G and J

Good grief. I thought I had crap to deal with!

Fingers and toes crossed. I see it as a simple equation, listen+think+listen+check*think more=hope. I’m happy for our designs to be criticised, once I’ve stopped sulking I’d have learnt something or embraced new ideas. I though peeps were worried about privacy (so far our plans have only been seen by a very select few of just about everyone who cares to look at our planning application lol)

I think this means not having a plastic sheet directly behind my service void. I thought I had to have one. Do I?

Me too by the looks of things.

I’ll tell Julia you said so. In fairness our architect is brilliant in that they accepted we wanted to design it, they’ve tested the design firmly and respectfully, and they are truly working with us. Which is what the architect said when we interviewed him on site before engaging him. But me being me I want to be an informed decision maker partly to ensure that we aren’t unconsciously falling foul of other people’s prejudices.

Wow, brilliant, thank you Iceverge. I’ll use those as a starting point. I did read somewhere on here concerns about the permeable membrane being inside the PIR but other than that that build up might be perfect (with the addition of a 25mm service void for cables and a skin of ply or osb just under the PB).

I’ve wondered about that. It does appear that a lot of SIP based designs use lots of timber splines rather than SIP ones. However, I did also think that in comparing SIP and stick built each has the same timber framing round windows and stuff s that’s just the next problem to work, and therefore not highly informative in the making of the SIP/stick built decision. Spot on. I also only want it to rain at night. Oh, and be buildable within a sensible budget. 😉

I’ve not investigated concrete pouring options for ICF as yet, but I will if when I look at ICF it looks like we can get a suitably warm and thin build up. OK, guilty as charged, I am set on working out the best possible SIP design for us. I think I’m close enough now to revisit the base case which is stick built. Once I’ve repeated that process for stick built I’m thinking the choice will be obvious. We shall see!

We will give up room space if we really have to, but we’re not at that stage yet, and we think we’ve already optimised our layout for what we think our needs and preferences are. God help us! lol

I’ve noted that many peeps seem reticent about posting their plans so I haven’t posted so far, but I don’t see why not. Whilst I appreciate that we can trade off u values between different elements I'm taking the approach that by working each element we get the best info we can to fuel those trade off decisions, and as a spin off I’m learning tons of stuff too.

I’ve not spoken with an ICF company or a concrete delivery company but the fact that the boom would have to arch over electric cables would be a worry. My target is a total wall thickness of ~300mm (inc. 70mm of battening and cladding on the outside skin) and I’m under the impression that ICF would struggle with that. Stick built is the default option, I’m exploring alternatives in part as a validation exercise but I’m learning tons along the way. My investigations so far indicate that a SIPs on site blank panel build would use 175mm PU SIPs or 200mm EPS SIPs to yield a u value of better than 0.17. Cost wise, and this is very broad brush, (and includes walls, joists, chipboard flooring at first floor only), it appears that: 1. Get a company in to do the lot and it’s just over 100k. Game over. 2. Have a different company make it in factory and deliver it for me to erect and it’s about 52k. 3. Buy blank PU SIP panels and build it myself, buying in joists etc. from other suppliers will cost about 35k. Each of these options require a fire board skin, cladding, internal battening and osb/plasterboard (I want good solid walls). So, next step is to repeat the same process for stick built. At present I’m struggling to work out a stick built wall build up that yields a decent u value and the right thickness.

I did like the macerator plan when I thought the macerator would sit just above the main sewer manhole invert level. That way if I disconnect the macerator there would be no backflow, and I could even flush the small bore waste pipe with a hose connection. I know macerators can handle constant back pressure but everything goes wrong eventually and it’s not a good prospect if a load of filthy water escapes when dismantling. I appreciate that a pump station is a proper job but I think the notion of dealing with a failed pump in a manhole full of filthy water really doesn’t appeal either. I think it’s either put my potty on a 500mm pedestal or give up on having a potty.

A while ago I posted seeking thoughts on what was, and was not, likely to be a good idea for me to take on myself. I’m retired but still time poor and I want our build to not take forever and cost an ok amount, and have a warranty. Perhaps I’m being nervous but making my own sips would feel dangerous unless I used timber splines everywhere, in which case I’m back to being stick built. Goodness there are so many factors!

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!