G and J

As most self builders only self build once, it comes down to a leap of faith. Air tight I get, because if my ‘91 built house wasn’t a wind tunnel it would be very cosy, but U values are harder to invest in and trust, emotionally.

Can that be done into a steel and concrete beam? I guess the SE will decide.

I suggest it would be safe to assume that the CIL process should be followed meticulously just like any other self build. Rather expensive if it turns out later it was needed, and it’s just a few simple forms.

Each time I’ve seen pics of an ICF house there’s always steel rods sticking up out of the slab to fit the polystyrene over. I get that they are great for basements but isn’t it too late to do ICF with AdTee’s foundations?

So, a sheet of 140mm PIR costs about £53. Gapotape to line it costs £36. Ouch. That means I’ll spend about £2.5k on gapotape on our build on just the walls. That’s a lot of Smarties. I think I need to research alternatives, I’ll start a new thread if I can’t find it covered elsewhere.

Good grief that’s odd. Is there even a legal definition of ‘self build’?

So it’s ‘squeeze-o-tape’. Invented by Wallace one assumes!

Don’t know about the need to protect the b&b but to me, with focus and a kind autumn weather wise I would be tempted to go for a watertight timber frame well before Xmas (but then, as my old Irish farmer friend used to say, I am like a cock at a gooseberry!). You are almost out of the ground so things could happen pretty quickly, funds allowing, especially as you’ve already got an SE engaged and invested. Go for it! And take no prisoners.

So you have already built a strip foundation designed to support the build up in your first diagram. And in effect you need a retaining wall outside of this to prevent bits of next door sliding towards you? Your second diagram seems to be using a block outer skin as a retaining wall. Doesn’t that mean your timber frame is a support for said retaining wall? If so that doesn’t sound like a good idea. In your shoes I’d pay an SE to design you a solution. I’d be too concerned at the risk of building something unsafe, or needing significant remedial work.

My apologies if I’ve misunderstood but aren’t you effectively building a partial basement without basement suitable methods?

Can’t imagine what you are trying to achieve. Are you wanting to partially hide the dolly course?

So does gapotape then expand to fill any gaps round the PIR?

Is that to create an unbroken layer of cement board and window?

We don’t have either built in steps or a permanent roof ladder. But the view from our ridge, across the fields, is something I’d sit and look at every day if I could. Whenever I’m on the roof doing anything I’ll often sit on the ridge and just enjoy. I do tend to be roped up mind, no point taking unnecessary chances, but I love those tile steps as that would make it quicker and easier and I could crab a rope to them as I go up. Brilliant. So I want to know where I can buy them for a 40 degree slate roof. That way I’ll be able to clean my solar pv every other sunny Tuesday morning. 😉

Just looked that up. Is it just for the ends of PIR sheets?

At the moment buyer ignorance is allowing some companies to use the MCS scheme to milk the buyers/system. I’ll call them skimmers. I refuse to believe all MCS accredited peeps are skimmers. There simply must be good guys. I think I’ve found one such good guy (fingers crossed). Market maturity, which I think is still a fair way off, will erode the excess profits for the skimmers. I would expect large companies will increase market share whilst there is still a high profit margin. That should stabilise end user prices nearer reasonable levels. Thence local good guys will always have to work under the margins of the large companies and generally buyers will get better value for money. But that process only happens because there is a market in the first place and without the grants there might not be. So it’s rather awful in places, but the MCS has got to be a good thing medium term. Scary thought, if you want to accelerate market maturity set Martin Lewis on it.

Sadly I’m also saddled with that belief. I just can’t see why I would design it in.

Is the foam flexible enough to continue to fill the gap after shrinkage?

Ok, I get that taping is needed to give a second layer of protection to help stop screed infiltration. But what does foaming bring to the party?

If one has two layers of PIR with staggered joints is taping and foaming really needed?

I have read on here many times that in cooler months upstairs bedrooms run a couple of degrees cooler than downstairs with what appears to be almost standard running setup of MVHR, ASHP, single zone UFH downstairs, no heating upstairs, decent level insulation. MVHR doesn’t, it appears, force all rooms to the same temperature as it simply doesn’t move enough air round to achieve that. That’s why it’s not the useful for cooling. It might distribute heat a bit, but not enough to equalise. Given that lower upstairs temperature I think the super simplicity of that setup is very attractive.

+1 But you don’t have to do it, you could get a chippy to do it. Take the door to them, shouldn’t cost much at all. But once you start playing with a router you may well become addicted to the precision, accuracy, and the finish.

I’m struggling with that. We’ve a gravity system in our ‘91 build that’s always been good. We’ve had pressurised systems in other properties and they’ve worked fine too, but no better. I have replaced the ball valve in the loft once in 33 years whereas the pressurised systems have needed much more regular attention. If one was comparing a poorly designed/functioning gravity system with a modern system I can understand the conclusion, but not otherwise. (Yes ok, in some areas I’m a Luddite!)

I know that feeling. So a hot wire won’t set the PIR alight then?

I wonder if two staggered layers of 6mm are better than one layer of 12mm. Can imagine 6mm cement board sheets being quite fragile to handle.