. Will be interesting to see what difference the MVHR makes. Can't agree with Stones more, we have a highly insulted, airtight house that's been designed to minimise solar gain (blinds and orientation). No one dictates how we live in it though. Solar gain is an issue whatever the standard of your house - our caravan suffered from excessive gain (was unbearable in the summer) and that was not passive by any standard

I don't understand the problem, all a passive house is, is a house that meets certain standards, the most notable one being the amount of heating input required. All of the concerns you have, air quality, solar gain etc could apply to a house built to less stringent insulation and air tightness standards. It's about how you choose to live in the house. I like a fresh, well ventilated house, and far prefer the air quality offered using an MVHR than a house without, I just choose to mechanically ventilate at more than the minimum or optimum passive house level. If I want to really freshen things up I throw open the windows. I like my house nice and warm in winter, and will happily heat it 24/7 at a higher temperature than than the prescribed design temperatures used when filling out PHPP. So what if it costs a bit more? At the end of the day, it's your house, and you do not have to be a slave to some predetermined rules unless you choose to.

FYI here is a 2015 image of [very] rough sawn untreated Scottish larch in 3 generations: gable end erected in 2005 logstore erected in 2008 patio pergola erected in 2015 The timber has blended into a uniform pattern. It has lasted well, and none has required replacing after more than ten years. If I were repeating that particular approach of using local larch, I would probably choose a finer cut, rather than using my late neighbour's sawmill, since the very rough surface tends to hold the rain, with a presumed impact on endurance. My view in 2005 was that the cladding had a life expectancy of 20+ years, and I have no reason to doubt that today.