Visti

Excellent, exactly what I've been looking at too! Did you deal with Zurich directly (and how!)? or via Self Build Insurance?

How're you planning on providing scaffolding certification to contractors who ask? and the weekly inspections? We may be planning on doing our own scaffolding too

Thanks for the input all. Cash account it is for us. There's quite a few BMs around so we'll be shopping around for each and every quote!

We're looking to setup an account with Travis Perkins just up the road in preparation to breaking ground shortly. There's the cash option, and the credit option, and little information on either. Only recommendation I've found online is to go for the Credit account, not for value but rather for the purposes of VAT paperwork! Alternatively there is a John Nicholls and Bunnings nearby. Should be bother with a trade account at all?

Great summary @TerryE. Our estimates are very close to yours at 44kWh/day using Jeremy's spreadsheet, but as you say it's all dependent on the build actual! Your average of 8.6p/kWh for Feb is pretty good. E7 I take it? or E10? To clarify, you use the grid for the Heating via the Willis, and PV for your DHW which is stored in the Sunamp units. Is there any cross over? And what made you decide on that configuration as opposed to all PV, or all grid?

I just raised the opposite in your welcome post @Dreadnaught, what a coincidence! At ~12p/kWh heating via electricity is somewhat more expensive than gas at 4p/kWh (average rates, not accounting for E7 or E10). Unless you charge the SunAmp via PV and well timed E7 or E10, you're looking at a higher £/kWh. Noted there are lower losses from storing the heat with the SunAmp unit (about a 1/4 of a conventional cylinder IIRC), which would reduce the total kWh and therefore lower your total £. If you did the calculations (which we need to do shortly) I'm sure the SunAmp unit can get very close to a £/kWh cost as a conventional unvented boiler+cylinder. However, the initial capital outlay when factoring in PV may be significantly more. Hence we're undecided!

It certainly appears so when combined with PV or you dont have access to mains gas. Anyone done a comparison against a conventional unvented cylinder fed by a gas boiler?

Thanks for the tip on the podcast. That's been added to the list!

Hot dang, that was quick and spot on! Never fail to disappoint @JSHarris That is a very useful source... it even gives a horizon outline:

I'm wondering if anyone has any excel model on sizing PVs? Particularly one that includes the annual cycle from month to month? I'm certain of the main variables that need to be considered (solar fall at geographical location, orientation to south, pitch, m2 of panels etc...) yet there's nothing via google that doesn't mean starting from first principles! Asking as we're looking to supply adequate power to our energy demands (below) and exploring non-conventional options like Sunamp! (£/yr is for a conventional gas boiler+cylinder which we're using as a baseline).

This previous thread covers some good ground on Scaffolding by Self-Builders:

Buying ones own scaffolding sounds like a solid plan. Used sets looks very affordable. How do folks get it erected however? I take it one still needs a scaffolding contractor with a valid CISRS card? Would they be willing to work on scaffolding not supplied by themselves? How about the weekly checks?

I highly recommend the Building Services Handbook 9th Edition as well as the Building Construction Handbook you've mentioned. Particularly once you're onto your heating, sewage, hot water and all the other systems involved in services. Very good technical book that'll give you the facts, so perfect for referencing. They can be a bit dry in that regard if you're not technically inclined! I've both the The Self-Builder's Guide To The Construction Phase and the Project Management version too. My recommendation is to skip these as they're quite shallow in content. The Self Build bible does a better job than the two combined.

We're planning on a power-floated concrete finish, no polishing. Still to get a £/m2 figure as we've awaiting the quotes to come back, but it certainly isn't the £75/m2 or resin or polished. Anticipating ~£35-40/m2 (I'll get corrected shortly, I just know it!) What bamboo supplier are you considering? We're looking at The Bamboo Flooring Company at ~£30-35/m2.

SP for the uninitiated?

What sort of m2 total you talking about? We're quoting for about 49m2 with Rationel, Internorm, Velfac, Gaulhofer and Katzbeck and for the ones we've had back they're all sitting within ~£500 of one another at £20k... similar specs too. Not sure whether it's coincidence, good pricing or some insider talking going on! Either way, it is expensive this building malarkey.

This is where I wish we had a passive slab foundation from them... but because we're not allowed I've now lost two weeks just trying to define who is responsible for what at the boundary between the foundation and the timber frame. ah well!

