JohnMo

All our rooms are vaulted. As @ProDave says you need a ridge beam then either plain timber, pozi rafter etc. Our pitched roof is 256mm pozi rafter, then below we have 2x 50mm battens, then 356mm of insulation full fill. Below we have airtight vapour barrier, a further 50mm battens and then plasterboard. Above we have 22mm sarking boards, vapour open membrane, and then slates direct to sarking boards.

The more boxes you try to tick the more confused any application, so more likely the planners say 'me don't understand' reject. If you are building to house rules minimum space requirements kick in, airtightness rules may make MVHR mandatory etc. If you are doing a caravan apply for a caravan, doesn't really matter if how you build it.

Point is why two heat pumps? When one will switch between the heating and cooling. Hitachi even have an auto settings that will automatically switch between the two settings based on what a intelligent thermostat reads.

You only need a single ASHP that does both. There is NO restrictions on cooling within BUS funding. There is via permitted development, but that is different. Just get a heat pump that does heat and cool out the box, Panasonic, Hitachi etc Open windows?

No sketch attached?

To the point that many said our house would be green from mould within six months.

Let's consider a few factors Air change rate. MVHR is in the range of 0.3 to 0.5 air changes per hour. Impact on room temp is almost zero. Two windows open on different sides of the house could 6 to 8 ACH. Look at the performance chart of cooling batteries, apply your flow rate and the cooling water flow temp and see the resulting kW heat removed. It is small. If you have cooling water, spend money on a fan coil or two instead of radiators or as well as UFH. If you have UFH just push the water through the floor, it's free cooling with solar PV.

Your issue is water tightness - keeping water out the roof structure.

Don't waste you money - read the many threads on here. At those prices I would be doing it myself and did. Your layout lends itself to a nice simple cascade system. First MVHR move away from bedrooms and install in cycle store. I would flow into dining and into office from there only. Dining flow will be most the house volume flow out of two outlets. Extract from all wet rooms and plant room. All other areas will be ventilated via cross flow or transfer flow.

Unless additional mitigating measures are taken any building can leak. Air tightness is all about details, that are added at the design stage normally. Brick and block benefit from wet plaster as it seals all the small gaps everywhere in the cement joints. Dob and dab done very well is ok also. Window and door design and fitting. Floor to wall and wall to ceiling junctions can leak a lot. How sockets and light fittings are done all need thought. Lots of small gaps equal a big leak.

2m X 2m is f...ing huge are you certain you need it that big. Price will be pretty huge also, by the time the huge support structure is finished, so hope you have deep pockets. Our sky lights came from Roof Maker, take a look at their website. The sky light will sit on upstands, the upstand will sit above the roof structure. So will be raised above the roof line, not flush.

Nothing like like having a good think about it. 1. Smaller maybe not, but if visually different you may need amendments or new planning. 2. Most are, but if you are uses your structural engineer they will need to handover. 3.? Interference not sure what you mean. Suspect these companies if you choose a plan that already exists they will not let you interfere much apart from some finishing details.

You could make holes in the wall and add plates, or just get the chippy to set door frame slightly higher in the wall. No skimming of doors, zero cost adder.

No issue blanking stuff off etc. I would make sure you have cone filters in the extract points and replace on a regular basis to keep ducts clean.

Because MVHR supplies air to dry rooms and extracts from wet rooms. Without the undercut air stops flowing when you close doors. Don't fret about acoustics the under cut makes zero difference. No You don't with MVHR but you need to allow cross ventilation with other classes of ventilation such MEV. But then you add humidity activated trickle vents to minimise ventilation when it's not needed. All houses need ventilation just a matter of how it’s done.

You use the power in watts to size each room radiator, so room 1 needs 618W output from radiator. Now you need to convert the radiator size from manufacturer data to your chosen flow temp. There is a calculation on here somewhere so do Google search on buildhub. You need to look at the pipe sizes then as most of the micro bore may need replacing(?). Did they install a buffer?

I hired someone as a labourer. Best money I spent. You have to get up to collect them at a fixed time. You work a proper 8 hour day. You drop them off at home again. You generally just tidy at the weekend so you are fresh on the Monday. You have a really productive week. You stop for a breaks and lunch. They are a sounding board for stuff. Doesn't matter if they know the answer, you have a chance to speak through stuff and it gets resolved quickly. If you fall, have an accident etc on your own you are stuffed, so a big safety bonus with someone else there.

We've got a Sarnafil mechanically fixed and welded membrane. Great stuff, easy to do upstands etc. Comes with 10 year manufacturer guarantee, only qualified installers get to install.

I do about (each way) 28mm pipe 2m above ground and then about 6m through an insulated shed and then about 5m underground. All done in 25mm closed cell insulation, below ground each pipe is in 110mm duct about 600mm below ground to the house. Plus I have 15mm pipe with 19mm insulation, wrapped in foil tape (keep rodents off) from insulated shed to summer house above ground a run each way of 16m It's do able and I don't see much effect. Decent flow rates and velocity from heat pump helps.

I would have done OSB, membrane, vertical battens and horizonal battens, corrugated. But with corrugated roof do the battens bring anything to the party? Do you need them at all.

But not attached?

If was a smelly oil boiler, that makes plenty of noise on full load you can put just about anywhere. I am in the camp of just install it, that's what I did. No one can see or hear it except me, no one really cares, unless you ask a question. If you want to get a grant however, the installer should be doing all this not you. He is supposed to know the rules and abide by them. So would locate based on PD rules and the noise stuff.

So the way I read it you can't do anywhere I have highlighted in blue, so first application didn't comply. So no surprise it was rejected, so just choose somewhere else to site the heat pump. Do the new noise calc - done

It may e the Scottish rules just read the English rules and it states On land within a Conservation Area or World Heritage Site the air source heat pump must not be installed on a wall or roof which fronts a highway or be nearer to any highway which bounds the property than any part of the building.

I have the same, think I bought mine in the 90s, when they first came out. Mine also in the garage. May plug in one day and use as a heater the screen got so hot.