SBMS

Small sites became eligible For BNG in April 2024. Small sites include sites of 1-9 properties. However, the self or custom build exemption still applies so you would not require BNG. If you have alternative policy please link to it but according to defra and west Lindsey’s own BNG guidance policy, your custom build is exempt. You shouldn’t! You should have continued reading because… They do NOT require passivhaus. They have set in policy the following, that should be demonstrated via an energy statement: Point 1 requires a net zero on electricity consumption. Point 2 requires, I would say, ambitious but not overly difficult or expensive to achieve space heating requirements. PH is 15kWh/m2. The policy I would say is poorly worded and I’d want a planning consultant’s view on whether 60kWh is a fallback for a single site self build. Your self build - if for a single site - would Probably meet these 35kWh requirement. It’s ambiguous and clearly targeted at multi dwelling sites due to the referencing of sites vs individual units. There are exemptions to point 1 - eg if the building is overshadowed for example. Also, note that the local plan is really just bringing forward the proposals in the future home standard. Also, this type of requirement in policy is untested and the local plan sets out a series of situations in which an application doesn’t have to even meet these (read S7 in the local plan). The references to passivhaus are simply to shortcut the planners having to assess an otherwise detailed energy statement as PH exceeds these targets. It is not mandated in policy though. It sounds like You’re making some decisions based on a local planner’s view of the policy. They will be biased and, possibly, misinformed. Engage a local planning consultant if you need a factual view of what your requirements are, but from a cursory glance I don’t think your appraisal is correct.

Are you sure they ‘require passiv haus’? I doubt they would require a modelled house scheme are you sure they don’t just have ancillary guidance targeting better than building regs levels of airtightness, wall u values etc? And even still is this mandatory or just guidance for a case officer to assess? and are you sure on BNG as I thought this was central planning policy - not delegated with defra setting out the self build exemption authority?

Has happened quite a bit round us. Planning passed for "2x self builds" only for then a developer to build them...

CIL isn’t as related to planning as BNG is, in that planning permission does not condition CIL payments in any way. CIL is therefore not intrinsically linked to planning permission and is a separate tax function administered by a separate department. BNG on the other hand is administered through planning policy and conditions for planning permission - so the mechanism for ‘breaking’ the self build exemption really has to be dealt with via conditions. You not remaining in a property for 3 years for the purpose of CIL doesn’t invalidate your planning permission. The same isn’t true for a BNG self builder exemption, hence why it falls to the planning department to condition it.

To be fair to the planners there is some logic here. This is down to a number of cases where planners had passed plans to ‘self builders’ that exempt BNG only for the self builder to sell the plot to a developer who then benefit from the BNG exemption. When we were going through approval this was thrown up at last stage, due to national policy changes, and our planner wasn’t sure how to deal with it. Their issue was that in the event we sold the plot with planning they would have no recourse to impose BNG on the site. Our consultant suggested a term similar to the above. If you think about it it, the condition isn’t aiming to keep you in the house for 3 Years - it’s to allow the council, in the event you sell the plot to a non self builder, to reimpose the BNG condition on the new owner/developer. In this instance what would happen would be the condition would be un-met, developer would go back in for a variation of condition and council would impose the BNG requirements.

Try selfbuildzone

Self build insurance only covers the period of construction. You might have got mixed up with latent defect/structural warranties which kick in once the build is habitable. insurance - in case builder accidentally drives into your house and knocks it down. warranty - in case builder didn’t put your brick ties in and it falls down.

Most latent defect warranties are typically index linked and have a maximum payout that is the sum of the reinstatement value at that point in time. Most self build insurance policies are not index linked and have a maximum sum value that is equal to the reinstatement value declared at the outset.

Have you tried getting a thermal camera and looking at where the heat is leaking?

Similar to smarts in that there will usually be a local fabricator and they might install or refer you to an installer. I get that finding a local firm is important. Where are you based?

Have you considered seniors? We looked at smarts but seniors looked better, lower u values and similar price.

What aluminium doors/windows you getting out of interest?

Here is ours. We specifically wanted a mix of red and a bit of buff but not something too modern. Weinerberger Hathaway brindled -71p per brick too!

Are you doing a level threshold? Can you change your facing bricks for thermalite or marmox at the top?

Got you so your threshold sits proud of the thermolite basically by depth of your finished flooring (tiles + adhesive)?

I get you. Your track doesn’t look 215mm deep though so what did you do behind that bit where your screed went?

Does that mean your track sat on a 430mm threshold? How did you get the upstand to butt up against the track - was there not a drop behind the track and the thermalite?

100mm PIR is a poor u value (especially with ufh) and we are aiming to exceed building regs which in itself sets fairly low standards. My primary aim is to minimise thermal bridging across the cavity on the thresholds so less about the overall U value and more about minimising bridging. What makes you say a 7N block is required below dpc??

Is that 2x100mm thermolite on top of each other lengthways (ie total ‘height’ of 200mm)?

We had the same issue and we did find it was too difficult to ventilate a cellulose filled cold roof. But we did have a parapet wall which really made things more difficult. In the end warm roof construction was much more simple in my view.

That’s a good catch yes. Think a lightweight thermalite block is 0.15 thermal conducrivity so around three times more conductive. @JohnMo do you have a detailing you could share? Did you put the block ‘side on’ so it was 100m deep, sit your track on it, pir upstand next to the track and then screed up to the block? Ie the same as nick’s brewdog powered drawing but swapping the marmox for insulite? I’ve got quite a few openings so it’s looking like £850 in total For marmox and that’s what I’m trying to weigh up whether it’s worth the additional cost.

@JohnMo I did consider this. The u value of a thermalite block is about 0.18 and thermoblock is 0.05 so about 3.6x more resistant. But to be honest I have no idea how this translates into real world thermal bridging?? Our current build, the cavity was filled with concrete and you can definitely feel the cold on the floor next to the door threshold. But the thermal resistance of concrete I read was around 0.56 so thermoblock is 10x better and thermalite would be around 3x better. Is it worth it?

Thanks Nick. Makes sense I forgot about the screed but in my defence im into a few pints of Spanish lager.

Ah good point. It’s a 75mm screed but then the track will sit slightly lower as the screed runs nearly level With the top of the track. Are You suggesting that the marmox needs to sit into the PIR and therefore be at least lower than the bottom of the screed?

Am considering using marmox on our door thresholds as others have suggested to minimise thermal bridges. We are doing 180mm PIR that will butt up to marmox thermoblock. Our sliding doors track/bifolds and door cills will sit on the thermoblock. question is: marmox do a 65mm deep block and a 100mm deep block. How would I go about judging whether the 65mm or 100mm block is preferable/ worth the cost difference?