Awesome feedback, thanks all! Thank goodness it's early days and I've got time to spend on this learning curve... I have decided with the good wisdom of you all not to poison the family with the UFH using wholesome water! The SO will be proud! Thanks for pointing that out, I've fixed the original post It's just Watts, so that'd 50.4 kWh/day, or ~1512 kWh/month. That's worst case however. On average it'd be about a 3rd lower, at about 32 kWh/day, or 950 kWh/month. Agreed, I got ahead of myself. It was useful to think about the pluming but it is clear I need to settle on the principle systems None as of yet. We've got nothing but the land so far, foundation is going in march, so it's a blank slate thankfully. No limitations at present! Good point. The system wont be centrally mounted (utility room in red), however the majority of the runs will be under 4m in the areas I've highlighted green. Only exception will be the Kitchen sink which will be about a 10m run. LHS Ground, RHS First Floor: Great diagram @Nickfromwales, I believe I get what a hot return is now. Given that I'm still getting my head around much of the terminology here, I'll summarize for myself: a hot return is basically a loop with a pump that constantly recycles the hot water feed. This eliminates the water from getting cold prior to the outlets, thus reducing the amount of time waiting for the water to get warm when you turn on the tap? Ultimately it looks like the gas UVC is here to stay, ASHP is out, and PV is a maybe (the capital costs may push it back to some years after the build is done!). The Sunamp heat battery comes up a lot on the forum, so I'll have to do a bit more reading into it - I take it they have to be combined with PV to enable you to forfeit the boiler? I know Andy from Sunamp will be at the NSBRC convention this weekend, so I'll update my design following everyone's input and shall see what he thinks.

Due to some of the astounding quotes for UFH and DHW systems, I have decided to have a stab at designing and specing our own system! This is the first draft, possible due to this forum and the Building Services Handbook recommended by @curlewhouse - an awesome book, I've left in the page #'s from where I've done capacity calcs. Even so, a sanity check is very welcome! It's currently a bog-standard unvented system + system boiler that is scaled for the DHW only. You'll notice I'm one of the converted to @Nickfromwales's Hep 20 Manifold setup, though I'm not necessarily sure that the 2nd hot water at 48'C manifold is necessary for us. Principle question here is whether it's safe to pass the output of the UFH back to the main cylinder, or will that have to be discharged? We're unsure as to how we're going to supply heating however, whether we scale up the boiler / cylinder capacity, or whether we go via the ASHP or Solar Panels/Thermal Store. We're looking at ~2100 Watts for the UFH based on our heat losses during the winter here in Oxford. There'll be no other heating in the house save for some electrical UFH matts in the upstairs bathroom. ASHP with a good CoE running overnight to take advantage of the E7 scheme sounds grand, though we're concerned with the noise and another hole in our external wall for this. Could this be plummed directly into the UFH, or would a separate cylinder be needed to store the output? Solar Panels sound grand, but we're concerned the timing of the heating will be at odds with when we'll need to heat the floor. Also, the initial outlay appears quite steep so we'd likely need to install it retrospectively when we've the money. Scale up the Boiler to ~18kW to supply the UFH along with everything else FYI: I used MS Visio 2016 which has several Pipes & Valves stencil sets out of the box. Very useful! Heat Losses calculated thanks to @JSHarris's calculator.

@divorcingjack Excellent, that we're glad to hear! We're thinking of a resin too to deal with the cracks, though the contrasting colour sounds like a great idea... just have to sell the SO on it. Did you have to specify the concrete mix, or did MBC have a standard mix that you chose to use?

Checkout Gaulhofer as they have passivehaus standard windows and are pretty straightforward. If you're not going after the passivehaus certification, I recommend you calculate your heat losses attributed to your windows and take a serious think if the higher quality glass will play itself off. Example: U-value range for Gaulhofer's Inline rage is 0.91 to 0.67. The difference in these U-values equated to about 1000kWh of additional heat los a year. Using Gas at about 0.03 £/kWh, that's a difference of £30/yr. Depending on the price difference, you may not make the savings on your ultra low U-value windows within the scope of your lifetime...

Correct! Nothingis going on top of this concrete surface. We're being quite stingey on the budget and both like the idea. Speaking of which, anyone else with bare screed / concrete able to share some pictures of the surface? The SO is worried about the potential size of divets etc...

The reason is exactly what you suspected; we have internal lead bearing walls that'll be resting on the screed. That's a good point and not one I'd known/considered. I'll ensure to bring it up with the engineer! The best PIR I can find is Kingspans Kooltherm K103, which is at 0.018 W/mK. That's a u-value of 0.12 @ 150mm for £43/m2 (2x75mm) Two layers of 150mm Jablite EPS at 0.035 W/mK gives an equivalent u-value of 0.117 but for only £19/m2. As we're not struggera 150mm, we'll stick with the EPS. Also, there also appears o be a nationwide PI0mmR shortage. Anyone clued up on that?! I think we'll be going with 100mm thickness overall. To be safe and account for the spacers too. That'll give us 5-10mm of 'headroom'.

It is indeed Peter, though it's a suspended Beam & Block rather than a slab. Composition below. I should note that the power-floated screed will be the finished floor. Nothing is going on top of that.