SBMS

Fair enough. It was a difficult one to predict as the tree was in a neighbours garden, 20 meters away, felled 9months ago (before we bought our plot) and was only discovered because BCO asked to use their toilet and spotted it in their garden.

How would you have known?

Nothing is predictable! As nod said - groudworks especially so. Our BC asked us to go another 1/2 meter deeper because he was worried about a tree that had been felled. Wasn't to the NHBC guidance, but he's a belt and braces guy. Cost us 5k extra. Our chamber floor was supposed to be here weeks ago - but they've got transportation issues because of the fuel costs (theyre trying to keep to quotes by optimising their deliveries) - certainly wasn't predictable when they quoted in January before Ukraine etc etc

I posted on a similar thread back in March here with our square meterage and costs breakdown:

I was going to say the only bit I can’t comment on is the superstructure as we are doing brick and block. I think as others have mentioned, your clearance costs are a bit low for muck away. Foundation costs are so variable, but just a 500mm extra depth dig for our foundations was an extra £5k. I think your glazing costs are optimistic we were over £20k for glazing and doors and that was double glazed. Surface and grey water drainage costs seem a bit low - we were 12k and that was for a scheme that was shared amongst 3 self builds so there were economies of scale costs. 1750 for UFH is pretty low. Our ground floor is larger but our price is coming in at nearly an order of magnitude higher. 7k for electrics including an EV charger seems tight; unless you’re just going for pendant lights throughout etc. We worked on a rough basis of £50 per ‘thing’ (socket/ light etc) fitted. Crude but fairly accurate. 4k for MVHR installed? Ours is nearer 7k(installed). I’m just picking out a few things here. To be honest I followed the same logic as you when setting out - your spreadsheet seems logical but when you start getting quotes and getting into the detail of costings I think you’ll need an extra 25% unless you’re doing a lot of the work yourself. My original estimates were not dissimilar to yours and when we got quotes back I was out by around 25%. But the variability in quotes was pretty high so it does depend on getting a good builder you trust.

Too low. We are right in the midst of our self build so have a fairly good handle on current costs and I think nearly every single estimate is on the low end - perhaps except your services costs.

Out of interest - with a modern unit that modulates output, is it a big issue over specifying? Is it the additional capital cost of a bigger unit you were trying to avoid?

Out of interest have you had a like for like quote from an MCS registered installer (giving the £5k discount through BUS) and one without? My experience when getting quotes has not been that prices have been ramped by 5k. But as I’ve said before on this forum in response to this: there are good installers and those out for profiteering. But that’s not a problem unique to heat pump installers or the BUS. We had a same experience when we got quotes for our primary contractor - some are simply more expensive than others and try and chance their quote.

Originally the scheme was called the Clean Heat Grant but I guess 99% of applicants will come from existing boiler upgrades (the only type of new build eligible is a custom / self build, so no house builders or developers) so I guess that’s why they renamed it Boiler Upgrade Scheme to cover the majority of type of applicants. I think it’s fairly forward thinking of them to include self builders actually as we face the same budgetary pressures as those with existing boilers in choosing whether to choose a greener form of heating or opt for a (cheaper to install at least) gas boiler.

The boiler upgrade scheme eligibility includes self builders.

What were your ground conditions? We are on clay and worried about ground heave? I don’t know how strong beads down to foundations would be?

Thanks. Out of interest did you leave any airgap from top of concrete to the beads? We are probably going to put a cavity tray across the top but wondered if you can fill the beads all the way down to top of concrete infill?

Hi Foundations done and our block and beam floor is down. We are having EPS beads (standard masonry construction). There’s currently no cavity infill from top of foundations to top of DPC. Building control weren’t bothered but some people are telling me we should concrete infill (up to 225mm below top of DPC), in the event of ‘ground heave’. Is this right?

It was around 400k

This seems really high. Our fees from buildstore: £300 broker fee £1500 lender arrangement fee £105 lender conveyancing fee £200 discharge fee £20 chaps fee £500 valuation fee We chose to go with an advance stage mortgage where funds are released in advance and the application is packaged and underwritten with an insurance policy and paid an additional £3k on top of this for that type of mortgage. This was 12m ago.

