Bitpipe

All good info, our BC was from an independent firm and was very approachable. I first sent him the detailed design from MBC, including calcs and he then sent me a bunch of follow on questions on that package plus our non MBC elements (basement) etc that needed resolved before construction could commence. Most of this was just clarification and explanation - we had nothing that was a show stopper. We've pretty much continued like this. Now that completion is imminent - he sent me a list of outstanding items which I've been able to tick off. If you have a good relationship then you should be able to run things past them (such as spec of plasterboard etc) - ours saved me a lot of grief by waving any need for an external SVP. Just remember to get a formal record (email) of any such phone conversations and make sure they respond to acknowledge and agree. We only had a few inspections, first was when some supporting drainage was going in (this was pre demolition but allowed us to officially 'start' ahead of a new issue of more onerous conditions). The first proper inspection was when the steel was being tied for the basement with the next one when the frame was erected and externally roofed & clad (had a small checklist of actions after that). We had one post 1st fix just before closing the cavity with PB and the last was to identify remaining items ahead of the final.

Quite impressed with the 900w Miele Blizzard - its powerful enough to come to a complete halt on a rug when on max. Have also learned not to empty the cartridge indoors as it releases a cloud of dust when it deposits into the bin.

Almost done with the external landscaping. Wall and gate pillars built, motors fitted in the ground and driveway edged in block, just a little more type 1 to go in before the 50mm porous tarmac sub base and 20mm bonded resin go on in a week or so. Driveway is H shaped with in and out gates and additional space in front of the garage and other side of house. I've decided against drive over lights in the tarmac/resin as they are quite expensive and making the connections with armoured cable is fussy. Instead, my electrician has recommended a 24v system, putting lights in the edging blocks and running the tails into the soft ground behind where the connections can be made in waterproof JBs. I will put duct in to cary the supply cable across the driveway where required, drivers in my kiosk that now contains meter, main fuse, DB for garden area, one gate controller and loop detector (getting a bit tight for space!). Will fit a lux sensor on the side of the kiosk so that all lights only come on when dark. I need about 18 lights, (allowing a 4 m spacing) and am looking at these two options, one is 1/2 W and other is 1W. I will have two drivers with 9 lights on each. There is also a dimmable driver available. http://www.collingwoodlighting.com/en/products/ground-lights/item/gl018c-uk http://www.collingwoodlighting.com/en/products/ground-lights/item/gl019f-uk Unfortunately I cant test a sample in time for the blocks to be pre-drilled next week and as they are different diameters (28mm vs 33mm) I need to commit to one or other now. These are just to mark out the driveway at night so don't need to be super bright - the expensive option is to buy the 1W units with the dimmable driver and turn them down if too bright. Cheaper option is to get the 1/2 W units but no option to turn them up if too dim. I've marked out the positions with tea lights and these look quite good - how bright are they by comparison?

We have a Lakeland electric clothes horse (integrated element) which we got when living in the caravan and it lived in a greenhouse with the washing machine. We still use it but almost never use the electric element. We have a heat exchange condensing tumble that only does towels and bedding (super efficiently). Everything else is hung in the utility on the drier and is always dry within 12 hours, quicker on warm days.

Being the owner of a MBC passive standard house, I am happy to finally have a built in letter box in the new front wall vs a cardboard box that postie has used for the last 18 months, although I'll miss our chats. A passive cat flap (£2k from memory) would also be welcome but aside from that I love the impact that air tightness & MVHR has on our house. When we had the recent -10 outside temps, we still could have the front door open for 20 mins with no draught or drop in temp.

Personally I think this is a mistake. MVHR is a £3-4k cost max and delivers significant benefit. It can be installed DIY and self certified, On a house your size (we are similar) it's a rounding error on the budget.

