Stratman

Like this: https://www.southwalesgroundtesting.co.uk/tracked-dynamic-sampling-and-strength-profiling

A two man diesel powered rig hammered 1m sections of 100mm pipe into the ground then withdrew the cores for analysis. Filled one hole with water then measured the level as it went down over a few hours.

I had six bore holes and a percolation test for £850 earlier this year. They were really useful in determining soil strata and a thin layer of clay so how far down to excavate to compacted shale. The holes went down nearly 2 metres.

https://vekauk.com/product/windows/softline82-passivhaus/ www.precisionpvc.co.uk/product/m70-windows-residential

@Nickfromwales thanks, that's good to hear. @Adrock So these are marketed as Passivhaus standard. I have a quote from Precision (who are based near Glasgow but supplying to Wales) for Veka's Matrix FS70 triple glazed system, but I'll probably go for the more modern bevelled profile of the Halo System 10 or the Softline Passivhaus.

I'm considering Veka which appear to have three seals on their flush profile. I'd be interested to hear what the forum thinks of this brand.

If East and assuming you are in a moderate risk location, you can have no more glazed area than 18% of your internal floor area. That's using the simplified method.

Is the most glazed elevation (by m2) south or west facing? If so you're more likely to get in trouble with Part O.

@flanagaj I used this online calculator to size psijoists roughly before getting the TF engineer to specify exactly: https://www.mitek.co.uk/span-calculator/span-calculator-uk/ If you are having MVHR then Total Homes specify an absolute minimum open web joist of 254mm to get 150 dia. rigid ducts through.

The appeal of engaging one of the big off site frame providers over a stick build timber frame is that they should have certain advantages for the (especially novice) self builder: 1. The off site nature should equate to higher levels of accuracy and better quality control: things are more likely to be put together better in the comfort of a factory (and subsequently checked for QA) than on a muddy, windy, rainy site. 2. For those interested in air tightness and thermal efficiency, the more insulation that is fitted in a factory, the better; it's likely to be precision cut and fitted tightly. 3. Small contractors are more susceptible to financial instability; large companies less so and more likely to have robust insurance in case things go wrong. 4. Large companies are likely to be more comfortable being bound by strict forms of contract that a small builder might be less comfortable with. In my view all of these things have value, and I'm willing to pay a bit extra to take advantage of these benefits to (hopefully!) get a better finished product with (evrything crossed now!) fewer hiccups along the way. That said, I've no doubt that more experienced and able self builders will be happier engaging smaller stick build contractors and achieve the results they want. I really hope it pays off ofr us!

I'm in a similar position, weighing up cost Vs performance. I love the apparent simplicity of insulated raft, simple one level excavation, no need for foundation walls or screed. It's just the potential cost that I'm trying to figure out, getting quotes from ISO quick, Greenraft and MBC.

Re opening windows, does NI have building regs document equivalent to Approved Document O? This may restrict counting some windows' contribution to night time cooling if they are on ground floor as they may not be considered secure.

Correction: your current design is for a 50m3 hole filled with gravel to obtain 14.85m3 water storage. By my rough calculation you may only need a 15.5m3 hole to get the same storage from crates. So you might spend £3k on crates but much less excavation.

In anticipation of getting our own soakaway sized, I've been trying to put together a spreadsheet based on the methodology set out in BRE Digest 365 (2016), so I can do it myself. It's a work in progress and I've gone down the rabbit hole with it over the last few days. I've noticed that the soakaway construction type has a huge influence on the size of the hole you need. Your calculations note a 'percentage free volume' of only 30%, i.e. 70% of your hole is taken up by your gravel fill. Plastic soakaway crate are mostly void - about 95% free volume, so less of your hole is taken up by the crate material itself so you can get away with a smaller hole. If your 15m3 hole is costing £3k in gravel, a smaller (say 10m3?) hole might cost £2k in crates (e.g. 10 x 5 crates/m3 = 10 x £40). Plus there's the difference in excavation cost and muck away.

@NickfromwalesThanks for the replies and I agree. Certainly getting the insulated raft from the same supplier would be better in terms of coordination and liability for defects, which is why I included MBC in the tender. I am still sold on the idea of the insulated raft and I think I can get it for a better price from Green Raft or a local groundworker using Isoquick or similar insulation - looking like a £20k saving potentially. I think I can manage the coordination. @LnP I've done similar - spreadsheet to equalise quotes with estimates in the blank that one or the other doesn't provide. Scotframe come out a bit more expensive but they do include for way more elements (insulation, windows, internal doors, plasterboard, SAP, etc, etc). Fleming cheapest but more exclusions.