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Hi all Curious what the general consensus is between blown-in wood fibre vs. cellulose (warmcel) for a passive(ish) timber frame home. So far what I'm seeing is that cellulose is a bit more commonplace. What I'm hearing so far: - Wood fibre is technically better. It gets installed to a slightly higher density and is less prone to slumping if it gets damaged. - Cellulose is more affordable and more common. And probably fine in the real world. - It's unclear which is better from a fire perspective? Anyone have any experience/thoughts on these?

How did you sort the 63mm battens? Did you fit them on site, or were you able to order it as part of your TF package? Is it doing double duty as a service void? With your ~200mm of rockwool, how are you finding acoustics?

Also a fair point. I'm pretty good at grunt work

I've done a bit more research and so of course have even more questions. MBC and a few others have a twin wall cellulose offering. I feel confident that this approach would be a quality option, but there are a few issues: - It requires really thick walls and roofs, approaching 400mm before cladding. - It's not exactly cheap - It feels like overkill for what I want to achieve thermally. I'd prefer thinner walls and a bit more space. ...but what are my other options? I'm finding that timber frame manufacturers standardise on 140mm studs, which doesn't seem enough for anything but PIR. - 225mm mineral wool would achieve what I need thermally (if my calcs are correct), but how would I make that work with a 140mm timber frame kit? - If I went with 140mm mineral wool + PIR board, what would the acoustic performance be like? Now I'm also wondering about the relative importance of wall insulation relative to glazing, especially with large spans of glazing? Money better spent on the insulation or glazing?

I've found that some of the TF vendors factory fit the (PIR) insulation. The argument being that factory installation is going to have better tolerances and quality control.

What's the thinking around STA assured wall build-ups? I'm thinking if you were to piecemeal the wall -- TF co supplies uninsulated frame, insulation is fitted on site separately... Would you run into issues with mortgage-ability or structural warranty going down that route?

The points around sound insulation seem really valid, that's something that is valuable to me. In general, I've been surprised how adamant the TF firms are around using PIR. Has anyone worked with a manufacturer that's actually open to something else? Feels like in twisting their arm to even discuss something different. Architect is in favour of cellulose, anyone have thoughts there? He's mainly thinking from an eco perspective, which I appreciate but it's not my only consideration. How are you guys thinking about structural warranty / STA assured wall build-ups?

Why did you end up going with mineral wool out of curiosity? What makes you think it's nicer? I'm trying to understand how to make a decision on this. The TF companies steer heavily towards PIR, but my impression is that it's because it's easiest for *them*. Sorry, I wasn't clear. 300mm is the thickness allowance for just the osb+studs+service batten. Complete allowances: - Brick walls: 500mm for everything (brick + cavity + OSB + studs + plasterboard + skim) - Rendered walls: 350mm for everything (render + OSB + studs + plasterboard + skim)

Rain screen would be brick (ground floor) and render (above)

The designs have an allowance for a ~300mm exterior wall thickness, excluding rain screen and plasterboard etc. Would be great to not need the full 300mm though. Design has a gable roof with a that overhangs about 50mm over the gable end. Distance to nearest boundary is 0.8m, and around 1.8m to the nearest building. No (known) nearby obstructions!

Hi all Wondering if anyone has any thoughts re: exterior wall insulation for my timber frame build. I'm shooting for an energy efficient build, but not chasing perfection by trying to hit passiv standards. I'd like to hit a sweet spot between price and performance. It looks like the "standard" exterior wall build-up from TF firms is 140mm studs + PIR to hit a decent U-value. But I'm wondering wondering if I'm missing a trick by not considering other insulation options? In particular, it would be great to have something that's a more organic material, lower VOC etc... Anyone have any advice? What's worked well for you all?

Access isn't terrible for London. It's suburban. ~9m no parking zone immediately outside the house and a off street parking space next to the house. Road could be wider though. How big would you expect the crew to be? One quote breaks down costs and has labour at 30K (10-12 days on site). That's either a big crew or a lot of margin. Would ideally get demo, groundworks and foundation done together, but we might have to book demolition in before groundworks/foundation plans are finalised. Great. Nothing specific has come up yet beyond the usual (ecology, tree protection etc). At what point did they inform you of additional restrictions? In response to section 80?

I need to demolish a 3 bed, 120sqm 2 storey detached house (so 60sqm footprint) in london borough of barnet. The house is near one other house (alleyway in between), otherwise we're pretty far from any other structure. I'm sorting out as much of the "pre work" as possible myself, e.g. fencing, utilities, asbestos. I'm getting quotes that I think are pretty wild. So far 70K and 50K from small demolition firms. At this rate I'll be doing it myself! How would you go about trying to get this done for a more sensible budget?

Hi all Does anyone have any recommendations for a structural engineer for a timber frame new build project? The scope of the work would be to design the foundation based on the site conditions and line/point loads, and determine if any retaining structures are needed as the site is on a slight incline. Ideally they could do the civils too? Ideally a firm that is pragmatic and cost-effective, rather than specialising in billionaire basements, if that makes sense This is in North London (Barnet). Would be super helpful if anyone has suggestions, or advice for how to choose a firm for this.

Thanks for the advice everyone. I've found a few firms from nearby planning applications that look pragmatic, and have reached out. I figure it's a good sign when some of their reports show no need for further action -- and reports where bats were found offer a range of solutions to try and problem-solve. A trick I've learnt on this journey is that money can be saved by skipping the preliminary assessment (i.e. the "do I need an emergence survey?" survey) when the conclusions are obvious. In our case, we have a roof in very poor condition, so there's no way that it could be scored "Negligible roosting potential". It still needs to be documented, but this can be done on the same day as an emergence survey to save an extra trip. I've found it surprisingly hard to actually get estimates though. Some ecologists only want to quote for the preliminary survey and won't even discuss ballpark/estimate pricing for what the emergence surveys might be. Others are happy to discuss end-to-end costs in principle, but want to discuss on the phone but are always on fieldwork and never call back.