Mr Punter

I would want the EPC run before doing the boilers. The other recommendations are not practical. There are thousands of properties let near me which wont have much chance of making C. Will the tenants need to be evicted?

I agree the gas safety is a potential issue. Our firm own the freehold so no consent needed there.

I have a few flats and they are all EPC E. Victorian buildings in Conservation Areas. They are electric heating and DHW. It may be that installing gas boilers will get them to a C most economically!!

It depends on the approach (head on or not), the corridor width and whether optional requirements have been specified in your planning consent.

I think that the solar gain will be via glazing, not walls.

Regarding the points raised as to whether a "ticket" is required to operate telehandlers, excavators and other site equipment, the answer is that you need to be suitably trained and competent. A "ticket" is one of the ways of establishing this, but far from the only one. If an accident happens and HSE find that the operator does not know what they are doing it can be bad news all round.

Agreed. Paint is as messy as hell and how do you know how much is applied? Are people really measuring the wet film thickness for every coat and applying the xx number of coats specified.

Won't they be protected by the plasterboard ceiling?

Often the standard flow rates are far lower. You may find that 30% is plenty.

That is very sizable. It is a fairly simple cube shape so should have a favourable surface area to volume ratio. I couldn't work out the orientation. I have seen Nudura around a fair bit recently and several people on here have used it. Not so much Thermohouse but it looks a fairly similar product.

Agreed. They use double and triple sole plates frequently on timber frame. You probably won't even require half lap joints, just stagger the layers. 47 x 100 treated timber is easily sourced, cut and fixed.

If there are more of these you could get the bricklayer to leave a couple of blocks out so you can clean the cavity. Often there is no cavity tray at the bottom, just separate DPCs

I don't think there will be an issue with 25mm. It will help a bit with u value and leave you space for services. I assume you have VCL on top of the ply?

I like it so that when the door is closed it is on the same line as the wall it opens into and only the architrave protrudes.

I have used Sikaflex EBT for this. You need to be careful not to smear it everywhere but it is a good product.

You will need fascia, soffit, gutters, painting and holes for services before you drop the scaffold. What are the quoting to strike it?

I have installed aluminium coping. It is pretty straightforward, so any competent builder or handyman should be able to do this for you. Try local roofer / roofline installers.

Just leave it. It is very difficult to remove. If it is properly bonded to the concrete I can't see a problem. I have tried to remove a small amount of overspray of diamondmatt from fully finished wood floors and it it is difficult to impossible without damaging the floor coating.

I would try a sample mix and see how it is. It would need a fairly thick layer.

Until the price of gas is much nearer to electricity I can't see them going away.

With the MVHR, the inlet and outlets like to have the same air pressure to keep the system balanced, otherwise the fans will be fighting to equalise. The MVHR and the ASHP are performing 2 very different functions and it may be best just to install them as 2 separate systems unless you can quantify the benefit of mixing them.

Even simpler with timber frame:

The ventilation to the undercroft will be dependant on wind conditions. You may need to change to a different size / shape of ASHP unit in future, so the build in option may no longer fit. The external option looks easier to service and inspect. Have you calculated the cost of the difference in efficiency? Where is the flood line below which electrics are not advised?

Is there a section detail through B1 showing the joists and ceilings either side?

I have seen far worse. It looks a decent size. I seem to recall that it sits awkwardly on the plot though. You covered your bases and are experienced on construction sites so you should find this easier than most. Good luck!