Dunc

I believe that is a non-aerated primary tank (i.e. just a settlement/septic tank) connected to a secondary treatment system based on filtration through fibrous media (peat/coconut husk) to bring it up to EN12566-3 (i.e. the same as a stand alone Sewage Treatment Plant). The secondary system is available stand alone: https://www.premiertechaqua.com/en-gb/wastewater-treatment/ecoflo I looked into it when we found we couldn't construct a suitable percolation area for a stand alone STP, but was told that it would still require a drainage field, as @ProDave found. I never found anyone who would clarify whether the purpose of the drainage field after an EN12556-3 compliant system is to provide further cleaning of the output, or whether it is solely to distribute "clean" outflow under ground thereby preventing creating a stream or puddle on the surface.

from the makers of one coated OSB3, smartply: https://mdfosb.com/en/faqs/smartply-propassiv Should fixings used to fix panel be taped over? It is not necessary to tape over the fixings used to install PROPASSIV providing that the fixings have not been removed and reinserted or predrilled. I take this to imply that if you put a screw in and leave it alone, then the integrity of the airtight panel should be intact.

This is a question I have on my list too (although for the distant future). Surely the battening itself is screwed to the coated internal boards. If so, is the supplier sealing each screw hole or around the edges of each batten? Or is the screw itself sufficient to maintain the airtight integrity?

Standard units to the wall for me. I did think that the two full height corner units were standing like menacing sentinels in the corner. I'd just blank off the opposite side as you've now got a kind of cubby-hole effect next to the oven unit. Or maybe blank it at half depth so that the kettle & toaster are behind the line of oven units, but the cubby-hole isn't a full 600mm deep. I'd want a large radius on all corners of the island unit, expecially if there are children around.

Hmm, not a strongly positive reception there. As most of the rest of the plot is covered in this stuff, I'm already OK for the driveway and a storage/unloading area. But I'm sure I could find some use for it. Was hoping it might save a bit of cash at this early stage.

Just trying to gather information so I don't get laughed out of the office when I speak to a SE about foundation design. Ground investigation reports "a safe bearing capacity of 75-100kN/m² will be available for foundations placed on the medium-dense, coarse sand found approximately 0.8mbgl." and "recommend trench fill foundations or strip foundations with a sufficient number of courses of under build to ensure that the dwelling is founded on soil with a sufficient bearing." All good. The site has previously been used and has a covering of some kind of MOT/hardcore/stone surface. The layers are, top down: Top layer is ~ 200mm deep Soft to medium - dense, grey/brown, slightly gravelly, silty, fine to medium coarse sand with crushed angular rock with an underlying white geomembrane liner. MADE GROUND. [what as a punter I think of as "hardocore"] Second layer is ~200mm deep Soft to medium - dense, grey/brown, slightly gravelly, silty, fine to medium coarse sand with crushed angular rock with an underlying black, hexagonal geogrid. MADE GROUND. Third layer is ~400mm native peaty topsoil which will have to be removed. Fourth layer is the suitable load bearing material - Medium - dense, grey, damp, slightly gravelly, silty, clayey, fine to medium coarse SAND with angular cobbles. Fragments of loosely bound clayey sand embedded with gravel. Occasional angular and rounded cobbles. I'm wondering if the made ground could be re-used as the base layer of an insulated raft. If I can strip that off and save it, remove the native peaty topsoil down to load bearing ground, could I stick the made ground back in, in compressed layers. An insulated raft is probably at least as deep (400mm) as the removed topsoil. Could I end up back at ground level without having to import much material other than the draining layer and fine support layer for under a raft?

I used worktop express for oak worktops. Seemed a good price and quality. I cut them to size on site (just in case their tape measure is different from mine!) but probably didn't need to worry as the 3m and 4m lengths supplied were within 2mm and spot on 635mm width. Occasionally there's a small knot or bit of filler in one of the timber pieces which can be exposed when a cut is made, which is presumably what the disclaimer is about. I never hit one, and the cut edges when coated with oil look exaclty like the pre-coated edges originally supplied. If the cut edge is against a wall it doesn't matter anyway. If you're using the cutting service don't forget to allow expansion gaps against walls/cabinets in your measurements.

