Impressive. I suspect there is a lot of drooling over computer keyboards going on amongst others on here.

Looks very interesting.

Do you have any technical details of the build? Target U values, target airtightness, construction details, etc?

How is the basement going to be insulated? How do you plan to make the beam & block airtight at the floor-wall junction?

David

I have all technical details, but suffice to say, the DER/TER is in excess of 110% so have tweaked the insulation down a tiny bit (for other reasons actually) to still gain max credits. The oak frame will be enveloped with OSB, insulation (165mm at least, possibly more as infill between oak posts) membrane and more OSB and finally mesh and lime putty. The warm roof will have 180mm cellotex or equiv.
The beam and block will have membrane then 100mm insulation then screeded 75mm, under floor heating then finally jerusalem marble tiles to finish.
-I have hit code 6 on pretty much all areas according to the assessor, I will play it by ear to see if still achieving. The SAP score hit highly with wood boiler, solar and also PV (10m sq) so already accounted for. The panels will be mounted on the log store as I think it will ruin my pretty tiled roof!

We, (the main contractor, timber framer, building surveyor and myself ) were of the opinion that it would basically add rigidity and strength to the external skin. I personally felt uncomfortable with having lime putty and mesh mounted directly on to insulation. Conversely fixing insulation directly to the oak posts (plus membrane) would not be able to cope with any movement in the oak. We are employing techniques similar to movable joints with the OSB/oak boundary. I guess it will also add to the airtightness levels having another layer. (albeit at extra cost)
Hope this all makes sense!?

Have updated blog to add SAP calcs, open pdf's

Posted By: pedro.mahonWe, (the main contractor, timber framer, building surveyor and myself ) were of the opinion that it would basically add rigidity and strength to the external skin. I personally felt uncomfortable with having lime putty and mesh mounted directly on to insulation. Conversely fixing insulation directly to the oak posts (plus membrane) would not be able to cope with any movement in the oak. We are employing techniques similar to movable joints with the OSB/oak boundary. I guess it will also add to the airtightness levels having another layer. (albeit at extra cost)
Hope this all makes sense!?

Ok, well they are all good reasons! Don't forget about a vapour control layer on the warm side of the insulation, and a drained and vented cavity on the outside of the timber structure. I would NOT recommend mesh and line render direct onto OSB. It won't last long.

Well that is better than rendering onto OSB. Over time the OSB will absorb moisture through the render and is likely to delaminate.

I would avoid CCS if you can afford the credits. We did it on the advice of our C4SH assessor. It rates on par with all the other bad advice he gave us. When the CCS auditor came to see us for the preliminary meeting the first thing he said was "who suggested that CCS was a good idea for a self-builder, you do realise it requires the resources of a major professional company". The auditor was right. It was onerous, expensive and a real pain. I tend not to back-off once I've made a commitment and even though mine was a self-build, I am also a professional. I stuck with it and did gain the necessary rating in the final audit to achieve the two C4SH credits. However, I don't think that would have been possible without the flexibility exhibited by the CCS auditor who adopted a rather generous interpretation of the standards on the grounds that we were self-builders. The elements we were marked down we just daft. I doubt many major companies would invest to such lengths on a small project. Come to that, I know they would never be doing a project of such small scale as one modest house in a distinctly marginal northern city.
I was building to C4SH level 4 (mandatory here).