G and J

This may be a daft question, but is a PH slab simply a foundation with lots of insulation and no thermal bridging? If so what u value is it required to hit?

So, I’ve done my measuring with my water level. Oh dear. Ground level around my man cave if 550mm below invert level of sewer access manhole at the front of my site. Sigh. I will never truly trust a laser level again. I think that means a rethink …

Goodness I’m hopeless at explaining things. By truly diy I didn’t mean making the SIPs myself, I mean getting a load of SIP blanks delivered to site from which I build our house. The quote I received for SIP delivered and erected as appears standard was game over level, so I then got a kit that I assemble on site (muscle being the only lifting gear). I then ran the numbers for me building with SIP blanks and it’s starting to look remarkably good. Problem is, they don’t sell SIP blanks at TP or any other BMs….. Do for a living? Don’t be daft, I’m a bum. (That’s an impolite term for a wrinkly. ;- ) I like b&b floors but I don’t like air bricks in wood cladding.

Our cladding is vertical, therefore we have to batten and counter batten. That’s why we have 50mm in our wall build up.

They will shroud next door’s overhead electric feed to prevent electric shocks but the feed itself remains vulnerable. We can also legally apply to close our narrow road while we build but we’ll be inconveniencing the peeps who we want to be happy neighbours with for years, so we’re seeking alternatives. In truth the simple cost of a company turning up and assembling a preformed house is looking ludicrously higher than other alternatives. When I went to the NEC self build show I saw the marketing spend and it alerted me to the profit margins that awaited the unwary. I’ve now got a good handle of the broad cost on site stick built and it’s a reasonable option. But my gut feel is a build with sip blanks might improve on that. So my investigations continue. And as for a telehandler,we might just be using simple muscle to pop trusses onto our roof. Just like we did in ‘91. I’m a retro sort of guy. 😉

May I ask what the factors are that are driving this decision?

I guess I want to see just such a video but with SIPs being put up the windows cut out, etc.

I’m struggling re the sourcing of a SIPs solution I can be confident in. I went to the Self Build show at the NEC. Lots of hard sell, ‘give us your plans and all your problems are over’, only they aren’t, as our site access doesn’t allow lifting kit and the amounts quoted were project killing. So I continued to investigate other options, and as I did DIY SIPs were suggested. I look at the specs and it does look like a SIP based build would yield walls of the thickness I want, with better u values and condensation handling than I can achieve through traditional stick built. Maybe with better acoustic and airtightness too. So I follow a link to a blank panel provider and then engage with them and share my plans and I get back a quote for a factory made total kit for me to assemble that’s a lot lower cost than the companies at the show, but it still leaves me scratching my head. It appears they don’t really sell blank panels any more. If I try and add up a list of the components it comes to an awful lot less than half the cost of the quote. When I ask questions like ‘what size of posi joist have you assumed’ the answer is ‘oh don’t worry we will sort that later’, which doesn’t work for me. I want to understand the nuts and bolts before we commit large sums, and being told not to worry, it’ll be ok is a bright red rag to an anxious bull. So, does anyone know of a company that will happily sell (and therefore share a price list of) blank SIP panels and associated stuff that I can buy which would allow me to build it on-site myself? Ideally I think I’ll need hybrid panels (i.e. ones with one skin being in anti-fire stuff as we are building less than a metre from our boundary).

That’s really good to hear, thank you. Whilst I readily accept that I shouldn’t ‘over think it’ it’s actually hard to turn the ‘CPU’ off. 😕

So, I might have a handle on R values. To check…. if layer A has a u value of 0.2, and layer B has a u value of 0.3 the combined u value is: 1/(1/0.2 + 1/0.3) =0.12 If that’s correct then if I can look up R values I can calculate u values. If I can look up R values will I ever need to mix it with k values?

Oh. k-value. The list of stuff to understand is growing faster than my reading speed!

Maybe too off topic but is a non softened feed needed with modern softeners? I was told recently that current designs mean softened water is safe to drink?

Plastic sheets I understand. I don’t understand how the outer sheet is fixed without causing water penetration points, or perhaps as the cladding prevents water reaching it it doesn’t matter once finished.

So, I need to read up on R values… I’m guessing that as the only practical alternative is stick built open panels filled with insulation plus a layer of pir then that won’t be that different. Unless I’m missing something fundamental. Gosh that’s incredibly useful. We can actually fit in 194mm panels thus improving the u value by 0.02. There’s roughly 160m2 of external wall area, and I think that means that if using a test case of 25C temp difference, a 0.02 better u value will mean 160x25x0.02 watts difference in heat loss. Using a COP of 3 (being pessimistic) that means something like 0.64kWh extra on the coldest day. I think. Does that sound feasible?

So it would look like… plaster skim 3mm plasterboard 13mm battens to give service void 25mm vapour control layer SIP panel 172mm wind tight but water vapour permeable layer double battens and vertical larch cladding (~70mm) Don’t understand this but at all. Goodness the amount I don’t know!

But for a softy southerner in a sheltered location the above build up would get to an ok u value (we aren’t going passive, haven’t got the space) and be good to live in?

Assuming this brick pier is holding something up is it a good idea to put that big a hole through it ? That’s an eighth of the thickness you are taking out and I’d worry about damage to the integrity of the pier.

As campervaners we have often wondered what the attraction was…. But going off (caravan) topic am I right in thinking that the wall build up for sips could be as simple as : (from inside, and ignoring membranes and vapour barriers as I’ve not understood them yet and they don’t add thickness….) plaster skim 3mm plasterboard 13mm battens to give service void 25mm SIP panel 172mm double battens and vertical larch cladding (~70mm)

Boeing don’t seem to mind too much nowadays…. 😕 In reality I wonder how vital the bolt becomes over time. I wonder if after construction it’s actually just a peg that’s needed. Hence bolt from the top would be sensible.

The cut surface invites corrosion more?

So hit it hard with a big hammer. Won’t help, mind, but sometimes it just feels good. 😉

Good point. And I guess if you angle grind through the bottom of the nut and the bolt the nut will never fall off. We never rivet anything (apart from pop rivets) nowadays do we.

Would it be quicker and more effective to invert them so the spare thread sticks up into the void? The bolt head may well be smaller than the nut. Might be an idea to do one at a time mind. :-0

I don’t know why, she swallowed a fly…