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I really don’t think materials and workforce shortages are an issue here, because I gave him a contract extension for the only spell when his men were stuck in the EU having gone back there for the Xmas holidays and I’m buying so many of the materials. The only things we have had to wait for are roof tiles and a set of posi joists, and he had plenty of other things to do so that wouldn’t have delayed him. What I’m trying to understand is whether he has made a mistake and not realised how big a job he was taking on, or whether he deliberately gave me a low estimate for the time it would take to make himself sound competitive.

I hope you are wrong @Big Jimbo but I fear you are right.

Building project started in first week of January. It's a big project: we are COMPLETELY gutting a 3 bedroom 1930s semi to its shell (literally only thing that is left of the house is the external walls and roof), putting in a new concrete slab, removing all external pebbledash, new porch at the front, replacing all windows, doing a two storey rear extension, then converting the loft, retiling the roof, new driveway at the front, then lots of insulation going in inside, screed floor with 3 zones of UFH on ground floor, UFH inbedded in XFLO boards on first and second floor, 5 sky lights, sliding door, new kitchen, 3 new bathrooms, new guest WC, engineered wooden floors on first and second floor, mix of tiles and poured floor on ground floor, feature wall being soundproofed and then tiled in living room (almost 30 sq metres), adding external insulation and re-rendering. Originally, the contract i signed provided for the project to be done within 8 months. I extended this by a week because most of the contractor's team were stuck in the EU until the second week of January. We then found out we had to do some pretty major underpinning so I asked the contractor in March what sort of extension he wanted given the underpinning. We extended by a further 3 weeks, so as at late March contractor was telling me we would be in end of September. Things are going really rather slowly, and I'm just trying to work out when realistically we are going to be in. They have finished building the first and second floor extensions, the porch at the front and they have done all the underpinning. They have also laid the concrete slab on the lower ground floor (well actually I'm not about that - they were meant to do it today, but I haven't gone to check yet) due to do the upper ground floor slab this week. They have removed two chimney breasts and done all associated structural work. They have put in posi joists at first floor level, but still need to do loft floor. They have done all the structural beamwork for the loft conversion, but for reasons I won't get into we are doing the loft conversion itself at the end. None of the skylights have gone in yet, although I think they are waiting for the roof tiles which have taken for ever to arrive due to the pandemic, they are due in the next 10 days. We are subcontracting the poured floor, new staircase, windows, sliding door, porch door, wood burning stove installation to third parties so that will save the main contractor some time, but otherwise he is doing pretty much everything. Kitchen will be pretty easy because it is all DIY Kitchen Units and we are subcontracting the worktop installation to a third party as well. So effectively, the main contractor still has to: do the slab for upper ground floor (about 25 sq metres) lay insulation, UFH pipes and screed for all the ground floor (81 sq metres) build all the stud walls for almost every room in the house (we only kept one room!) install a new boiler, UHWC, buffer tank, manifolds for UFH and commission it all, and first and second fix plumbing, which will have a secondary loop do all the first and second fix electrics, including installing a new consumer unit and a couple of external lights and all the internal lights for a 5 bed house install and tile 3 bathrooms (one small, one medium and one large) as well as a small understair WC, they all have wall hung toilets that need doing as well retile the roof and install 5 skylights internal plastering and painting (although there is no paintwork on the ground floor as we are using a special plaster that doesn't get painted and tiles) driveway at the front (for one large car) about 32 sq metres of patio needs to be tiled at the back pointing on rear ground floor extension (probably only 20 sq metres of brickwork needs pointing) rendering rest of the house (as well as installing the external insulation. I am pretty organised and have ordered most of the stuff we need to supply for him to finish the job. Apart from the roof tiles, we're not having too many problems with lead times, so I don't expect there will be any delays on the supply side. My question is, can all of the above be done by the end of Sept? The team onsite consists of a foreman and two to three other guys. The four of them are there everyday mostly, although there are ocassions when they will drop down to three. The contractor is there most mornings to make sure they know what they are doing. He also brings them supplies. At the beginning when there was a lot of demolition work, there were two more guys there as well, but I haven't seen them for a couple of months. I'm eager for the project to finish on time as some of it has been quite stressful and we're just getting impatient. But at the same time I don't want them to rush the final stages as it's complex and will take some care. S Based on the gant chart I agreed with the contractor, they are about 4-6 weeks behind. So I know I should adjust my expectations but not sure to what? November? Christmas?

If I were to leave the plywood as is, i.e. without expansion gaps, is it still worth applying fibreglass tape over all the seems? Any reason why this can't go on top of the seams rather than underneath it (which would require removing the plywood?

Thanks @Bakersdozen. So I've got some further info from site today. The plywood that has been used is WBP Plywood. I asked my builder why he didn't leave expansion gaps and he said that there are a couple of expansion gaps but mainly it's been laid "board to board" because WBP is resistant to expansion or shrinkage. Googling WBP seems to back this up (e.g. this website says: "because the WBP plywood layers are bonded with the grains running against each other the WBP plywood is highly resistant to expanding or shrinking, it is less likely to split when nailed at the edges, and the sheet strength is consistent in all directions." I don't know whether the WBP used is EN314-2 (class 2) or En314-3(class 3). In an ideal world class 3 would have been used, but given the plywood deck will be protected by the GRP only has only had one or two days rain on it, which has since fully dried (they patched up the tarp tent protecting it and dried it with an huge industrial style hair dryer), I'm hoping that even class 2 will be okay, or am i being naive?

