ADLIan

Hi Mike. Don’t want to rain on your parade but I’m not sure the fire resistance value for the floor can simply be extended to cover the wall too. Also from memory the white book gives solutions for one hour fire resistance based on solid timber studs plus plasterboard - note different stud sizes for 30min & 60min.

Surface spread of flame (Class 0 etc) is a different part of BS 476 than the fire resistance tests. A Class 0 facing material does not automatically give 30min or 60min resistance (PUR insulation can be Class 0 and look at Grenfell). For external walls normally 60min resistance is required from BOTH sides. It appears that I-joists are being used and this may be the issue as they are only as strong as the relatively thin web in the BS 476 fire resistance test and this may be ringing alarm bells with your BCO. Perhaps have a chat with the I-joist manufacturer as there is no mathematical modelling here, reliance is made on actual test results.

They meet Regs provided you know the solutions (they wouldn’t have a market otherwise). Normally use mineral wool so acoustic performance is fine.

Don't think this one has been covered here and been slipped into AD L1A/B when no one was looking. The Domestic Building Services Compliance Guide has been updated and effective April 2018 promotes the use of more complex control systems and flue gas heat recovery. See the Planning Portal website. Ian Full link below https://www.planningportal.co.uk/info/200135/approved_documents/74/part_l_-_conservation_of_fuel_and_power/5

Changing 2 houses into one may require planning permission (material change of use) but depends upon local policy (one less house in the area is the issue). Building Reg required including Appr Doc L1B which dictates required U-values and upgrades required, though BCOs have a lot of flexibility in allowing relaxation of some of these (not being able to afford the upgrades is not an allowable relaxation I'm afraid). The new dwelling may also require an on construction EPC on completion.

The fire rated foam (and mastic, putty etc) is for fire stopping where services penetrate a fire rated wall and NOT intended for cavity barriers (see Appr Doc B). Also not sure you can make your own as most manufactured products appear to have certification to show at least 30 min protection when tested to BS 476, part ??. Best check with your BCO.

In a warm pitched roof it is acceptable to put a limited amount of insulation between the rafters (depends on thermal resistance of this layer). In a warm flat roof additional insulation should not be used between the roof joists. Probably OK in a limited area, but keep to minimum above the wall head, to improve sound insulation.

Item 35 is a requirement of the Regs but very rarely enforced. The actual wording is a bit vague - a full 20+ page report would look great but a simple, single paragraph statement has been accepted by BCOs. Perhaps keep statement short & simple and hope this satisfies BC.

Both mineral wool rolls and slabs will do the same job acoustically. See AD E which recommends mineral wool, min density 10 kg/m3, min thickness of 100mm in intermediate floors and 25mm in stud walls. Rolls normally cheaper than slabs. Do not over fill studs and compress the insulation, especially with dense slabs, as this will acoustically couple the layers of plasterboard and degrade the overall performance.

Requirement was U=0.22 from memory. I'm sure older versions of Regs are archived on DCLG website.

Not sure about that Nick. See instructions/recommendations from both flooring and insulation manufacturers. Problem is lots of relatively narrow planks rather than large area of flooring grade chipboard.

Use correct underlay for laminate floor. Celotex, or similar, is not suitable for use directly under laminate flooring.

U-vals look to be correct for brick outer and probably only slightly higher with cladding of weather or render board.

Depends on fuel used, if mains gas expect approx SAP of 85, Band B. Figures above refer to existing housing stock.

+1 JSH. PUR manufacturers sell heavily on conductivity - try selling 0.023 product against 0.022 product and you’re dead in the water! 4.5% degradation does not sound much but on 8 years production it adds up. Temp variation effect on conductivity is not important here compared to USA which has massive changes in climate from north to south. Under BS conductivity is normally measured at mean 10K (0C - 20C).

With lamba value lower = better so ‘understating’ is not good. Since 2009 they’ve been claiming 0.022 W/mK when it should have been 0.023 W/mK. Makes all your U-values higher (worse). Not good for their certification and CE mark especially on the back of Grenfell and incorrect quoted fire performance - all on website.

See Celotex website , www.celotex.co.uk. Appears they have not been exactly truthful with their thermal performance!

Compliance with relevant British Standard, harmonised European Standard (CE mark), BBA (or similar) or European Technical Approval normally acceptable routes to show compliance/acceptability . Mainland European countries all have their own version of BBA but BCOs often reluctant to accept these. See Approved Document 7 of the Regs for mor info. Ian

Beware!!! Switching from gas space/water heating (especially heated floor) to mains electric will totally screw up the CO2 emissions. Failure here under the Regs is very difficult/expensive to remedy! Your assessor should be able to advise.

That version of BS 5250 is now out of date and BS 6229 is more specific for flat roofs. Calculation method for condensation analysis now in BS EN 13788. Remember these standards/methods are basically steady state rather than transient conditions you can however change internal/external conditions to asses greater/lesser risk.

In a house of that age I assume cavity to be only 50mm. With a medium/dense block the 'balance' of insulation with 100mm EPS externally should be OK to avoid condensation. As stated above even if condensation is predicted is it harmful? Bear in mind amount of condensate, net build-up (if any), location & nearby materials.

Agree with above - vent cavity negates effect of EWI. As regards condenaation it not just if it occurs - also how much, is there a net build-up over the year, are moisture sensitive materals adjacent. Suggest you get the insulation or the render system manufacturer to look at this for you in accordance with relevant BSs - the Vesma calc looks very rough and ready and is not using correct values in the bit I can see - not sure what's going on behind this!

Glass wool (unfaced) from all the major manufacturers is normally classed as non-conbustible. If there is a facing (or encapsulation) such as paper or polythene this will burn. Loft insulation is generally not faced or encapsulated (some are!)

For conversion to dwelling work EPC still required. No air permeability test required under Regs so default of 15 is used. You can still get test done and use that value in the as built.

Recticel traditionally been great quality. As for Celotex - after recent events make your own mind up. If the foil face is that bad then thermal properties must be open to question too.