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Yesterday was air tightness test day and MBC's final day on site getting everything prepped for the final test and then finishing off a few details. For those not so familiar with this kind of thing, a few details of the process follow. Our house isn't a passive house as it hasn't been designed with that in mind - it was the design first and then build to passive standards, so no accreditation or anything like that. That said, I wanted a low energy house and hence the choice of the passive system offered by MBC. Part of this system is that as well as the building and foundation being highly insulated, it also leaks very little air, as this is one of the major sources of heat loss in buildings and houses. The leakiness of a house is measured in terms of the number of times the volume of air contained by the building passes out of all the various gaps in one hour. As mentioned on this forum elsewhere, a modern well-built house without any special air tight measures would probably change its volume of air between 3 and 5 times per hour. The final part of MBC's construction method is to tape over anywhere there is likely to be a gap and make the building as air tight as possible; the target is to have 0.6 or less air changes per hour. One exterior door into the house is chosen as the point of measurement and this is where all the kit goes. Note that the air tight test is testing the quality of MBC's work and whilst it will highlight gaps elsewhere, it's not MBC's remit to correct leaks caused by others, only themselves. The point of measurement for my house is the door between the garage and the utility room, where the FD30 rated door was recently installed. The door is sealed up with a membrane that's supported and held in place by an adjustable frame: The hands are those of Steve, of Melin Consultants, who carry out most of MBC's air tests. This is the frame/shield being put in place in the doorway. I really did try and get a photo without builder's/air tester's bum, but to no avail. Those with delicate sensibilities should look away now and skip the next photo. After the frame, the fan is put into the hole in the shield, drawn tight and any gaps between the frame and door frame are temporarily sealed up. The rate of air flow into and out of the building is altered by both the speed of the fan and the number of vents that are opened up on the fan. The building is de-pressurised first, then re-pressurised and the readings taken. Because of environmental factors such as wind, this is done 10 times to get a data set and the average is taken for the final result. When this test was done yesterday, it was a windy day with the wind coming from the north east, the direction that the garage door faces. As the test progressed, it became clear that the house is well sealed and so it needed a smaller fan. The red shield was swapped over and the smaller fan put in place. The rest of the readings were taken and we got our final reading. Darren and his MBC crew aced it - with a target of 0.6 ac/h it came in at 0.25. Brilliant. Darren is a calm chap under all sorts of pressures but the air test was about the only time I've seen him display (slight) signs of nerves. He was equally understated in his satisfaction with the result even though it turns out that this is one of the lowest numbers they've had in 7 years. Well done, Darren and crew. If you're wondering what all that foam is doing on the floor, that's left over from work on the foul wastes over the weekend and foaming them in before putting air tight tape around them to make sure it wasn't detrimental to the air test result. We have a few very minor leaks, mostly gaps between the panels in the windows that have several sections. No surprise and these are due to be siliconed once we've finished most of the pretty stuff. There is also a bit of air flow through the keyholes but I've been advised that a good coating of vaseline on the key and in and out of the lock a few times should seal it up well enough. I daresay that would seal most things. The gaps were temporarily sealed up with a bit of low tack plastic for the air test, so the result assumes this has been done. All the battens are in now and the downstairs was finished off yesterday, and concrete was put into the remaining recess that had been formed for the lift and slide doors to get a level threshold. I am, of course, delighted with the air tight result and really pleased for MBC as well, as they have worked really hard and whenever there has been a problem, come up with solutions. I know that others have had varied experiences but for my own, I have found MBC to be a pleasure to work with right from the start. At the design stage, David worked his socks off liaising with my architect to get all the details right and to work out how to build the design using their system, and this has been the case with any third parties I've asked them to speak with directly. The communication from Trish has been great - I've always know what was going to happen and when and been kept informed when timings have had to change. The guys on the ground have worked like machines; I'm astonished at how hard they work, to be frank, and throughout the whole time I've never heard any rows or arguments. That's not to say that there haven't been any, but if there have, they didn't take place in front of me. For me, this has been a really good experience. What next? There's still plenty to do but the next main contractor is largely doing all of the internal systems, plumbing and wiring (note - I'm no longer giving details of this as I can't recommend due to unfinished work). The MVHR ducting and manifolds have been worked on but will kick off in earnest on 3rd December once the cellulose has been blown in upstairs. The cellulose is arriving on Friday 30th, along with Gordon, who will put it into the walls and ceiling. All 520 bags of it! Before then, my Ryterna garage door is due to be installed next week so I'll report back on that. That's being supplied and installed by Joe from Dorset Garage Doors Ltd, just up the road from me in Lydlinch. There's a lot of work to be done outside, too, but I'll be thinking through that today and get my plan of action together. Whatever else happens, some gentle heat will be put into the slab this week, using a couple of Willis heaters. It's getting pretty chilly on site now and it will be nice to get the house drying out properly and check that side of things is working properly. A good week and, hopefully, more to come.

