PeterW

Always drill after. Conduit cast in during a point can get bent or moved and then you need to re-drill anyway. The other issue is always light placement - until you know what the outside looks like, you may want to move the outside lights about so that is much easier to do if you haven’t been constrained by conduits already installed. 32mm dry core diamond bits aren’t expensive for what you get and can be used with an ordinary SDS drill. That is more than adequate to get most services into a house and can be sleeved with waste pipe and sealed without too much issue. 20mm conduit ideally needs a 22mm SDS bit but is easily drilled with a standard bit.

Can just see one here in the top right - 4.8m up mounted into the front of a false chimney breast. Just think before you finish though how you will adjust it to balance it ....

25 x 50 lath and should be fine. Issue normally is the laths aren’t down tight so bounce, so double nail them

Don’t RIBA require you these days to issue a fees schedule and estimates before work is commenced ..? I thought in the dim and distant past it was part of membership code of practice ..? Or has that all gone ..??

Local guy I’ve used for a while - he fits a standard egg box door in about an hour. Measure scribe and trim and then it’s jig and router on all the hinges, same with the frame. Latch goes in once he’s happy and job done. I’ve seen him do 6 in a day without breaking a sweat !! He got booted off a local developer site as one of the regular chippies moaned he was twice as quick and was harming their day rates !!

@Omnibuswoman does that include supplying hinges and latches ..? I pay £35 for standard doors and £50 for oak/fire doors labour only to fit internal doors.

Not required as long as they inspected the chimney and it was in good condition.

Do the pour and let it start to go green. Then you need to dig out the excess down by 40mm, and put a piece of wood either side and level between. Get a sheet of polystyrene insulation and weight it down between two bits of wood that mark the gaps you need.

You then end up buying expensive batteries and somehow split wiring the house to use battery for some non critical areas. That seems much more complex than having a standard build that has a (much cheaper) grid tied inverter.

This will cost the vendor £2-300 for a latent defect insurance to top that up - tell them to get it or deal off

Yep hence why I said beam size as lintels to 4m length really don’t exist in single skin. I agree with @nod that you need an SE to design this as it needs to be stiff enough to both resist bending and also resist twisting over that length.

This is why the motorised auto balancing actuators are good as they respond in 3-5 seconds.

OK so which way do the roof joists run ..?? If they land on the lintel then there is a huge load, if they are parallel then the load is negligible. That affects the size of the beam.

How are you planning on insulating this room ..? That will have a bearing on the beam type and also the lintel construction method

Really..? Never seen that on any install guidance and know a lot of Fensa fitters who have never removed it ..? I was advised it was there to protect the gas seals from damage.

@pocster is your man here - he is the resident Buildhub slum landlord ... ? In seriousness - if you want cheap then contract suites in white from the merchants, or even Wickes or B&Q. The downside is they aren’t the best quality. Have you tried Victoria Plumb or British Bathrooms..??

as long as he thinks it will all work then that should be fine. Alpha 2 are latest generation pumps so should hopefully be as quiet as the Wilo ones.

Stays on and also protects the glass edges too

That is gas sealing tape - it needs to stay on !!

Blown beads all the way. 175mm gives you 0.165 which is what I would go for.

That is the Mitsubishi standard design. Nothing that is bespoke for you ... Also missing the immersion connection - what is controlling it and does the ASHP need the immersion to hit its target temperature ..?

Ok - not sure why he’s got 4 pumps but worth checking. Has he provided a design schematic ..? Expansion vessel, low loss header would have been needed regardless as they are not built into the pre-plumbed tank. Also ask for brand and spec on the pumps - some are really noisy !!!

A direct UVC is just that - electric heated. You can get them with a pair of 3kW immersions or a 6kW immersion and a 3kW booster. Heating UFH with electric is the sweet spot for an ASHP - 35-40c flow all day long gets maximum CoP so even at 18p/kWH a decent ASHP will be costing you 6p so it’s equivalent to oil. In terms of servicing, there is nothing to change on a UVC - it is a safety check. On an oil boiler budget £200/yr for service and other bits.

Tanks are a personal preference but assuming he is going with the Gledhill pre-plumb it seems ok. Is he integrating it with the heat pump and the Mitsubishi controller as I thought the quote was for the Mitsubishi pre-plumbed cylinder ..??

Unless you need the clear headroom I would put a double ceiling tie at 2.5m from either end with a king post to the ridge. That would be 8x2 doubled and bolted. Then every other rafter would be 6x2 collar truss single side and bolted at 1/3rd rafter depth. If you need headroom, then it’s going to be doubled collar ties at 1/2 depth all the way down, especially if this is a timber frame with a garage door opening at one end.