Lots of good advice above. Depending on your construction type and how easily it can be modified during 1F, you may need to make structural allowance for the bulky services such as foul drainage, gas flue, electricity & water supply and MVHR (externals are the bulkiest but the internal runs need space also). Steels are the one element you don't want to be modifying on site - penetrations need to be designed in and SE signed off. Most of the other 1F services (gas, electrics etc) can be run / penetrated where required in the usual service void. Our sparky took the floor plans and marked out socket, data, tv, lights & switch locations (internal and external) to enable him to cost up the job and plan distribution etc. When the frame was up we made final decisions on locations with pens and gaffer tape, still left a lot of decisions to his discretion. Plumbing was a case of deciding what went where in bathrooms and then working backwards for fouls and supply. Nothing beats doing lifesize cutouts of baths, loos, showers etc and positioning them on the floor once the room is framed out - we made quite a few tweaks. MVHR goes where it can - most vendors will do you a design for pricing purposes and will supply excess duct to allow for tweaks. You can pay for a plan in advance but I guarantee that there will be significant deviations so would question the value. Best advice is to get sparky and plumber onsite (after you've nabbed all the space for MVHR) and get them to agree how they'll work together. Then leave them to it. Should all be included in the price TBH.

Go read the MVHR threads as well as the MVHR anemometer hire threads. The design principals are pretty straightforward. Have an extract in every wet/smelly room i.e. bathrooms, cloaks, ensuite, utility & kitchen (you may need two if it's a large space). Have a supply in every other habitable room. Position these so you get the best possible cross flow of air through a room. Allow 7600mm2 gaps under doors (i.e. 10mm on a standard 760mm door). Try to locate MVHR unit so that you minimise very short or very long runs - helps with balancing later. You also need to try and get intake and extract on the same face of the house to avoid unbalancing due to external wind. It'd a bit of a compromise all round (mine is in basement so I break the even duct run rule), plus minimise the external duct runs as these need to be insulated and are larger diameter (ours 180mm) so harder to route. Plan ahead for duct runs, even with 75mm duct, bend radii are can be large and when you have a lot of ducts coming together it can get quite tricky. Balancing is all about satisfying three separate conditions - Min extract on boost for kitchen, bath and cloak rooms (on boost) - this is normally pretty easy. Balancing supply and extract - bit trickier, involves lots of running around and tweaking each vent. Whole house ventilation rate - this is calculated on your floor area and for large houses can be tricky. You need to show BC that your system can meet this req (normally by cranking up the fan speeds) but most of us here seem to run the system at a lower rate with no ill effects.

You need to look at part F and satisfy BC that you have adequate ventilation for each part of the house depending on your system (mvhr or more traditional methods). You can always take a risk and bluff but depends on your inspector!

Quite impressive You could potentially wrap the whole basement perimeter in EPS 200/250/300 depending on loading spec. You would lay it first directly on the ground (on some blinding), lay your steel on that and and build your slab off it. In doing this you can copy the MBC method of attaching the UFH pipes directly to the steel and save on screed and additional insulation & labour. It will be a very low temp (35o) system with slow response but will keep you warm underfoot especially if you tile the floor Then Fix EPS against the steel piles (low expansion foam would be enough to old them in place and fill gaps) and then build your steel against it and effectively using the EPS is as one side of your shuttering (or do the walls with ICF). Build the lid with RC as normal and clad the top with EPS before backfilling - effectively you strive to wrap the whole basement in insulation from the outside. You can then run this EPS up to the perimeter of your house walls. Laying EPS in this way is not a skilled job, I should know as I did all of ours . Note I did not use custom made EPS (i.e. the Kore system that MBC use) just bog standard 2.4m x 1.2m blocks in 200 and 300mm thickness. It can be cut easily with a chainsaw and the heavier stuff does not go anywhere when positioned. You can also use small lengths of rebar as pins or bent into staples to hold it in place. This is contingent on using WPC but I really suggest doing a full cost breakdown of the two systems as there is a lot of additional cost with internal membrane, its labour intensive and the detailing is critical. Plus you have the ongoing maintenance of pump systems etc, contingency for power outages etc. Finishing our basement internally was very cheap - a bit of latex to level the floor (could have power-floated to avoid that) and dot & dab plasterboard on the walls with services behind (D&D gives you 30-40mm to play with). Inherently airtight too so. Look at https://www.mea-group.com/de/ for their range of lightwells and basement windows etc. We used three of their largest GRP lightwells and they were very easy to install. If you need sumps & pumps to deal with those, at least they are external to your waterproof envelope. If you use SIPs or another TF system, your soleplate would be sitting on the slab (basement lid) but inside the EPS envelope - protecting you from cold bridging at the sole plate and the associated issues. Or build the walls from ICF and continue the insulated layer vertically with that. You can use suspended concrete floors with ICF or cast in (or retro fix) support for a timber floor.

