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Think 0.5mm steel rather than 0.8mm. @G and J & @Owain1602 Can I ask - did you do intumescent strip at the bottom of the cladding cavity? @Owain1602 - interested on why you didn't do the gables - did it not have the same circumstances as the eaves? BTW this is what my BCO said on this subject: Fire stopping cavity barriers are not enforceable under building regulations for individual domestic dwellings. Only enforceable in buildings with separate compartment ie flats or semi’s. Although I do think the fire stopping strip is a good idea it is your choice in this circumstance.

Is that because the screwdriver operated ballofix valve is less easy to operate or because it's less reliable? I notice it isn't full bore either

Firstly, if this is a bypass then you’d want to get rid of the screwdriver operated ballofix valve, and fit another 1/4 turn lever (butterfly handle) tap. It’s likely a softener bypass / kit. https://wrekinwatertreatment.co.uk/products/22mm-bypass-set-with-integral-tees?pr_prod_strat=e5_desc&pr_rec_id=1e7714181&pr_rec_pid=10023003554121&pr_ref_pid=10023006011721&pr_seq=uniform

The pipe run between plant and outlet is defo getting heated by other influences, as at worst it should be tepid then cool then cold. 24° to 30° and then downwards means this is more of an instance of negligence methinks. @scottishjohn, you need to approach the builder with your concerns and intended path of HSE, and simply say you’ll accept him (re)doing the work as cost effectively as is practicable, under your immediate supervision, or he can pay for someone else to be appointed. Legally you MUST offer him the opportunity to rectify, do NOT touch a thing until you have your ducks in a row.

Nice solution. Shame these couldn’t be joined internally and one pipe existing.

Edit: Posted before I'd typed anything! 😂 Anyone else see the problem?

The regs say 0.8mm steel (or thicker) and 38mm wide timber (or thicker). I agree, this can be quite a confusing topic. Whatever you do, don’t try and read the STA documents seeking clarity….it will confuse you even more! The cavity barrier element of the regs doesn’t have anything to do with the fire rating of your cladding, that’s a separate topic. They want to see how you will stop a fire from using the external cavity behind the cladding as a means of bypassing the internal fire resisting elements. There are numerous arguments and nuances that can be put forward such that the guidance as read do not apply in certain sections. Obviously, a lot of this came out after Grenfell. My understanding is that the fire service couldn’t understand at the time how fire was spreading throughout the building, especially from floor to floor so quickly. They couldn’t see the fact that fire was spreading inside the cavity behind the cladding. We had two different external claddings, one for the ground and another for the first floor, both had ventilated cavities. I specified a steel drip flashing between the two (which ended up 3mm thick). The ground floor cavity ventilates at the underside of the drip, and the start of the first floor cavity is above the drip. In the event of a fire, we wouldn’t fully close off either cavity, just that fire in the ground floor cavity would come up against a 3mm steel plate. It would have to come out of the ground floor cavity at the drip, come out 100mm to get around the drip then turn back on itself to get back to the first floor cavity. That is the detail around a lot of the house. at the heads of windows we have intumescent strips, side and bottom of windows is fully closed with 38mm or bigger timber. I had agreement from the BCO that the detail and argument I put forward for the eaves to roof was okay. But as I was doing the cladding, I had to change something to better attach the gutter. Rather than go through the whole approval loop again, I just ran intumescent strips around the whole of the eaves (not at the gables). Value my time and sanity more than about £500’s worth of strips. If you can post a bit more detail, I’m sure that we can come up with more specific suggestions.

I've tried several and now mostly have Ezarc, which seem decent. Though probably made in China too.

I was thinking of the higher rates! They were 15p, now 12p And I suspect they will keep falling as solar generation gets more and more common. https://www.theguardian.com/environment/2026/aug/02/solar-powers-record-share-britain-electricity-july

You don't need to, plug in batteries are almost here, if they want batteries they will have them like it or not.

I can imagine steel cavity closures round penetrations. I think the key thing is to close off the chimney (behind the cladding) when there is a fire.

If MCS or octopus approved why not higher export rates, they are not limited to 3-4p kWh.

Yes, no plans to sell. I've looked at the multi tenant systems (solshare or something). They are pretty pricey (5-10k) and have 15 outputs (5 x 3phases) so make the most sense in blocks of flats. That is the most hard nosed approach but the benefit to the tenants is much more limited - especially with lower export rates.

