ADLIan

SAP assessor and BCO will want documentary evidence of window performance including Uw value & G value (and, as above, safety glass where needed for BCO)

I assume you mean Ug value for glass only U-val. G value of the glazing is very different.

If the roof space is not being used and there is a horizontal ceiling use mineral wool at horizontal ceiling level. Will save you £1000s!!!

Also is there an option to use SI units? Written around ASTM Standards rather than British Standards so not applicable to UK Building Regs.

The section on cavities and cavity barriers in dwellings in Approved Doc B is relatively short and straightforward. Follow this and if BCO raises an objection ask exactly what their issue. Rockwool will insist that you use their insulation with their cavity barriers - if so try another manufacturer such as Promat FSI or Siderise. The type of 'cavity' insulation is not relevant.

The cavity barrier would normally be from the main stud (structural) wall through the 'external' woodfibre insulation to the back of the cladding - in this respect I would imagine there are quite a few manufacturers. There are some cavity barriers that can sit external to a non-combustible 'cavity' insulation but in this instance the cavity barrier must be tested in conjunction with the cavity insulation. I note the ply/OSB sheathing is internal in this instance, perhaps this is where some of the problem lies. In dwellings the cavity barriers are normally around openings and at each storey height and at the top of the cavity. I doubt the company linked to above will have the technical resource to comment and advise on something as specific as the English Regs & Approved Docs. NHBC and/or LABC technical manuals may help. Perhaps ask your BCO for guidance, citing specific requirement and sections in Appr Doc B.

Hi Nick - I doubt this will happen. Again post Grenfell manufacturers are very careful on what they claims. There is a big difference between reaction to fire (above discussion) and resistance to fire.

Post Grenfell the Building Regs were updated and walls of high rise buildings had to use non-combustible materials, Euroclass A1 or A2. There is a list of exclusions for items such as gaskets, brackets and membranes. ‘A2’ rated breather and AVC membranes are now available giving enhanced safety. Bearing in mind their position within the construction not sure there’s any real benefit of the non-combustible version in normal low rise dwellings but at least there is a choice.

Appears there is some dumping of commodity building products on the UK market by Turkish manufacturers - seen similar with insulation. Provided the product is manufactured to and complies with the British or European Standard and carries the correct CE label then it is deemed fit for use. Not sure what would happen if you needed sales or technical support from these companies. Pay your money and make your choice. Caveat emptor!

Cavity tray at abutment missing?

No need for insulated cavity closer or similar measure as garage is unheated (normally).

Any clear cavity in the cavity wall should closed at the top to stop fire/smoke being able to spread into the roof void.

If it’s superglass insulation phone their technical department and get their advice

What is the span of the roof? More than 5m creates a problem. Do the proposed vents allow cross ventilation to each roof joist void? They appear to comply with the British Standard and Building Regs for open area. Can the vent manufacturer help? On a general note cold flat roofs should not be used with current levels of insulation. Relying on unknown and unquantifiable ventilation levels leaves a big question mark over the long term performance. Perhaps what the BCO is alluding to.

As the name suggests Koolduct is for insulation of A/C ducts and not for use in floors, walls or roofs. Not sure who would risk that in a floor under the slab or screed!