I worry about corrugated steel. One timber kit supplier pointed us in that direction but I'm concerned about how poorly it ages. For example: as built 2011: https://maps.app.goo.gl/87Emx8RcxWQobNC49 10 years later rather rusty: https://maps.app.goo.gl/ZnLtrH7N5X3VUR8x9 maybe it's supposed to be "rustic"?

For me this is the key point: if one installs a tertirary treatment such as the puraflo (they use coconut fibre now that extraction of peat is not considered environmentally sound) where would its outflow go in the situation where the ground is too wet for an infiltration field? Still have to be piped to a watercourse or can it drain onto an above ground surface?

@DerbyLad I spoke with OR about this yesterday. The surveyor who looked at your site should be able to tell you where they wish to bring a connection to at the boundary of your site. Its up to you how you then duct within the site. As @IanR says, so as long as you use approved ducting you can intall it (with a draw string inside!) before you request a connection. OR offered to drop off the ducting for free.

Just addressing some of these really helpful comments: Wayleave won't be a problem - the estate now knows that the plot is effectively worthless without the ability to put in suitable wastewater management and they own the ground we might need to cross. Solicitors are already on the case, thanks to all who suggested. It was one of your early posts @Kelvin that made me aware we could make these investigations part of QA! But we will need to have a design and SEPA approval before we sign on the dotted line. I hadn't thought about risk of a long pipe in soft ground settling - obvious when you say it! So @saveasteading you'e suggesting a small diameter "hose", (perhaps within a larger rigid pipe to prevent pinching?) being pumped so any undulation is dealt with by pump rather than gravity. Probably from a collection chamber downstream of the treatment plant so the pump only runs e.g. 1x/day and gives capacity for collection during power failure? But as @crooksey said, gravity is free. Either option will likely work though so just a question of cost and practicality. Intriguing point @Redoctober if we can find a drier bit between us and the river we may not have to go all the way. Seems unlikely, but worth going bushwhacking... No intention of putting untreated waste into a watercourse (or anywhere else!). Assuming we can anchor a treatment plant so that it doesn't float, and ensure air inflow and access ports are above water (and any surface flooding) I'm not sure that I see the issue with a buried treatment plant? @Dave Jones The only bit I'm missing (and apologies if I'm just being thick): if we have suitably clean outflow from a treatment plant (and obviously it would have to be if it were going to the river) is there no way to discharge this within the plot via something like a sand mound? Only keen on this as it's entirely contained and within my control so if it goes wrong in future I don't have any problems dealing with it.

thanks for lots of thoughts. We don't own the plot yet, this is part of due our diligence. Fortunately the estate we're buying from also own the land we might need to cross, so wayleave shoudn't be a problem (phew!) No pump required - the plot and intermediate land falls towards the river. It's just that the river is a good 300-400 meters away so I wondered if there's an on-site solution. "a fail doesn't matter if it fails by flowing away to fast or slow." - but the issue here is that if we dig a field like @JohnMo's it'll just be a swimming pool from the ground water flowing in. Reed bed sounds interesting...more reading required.

I can probably agree wayleave with the estate whose land we would need to cross for access to the watercourse. I'd imagine a 300-400m trench & pipe might be rather expensive so was just wondering if there are other options to be considered (i.e. an above-ground solution). But given the general boggy-ness of the ground, even a surface-level hole will likely self-fill. Do I understand correctly then, that even after a tertiary system such as a sand mound or a co-conut filter box, there is still a requirement for the outflow to then percolate into the ground rather than become surface run-off? thanks.

