Tony L

Perhaps it may be OK if your ground type drains quickly, your water table is low & your foundations are not so deep as mine, but having had experience of problems digging foundations after wet weather, I definitely wouldn't be doing it in my locality this week or next. Here's a picture from just after we started pulling the foundations. Shuttering was required to prevent the trenches from collapsing. 2nd picture is the same trench, with the picture taken from the other end. it didn't rain in between - it took the water 2 days to come up to water table level. Perhaps you should dig a test hole, then wait two days to see what happens.

I need about 75 x 100mm wide Thermoblocks & 18 x 215mm wide Thermoblocks to deal with the perimeter (inner leaf) & internal block walls on my design. Based on the very first website I looked at, these will cost no more than £1200, allowing for overs. I haven't worked in the cost of the special glue, but neither have I deducted the cost of whatever might have gone where the Thermoblocks will go. Given the anticipated value of the completed house, & more importantly, the added comfort & other benefits, I'm happy to spend the £1200.

It is a bit. Yes, although, we're steering it back on track with our discussion of Aircrete blocks. Very good point - thank you. I amended the drawing with the Marmox & then thought, "I probably should have put the brick & the block that goes on top of the Marmox the other way round.", even though I didn't have the reasoning you have provided in my mind. I think keeping the change of materials below skirting level (or as low as possible) is another point in favour of a run of Marmox (65mm high vs 215mm for Aircrete). Blown beads. Thanks, @Gus Potter. When I think about it, I agree with you. I had only been thinking about water coming down from above, but I see there's the possibility for moist air to come up off the trench blocks. I think I need to find time for a new drawing & some more questions - I'll start a new thread.

I can't help you, Russell, but I'd guess different BCOs/LAs will have different views on this. I suppose once you have your completion cert, you won't be getting the VAT back on anything else you buy to finish these two rooms.

I don’t know how either, but it happens. This wasn’t a thought experiment. It was a real experiment, with different brands of dryer running in a lab with clever chaps & machines measuring the particles that came out of them. I suppose it happens because the dryers leak. These particles are very small & they don’t need much of a gap to find their way out.

I think this is the best strategy if it works for you. I bought a heat pump TD for my mum. We installed it in her garage. I heard a reputable source explaining on the radio, TDs fill the air with microplastics & other pollution. I’m not having one in my house, although I plan to have one in an outbuilding, so I won’t have to breathe all the crap that comes out of it; also, my MVHR filters will go longer between changes & my utility/plant room (they’re the same room) won’t overheat so much in the summer.

Sorry, I can't help with this, but I must congratulate you on moving in, having completed your build so quickly. You're an inspiration to us all. & thanks for documenting your progress on here too - it's a real help to those of us who are not there yet.

Yes. Dura Composites, who sell very nice, expensive cladding, will sell you some special aluminium batten bars.

Aircrete version: When I did a cost analysis some time ago, the Marmox Thermoblocks didn't seem too pricey, for the perceived benefit. When I find time, I'll dig out my figures.

I have a very high water table, so I think this will likely make the ground colder than if the trench blocks were sat in dry ground. My trench blocks are going to be almost permanently damp, & I note @Iceverge's point about Aircrete blocks having to be kept dry, which is another reason I can’t copy the @Iceverge detail. I’d be grateful to hear comments on these two ideas, below. Could I wrap the DMP around the outside of the bottom of the inner leaf construction, as shown in blue? & sorry for the thread drift, @flanagaj. I hope you find my problem interesting & helpful, as you consider your build.

Thanks for your input @Gus Potter. When I say, “I designed the house.”, I mean, I did all the planning permission drawings & passed these over to an architectural technician, together with some notes about materials & build method (the Thermoblocks were part of my spec’). The AT has done the drawings my detail drawing was taken from, above. I expected him to do a lot better than this. Now I am spending hours & hours teaching him how to do his job properly so he can improve the drawings before they go to building control. My intention was to have EPS beads filling the cavity, with these going all the way down to the trench blocks. I imagined the EPS installer would drill through the inside leaf near the floor to fill the area below the tray. If I don’t need a tray & I can have two separate DPCs that would seem to me to be a better solution. This was suggested to me on an earlier thread, but I thought the 2 separate DPCs suggestion was just for below my windows. If we can use 2 separate DPCs the whole way round the house, that would be great. Are you sure omitting the Marmox blocks is a good idea? This is going to mean all my walls will be sucking heat out of the house straight into the ground. I can’t follow @Iceverge’s detail above (thanks for putting this up, @Iceverge) because I’m building my inner leaf off the top of the B&B, which has already been built. Here’s a picture of it during construction. As discussed here previously, the cowboy builder sat the B&B on trench blocks, instead of on dense blocks (which were on the drawing), so there’s no cavity beneath the level of the B&B, & although he put the beam ends on DPC, he then bridged the DPC with mortar - see below. The bit on the right of the picture, with the light coloured slips, is where the air brick periscope feeds air into the B&B void.