I have checked BR497 (I have the latest copy). This document states "In all of the examples modelled, the inside room temperature is taken to be 20°C and the external temperature is taken to be 0°C. For simplicity, these are the usual temperatures to use when modelling, but other temperatures can of course be used. Note: the ψ-value and temperature factor, g, are not affected by a different choice for the internal and external temperatures..." I don't know why -5 is I will send a note. The I-Joist flanking elements in my drawing are compound assembly and do not show the repeating elements,. The I-Joist bay itself is also in the report at 0.0391W/(mK), so the report itself looks complete to me. With respect to repeating elements BR497 states that the approach I have taken is correct, which is why I did it that way. Indeed, BR497's own example follows this approach and it states that drawing every stud would be over modelling; "Repeating bridging perpendicular to the junction (§3.1.3.2) can be ignored entirely if either: the bridging element's thermal conductivity is ≤ 0.5 W/(m·K), or it doesn't bridge the primary insulation layer." I'm not sure if you are providing a critique of my report or the software or if you are saying when you where an assessor you would have resorted to default values if given this report. If it is the last of these I don't think there is anything technically wrong with the report but I would welcome anything that would give you real technical grounds under which you would be able to justify default values and non acceptance of the values presented. Since I have to do a SAP10.3 assessment this feedback would be very helpful. If you just don't feel comfortable because you don't know the product that's fine. New products appear all of the time and the cost of doing psi-values should not be a prohibitive, as it is now, so I personally welcome this approach.

Thank you all. Definitely going to go custom to our measures once the screed is in! For a couple hundred quid difference it seems a no brainer.

Rendered concrete block outer leaf, 50mm cavity, Rockwool insulation between 140 studs, 40mm PIR, 25mm service cavity, resilient bars, plasterboard. Inexpensive and very effective. Less than 400mm.

All build methods can achieve that. Specify exactly what wall thickness you want, because its normal for say 140mm, nothing stopping you saying I want 200mm, then do it in I beams or posi joists style. If restricted to 140mm and then apply counter battens to increase wall thick and get rid of most thermal repeat bridges. Then any high density insulation you want.

So these properties are all owned by a single person with no plan to sell separately? If you wish to preserve an easy option to sell separately it sounds a fair bit more complex than otherwise. If operating as a pooled resource there may be options to get more efficiency out of the system. (Multi-tenant inverters exist, someone posted a link here recently).

It's a slow section of un-electrified line (I believe 50mph), with no points in the proximity. I don't hear any 'clacking' and from what I can see its welded rail. So I believe the main noise will be external from freight diesel engines and squealing of freight wagons. Thanks all - sounds like best to avoid PIR then 😅 The downside is it narrows the field a lot in terms of TFs from the usual TF suppliers, which are high performing thermally (but aren't twin stud cellulose). Aiming for high airtightness, insulation levels and convenience (e.g a subcontracted package) was leading me towards a TF from one of the usual suspects. But would consider ICF if it ends up being a better compromise. For noise, where do we would think ICF ends up compared to the twin stud cellulose?

If that is the case, make no provision for them. Do not suggest to tenants that they are authorised to install batteries. A world of liability for you.

Here you go @PSC88.

If I did an AC transmission system the temptation would be to make it a non battery system and leave fitting of batteries to soak up the excess something for the tenants to do if they wish. This might be easier with plug in battery systems.

There are 4 houses in a loose crescent around a "green". A field backs on to the "green" to the north with a high hedge The panels are being fitted to comply with the EPC regulations and get each property to. "C" grade 1 house is a good candidate for normal E/W roof solar being a bungalow with a low pitched concrete roof. The other 3 have problematic roofs. Either not good aspect (shaded) or not good enough condition to allow solar to be fitted with out a new roof first or both But a ground mounted array could be fitted in the "north" field out of sight (and far enough back so it's not shaded by the hedge. I figure it's easier and cheaper to install and maintain one array in a field than 3 arrays on 3 roofs. And then for the bungalow I have to decide if it's cheaper/easier to put panels on the roof Vs chuck some more up in the field array and run a cable to it (that would be the 100m one. The others are closer to 50m) Strictly speaking the batteries are not needed as the EPC system currently only accounts for the panels and inverter - you get no points for batteries. But it gives so much extra benefit to the tenants it's hard not to justify it beyond the purely mercenary view.

There are two incompatible standards for wiring the connectors. As long as both ends match it works, but if you mismatch and there is a non-standard power setup on the cable you might be in trouble. (it's safe if there's no power feed or if its POE standard)

I guess if you wanted to try it, fit a Cat 5 / 6 plug assuming standard colours. If it doesn't work buy a new cable, deny all knowledge and report a fault (and this thread can be made to vanish)