Our percolation test failed - too wet. What are my options? We're in Scotland. The plot does not have access to mains sewers. The trial holes were filling with water as they were dug. The engineer reported: "wet peat overlaying wet, very clayey sand." My engineer is suggesting that the only viable option will be to discharge treated waste via pipe to a watercourse which is a few hundred meters away. Just wondering if the collective have any other suggestions?

Just coming back on this to confirm I registered with my own name as company name. I then filled in the very minimal plot registration form and uploaded site and block plans. Openreach have just come back with a quote and contract document of £2000 for "Full Fibre gigabit capable infrastructure for your new development". Looks like boiler plate email and contract. It does say that copper or FTTC is available at no cost. I was surprised that no additional info was required. I am even more surprised because my area (rural Highlands) doesn't have full fibre available 😂. Of course there's no phone number to follow up with 😕 (all I want right now is to know where the local cabinet is so I can look at ducting under the public road adjacent to the plot while the council have it dug up for other purposes next month).

I filled in the "contact us" form to ask about how cope with the required "company name" field on the registration form and they phoned me within 24 hours to explain. They told me that self builders should just use their own name as "company name". Seems to have worked fine.

Useful list, thank you. I came across AFT: https://www.advancedfoundationtechnologylimited.co.uk/ [no experience, just found the website].

Some very helpful thoughts here, thank you. Takeaway thus far: DHW cylinder will kick out a lot of heat (despite being insulated. Can you box them in with additional insulation?) Probably better not right next to the bedroom. ASHP/UFH pump can be noisy - sound insulation & distance from bedrooms required. What is a "plant room" anyway...maybe it doesn't need to be separate from other functional areas (i.e. utility). There are indeed a lot (too many!) doors. @Blooda's questions: "Ent" is the sole entry to the house other than via the garage. My better half, who is of course in overall charge, doesn't want the utility visible as one walks in the front door. @Bozza I'm a little reluctant to stick it in the garage as any heat lost there is gone. If it's inside the thermal envelope then it's not lost energy which is useful during the winter...? @JohnMo architect just stuck the ASHP there. I suspect the detail on the location is TBC; agree it looks like it could be too close to 2 adjacent walls, but theres' plenty of space to move it away. I'm tempted to swap the plant and w/c. But not wall off the plant, just have it as part of the utility. Also loose the door between entry area and circulation area outside the bedroom. That's 2 doors gone

I would appreciate help on locating my plant room: Any thoughts on whether to swap the w/c in the utlity with the plant room? Entry area, utility and w/c are planned to be single storey flat roof. Plant room, en-suite, bed 1 are planned to be 1.5 storey. Working to Scottish regs, so must have the store area available as the "convertible-to-accessible-shower" and connectable to the w/c area. Current layout: Entry, utility and w/c are all within a "dirty" area of the house - useful for when working in the garden or garage. Plant room inside 1/5 storey area - easy to route services across the rest of the building. MVHR and ASHP main supply/return pipes are further from outside wall. Unsure of possilbe routing. Risk of noise from plant room? - bed 1 is the master bedroom. Risk of excessive heat from plant room? [aiming for passive-class build] Swapped layout: w/c more in the "clean" area of the house - more appropriate for visitors, but no window. Could remove the door between entry and internal vestibule bit and add a standard door in to the kitchen & rest of house, expanding the "dirty" area slightly. MVHR & AHSP main supply/return straight through the wall seems more efficient? Would it make services to the rest of the house harder e.g. longer run to kitchen for DHW. Is it easy to access the ceiling-floor void in the 1.5 storey part to route everything? Reduced risk of noise/heat?

I was going to suggest that if it's OK from the inside, and only because of the extended history, perhaps accept a reduction in cost and move on with the build. But if you're going to see it every time you're out, then as most others here it seems reasonable to reject it.

Does it look any different from the inside looking out, and is it in the same room as another different tint pane? How often would you look at the house from the outside and be able to see both sets of glass?

