ADLIan

That's why I'd suggest getting chapter and verse from your BCO as he's the guy that enforces the Regs. If he's relaxed about this then you may be disappointed by the acoustic performance of your wall, perhaps have a look at the some of the solutions in Part E and adopt some of these measures.

But that new stud wall will add little in the way of acoustic insulation . I would expect double layer of plasterboard (to add mass) and mineral wool between the studs (as an acoustic absorption material). Perhaps check exactly what standard of thermal and acoustic insulation, with numbers, your BCO is asking for.

Your BCO needs to go back to building school. PUR is no good for sound insulation - must be mineral wool between the studs for acoustics. There will also be a thermal requirement for this wall if the other side is an unheated space.

Ed. Read the BS you refer to (there is a more recent version) for surface and airspace resistances and their definitions - values are tabulated but calculation methods also shown. As far as I am aware BRE Digest 108 was withdrawn many years ago (I remember using it at college), the basic principles still apply however but some of the values have changed.

Jeremy - couple of numbers transposed in the BS EN number should be 6946. Also probably easier to remember that an airspace of between 25-300mm, horizontal heat flow and high emissivity surfaces each side (covers most airspaces you're likely to encounter) has a resistance of 0.18 m2K/W. Will be slightly lower for smaller airspaces. Ed - the surface resistances only apply to inner and outer most surfaces of the wall (or roof, floor etc) and are not included in an airspace resistance. Andy - a low emissivity surface does make a BIG difference to the airspace resistance - Ecotherm number looks correct. It will also affect the surface resistances but it is not often that you have low emissivity surfaces internally and/or externally in standard construction. Question to ask is does the Low E, bright, shiny surface stay bright and shiny in the long term!

No need to do the calculation as there is an alternative fittings based approach in Table 2.1 of Appr Doc G - comply with this and all is OK!

Because house is now all 'electric'. SAP rating is based on energy cost. Electricity as main 'heating' fuel is expensive so SAP rating suffers. Electricity has high embodied CO2 (from legacy coal fired power stations - will change in next version of SAP) so CO2 emissions will be higher. Efficiency of ASHP counters the above to some degree. Heat pumps in general make compliance with the Regs easy.

Look at the close up shots of other slates. Slates are normally nailed twice towards the edge not once at the very top edge and man made slates normally riveted too. Looks like rivets may be missing in general roof area too as the slates are too far apart to secure the rivet.

Slates are not upside down those holes are for the copper rivets that secure the bottom edge of the slate. Poor roofer if he does not know how to fit these especially in cut slates such as around skylight, probably at the verges too. All needs redoing otherwise roof will last no time at all.

Thanks Jeremy. Not sure if I agree with BCOs interpretation but as long as he/she is happy that's another hurdle crossed.

@JSHarris Jeremy where is the exemption from the water efficiency calculation if you have a private water supply?

Controlled fitting so comes under Appr Doc L as well - FENSA or Building Reg application needed. Min standards for U-values apply.

Adding more acoustic insulation will achieve little. Next improvement is to add mass with 2 or more layers of plasterboard and then to decouple the plasterboard from the joists using resilient bars

Assume this is the floor to the attic rooms and above rooms below. Acoustic insulation required under Building Regs normally 100mm of mineral wool with min density of 10 kg/m3. Loft insulation is normally less than this so does not comply - in reality I greatly doubt there would be any difference in overall acoustic performance if the density is a little low. Using 200mm rather than 100mm would have little effect - case of diminishing returns. You would have to convince Building Control that 200mm offsets the low density or use 100mm of the correct acoustic product.

If attached garage but unheated then no need to insulate roof (or floor or ext walls)

MIs and BBA for EPS, XPS & PUR all require DPM under insulation. All will absorb water to some degree - a search of the manufacturers website should give this info.

Manufacturing tolerance on thickness normally +3mm to -5mm so expect to see bottom of tolerance range for most production runs. 95mm it is!

Will depend on grade of rockwool and polyurethane assumed. Remember to include 15% bridged proportion. Should give approx U of 0.20 W/m2K. Condensation should not be a problem if care taken with the VCL & PUR not sealed though not much safety margin.

Sorry - yes it's Appr Doc F that applies

In England Appr Doc C, Section 7. Looks like BCO is correct.

Be careful with Kingspan TF solutions - in the small print in the brochure tables they often include an insulated plasterboard internal to the studs to improve the U-value.

Monarflex?

Just an excuse for bad manufacturing and poor quality control. The manufacturing spec for PUR is in BS EN 13165, among many other things it gives tolerances on board dimensions (thickness, length, width, flatness etc). A trip to any BM will show their products to be 'pushing the envelope' for these tolerances, especially thickness (100mm thick board for example should be within +/-3mm) and flatness. Remember shortly after Grenfell Celotex were found out not being entirely truthful about the fire performance and thermal performance of some of their product range.

Building Control will probably look at U-value and fire performance of external roof finish - this later requriement is down to building height and proximity to local buildings, etc. Note that Scot Regs strongly advise aginst use of cold flat roofs as do relevant British Standards

@IanLow SAP probably due to use of bulk LPG. Would be very diferent with mains gas.