davejura

Ok thanks. What I have found is that it's obvious that the architect or engineer isn't paying for the build as they seem to specify hi end stuff. (Mine originally had marine grade ply down for the sarking. Soon got that changed!) So the reflex seems to be the most expensive Tyvek as opposed to say the housewrap. Every £ is a prisoner with the way things have gone, so if anyone can come up with a cheaper option that is just as good, that would be great thanks!

Yes but surely it all helps? That's why I was asking about the TF200.

Hi folks. Our architect has specified Tyvek reflex breathable membrane for our kit. Just wondering if anyone has any other options that are possibly more thermally efficient? Was thinking possibly Protect TF200? We are using Cedral or Hardie planks cladding if that makes a difference. Thanks.

Was concerned about thermal bridging. How do we deal with that Russell with the structural wall? Thanks.

Not sure if this is the right forum for this, but here goes! We are stick building our timber frame. The ground floor is beam and block with probably 100mm insulation and 90mm screed with UF heating. My builder wants to put up all the partitions first (only 1 is load bearing) before the insulation and screed goes down due to perceived risk of hitting a UF pipe. I would imagine this would lead to thermal loss as well as using extra timber. I can understand the load bearing wall having to be done this way (or does it?). Just looking for advice please. He isn't being hard and fast about it by the way.

Thanks. Makie what clips are you using? Roofer is concerned that they have their own clips as ones I was quoted for may not be compatible.

I've just been offered Northstone Donard tiles as an alternative to Marley Modern (supply issues!). My roofer has never heard of them, so just wondering if anyone has used them and if so were they OK? They are about 20p per tile cheaper by the way. Thanks.

To save money, we are seriously thinking of making the attic space "cold" for the time being. We are also thinking of changing the gable design to lose some of the glass. The sliding doors and glass panel above make up over 50% of the glazing cost! I've attached a photo of a local new extension which is a similar size to our gable (minus the ground floor!) and would hopefully save a fair bit whilst still looking good. I'd be interested in peoples thoughts. I can post more drawings tomorrow if anyone is interested!

Here's a couple of my plans. House is on a sloping site and is "upside down". Views are from the garden elevation side which is not seen from the road. AL(00)001_ upper-plan.pdf AL(00)002_lower-plan.pdf AL(00)201_garden elevation.pdf

Thanks folks. Pasquall working on it at the moment. One option could possibly be to keep the attic space as cold for the time being and just use 350mm of mineral wool. Would be a substantial saving and could convert it properly once we have money and sanity again! We may also simplify some of the glazing. A spandrel panel is also mentioned on the plans which the agent at Pasquall doesn't quite understand why! I'll maybe try and post some of the drawings at the weekend for comments.

It's not just the trusses. There are 3 x Velux windows, some fancy glazing in the gable which is expensive, a spandrel panel, glulam beams, extra insulation costs, flooring, larger heat pump to allow for the extra floor and that's all before we create any rooms up there. Just exploring options at the moment before we break the bank!

We have finally started our build and so far have the foundation walls in place and are ready to fit the beam and block flooring. I have just been pricing up the attic trusses and windows and in all honesty got a bit of a fright! I'm now considering changing the trusses to regular ones and doing away with the potential for future expansion (it was just marked on the original plans as storage). I'm just wondering if we would have to go back to full planning with this, or would we possibly get away with an NMA? House is 2 storey on a sloping site, so first floor is main living area. Houses in the road are all mixed regarding styles and roof heights, so can't see any issues with planning regarding the change. Appreciate any thoughts or advice.

Thanks folks. I've ordered a roll of non woven geo textile and have 100mm perforated twinwall. Onwards and upwards!

Hi folks. We have a sloping site and our concrete foundations are about 1.4m deep on the upper side. The brickie has started the blockwork and wants me to put the drainage and backfill in after 2 courses to make life easier for him (and me!) The wall is classed as retaining and is 3 blocks thick. There is water seeping through the upper face of the trench and the soil is classed as boulder clay. So I need to drain the water away from the rear wall. I was thinking 100mm perforated twinwall surrounded by 50mm max gravel (read that is the best size for clay soils). Should I also use a non woven membrane? And what's the best way to get the water to flow as obviously the foundations are level? Was thinking sitting a brick centrally and running the pipe both ways. Foundations are stepped, so once we turn the corner it shouldn't be a problem. Any advice much appreciated!

OK thanks, so a bit more then. Heating will be by ASHP and UFH. Really struggling to get my head around this SAP calculation carry on!

Thanks. So about £40 - £50 per year for a 175 sq M floor area 2 story house, at a guess? I'm keen to use Frametherm as it is cheaper and easier to fit. I'll look into using the Protect 200 thermo and also an internal layer of 25mm PIR.

Sorry to jump in, still trying to sort our insulation! So, out of interest, how much more thermally efficient is a wall with a U value of, say, 0.19, compared to one at 0.22? Are we talking a few ££s a year in heating costs or a lot more? I'm still trying to get U values calculated for mine, based on 140mm Frametherm between the studs and 25mm PIR inside. Also, is there a thermal membrane that can go on the outside of the kit that may help?

I'm not kidding on I have a clue when it comes to this. Just going by what the architect and company that did the SAP calc came up with!

No PV, just ASHP with UF heating. Our SAP is passing with 100mm plus 25mm of PIR, but would obviously like to improve on that.

I presume you are talking from experience? ? Just pinged her now to make her Saturday! Actually, hoping if we don't change the make up, just use the 140mm of ThrameTherm or similar instead of the 100m of PIR, it can just go through as an amendment to warrant at the end. Obviously, will need a new SAP calculation.

I do actually. I'm lucky in that I have secured the services of a local builder on an advisory basis. I'm doing some fencing for him as a trade off! He is also going to mark out and supervise the foundations. Thanks for all your advise. I'm just going to email my architect and get her take on it all.

Would there be an issue with air tightness using minerwool 35?

Interesting. Thanks for this. Where do you get the extra 20mm wall thickness? If I put 140mm of mineral wool 35 in instead of 100mm PIR, that could work. Here is the build make up.

Going to have a few amendments to warrant anyway, so that shouldn't be a problem! Yes, architects do tend to over spec things and I'm sure they have shares in Kingspan!

I'll look into that, thanks. As long as I don't have to go back to the architect again, it shouldn't be a problem! Is the Glasswool 35 cheaper than PIR insulation? And what site did you use for the calculations please? My local supplier of PIR has just quoted me for IKO Enertherm and Recticel boards, and has said there will be a 17% price increase on 1st April!