G and J

I took best bang for your buck to mean final heating requirement vs total build cost. Sounds easy when it’s in a list like that but I’m finding out that there’s soooooo many factors.

How noisy, dusty, and unpleasant fir the neighbours was the crusher?

We’ve budgeted rather more than that. Did peeps have the timber for firewood? I’d worry about the chemicals they used 100 years ago.

Ummm, why don’t you have choice of installer?

I used to use a pair of petrol huskies, but having gone battery I’ll never go back to petrol again. The little one (see above) being one handed is like a light sabre, it’s brilliant. But I do need the bigger, double battery one for much bigger things. Re the skips etc. it upsets me that there’s every incentive not to bother to try and reuse. Apparently it’ll work out cheaper to cart all the hardcore away from our demolition and then buy hard ore back in, than it will be do reuse on site. Depressing.

(Maybe a teensy bit off topic, but….) We will be building in an urban environment, replacing a bungalow with a combined system. We believe we are on very well draining sandy soil, and the one time I’ve dug down so far I hit pebbles and orange sand at 20”. Yet everyone in the trade I’ve talked to so far have said something like “save yourself aggro, just stay combined”. Anglia Water reduce your bills by virtually nothing for spending extra and dealing with surface water locally. There’s simply no incentive not to dump the problem on them. Sigh.

Are ewe joking? 😉

May I recommend this sort of thing (I don’t think the 18+ is a reference to higher voltages!). Keep it sharp and it’s fantastically productive. Even if 50% of the time you are waiting for your only battery to charge (obsessives like me have several, thus avoiding said problem) you’ll cut through more than with a reciprocating saw. Charger will run off a cheap 300w inverter off of your car. I’m sure all the 18v tool companies have a version of it. https://www.toolstation.com/makita-18v-25cm-top-handle-brushless-cordless-chainsaw/p94170?utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dc&pcrid=null&pkw=null&pmt=null&gad_source=1&gclid=EAIaIQobChMIq8emmPPfhgMVUJpQBh3KNgO9EAQYAiABEgKLcfD_BwE&gclsrc=aw.ds (But don’t buy if from toolstation as there’s always cheaper online even with next day delivery).

I noticed that, but I figured that maybe building control might need to be a bit less directive in a country where lots of peeps carry firearms in case anyone annoys them.

We’re likely to end up with trendy thin metal switches and sockets so they won’t hide what is in effect a surface mount rim on the dry lining box, so I think plastered in is definitively the best way for me.

Those protectors are great, thank you. I’d not be confident about stretching the membrane - I’d worry that thermal cycling would maybe wear holes, but I think the plan works without that.

Do peeps generally fit the backboxes before plastering like with solid walls? I’ve only ever retrofitted to plastered stud walls….

Ah. So I have to oversize the hole in the OSB/ply. I think.

Bingo! https://www.ukelectricalsupplies.com/norslo-dry-lining-box-2-gang-32mm.htm

Good thought. In fact that will be the case in some rooms, especially bathrooms. But our big downstairs everything room thingy (I call it The Great Hall as I do enjoy irony) will need stuff both sides.

When I first watched this guys videos I thought, naaaah, can’t be that simple. We live and learn.

I’d identified that EPS based SIPs wouldn’t give any advantage over stick built early on, so I focussed on PU SIPs, and that, combined with the limited thicknesses available in the cement board SIPs lead me to discount them.

In that case I’m guilty of giving a more negative impression of our architect than is reasonable. We are scheduled in to start detailed design soon, and the discussions we’ve had have been those needed to get through planning, now thankfully obtained.

