saveasteading

It's not worth changing washers etc. Fit a new one of whatever you've got.

Timber building is standard, but some insurers don't know anything about construction and rule out cover on a whim or misunderstanding. If you get building regs you will get insurance. But timber cladding on a timber building? Of course there is more risk. You would want a fire barrier between them, but would still have to tick the insurance boxes for timber structure and timber facing. On what basis are you choosing the construction? Why twin wall?

Cement board will be stronger and provide fire protection.

I'm expecting that to be much more expensive.

Exactly so. The fire stopping is easy so we can look at that when you have decided on a simple route and the pipe and cable and insulation sizes. There seems to be eps exposed in the garage. Does that get protected?

You'll lose so much heat out of the side and top that it isn't a great concern. But I agree with @crispy_wafer, and you could score the boards to threepenny-bit principle to nearly a circle. Have you checked the insulation strength? If it squashes it becomes useless.

I don't agree. Air to water I think we all know about. Some of that is taken to a plenum to heat air which is pumped into the room and a duct returns it from the other end. Simple but prob not for the typical installer who buys a kit.

It's good enough to find them. Thanks muchly. S and B EPS. Their website is comprehensive on strengths and insulation, and some other products. But nothing on where to buy or costs, so I've sent them an email. Strangely the strength and insulation vary by thickness, presumably a manufacturing density thing. And they make consciously stronger stuff too. k = 0.036 average.

We had an office, now sold, that used air to air. It worked well and quickly in heating and cooling and suited the big open spaces as well as the small. But we didn't walk around barefooted. In a domestic situation I have no experience of barefoot winter use on an unheated tiled and well insulated floor. But the principle is simple enough. If the floor is 25°C or so from absorbing space heating then it won't suck heat from your feet, but that won't be an efficient process. That's the main issue I think. Ufh is inherently warm and gives you cosy feet then spreads to the air which can be cooler. I don't see any reason against having both, it's just heat transfer through pipes to the floor or to a fan.

2 at least are further north than that.

Windows do that.

Yes, but does the floor screed move or crack under the foot of Xander Fagerson? And will the tv packaging be strong enough?

This is getting into science fiction. I need a lie down. What is the cube root of time anyway? Or is it a way of proving that that entropy isn't what it used to be?

They have the best of the quoted prices online at present, along with Insulation Wholesale. Some others say they will match any quote but I resent that attitude and will tell them that they must quote their best price first as I don't give second chances. If they are too scared to do that then I don't fancy their service or security will be great either. What is the point of matching another quote unless their is some other benefit? @Susie was this recent?

I meant after a winter of the ground source pipes removing the therms. They look like this but with arms and legs: That needs an Ancient Greek letter. You mean deeper to the perimeter? It makes sense to have deeper insulation round the perimeter, and shallower to the middle, but that isn't happening. It's just going to be a less efficient area of the building, balanced by the centre of the slab being over-insulated. Perhaps PIR to full depth around the perimeter and 2 layers eps centrally is the pragmatic (and finicky) decision. It is intuitive rather than proven, but I'm confident I could write a page of 'proof' for the building inspector if it was necessary... but it isn't and will just be our decision.

We were discussing what to do with rooms that should be cool. Larder/ cupboard etc. and does the Utility room need to be warm? The current decision is to put the ufh pipes in anyway but not connect them, so we have full flexibility if (when) there is a revamp. I think the same logic can be applied to the whole house if ufh is a likely addition in future. If diy'ing the cost isn't great at this stage but simply wont be done at a future stage.

where, where, where please?

that's great to get real figures. Thanks. We have the constraint and advantage of an existing 175mm slab, and the insulation will be 200mm thick. Because of its HP/A being 0.2, we start with a U value of 0.35 with no insulation, with 100mm pir this becomes 0.21. For 200mm I haven't looked. It is from a very old manual with 'never throw this out', scrawled on it, because the 'uninsulated' graph is not often published. Interestingly one of the graphs shows that 25mm or 40mm are almost equally effective when hp/a reaches 0.15. Also that 60mm and 200mm converge at about 0.07. With beam and block, which I like in certain situations, the hp/a does not apply. I've just been reading a rather superficial article in 'Build-It' magazine. It happens to have an advert for ground-source facing it. It does mention the very high area of ground required for a surface system (3 times the house size) and the high cost of boreholes. But it doesn't mention that some ground is worse than unsuitable and that the pumping takes a lot of power. It says it never needs defrosting but I know that to be untrue for all cases.... or maybe the issue has ben sorted. In reality, surface systems are not heated by the ground, but by last year's sunshine. Slinky coils seem to have disappeared as they aren't mentioned. I wonder how much the temperature at 1m depth drops by the end of winter.

So far, simply using online published rates with no allowance for quantity.. celotex or other names all seem to be the same price as listed below, since when I've found cheaper but must check the spec. eps varies by vendor and many don't do it. please excuse that the Tab key doesn't work PIR thickness £/m2 £/m3 25 4 161 50mm 6 121 75 8.4 112 100 10.4 104 Now found approx £88/m3 120 12.7 106 EPS 25 2.16 86 50/75/100 all 86 unfaced pir 90-100 £8.51 £85/m3 as you will see, this bears out what some of you clever people have said about 100mm being the most competitive.

Apologies for an oversimplified discourse. I meant 'we' as the simple requirements of the regs for a new build, but with BH level of care and supervision. So it will satisfactorily airtight but with the resulting dribbles of air through the fabric, and more at fans and any vents. Good pun on manor/manner. Draughts was a deliberate over-statement. I meant airflow that isn't designed. Every time the front door is opened there will be a few m3 of air in or out, however well mvhr is designed. I don't suppose we will ever know the reality unless we here of a newbuild without MVHR that is failing on air quality, or someone builds 2 otherwise identical houses for comparison... and that won't happen. Plus cynical me says that there is an industry that sells mvhr, but not one that suggests not adopting it. Included in the decision are the weaving of ducts through the structure, the ease of maintenance , and the unknowns. Me? It remains debateable and I have plumped for 'not'.

I'm aware of that but reminders are no bad thing. I wonder how well a soft packaging eps would fare beneath 100mm or more of PIR and a grand piano on top. perhaps with a big enough dish under each wheel it would be ok. This is whimsical: I am not saving amazon packaging to try it.

Something else I didn't know. Seems to be a saw tooth but with a wavy profile to avoid sticking, and produces less dust. Between a saw and a knife. £22 The Bahco insulation saw has been specially developed for cutting various types of insulation material

Sorry I don't understand the question.

Best wishes everyone and esp thanks to the moderators.

Excellent graph thanks. May I ask it's origin? That's for an infinite area or based on some HP/A assumption? Theres a bit of a kink at 100mm ish thickness which seems wierd and that really underlines how worthwhile 100mm is. Severely diminishing returns after, I'd say, 200mm PIR. And no significant benefit after 0.3? ie a complete waste of resources.