Nickfromwales

They over-egged the shit out of a project of mine previously, and cost the client a lot of unnecessary expense. The issue is that these 'giants' stomp about and stipulate things and folk just take it for granted that their requests / demands are kosher, but sadly the majority of private are pretty hopeless. I'd stick with LABC as they're usually more grounded as it's not about self-preservation or perpetuation of their companies commercial future.

You have to grab hold of both the negative and the positive of the same string of the DC feed to get zapped btw. But if you do get zapped then there's no coming back from that, as it will be a one-time pass to Jesus-land. Fitting the aux rotary isolator will always be my default, but it is also handy for changing cable disciplines; from strings off the roof into SWA for eg, where the DC needs to travel some distance internally to get to the plant room / inverter location. We have these in attic / eave spaces on most installs. In the real world, this is a very isolated risk we are discussing here, and you pay less attention to the tumble drier which is more likely (statistically) to burst into flames sporadically.

Capillary action will suck the water in for miles, it's a git. Water is also a git. This is why I go bonkers on waterproofing with my bathroom / wetroom installs. For this, you need to stop using the shower so it can dry out, and strip out all of the silicone; use a plastic tool to get the worst of it taken out, and then CT1 Multi-Solve to break down and emulsify any remnants. You spray it on, leave it to soak in for 5 mins, then use the plastic scraper and / or a cotton cloth (like a dishcloth) to get rid of the remining snots. You'll need a couple of applications to get this back to a blank canvas (eg zero evidence of there ever having been any silicone there whatsoever). Get a hoover and suck the tiny bit of residual water out from under / behind the tile, as that needs to go, if you have compressed air this works better to blow it out and dry it all out, but not everyone does. Then leave for 24hrs to dry out; I'd put a small desk fan in there and have it blowing down at the gap where the tiles meet the tray to speed this up. Once you're happy it's dry and clean, you can reapply some fresh, quality silicone sealant. It doesn't look like there's been much gap left between the tiles and the tray, as otherwise I would be saying to first inject some clear CT1 into that gap, and wipe it back to almost nothing, and THEN silicone over the top of that. Do you think there's any gap there that you could get some CT1 in to?

Ground floor doesn’t need AAV, for sure. First floor does (do) via AAV or SVP to atmosphere. As I’ve put a bit of weight on, my vote counts twice. So 2 B and 1 A. lol.

£120k for a garage conversion sounds expensive, but I haven’t seen the scope of works. Can you anonymise the quote and post it here for us to see? Please be sure to remove yours / builders details completely before posting. For VAT, the builder is obvs VAT registered so every invoice they give you will have the VAT on it at 20%; I don’t think your project will attract the lower VAT rate, why do you think it should? No builder will ‘fiddle’ with VAT as HMRC really do have a disliking for anyone doing that, by even as much as £1. Ask them to remove the windows from their quote, and explain that the window company will be carrying those works out in isolation. Pay the window company directly for supply and fit. VAT can only be charged once then. Expect the builder to charge 5-10% of that window program for “attendance” as the site set up and welfare will be in place already, and they’ll need to organise themselves around it, and lose the revenue from…….watching them being fitted! Can you post some plans so we can see the scale of the job? The more info you can provide the better the advice will be.

You don’t need to get the B&B so accurate, you can have a day off there The levelling is done entirely by the screeder, and if you get a good one you definitely don’t need the SLC. My guy gets the floor down so well with a dry screed that you could paint it green and play snooker on it. However, if you choose a poor screeder then expect to have to level it. 12mm adhesive at least for the limestone, but it depends on how well honed the rear of the tile is, some are quite rough. Your tiler will know this, if he’s a good‘un. For this situation, where you’re jumping old / new and it’s a bit of a mix I would use a decoupling membrane, as the limestone will crack over the years wherever the transitions are happening. This will virtually guarantee excellent results, and longevity. You mention decoupling adhesive, which one have you looked at / has your tiler suggested?

If you’re overlooked that is a possible issue, if you’re not then a ‘tweak’ of the ridge height often goes unnoticed. If it’s < +200mm then I doubt anyone will care tbf.

Nope. The only outward force will be from your heated slab potentially expanding, but below that everything sits where you put it and stays there.

The fitting outside can simply be an 'access' fitting with a screw cap on it.

Then you have destroyed these, basically. They come with dust covers, and they need to be in place every time you do work. Try buying a can of air duster and blasting the grot out, but you've shot yourself in the foot here.

Both of the 100mm layers of insulation would just push up as hard against the foundation as you can, so the upper layer there looks like it could slide over by nearly 100mm for eg. You don't need expansion for anything other than the heated slab, so again the 25mm perimeter insulation (with an additional 10mm expansion foam skirt in front of that), sorts that.

No real need for the 50mm vent btw, as you only need air admittance / air break if the invert (drop) is >1300mm. The fact that the pipework is largely horizontal provides the air break. I assume this is a ground floor so no need for air admittance imo.

I'd give you a job Looks good afaic, just I prefer to solvent weld everything; as much as I can that is as the 110mm stuff I always use push fit for a bit of 'give'. I think I'd bed the joints and changes of direction with some 8:1 sand and cement haunching, and let that cure before going over, unless you were going to back-fill with concrete anyways?

Glued and screwed every damn time! 100% defo need to be screwed down before the glue cures or the board won't ever pull back down, the glue will win that fight. I use 5.0 x 50mm screws which are partially threaded, to prevent 'jacking' that a fully threaded screw promotes. No need for a pilot, as the impact will send these through and out the other side with complete ease, plus you want the meat left intact to maximise on the purchase of the screw. If you're at all worried about weathering, then just fill each screw hole with a scraper and some cheap clear silicone, seriously unnecessary imho though unless this is going to be open to the elements all winter?