I fitted a DIY Kitchens 2 years ago. I'd say it's a little better than some of the cheapest flat pack stuff but really it's marginal once it's fitted. Hinges and handles are probably the biggest noticable difference. Slightly heavier grade back board to the unit. Leg adjustment pretty good, unit alignment reasonable, choice of unit interior finish....er, that's it. The fact that the units come preassembled saved a lot of time. I'd happily use them again but I'll also be shopping around just to ensure best price. Oak worktops were cheaper elsewhere. Customer service was very good [couple of small items were missed in the original delivery and were sent within 24hrs of lodging an issue. I requested dry assembly for one unit so I could cut it to fit, which they forgot to do. They did want to see photos of the fact that I couldn't take it apart 😆 before they sent a replacement but that was only a 48hr delay]. The only real disappiontment with DIY Kitches was their showroom display where they have their own base unit lined up next to half a dozen compeitor units. All the competitor units were deliberatly misaligned or mis assembled to make the DIYK unit look better. Smacks of desperation and slightly underhand tactics. All could have been fixed easily and would therefore have been nearly indistinguishable....which for me is the bottom line - go with whatever you like the look of.

Yes, we interviewed 4 architects/designers in detial in order to select one to work with. That inculded giving them a brief, having a 1hr call with them and asking for their fees and their expectations of build costs. We did this in paralell with looking for a plot. None of the architects we spoke with included professional fees (architect, engineer, solicitor) or utilities provision in the cost/m2 estimates....so, as pretty much everyone else has said: it's a guessing game!

We've just been through this and are now in the process of purchasing a plot and working with an architect towards a planning applicaiton so I can share a little recent experience, but the short version for me is there are too many variables to get an accurate cost. Some thoughts: £/m2 ususally doesn't generally include cost of plot, professional fees (solicitor, architect, engineer, other specialists), getting utilities installed, or lanscaping the garden afterwards. Ground work/foundation seems to be the biggest unknown - untill you dig a hole you don't really know what's giong to happen, although if your architect is local and has done other work in the area they may have a general idea of what's likely to be in the ground. Architects may be able to give you an early estimate, just based on your general requirements, location and their ethos. However I had a range from £1800 to £3500. The architect (actually an architectural technologist) we've gone with reckons £2000-£2500/m2 for a timberframe build in the Highlands. We had a quote from one local timberframe company with their in-house architect for a turnkey build (this is before having any desing, jsut a bullet list of "wants" and an idea of size to form an architectural brief). That was guide-priced at £3500/m2. I found this really hepful as the spec included things like oak internal doors and skirting, a Mitsubishi Ecodan ASHP, Paul MVHR, 4kW PV and Tesla Powewall. i.e. there was enough info to see it was a high spec finish. So I see this as a ceiling price to beat and a worst case scenario. If timberframe is of interest, have a look at the catalogs of some stock stuff e.g. scotframe, hebhomes, dan wood who will give you prices to get a ball park for the main structure [but keep in mind there's probably the same cost again in turning a shell into a useable house]. I don't know if there are similar offerings for other build methods? Architect & engineer fees vary quite a bit and the more expensive architects we had quotes from were in the 10-15% of build budget range (even though they quoted a fixed fee). Allan Corfield architects have a pretty good resource on their website and do provide ballpark costs which were pretty close to their quote for us.https://acarchitects.biz/self-build-architect-cost/ and https://acarchitects.biz/professional-fees-self-build-project/ As above, there seems to be a certain level of commitment required just to get an idea of what it'll cost and it seems one has to start investing some cash to even find out if it's going to be possible. It feels like a big leap of a cliff wondering if the parachute will open!

Thanks all for the thoughts! Reassuing. I'm guessing one architect who spent a good 10 mintues stressing "we really understand TF sizing so will make an efficient design to manufacture" was perhaps slightly over-selling. All I want is a basic rectangular form...but I guess to keep £10k corners to a minimum we could go for a circle 😂