My word I’m such a bonehead. My head is so full of stuff explaining myself isn’t easy sometimes, there are so many disparate thoughts jostling to get to the front of the queue. The plan is to have an OSB or ply skin behind the plasterboard. This is personal preference (read OCD inspired folly, perhaps) but I like the idea of really solid walls I can hang stuff from anywhere, and maybe with better acoustic attenuation too. But I hadn’t thought about back box depth. 12.5mm PB, then 11mm OSB, then 11mm void = tight. OK, time to research back boxes….. And I have an ‘every millimetre counts’ attitude. The plot is 24’ wide, the house, externally, will be 21’. So to me and our already advanced layouts based on 1’ thick walls, it will make a difference.

The outside walls of our house are within a metre of our boundary on both sides. On the south side there is bang on a metre wall to wall with next door. On the north side it’s a whopping 1.5m. At the planning drawing stage the architect mentioned that we’d need to use fire resistant sheathing on the frame. Apparently part built timber frames make rather intense bonfires. 😕 I’ve not researched this, as on a few quick searches it appears credible, so I've accepted it as a constraint. He also was ok with larch cladding, but I think that will need to be treated for fire resistance.

I clearly need to research cement board prices more, I did my coatings on what I could quickly find in more than one place so as to reduce the risk of skewed results from a particular offer, so I readily accept I may have overestimated the stick build related costs. The SIP ones were from quotes capable of acceptance, so I’m more confident in them (but not necessarily in how comprehensive my list of things needed in addition to those quotes….) The target is a mostly two storey, mostly slate pitched roofed, mostly vertical larch clad, with some render, low risk house. Low risk means nothing ground breaking or bleeding edge, I seek the best options for us amongst the tried and tested. Sadly my curiosity demands I understand the less mainstream, but I bring myself back to heel soon enough. I hope. We soon start detailed design with the architects, and though I’ve a lot more on my knowledge shopping list, I’m already a much more informed decision maker.

Peeps talk about a service void behind plasterboard being 25mm or 50mm. If it’s only for cables, almost all maximum 2.5mm2 FT&E, is there any reason that void couldn’t be smaller? Say 11mm?

In truth I remained open minded, but to give a technology the best chance of being judged fairly one has to try hard to devise the best option. I started with the assumption that I’d be able to buy SIP panels with the outside made of cement board, but I failed to find a current supplier. One did say they used to do them but they discontinued them due to problems (unspecified). Our base case is exactly that, cement board sheathing our frame. It is a lot more expensive than OSB3 though.

I will readily admit I like the idea of SIPs and I did try really hard to assemble the best possible case for them. However the result is not favourable. It’s worse in my case as I have to have a fire resistant layer on the outside. The SIP companies I’ve consulted advise that that needs to be battened rather than fixed direct so that adds to wall thickness with little improvement in insulation. It negates the width vs u value advantage PU based SIPs provide. Even without this the extra cost of SIPs is significant. I think this is likely to be because there isn’t an active market in sufficient volume for what I would call diy SIP build, meaning from blank panels. I did find suppliers of technically suitable PU SIPs. (I focussed on PU SIPs as EPS SIPS yield a thicker wall given the above than stick built for a given u value.) But it’s not like the supply of OSB3, there simply isn’t the competition. The end result is I can source and have built for me a stick built frame for a lot less than I can source SIP panels for me to erect. Yes, I then have to insulate but that’s ok with me. I’ve learnt a lot about SIPs in this process, and I remain shocked by the way the industry is so dominated by companies that sell hard and clearly have very pleasant margins. I understand that even local building companies don’t build using SIP blanks, they get a specialist company to put up the kit and they take it from there. The supply is simply not there competitively (yet?) I now have a high regard for SIP technology, and I’m grateful for inputs from enthusiastic proponents - it’s helped me enormously in my data gathering - but my numbers are what they are. And as those numbers translate into Greggs sausage roll tokens (our build is just in walking distance - praise be!!) then those numbers guide me. My next research area should be diets, but it’s probably going to be warm vs cold roof and roof air tightness. 😕

Slander and calumny! Such wisdom cometh not from me, that was from Iceverge. It made sense to me but maybe I’m missing something. Again.