I shouldn't think so, but I don't really know, because I didn't learn about ground bearing slabs before I designed my house. I should think with a ground bearing slab, you'd have a continuous platform of insulation to separate the top part of slab (including the bit the walls are built off) from the bit that's in contact with the ground. In my case, I have concrete foundations with trench blocks, & the trench blocks support a beam & block structure, so my inner masonry leaf would have a direct connection to the ground, through low R-value materials, were it not for the Marmox blocks. Perhaps I should have left this question for somebody more knowledgeable than me to answer, but it seemed to be directed at me.

That's exactly what I have planned for my build. I also have a couple of dense block internal walls which will sit on Thermoblocks. One of these will be built from blocks laid flat, so it will be 220mm thick & will have 220mm Thermoblocks beneath. The idea is, if there's any money left, I can hang a floating staircase from this wall. & I'll have super THERMAL MASS - there, I said it too. Now we'll both be in trouble when @SteamyTea reads this thread. Here's my detail. Yes, I know my Arch Tec has drawn the air brick at the same level as my patio, with virtually no insulation below DPC level & the periscope sitting in the middle of the cavity instead of up against the outer leaf. I have already told him off. He really is rubbish. & I engaged him in May, & I'm still waiting for my second draft drawings.

This must be why Veka's T&Cs say, "In the absence of any express warranty to be specified by the Seller in respect of Goods which are not “white PVC -U profile” no warranty shall be given in respect of the Goods.". If you want a warranty for a colour, you have to ask them for one, & I don't suppose it's going to be 10 years, which is what they're offering for the white PVC-U.

I had a look at the Veka website, earlier today, following @Iceverge's tip, above. They offer some colours in what's called "Feinstruktur" finish, which they say looks like aluminium.

Well done, Russel. That looks fabulous. I hadn't realised you weren't already in.

This has got me thinking: due to planning constraints I've ended up with a messy roof design - I can likely go for wide gaps between the sarking boards on the sections that will likely never be walked on, & this will give a worthwhile saving, but I'm guessing my standing seam will be going on before I get onto cladding the dormer faces & cheeks, so I'll need the adjacent roof sections to be more robust.

Russell's 100 x 25 is probably a better suggestion than my 150 x 25 - assuming there's negligible increase in flex. The 100s likely save more in materials than they cost in additional labour. Furthermore, I can see that fitting these is a job that I'd enjoy doing myself, so it doesn't matter too much if they're going to take an extra day.

That's good to know. This is something like what I have in mind for my build (left side image). What this drawing doesn't show clearly is, there's an air gap above the red membrane (4). The air gap starts at the gutter & goes all the way up to the vented ridge. Also, I'll leave gaps in between my 150 x 25s - the gaps will be as big as I think I can get away with & still be able to walk on the roof without any risk of damage; the bigger the gap between each board, the cheaper the roof.

@SimonD didn't suggest woodfibre. My understanding is, woodfibre sarking boards are used when extra insulation is required, & they're likely held down onto rafters with softwood battens, so their sub-optimal pull out qualities aren't a concern. If you already have a ton of Kooltherm on your roof, as your drawings show, you don't need to worry about another few mm of insulation. I think @Russell griffiths is suggesting 150mm x 25mm treated softwood planks. These don't fully cover the roof - I've seen them installed with 10mm or more gaps between each plank, so they support the standing seam & the gaps assist in drying, should the wood become damp. I'm no expert, so listen to others' views, but I'd want some ventilation under the standing seam. I'll try to find a picture... Of course, the problem with the treated softwood 150 x 25mm is, the materials cost is going to be more than OSB (or even 22mm ply) & they're going to take a lot longer to install, as well. I haven't done the maths yet - I need to, because this is exactly what I'm planning to do for my roof.

Thank you very much @Gus Potter & @Iceverge for your recent posts. I have so much to do before I go away, I'm going to have to leave this now, & pick it up again the week after next.