It's essential for the twin wall system as the inner load bearing leaf of the twin wall sits on the outer edge of the basement wall and the outer (non load bearing) leaf sits on the outside edge to the basement insulation. When the void is pumped with cellulose, insulation meets insulation so there is continuity all around the building envelope. Not sure how you'd manage with the single wall MBC system (or equivalent or SIPs etc), potential of a cold bridge where the basement wall meets the soleplate as its outside the warm envelope. I found ICF more expensive over all as the SIPs roof added a lot of cost (could go timber and self insulate I suppose) plus the construction of floors, walls etc. The attractiveness of timber frame, and MBC in particular, was the completeness of the quote (you get a lot for your money, you can pretty much move straight to first fix once your windows are in and roof on) and the speed of onsite build. I did look at Thermohouse which is an ICF product with a structural floor and roof element.

My build is 400m2 and the Vent Axia Sentinel Kinetic Plus unit I have (about £2k ish) would easily support your build. Usual challenge is trying to centrally locate it to equalise duct runs as much as possible but I broke that rule by having it on one side of the basement and I've been able to balance it fine. Standard MVHR units use very little electricity, beyond a certain airtightness level they will not be efficient at recovering heat but this is usually a challenge in refurbs, not new builds. If you're serious about maximising your energy performance then you want to consider airtightness as much as insulation - you don't need to be striving for passive standards to have good airtightness to minimise heat loss. MVHR then becomes the most effective and efficient way to ventilate a space that has good airtightness. Regarding basement insulation, I had to go for external as I needed to replicate the MBC passive slab design. If your construction method negates that then inside is fine, just do the calcs to see what you need to hit the desired u value. Keep in mind that although the ground has a higher min temp compared to the outside air, it is more conductive so insulation is still required. You'd be surprised how little heat you need to inject into a well insulated airtight space (and basements are inherently airtight) to make it comfortable. Nearly everyone on this forum is challenged with keeping their build cool in summer vs warm in winter. That said, a few strategically placed electric wall panel heaters can be used in your basement - best strategy is to run the wiring for these and only install if you feel the need. You seem to have some experience in building basements so I probably can't add much more. That Newton system is not cheap but if you go for it (from memory) I don't believe you need an exterior membrane as you're assuming that the wall is inherently leaky to begin with. From that pov, ICF may be a good way forward as the skill level is low (many DIY it) and you wont be concerned about getting a perfect pour. Back in 2015 I was quoted £120/m3 for standard and £200/m3 for Sika waterproof (this was to supply & place, the raw material cost obv. lower).

As we had a passive house design, I needed a full wrap of insulation around the house. I have no heating in the basement and it's fine, even in this subzero spell we're having. A few humans and gadgets, plus the plant room, kick out enough heat to make it more than comfortable. BTW, if your crew are very unskilled then I'd be wary having them build the basement without some supervisory expertise as any mistakes may turn out to be very expensive later.

First things first - what did your ground survey say re-water table? Are you above it or in it? We're above ours so went for The design above is not that great as it assumes that the basement will leak and you're effectively building a membrane inside the basement to catch water and take it to a sump, which needs a pump (and a spare or alarm etc...). Works well for retro basements but you can do better. Sika, Kryten or similar will give you a warrantied watertight box, assuming that the crew are trained and licenced to use that system. The waterproof reps will come to inspect work and sign it off to generate the warranty. External membrane is optional - I didn't bother. Warranty provider was fine with that. To insulate, we laid 300mm EPS 250 (as approved by the SE, you may need higher/lower spec depending on the weight of your structure) on a 150mm blinded base and then put some Radon membrane over the top. The basement crew treated this as ground zero and laid the rebar on top and made the slab with a 100mm kicker. Then each wall section was cast in situ with penetrations made for lightwells, door to external means of escape and services. Sika waterproofing bar & mastic at every join and the holes left by the shuttering support bars were plugged with a rubber bung that screws tight to the hole sides We designed an 'open box' basement which meant stronger walls (effectively cantilevered) and then had a steel & suspended timber floor vs a poured lid. Cost wise it was probably marginal but gave us more flexibility on the internal layout (which we framed in timber). MBC did not blink when we suggested doing a house over a basement and I think they're still in touch with the contractor we used if other clients requested similar. Design wise, MBC did the house design first and then we passed everything to the SE who designed the basement & steel floor to match up, we then passed this design back to MBC who took care of the steel & timber ground floor and another contractor did the basement construction. I was quite nervous about the whole thing coming together but needn't have worried as MBC took final measurements off the finished basement before putting the frame into production. If you go for a more traditional cast lid then it can be treated just like a slab foundation but you will need to make sure point loads are catered for. MVHR is a must, cheap as chips in the grand scheme of things - superior ventilation and significantly reduces your energy bills through efficient heat recovery. You can turn it off, open windows if you wish (although you'll want windows without trickle vents). The only other reason I was wary of ICF is that you can't inspect the pour quality, which if that's all you're relying on is a bit of a leap of faith.

