Thanks, that is is an interesting perspective and maybe what they are driving at. I will see what finnjoist have to say!
@PeterW we are not skimming the PB, dry lined so I guess it will all be down to thicknesses of Fireproof PB.
It doesn't really take that long to prep as the only thing that needs covered up are Windows and the front/back doors. As glynn has said it's done before the sparks put anything in that you would usually have to tape of. There will be no internal doors or skirting either so just your door frames if you are going for oak that will need taped of.
Sounds to me like he does not know Cornwall too well and is sticking to the places nearest Devon.
He should look at places like Perranporth (one of the best beaches in the world), Porthtowan (if he likes surfing), Portreath (if he likes cheap), Hayles (if he fancies odd, but near St. Ives). St. Just (if he wants isolated and where the ice aged ended and made a beach), Lamorna, if he fancies being washed away with the harbour wall), Mousehole (no parking, but nice lights), Newlyn (for history and cheapness), Penzance (for just about everything, and still cheap), Marazion (for cosiness and one of the best views in the world), Praa and Breage (still decent and underdeveloped, though I see that R&J Supplies are selling up), Porthleven (get in quick, it is the new Padstien), Cury, Mullion, or just about anywhere on the Lizard Peninsular (no mobile signal).
Then you are around to Falmouth, which for some reason thinks it is a lot better than it is. Penryn if you like sailing and students.
Then you can cross the estuary and join royalty at St. Mawes.
Around St. Austell is still reasonably priced and close to Devon, but avoid the town, it is just dire.
There are a few places inland, but generally it is very deprived, I know, I live in one of the most deprived areas of Europe, 50 quid makes you feel wealthy, but a few pills and a bit of blow takes the pain away for most around here then they rob my house, or set fire to a neighbours (4 house sin the last decade within 500 yards of me).
I took the below picture earlier today, it is where they are developing some new flats where the price starts from £216,950, and if you want an extra bedroom (so that will be 2) add an extra £94,000.
I hope the owners of the sleeping bags find somewhere warmer tonight, and with less dogshit around them.
Oh, and not on the noisy main road either.
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.
My experience was that the wall/ceiling prep was no different at all. Prepping the paint is a little more involved, as it has to be very, very thoroughly stirred, far more that most would bother to do when painting with a brush or roller, but really just a matter of using fresh cans of paint and a drill-driven mechanical paint stirrer well.
Flat surface are dead easy, corners less so, but I found that swapping out the nozzle for a smaller pattern one and doing all the corners first, then fitting a wide nozzle to do the walls etc, worked fine. I used a large painters george as a hand held mask for edges, very quick and easy to do once you have the knack. Getting the pressure right for the paint and nozzle was a bit of a knack, too. Too much pressure and you get some bounce back that creates dust, so best to dial the pressure down so it's just enough to get an even pattern.
By far the biggest issue if the clean up time required for the airless sprayer unit, hose, gun, nozzle and filters. I found it takes as long to clean the kit properly as it does to paint a whole room, so best to plan to do as much painting in the same colour as possible in one go, that way you only get the clean the system up once, rather than several times.
I never found a reason to use a brush or roller, and managed to practice enough to be able to spray pretty precisely with a good surface finish. It would now be my first choice for a big emulsion painting job, for sure, but then I detest painting anyway...............