The shell of my ground floor extension has been built. It has a gable roof, more or less, with an 18 degree fall. I say "more or less" because it is rather bespoke and has some unusual features so as to conceal a gutter and skylight behind a parapet wall. My builder has done the external deck with weatherproof ply, I think it's 18mm thick. We were then going to cover this with GRP before putting down trays for a seedum roof. Engineer has specified the rafters for this, structurally no problems. Because the roof was quite bespoke, my architect - who designed it - mentioned that it might be worth running the design by a specialist. I did and the specialist (who is a RICS surveyor and building engineer) made some tweaks which were quite sensible and also recommended we outsource the GRP and Seedum installation to a specialist roofing contractor that could give us a 20 year guarantee. Also sensible I thought. That contractor has now come and surveyed the roof. He has put the cat amongst the pigeons with the following: He does not think that the "non-standard" angles we have where our concealed gutter and skylight connections are will work with GRP. As the cross section below shows, we have an obtuse angle that is probably about 110 degrees just to the right of the skylight and reflex angle that is probably about 250 degrees just above the gutter. In both cases, I think the plan had originally been to use a 90 degree trim and bend it slightly to fit the angle, even though in both cases it would be out by about 20 degrees. The GRP contractor doesn't agree. He says: I have not quoted for a GRP system due to the angles as the preformed trims are all set at 90˚ and will not work with this angles of the upstands / downstands. If GRP trims are forced into position there is a risk of them cracking when thermal movement occurs. Instead he has quoted for the following: The Triflex product is a latest generation PMMA resin system that forms a monolithic membrane that is elastomeric when cured and is the same waterproofing that we use on curved garage roofs. Triflex resins are more expensive than GRP but in my opinion Triflex is the correct product for this project. My architect is quite surprised by this, because he thought GRP was very tough. Reading up on the forum, i see that others like @nod and @SteamyTea think it's tough too (e.g. here and here), although @markc did think it would crack if severely twisted. Does the forcing something designed for 90 degrees into a 110 degree situation, or perhaps even a 120 degree situation, count as severe twisting? If so, can't I lay the trims without twisting them and just have a slight air gap because it won't be flush due to the mismatch of angles? If GRP is really out, then the problem with using the Triflex PMMA resin, is that it's more expensive in terms of materials, but also the Contractor reckons the way my builder has built up the ply wood won't work as a base for the resin and will need to be redone. He says: the current roof deck is plywood that has been exposed to moisture, the correct roof deck board for this type of installation are 18mm tongue and grooved OSB3 It did get a bit rained on when a tarp tent that was meant to be covering it leaked (turned out it had a few holes on it) but my builder dried it with an industrial sized hair dryer and it's marine grade ply anyway, so I'm not too worried about the moisture as i think it's just cosmetic damage - though if anyone thinks I'm being naive, please do shout! We asked him what difference T&G OSB3 made vs Plywood and he said that the problem with plywood is twofold: (i) it could chip; and (ii) as it is not T&G it should have really been installed with a special tape under the seams. I'm guessing he means glass tape, but I'm not sure. So if we now want to go down the Triflex PMMA resin route, we would probably need to do the plywood deck again, either replacing it with T&G OSB3 or taking it up, putting down the tape and relaying it. It's about 22 square metres, though because of our first floor extension that sits on part of this roof and the rooflight, it's not just two simple rectangles of 11 square metres each, a bit more fiddly than that. Another option is possibly to add OSB3 onto the existing ply simply to save the labour of taking up the existing ply. I'm sort of leaning towards finding a way to make the GRP work rather than start from the beginning so that we can get the 20 year guarantee, as we're low on cash and already very behind on the build and I'm sure if I tell my builder he's done the plywood deck wrong he will just blame my architect for not specifying OSB and we'll just get into a game of pass the buck. But I'm not leaning that strongly as it's not exactly a nice direction to lean in either way! Any tips or advice greatly appreciated.

Yes, that is how ours was; we knocked down the wall between the kitchen and dining room and then lived in it for a couple of years whilst we waited for planning. Now we have knocked out the entire back and done a full width extension. The only way we got permission was by having the extension with the roof sloping downwards as it approaches each of our two neighbours’ houses. Hence the slightly unusual ceiling.

Here are some digital renders of the open plan kitchen diner we are doing with our 1930s semi

Thanks all. I should have updated you earlier. I think it’s all sorted now. Builder contacted the council after I got a little contractual with him, and he paid the fee for the licence (peanuts) plus an exorbitant deposit of £1600 in case he damages the Council’s pavement. I put my legal knowledge to use and did some research and came to the conclusion that the Council is probably exceeding their powers by demanding such a high deposit and such a high insurance cover, rendering their scheme amenable to judicial review. Unfortunately, I don’t have the time or energy to apply for judicial review, so I have just left it for the builder to resolve. To cover myself I wrote a polite, but firm letter to the Council attaching copies of the relevant clause in my contract and the emails between them and my builder confirming they had received his payment. So fingers crossed it’s all done, but I think the problem might resurface in a couple of months when the licence “expires”. This red tape is unbelievable. oh, and having the hoarding 1m in would only have been a temporary solution for us because we are digging up the driveway in a couple of months.

