SBMS

Metal web… I wouldn’t pick the easy option would I?! I’m going to speak to Steico today as they do a blown cellulose and a blown wood fibre product. I think their installer network is a bit more mature than warmcel…

So we have designed our roof using posi rafters. Originally our makeup was going to be from inside out… plasterboard battens propassiv 304mm blown cellulose 22mm Steico sarking counterbatten slates This Yielded 0.12 u value. We have really been struggling to get someone to do the warmcel blown insulation so I am now considering other options… I would rather not change out the posi rafers So I have 304mm Of rafters depth to work with. Could I just swap out the cellulose for 2 layers Of say 150mm mineral wool? Would I need batts or the roll? The warmcel was 0.038W/mk so I think a 0.035 or even 0.032 would give a better u value… does the above makeup support this or would I need to change it? Reason I went cellulose was to minimise issues with fitting which is the same reason I don’t want to go PIR..

Thanks Nick - the 1650mm would be the height just for the sunken area for the pool! I would have to crawl into a room if it only had 1650mm ceilings. Option 2 would have ceiling heights of 2300mm for a cinema room.

Thanks @Nickfromwales. I was looking to see if anyone came back with "never use a cinema room, waste of money" - having never had one I worry about not using it, but it costing ££s to build it into a basement. I think I need to price up the difference tbh and then understand if its worth doing or not. This is the rough structural difference:

Is it in a basement?

We are in the middle of our self build and up to first lift. We are planning a side extension (always planned but had to come later due to planning restrictions). We are designing this to include a gym and indoor pool (a sunken swim spa actually, discussed on another post). My ambition is probably running away.. our builder suggested that as we are digging an 8x3m hole (at depth of 1.6m) for the pool, why not make the whole building a basement level and go 18mx4.5m (at depth of 2.5m)? This would give me space for a 6x4.5m basement cinema room… I’ve always wanted one but not sure if it’s the geek in me kitting it out rather than actually using it. Q1 - for those with a cinema room, was it worth it? Is it used sufficiently that you’d do it again? Q2 - I can predict the answer on here, would anyone recommend the additional cost and headache to dig out and down just to stick a cinema room down there?

Thanks @saveasteading I have been asking for past 6 months on here. It’s our second self build so learned a lot on the first one. Like bouncy floors because they werent designed to minimise deflection. Not best airtightness etc which in trying to remediate. Got the builder doing a Tony tray for example around the joists. Posi rafter roof with blown cellulose instead of attic trusses with PIR. Architect designed cold ventilated flat roof for a portion of the build. This forum had me switch out for a warm roof.. Learning a huge amount on here. There is definitely a lot that I don’t know!

Thanks both. Thought that’d be the case but wanted to check

Looking at specifying some of our floor posijoists to be 400mm to minimise deflection. However we need to use eger protect or caberdeck as floor will be exposed until watertight. Most flooring sheets are 2400x600mm. However does this work for 400mm spaced floor joists?

You can have a toilet/sink/water supply to an outbuilding. Only restriction is that it cannot be separate living accommodation (and even that is vague). nothing I have ever seen about combustible materials in PD… your building can be within 1m of boundary as long as it is under 2.5m at its highest point. building regs nothing to do with and not required for planning or PD. it sounds like you’ve built a fancy, but compliant, shed!

First question - is this not covered under permitted development? If not - simple indemnity policy in the event it’s even picked up at sale stage. £200 tops for a simple planning consent insurance. Probably less than the cost of an LDC.

Why prefer Siemens @nod? We are looking at neff this time round (aeg last time, not impressed).

Have you seen this is any official policy, local plan or is it individual applications that are experiencing this?

It tends to be about the displacement of biodiversity from the building and works, so basically the loss of green spaces for driveway, garages, hard standing, and the house itself. I think they even now apply a percentage of expected future loss through sheds, permitted development etc! So quite hard to game it. Maybe tarmac or hardcore everything first!

Actually it wouldn’t be simple and would be more difficult and expensive to meet than the energy requirements. BNG does not work like you suggest either. It’s a highly technical assessment driven framework that determines exactly what net loss or gain there is. It’s not really something that can be ‘fudged’. Sure, some elements are open to interpretation - but £1000 and a nesting box is extremely wide of the mark! However it is relatively easy to offset with offsite schemes if onsite offsetting is not possible (environment bank, wild capital and others).

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?