G and J

We’re planning a cold roof, and whilst I’ve not read up as much on this as perhaps I should, I’d gathered that counterbattens and ridge vents would mean the tiles and the solar pv panels will be nicely ventilated behind. Given the airtight(ish) envelope of the house that should mean that little moisture found it’s way from the house to the loft, and what does find it’s way in there will escape through the breather membrane. All that I think means no soffit vents so no plague of insects in the loft. Does all that stack up?

Unfortunately we are cheek by jowl (1m one side/ 1.5m the otherside) between 2 1920s timber framed properties....BC won't wear it.

It looks good, but we are in a an area(residential) that was up in arms about cladding, even though the silvered timber will be in keeping with the boat yards in the conservation area about 500 yards away......our planner was supportive, the neighbours not so much....

Thanks @HerbJ that' kind. The problem we have is finding something that can take both the fire treatment and the coating that accelerate and even out weathering to silver.

Would you be happy to post a picture? And am I right in thinking you used thermopine on your deck.....a picture of that too would be fantastic......... We are really impressed with Russwood and its an important element of the build for us only snag is they only offer either scottish larch in b on b (we weren't originally thinking of that profile) or thermopine with both the burnblock and sioox treatments.....ta

So, an installed window with a total of 1m2 showing (frame and glass) would lose 0.712W for each degree in temperature difference. I’m assuming Uwindow means the overall u value of the window when it’s installed. if Z fraction of the window is glass then: (Z x 0.522) + ((1 - Z) x 1.132) = 0.712 Therefore: (Z x 0.522) + 1.132 - (Z x 1.132) = 0.712 so…. Z x (0.522 - 1.132] = 0.712 - 1.132 = -0.42 thus…. Z = -0.42 / -0.61 = 0.689 AKA 68.9% therefore : 0.689 * 0.470 + (1 - 0.689) * 1.132 = 0.32383 + 0.3521 = 0.676. Wow. I did it! Do I get a sweety?

Yes I do! Go on, pick one window to use as an example. I’ll be sitting round waiting for heavy drilling equipment to come available (yep, the dentist) and doing a worked example will distract me.

Having been reading about this stuff incessantly of late I think I know how this works but how about you post some dimensions and I’ll use it as a revision question and work some numbers? (and in the meantime I’ll revise!)

Given what I think is built already I guess you are limited on your options. As your VCL is under your inner PIR then channeling into that is messy and a pain but won’t affect the VCL, so I guess that sounds ok to my limited understanding as long as you never puncture the VCL and don’t go too deep too often to undermine the insulation. I wonder how much ventilation is ideal for the void between stone and frame? Given that you have a breather membrane between that void and frame I assume the frame dries with moisture vapour travelling into the void. The stone itself may not be vapour permeable but the mortar may be plus cold stone will at times be cool enough for condensation to form on the inside face to either soak into the mortar or run down to the weep holes. Perhaps whoever designed the build up made an assumption based on the above rather than ventilation - can you check? If you do need that cavity to be ventilated I would always look to close with metal mesh but how you get air in at the bottom defeats me. I’d be interested to hear the resolution.

@nod PS, congrats on moving in! Hope it goes well.

17 years after we finish our build our warranty paperwork will have long since been firelighters, the faded PassiveHaus Certificate will still be proudly displayed in the hall in the vain hope that it’ll help the valuation for the lifetime mortgage which we will need to replace the old wheeled campervan with a new thermonuclear (food waste based) powered hover van with integral health suite and coffee maker. You never know, PH might become trendy and help sell in the future…

Architect just had a case where a 100mm over height was complained about and they had to re work..........one of our neighbours to be would notice.....they did a lot of measurement and comparisons in their objection and are peeved their objections were all ignored.......we may have this issue as alternative to a slight kick in the upstairs or lower ceilings in which case we'd do what @joe90 did and lower pitch very slightly .......for running of mvhr and cost we want to use 304mm posi joist, architect had assumed 200mm and we didn't check...... ho hum

Ah yes, thanks..... should have said we do want actual wood, which will have to be factory fire treated and therefore the sioox coating (which we like) is not effective. Also should have said the ayous would be thermally treated. Plan is just to let the wood go silver, so knot holes etc (half rendered) is not the look we were hoping for.