I’m sure the quartz we had at our last place stained. Isn’t it a mixture of resin or some other agregarte and ground up rock, so the resin/aggregate part can stain? Or is it just a question of what cleaning agents to use on it?

Yeah, I’ve also been messing around with the samples. See photos attached. It survived the blackberry/ketchup/soy/honey and used tea bag 8h test, but the jury is out on the 24h tea test. My wife is convinced the sample has slightly browned where the tea was, but I’m not sure (it’s the Primordia colour, which has a very subtle and tiny undertone of beige/brown). (the other sample is Unistone by Brachot Hermant, which we are also considering.)

Yes or no?

I think it’s in most architect’s DNA to go off piste sometimes. We were extremely clear with what we wanted, but the first couple of plans the architect did go off on a tangent when he thought he was improving matters. He might have been for another client, but not for us. But I’m this case it looks like more than just a tangential problem; sounds like he’s in another dimension altogether.

I struggle to see why one would need 3mm or even 4mm accuracy for such maps vs 40mm.

I think you mean melted tv.

Following some helpful recommendations on this thread by @PeterW and @dpmiller, I have found a Trojan Supercast bath that fits all our requirements... bar one. My better half has pointed out that with two toddlers we should really be looking for a bath with handles. I asked the supplier if they could supply the bath I've found with handles. He said he couldn't and that if I fitted aftermarket handles, it may well be fine but he washes his hands of it in terms of warranty etc as it would invalidate the 25 (or 30) year warranty. Has anybody fitted aftermarket handles to a reinforced acrylic bath such as the trojan supercast? Which handles did you use and how did you get on?

This really is very helpful thank you. I assume I would make the secondary loop itself 22mm as well?

Is it possible to restrict the flow using narrower pipes. I'm having a secondary loop for the hot water to the bath and basins (but not the showers). For for the basins could I just use a narrow pipe to join the hot water secondary loop to the basin, and supply cold water with narrower pipes as well?

Thanks, that's helpful. The taps are supplied with restrictors but these can be removed to increase the flow rate. The only area where I would actually want to do that and get as much flow as possible is the bath filler, as it's a HUGE bath and possibly the rain shower. I'm assuming I will lose some pressure anyway from the 2.8 to 3.2 bars coming in to the property at ground floor and the location of the UHWC which is about 6.5m or 7m above that on the second floor, so in actual fact I won't get the flow rates advertised for these taps/showers at 3 bar, but slightly less. Is the calculation simply 0.65 to 0.7 bar less to account for the 6.5m to 7m height travel?

I’ve purchased a bath filler with a 33L/min flow rate (at 3bar) and thermostatic valves for the showers that can do 30L/min (also at 3 bar). Guest WC basin mixer and kitchen tap are both rated at 24L/min each. So as long as i fit wide enough pipes, I’m not sure the limiting factor will be the taps?

I think I was just trying to understand the relevance of the flow rate of the tank. Is what you are saying that if my main water supply only gives me 20 to 25 L/m, i won’t see a difference between a 55L/m tank or a 130L/m? In both cases I will just get 20 to 25 L/m? But what if I have three outlets open at the same time? Won’t the 55L/m limit on the Telford Tempest kick in then, and limit my flow per outlet to 18.33L/m ?

That's helpful thanks. I've actually just found a 400L horizontal one. But what I'm confused about is that the flow rate is only 55L/m. That's less than half the flow rate adverstised with a Megaflo from Heatrae Sadia which apparently can do 130L/m. My understanding is that the main difference between the two technologies is that with an indirect unvented system, the Telford Tempest would need a separate expansion vessel whereas the Megaflo has some sort of air gap built in, so more efficient in its use of space and easier to install. But why would the flow rates be so different? Or is this all academic if the flow rate I'm getting from the street is about 20L/m to 25L/m with pressure of 3 bar?

Can anyone recommend a 400L horizontal unvented cylinder? I think the largest horizontal one Telford does is 300L.

The CO alarm point is a good one! Hadn’t thought Of that

I'm still on the fence. I've fallen in love with the Bora corner stove and had managed to get the manufacturer to sign off on the length and layout of our rather long air supply pipe, but it's not DibT certified, but maybe it doesn't need to be and this is just a lot of hot air from the HETAS engineer. He did try to scare me though, by saying "it's not just smoke that will leak, but carbon monoxide too". Now considering: Spartherm Cubo L Spartherm Seo S Rais 600 Max Rais Q-Be all of which are DibT rated (i think!), but still need to find out if they are all Defra approved for smoke control zones (as I live in one). Maybe I should just go with the Bora corner stove and set the MVHR with a bit of positive pressure and just find a non-HETAS approved installer.