Hi, did someone say basement We built a passive* 'cast in situ' basement made of Sika warrantied waterproof concrete in Berkshire and then popped a MBC passive standard house on top. *essentially sits on 300mm of EPS250 with 200mm EPS70on the sides to meet the insulated layer for the MBC house. Very happy to bore you senseless on the details. Also looked at ICF all the way but it was much more expensive than the option we ended up going for TF.

i bought a cheap laser thermometer and used that to get a proper reading of floor & pipe temp.

From experience, NMAs are just that, non material. I got away with increasing front window sizes slightly using one but had another for front roof solar panels turned down (which was fine, they're allowed under PD anyway). As it's at the rear of the dwelling, I doubt the planners would have an issue. You could take a chance and crack on while do your planning update in parallel? When we decided to extended the basement & adjust the front boundary treatment, the app (our third) sailed through. First (rejected) and second (approved) were the ones that generated all the attention from neighbours, the third did not get a single comment as I suppose they were resigned to it.

Drove into Soho last night from Maidenhead, 1 1/2 hours leaving at 7pm. Though the way back would be quicker @10pm but didn't count on the M4 elevated being closed so pretty much the same. Pretty drive though with all the lights up, even if I had to play 'dodge the drunk' on the way back...

They guy we used was excellent, came via the reseller and is very experienced. Was amazed to watch him & his crew thread the huge sliders through a slot in the scaffolding. He did a site survey prior to install with MBC to ensure that all the thresholds & apertures were correct. Also used compriband & an airtightness fabric round every window. He's reasonably local so I've been able to have him out a few times since to do some snagging.

MagicMan is obviously a franchise but the one we used in the Berkshire area was excellent. They can pretty much fix anything - we had a chipped stone bath and a cracked sink. While he was here, he also touched up a chip on an oak veneered door and a scratch to our RK front door - all flawless. We also had scratches on our powder coated AU doors by the renders plus a blob of GRP top coat on a frame. For that our independent installer got a contact who does mobile car respray (high end) to come to site to fill, sand and respray the damaged areas- we used RAL paint supplied by the window company. That also turned out well. Fear not, if there's one thing I've learned on the build it's that more or less anything that goes wrong can be remedied!

I had a feeling that a few of us would be racing to hit that target!

Fixed that for you Ed.

I think @HerbJ build used the yellow material, we were done about 6 weeks apart. I only know I was one of the first to get the green OSB as the firm that makes it came to site with MBC to see if in-situ and take photos for their brochure. The yellow fabric is pretty heavy duty but can tear if caught with a sharp edge - I poked a few holes in the loft while boarding out the eaves floor for storage. Easily repaired with spare airtightness tape and the insulation was not going anywhere - it was packed solid. Other advantage of the green OSB is that you can nail or screw into it without compromising the airtightness (providing the fixing stays in place) plus I assume it's much quicker to install.

Most of the airtightness layer in our MBC build is a special green faced 12.5mm OSB, however I believe that up until then they were stapling the yellow airtightness fabric to the inner wall studs with the service void battens laid on-top - this is the arrangement we have in our loft. The advantage of the fabric is that you can see how tightly the warmtherm is packed - it really pillows out between the joists.

I'd expect that you'll also be less susceptible to gusts of wind unbalancing the system. Not sure if the cooling effectiveness in summer would be compromised as the ground releases heat in the evening - our spot is shaded so not much of an issue.