Having got all my water issues out into the last post, it's time to move on to happier things and talk about other progress. Actually, that's a little unfair because there is a lot of work in all the flat roof stuff, far more than the pitched roof, and aside from the wet stuff it's going well. At the end of the penultimate post, the solar PV panels were just going on and the pitched roof was also still a work in progress. The building was still a shell with no power and plenty of work left for MBC to do, and outside was largely untouched apart from the buried mains cable that was terminating in the garage, into the meter moved by the meter fairies. Let's start at the top and work our way down. The solar panels are all in now and all the slates around them are done. All the velux windows are in and the ridges were done last week. We have a dry ridge system. I had to ask what this was and was told 'that means there's no gunk underneath the ridge tiles'. So technical that even I could understand it! Here's the stuff that they line it with. When they roll it out, it has a corrugated wave shape to it and each side is sticky - one for the roof ridge surface, the other for the ridge tiles. This is Mike, one of the roofers, bringing the final tiles right up to the ridge before putting the dry ridge stuff over it. And here's a view of the ridge tiles in situ, fixed to the sticky stuff and clipped together. We have 3 ridge lines on the roof, all meeting somewhere over the north east bedroom. A plate of good old school lead was shaped to cover the meeting point of the 3 ridges, creating a neat flashing for the centre. Here's Terence welding the lead to create the flaps going down each gully. Here's Terence putting it into position on the roof: And here's a close-up of the same thing. You can see the fixing for the dry ridge system unrolled next to it. Staying with jobs going on outside, there were some groundworks that week, too. I needed to get the electricity supply cable trench back-filled and whilst we had the plant on site I decided to get a few other jobs done. The Openreach guys turned up that week and the old redundant BT cable was removed, so that old electricity pole is all clear now. My neighbour has already bagsied it, so there's no problem with disposal. One of the groundworks jobs was to open up the ground between the garage and the lane. I'm not getting the driveway done quite yet but I did need to get it clear because my sunamps will live in the garage and it will be a lot easier to get them forklifted straight into the garage from the lane rather than trying to drag them all through the house. Keith got onto it, clearing around the side of the garage a little, too. There is an area of concrete there that used to have a shed on top of it. For the time being, I'm keeping that there as it's nice to have a surface that isn't clay. And then this is the view from the lane up to the garage. This is, in fact, where the pedestrian entrance to the old bungalow was, hence the gate that is still there. Once we've got rid of the scaffolding, we can clear the remaining few feet of the entrance and make the proper driveway. Keith will be doing most of the work on this, but I need to get someone with a ticket to do the dropped kerb between the lane and the verge. It's outrageously expensive for what it is - just for the 6m stretch of opening and 2m back, tarmac surface, that will be the princely sum of £1,200 plus £285 for the licence from the council. And that's the cheapest quote out of 3!!!! I will be continuing the tarmac for the driveway, and also around to the side of the garage so that there's hardstanding for a couple of vehicles next to it. And Keith's final job for that week whilst the plant was still on hire was to scrape the grass from what will be Paul's pond. I marked out the original perimeter and he took out the line for this but then I did that typically female thing and told him it was no good and I wanted it to be bigger. Naturally, he obliged. Not that we had much doubt, but for the sake of interest, Keith dug out a small trial pit within the pond perimeter, about 1m deep. It has filled up nicely with the subsequent rain and shows no sign of draining any time soon. I may have cursed our clay for its giving the need for