We are advised that our planners will, rightly methinks, come out and measure if there is a complaint.

So, we put in our planning permission with our design substantially covered in vertical Siberian larch cladding. Separately to this, I read a lot about the war in Ukraine, and I’m very aware of the embargo on Russian products. So why I did not put the two together? Perhaps I assumed that Siberian Larch was a species grown in many places not simply larch from Siberia. Please don’t answer the “question how dumb is that?”. So we are now seeking alternatives. We have to have a fire treatment because we are within a metre of the boundary . We are committed from an ascetic point of view to vertical cladding, preferably 100 to 140 mm wide, and we want something that never needs to be treated because one of our goals is a low maintenance house. We are being directed by several companies towards a product called Ayous. Has anyone on here used that already? Does anybody know anything about its longevity other than the sales staff I’m talking to? Are there any other alternatives we should be seriously looking at? As always help gratefully received.

So, imagine in parallel universes that two almost identical builds were happening. The only difference is that one is going for PH certification and the other isn’t. All build costs are the same apart from PH consultation stuff and PH certification and whatever else is needed to get a ticket. How much extra do the PH certified project cost?

Would be a good name for a care home.

One advantage of being in one’s seventh decade is that ‘forever’ is a different time span compared to when we first built with us both in our 20’s. 😉

I’ve approached this from the other direction. When we started planning our build, (informed by TV programmes like Grand Designs) PH seemed like a daft idea, requiring houses with two foot thick walls, two acres of meadow for the GSHP, and 18’ deep concrete slabs and acres of glass so they looked like an Asda. I suspect that’s still the image a high percentage of the population who have heard of PH have. But I figured there would be elements that would be worth using on our modest home. We were committed to disconnecting gas from the word go, and that meant an ASHP as I’d already learnt that GSHP wouldn’t work for us. Airtightness and MVHR was clearly the way to go, so they were the first elements adopted. I was very keen on a long underground pipe to feed the MVHR but concluded that that wasn’t yet proven technology and wasn’t one that the MVHR suppliers were happy with so ditched that, sadly. Turns out our design had a sensible form factor anyway (2.75 if I’ve calculated it correctly), so that made me smile and feel we weren’t so bad. We’ve not that much glazing and can’t take advantage of solar gain because of the restrictions of the site, but we do have an east/west ridge on our bog standard 40degree pitched roof so south facing solar PV should be productive and offer a quick payback especially with the slate saving. Cold bridging is boiling my brain right now, and I think that’s the area I would fail most on as we will have to have a cheap strip foundation b&b construction and I’ll do my best but it won’t be the same as a polystyrene raft based build. What I’m ending up with is, I think, sort of a PH Lite, on a sensible budget, and where it won’t translate into volume house building is the extra time I’ll put in to airtightness. But as the practices become more widespread and the kit makes it easier and MVHR becomes a basic then I’m sure airtightness will steadily improve. So I’m starting to think that our house will be not an inspirational green build icon, but simply one of the earlier examples of the new basic houses of next decades volume builders.

I tried to engage with Octopus re the zero bills thing and they informed me they aren’t doing zero bills for self builders.

So is this Passivehaus Lite?

So more akin to osmosis?

The window is for passing in sheets of lavatory paper….

Is its behaviour determined by the ambient temperature it experiences? And if so, isn’t it always sort of summer indoors in a well designed house?

I’m using it for thermal performance only. I’m striving to be as informed a ‘buyer’ as possible, but the final answer will be underwritten as a minimum by appropriate professionals. I might be suffering from an inadequate understanding of terminology (amongst other things). When I tried to look it up I thought it indicated that this was moisture permeable. If not then I am royally confused. The good news is that I’m used to being that, but I try not to stay that way.