You could go direct if you’re good at scouring the market and finding the cheapest rates yourself and have a simple financial situation (full time employment, employed). If you deviate from this (self employed, company director etc) and have a more complex financial setup with regards your income sources I think a broker is highly valuable. For example, if you’re self employed/paid through dividends some lenders assess your income based on your tax return income, others on net company profits. This could make a huge difference to what you can borrow and it’s very difficult to ascertain which lenders use which method without phoning them all up and asking. Secondly, I would recommend someone like buildstore if you’re looking for an advance stage self build mortgage as this mortgage requires an assessed build budget and these sort of brokers have an in house team that can help with this. All in all, I would say a broker is worth the few hundred that you spend in fees.

We had to have this. Attenuation via stone system with a hydro brake to slow discharge into the ditch. On clay.

We had exactly the same setup (including the Nibe 12kw) specified for our build. Was priced up in January and came to 11k for supply and install. Yours seems high but I know that ASHP have gone up. Be careful re lead times - we had to order our Nibe in April and earliest deliver is September. FYI At 11k less the 5k grant I think the equipment cost is more than the net £6k.

I think you should be able to get a simple self build mortgage, just because you own the plot doesn’t preclude you - it’s probably viewed more favourably by the lender as your LTV would be much lower. We borrowed to purchase plot and build house. That will be calculated as part of your equity and therefore your deposit. What I would imagine is that most lenders won’t lend for the site preliminary costs which demolition might be included under but it sounds like you can fund (and prove you can fund) that portion. Is there a reason you’ve been told a commercial loan is required?

That’s really useful @joth it’s great to see some real world data. Makes me wish we had gone for a zehnder as I don’t think vent axia’s app shows as much info as this.

Not necessarily. Radial will eliminate crosstalk but may be noisier due to a smaller ducting radius (more air resistance - noisier). We went through the same dilemma when picking our MVHR design. We ended up opting for branch with rigid metal spiral ducting. We’ve got crosstalk silencers as well. One of the things that you have to be careful of with semi rigid radial is making the bends too acute and introducing resistance and noise. Rigid ducting have pre manufactured bends which maintain the designed air flow. If you dont have web joists you could struggle with a branch system as they use higher diameter ducts. If youre self installing, radial might be easier. I don’t think one is better than the other I think the things that impact your decision are: - joist size - ducting routes - self design or pro design - self install or pro install If you’re going radial you would have a better chance of self designing it, but you’d still need to calculate ducting runs, air pressure and extraction rates (and need to certify it meets building regs). If a branch system I would get it designed as you have to simulate intake along the branches and main trunks to determine ducting size. And you’d have to be sure about where your crosstalk emerges and silence those (usually bedrooms).

I get you. It’s difficult to draw any actual conclusions, for comparing overall effectiveness I mean. If the electricity usage of DCV was 10kWh then 50kWh for MVHR is negligible for say, a 6% energy saving on a 10,000 kWh annual heating demand.

I might be misunderstanding but is the report saying that although MVHR ‘saved’ 6% of heating energy, 5x of this energy saved was utilised in powering the system? Ie if it cost £1000 to heat on average and 6% equates to £60 saved; are they saying it cost 5x the savings to power the system (ie in my example £300)? If not I’m not sure how the two things can be compared.

One thing to remember is that ideally your ductwork needs to be within the heated envelop of the building, or you need to make sure that your supply/extract ducts are well insulated in the chimney void - or that you insulate the chimney void before installing the ductwork.

Seems high. Our foundations have just been dug on our build. All contractor managed: House and garage strip foundations excavated and concreted - £17k Build to DPC on house and garage, drains and scaffold mat - £12k Block and beam to house and concrete slab for garage - £10k Services for water and drainage etc were brought to our site at a previous phase but still our groundworks are less than 40k this is for a double garage and 12m x 11m footprint house.