piles, but we certainly won't need a pond liner. That's most of the outdoor stuff for the time being, so let's step inside and see what MBC have been up to this week as they've starting on the prep work prior to the airtight test. This is scheduled for next Tuesday, 20th November. The velux windows have all been boxed out and they've been drawing the airtight membrane up around the web joists forming the roof/ceiling. This will be the main/shared bathroom and it's only natural light source is the velux. It's rather nice to think I can lay in the bath looking at the stars. Assuming it's not raining. The green tubes on the far wall are for the MVHR. A close up of some of the MVHR tubes to show the careful taping around them where they come through the membrane. This is the main bedroom that has been battened out now. I've wedged some bits of timber under the membrane that's underneath the window to dry out the water that came in at the weekend after the tanked balcony incident. All the battens have been screwed on, much to the chagrin of Darren. It's probably not so necessary somewhere like a bedroom, but in bathrooms and the like where the weight of tiles and mirrors can be considerable, I wanted the peace of mind that the battens weren't going to move for anything and so requested screws rather than nails. This is the north east bedroom, below where the three ridges meet. The guy putting up the plasterboard will be cursing me here. Heading downstairs, the insulation changes a bit here. Instead of being all blown cellulose held behind the membrane, there is celotex in certain places. This is beneath the parapets and the balconies and it's been used here because less depth is required than for the cellulose, allowing the ceiling to be level throughout the ground floor. If blown cellulose had been used, the entire outer edge of the ground floor rooms would have had a step down to allow for this. That's pretty much it for now, but the next lot of work has been scheduled. The vertical slate cladding is booked in to start on 3rd December and this is being done by my roofers as it seemed logical given that they're using the same materials as on the roof. I'm nagging and cajoling them to see if they will do the stone board cladding on the stairwell walls as well; they may say no eventually, but I'm working on it as that will be pretty much all the stuff at height done other than rainwater goods. It would also protect the south west corner of the building nicely, as that's the direction for the prevailing weather. I'm aiming to get some more groundworks done in early December; at some point I need to get the sewage treatment system set in and also the rainwater storage tank. There is, of course, the rest of the pond to be dug out and that will need some muckaway. I'd rather get it done this side of the winter as we can then let it fill up with rainwater and see how it settles. Internally, there's some work on soil pipes and the MVHR, but no sign of the MVHR unit itself. Once MBC have completed their air test next week, we can really go at it with first fix, so I need to make decisions on external electrics. On order is the big brise soleil for the floor to roof window in front of the stairwell. The plans for this look great but I'm waiting on a production date at the moment as the framework is a first fix item. The wooden fins can go on any time after that. Similarly, I have a guy coming to measure up for the external motorised roller blinds for the other large south facing windows. As long as sufficient clearance is left with the cladding, these don't need to be installed as part of first fix so we're not so reliant on a production date for these. They have a lead time of 3 to 4 weeks. There's plenty that I've omitted, I'm sure, but it will all follow in due course. It will be great to get past the air test and make some good progress in doors. No aviation buzz this week, but the hunt was out today. I stood on the top lift of the scaffolding late this afternoon watching the horses and riders galloping over the distant fields down near the river and could hear the hounds baying and the horn being blown. I'm not sure what they were hunting but it all seemed very evocative on a late autumn afternoon and really brought home just how rural our place is.