The orange 150, above, is supposed to represent the height difference across the orange tray. I've just realised the top bar is drawn a little low, & my 2 minutes, or whatever is allowed, of editing time has expired.

I thought I'd put up a clearer picture of the poor detail @Gus Potter pointed out so that anybody who's interested can see it clearly. I'm wondering if the cavity tray went in under a full block (see orange line), this would make the arrangement sufficiently robust. We could also attach some steel brackets under the window (green line), with bolts into resin & appropriate attention to air tightness detail, behind the brackets. I've only just come up with this idea. No doubt there will be a proper way to do it, which will work better & cost less - please advise. The cill projection, at about 100mm, looks vulnerable & is much wider than I want. I've asked for this to be reduced to 45mm.

Thanks very much for pointing out this error - I hadn't spotted that one. Although, I don't understand which bits are, "the shaped insulation". I'd expected the air brick periscopes would be drawn, hard up against the outer leaf, & I'd have more EPS beads under the cavity tray & between the periscope & inner leaf, right down to the trench blocks. As it is, there's a gap on one side of the periscope & some unspecified board on the other side. The brick sized cross section at the bottom of the inner leaf, on top of the block & beam, is a Marmox Thermoblock. Yes, it does. Thank you. Yes, it's hard for me to learn, especially with the house build being just one of several significant responsibilities I must devote time to. I am keen to learn all about this, but when I began this project, I didn't imagine I'd be forced to learn in so much detail, to mitigate the losses from people who want to rip me off & others who are just incompetent. I have already been thinking, with his limited talent, this arch tec’ is only going to be able to get us so far & unless I start again with somebody else (4th re-start) with the drawings, I’m going to need to pay somebody who knows what they’re doing to go through everything the current arch tec’ draws & re-work the details he’s not able to design properly. I know I can’t trust my arch tec’s work, because, even with my very limited understanding of what needs to be done, I can spot many errors & I can see he doesn’t fully understand how to do his job properly. Even if I start again with somebody else, there’s no guarantee the next person would be any better. I came across Richard Bendy, who may be the right person to check over the drawings. I haven’t made contact yet: https://www.thehealthyhome.uk Ideally, my arch tec’ would pay Richard to show him where he’s gone wrong, & teach him how to do what I’ve contracted him to do, but I know this won't happen. Richard Bendy's services include training architects. Re. paying professionals: I had a good meeting with a proper architect, who has designed & overseen the completion of some certified passive houses. His quote (& this is for a house that has already been designed to PP level & for which PP has been granted) was £28,272 inc VAT. This included 12 hours for electrical layouts, which my current AT’s contract doesn’t specify, & some of the things that my AT has so far failed to include in his drawings, such as door threshold detail & intermediate floor to external wall detail, were specified in the £28k+ quote. There was also a substantial fee for, “building contract admin, PD & on-site support”, which I negotiated down from the quoted fee to £2,160/month (inc VAT) for the duration of the project. I was told that it would be very unusual to proceed without this monthly fee, but if I chose to do so, I’d be completely on my own once the drawings had been handed over & I wouldn’t be able to call for help with the build (a condition arising from the architect’s insurance policies). So that’s £50k, assuming we pay the monthly fee for 10 months & don’t need any extra drawings. & this fee was based on me providing the .dwg format drawings (which I had only as .pdf) from the AT that I was about to sack, for being quite a lot worse than the current one. A prominent member on here explained, many architects overcharge for work that’s often sub-standard. He highly recommended the AT I‘m trying to work with now. This BH member gives out good advice here on BH all the time & I trusted his judgement. Here’s an excerpt from the current AT’s quote: My fee to prepare a detailed set of construction drawings for a dwelling of this scale and design, including detailed floor plans, 2 x sections, annotated elevations, site plan showing drainage and services, specific details of key elements which require further thought/ironing out such as the cantilevered box and corner glazing and a set of construction notes/specification, would be £6000 plus VAT, 50% of which would be payable upon instruction with the balance payable upon issue of final drawings. This is an all inclusive fee for the complete set of drawings and details. There are no further charges for any amendments required or liaison with structural engineers or building control, or indeed yourself. Therefore there are no nasty surprises further down the line. Thanks again, Gus. I’m away from Friday, for 9 days, so I must just explain: any comment anybody posts will be gratefully received, although I won’t respond until the week after next, because I’ll be having a fantastic time snowboarding & screen time will be limited to essential work comms only.

Sorry - my fault. I should have quoted or namechecked you when I posted, so you'd have receive a notification.