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In our build the architect included a continuous row of celcon blocks around the inner leaf at insulation and concrete slab level (your screed level) to provide some insulation in the inner leaf between foundation/footing level and wall above. I think some people also build the inner leaf entirely from celcon blocks. I think our builder put the 25mm PIR around the perimeter and then used the underfloor insulation butted up to the edge of it to hold it in place - simply a matter of practicality to hold the edge insulation in place for our concrete pour. Think it may help if you can say whether you are doing new build or retrofit, and to describe the makeup of your wall structure - concrete block, celcon block, stone, sipps etc.

Can you please explain the difference between a vapour barrier and vapour control layer and why one gives a higher condensation risk?

Yes, not banned as such. Massively difficult and expensive to “engineer” a solution that will ensure compliance with the Regulation for all the above reasons.

I think you have a good point. If built as your first picture, then the heat is travelling from the screed horizontally through that thin isolation strip, and into a masonry wall. That block wall presumably sits directly on a footing in the ground. So increase the heat resistance of the strip by thickness and choice of material. Eg 25mm of PIR instead of the thin strip of something as shown. On the other hand, the surface area of screed to wall is minor as compared to the lower face of the screed. And heat loss through to earth is much less than with exposed surfaces.

As a last resort there are some pull down TV wall mounts that allow you to mount the TV above a fireplace but pull it forward and down for when you want to use it. Not personally keen on the option but wanted to make sure you know it exists. I was thinking that (with a small sofa). If you put a single rotatable chair to the fire side of that and then other chairs (or another sofa) in the other parts of the room you could effectively divide the room into a smaller TV snug and a somewhat larger social space, though the dimensions are a little tight for this. He wants this room as mainly for TV or he wants this room as a living space and to use another room as a dedicated TV space? How much TV do you watch?

Yes I could shuffle it all down there, maybe get another sofa so it doesn’t make the room look unbalanced? I thought it was an ok room but once you think about furniture it’s a daft room with too many doors.

Of course that's right. & neither does it go within a few inches of the ceiling (another current fashion). I'd be putting it to the right of the fire place, with the sofa directly opposite. The rad isn't ideally positioned, but that wouldn't stop me optimising the TV.

It’s not explicitly banned, but you’re talking a very expensive and different approach to it than those on the continent. It’s basically a legal nightmare, for everyone involved, forever. It probably wouldn’t pass your gateway 2 submission and raise a lot of red flags with the BSR and all the golden thread. At the moment we have materials like pipes and conduits that aren’t tested for certain applications, so you can imagine where plants and their watering systems, waterproof membranes etc are. Proving that can’t go wrong and the plants won’t die and burst into flames in the summer, impossible. It might be easier to get it on commercial buildings, so nice facades aren’t out the window yet, pun not totally intended.

Hi all, we are renovating and can’t seem to agree on this room. It has a fireplace which we would like to keep, and doors on three sides. Obviously the tv does not go above the fireplace… right? I don’t want to watch tv with my head at an angle, so what else can you do? Is it just impossible? Partner says he just wants a tv room, then what’s the point of the living room? Any ideas?

I have enclosed a shot, it is inside a hall cupboard! I fitted 150mm celotex tight to the walls, taped all the joints, fitted plastic sheet, taped then UFH. The perimeter edge insulation has an adhesive strip on one side which fixes to the upstand / wall and polythene apron which lies on the floor. Just need to make sure the screed cannot escape. Hope that helps.

@junglejim Does the picture depict your situation? Masonry build with a cavity?

I’m a bit confused by what seems to be standard practice so must be missing something…. The advice is to fix the expansion strip to the perimeter prior to floor insulation. (See attached) Surely as this is much less insulating than pir it provides a potential cold route to the slab around the edge of every room? Would it not be better to fit the insulation tight to the edges and then add the expansion strip above this. Taping the ‘skirt’ to the top of the insulation / visqueen layer will ensure a good seal for the screed without the need to compromise on floor insulation? i also thought it was good practice to install a vertical strip of pir around the edges but does the expansion strip negate the need for this? I’m likely missing something so any advice greatly appreciated. Thank you

It's gaping air leaks to worry about not diffusion. OSB will be adequate for your purposes if you tape it diligently, however a vcl may be faster. Beware the difference between a vapour barrier and a vapour control layer. With a barrier you'll always run a higher risk of Interstatial condensation.

Will give it a try tonight. It’s going to be hard to get an accurate reading from start up as it’s output % does change quite for the first 10 mins from start up. It goes higher and higher. I’ll wait for it to settle at a high % then do the 3 min tests.

Similar boiler on third heat exchanger

Chocolate, new wallet to replace the one stolen in Paris, socks. I'm easy to please.

Just had a phone call from NIE asking me a questions about power consumption I would need, the guy said if I wanted a larger supply I would need to upgrade the transformer on the pole which is 150mtrs away, he said that could end up being tens of thousands, he said that maximum supply of existing pole outside property is 18.4kw/80a, price for standard connection may be between 2k and 5k, if cable is more than 33mtrs long that’s another 2k to put joint in it (do cables only come in 33mtr lengths), he also said allow 10mtrs for the pole side so only 23mtrs from pole to meter box, I explained I may use a welder occasionally and I shall probably end up selling my large welding machine and buying a smaller inverter type but he was still a little concerned even though I can draw 8kw maximum from a modern 250amp multi process welding machine, everything else I shall have shall be an electric range cooker, general sockets and lighting and a hot tub if my wife gets her own way, I’ll wait for the official quote to come through…

Not answering for @John Carroll but I'd do readings from start up Logic is I'd want to establish that what the boiler is stating it's modulation state actually was. My 16kW Viessmann modulates from 100% to 10.8% - 100% is 19kW 10.8% is 4.2 kW the % values between the two aren't very linear or put another way if 10.8% is 4.2 kW 100% should be 38 kW

No worries, it’s been the bane of my life for some time now. NN is basically when you have an area where the powers that be have deemed the rivers are at risk of being overloaded with nutrients, and so they have effectively banned new housing in those areas. They are quite significant areas of the country. The same powers are working to a solution, which is to have housebuilders give money to the government to give to farmers. Nominally to buy ‘credits’ much like the ecological credits for biodiversity. So my main problem with this, is the excess nutrients in the river are caused mostly by the runoff from fields, *caused by farmers.* I don’t think one off self-builders especially should be punished for what is happening, when they only contribute minimal wastewater which is treated by sewage treatment plants anyway. The whole thing is a scam.

It's more than likely that it won't or shouldn't be at 100% firing at target temp so best window is well before it reaches target temp as it should then be firing at 100%.

Thanks John, does the boiler need to be at target temperature when I do these tests or does that not matter?

Mimo is the in the house network i think. Not the link to the outside world.

When does this come into effect?

@gc100 >>> I just got a good passive aerial/dish and pointed it towards the nearest mask (looked up online). It’s just plugged into the back of the router that has the sim Possible to say a bit more? This was a directional aerial? With gain? More than one (I see some router ads wasping on about multiple aerials and ‘Mimo’). 4G, I assume?

As above, more or less, get the boiler to fire at 100% for say 4/5 minutes, during that time take two gas meter readings exactly 3 minutes apart, should then get a fairly accurate feel for the actual boier output in kW. If the output is 36kW, then the flow/return dT should be 23.9C until the target flowtemp of 65.5C is reached, assuming a flowrate of 21.6LPM. Target temperature of 65.5C should be reached when the return temperature rises to, 65.5-23.9. 41.6C Maybe clamp the pump minimum output to 95% until all tests completed. Post back.