Alan Ambrose

>>> a gold star The buildhub olympics, yeah...

@saveasteading Thanks, that is interesting. The info I've been given is that it's largely down to the quantity of steel. Nobody said anything about the density of the mesh - although small mesh sounds logical. The bentonite filled sheeting sounds like Sika BentoShield or similar? Did that all work well?

>>> Do I get a sweety? Certainly for effort . Well yes, given the data you were given, you're right. PHPP, for my windows, says Z is between 62% and 82% with an average of 71%. Not sure where the discrepancy is - I guess I was giving averages over a bunch of windows, so that's it.

Seems reasonable (to me at least) that the long term direction of oil & gas is up, and the long term direction of renewables (i.e. electricity) is down. So, sooner or later the gap will narrow.

I've seen it specified before for areas that would get some occasional traffic. Its probably good for the purpose if it's laid well. You can get a feeling for the load bearing capacity between types simply by looking at the weight of the grid per m^2. I wonder though whether continuous usage by a car (and therefore sun & rain shading) and 'poisonous' drips of oil etc. onto the grass would make it not great for heavy use.

https://www.si-eng.org/post/a-journey-of-designing-self-healing-concrete#:~:text=The allowable crack width for,are harder to self heal. Suggests, for the typical self-build single storey basement (say, roughly 4m deep & 0.25m walls - i.e. 'pressure gradient~=16'), the optimistic value is 0.2mm based on the old BS8007 and the new C766 and the pessimistic value is 0.15mm from EC2-3.

OK here's a few numbers - from my window schedule in PHPP nominally using Rationel Auraplus & Velux. S/W/E windows using Rationel Sun SKN176; N wndows using Rationel Auraplus 4/20/4/20/4; Veluxes using Velux Heat Protection Glazing 69: Average Uframe=1.132, Uglazing=0.522, Uwindow=0.712, Uinstalled=0.822 If I change all the glass for better stuff with 90% of the U-value (e.g. 0.5 glass becomes 0.45 glass etc), the numbers become: Average Uframe=1.132, Uglazing=0.470, Uwindow=0.675, Uinstalled=0.785 So, sounds like the Uwindow/Uglazing factor (the discrete derivative? ) might be around (0.712-0.675)/(0.5-0.45) i.e. 74%. Hope that helps . I guess you can also sometimes get this from the window frame supplier's various double/triple glazed offerings - if you believe their numbers... You can play these type of games fairly easily by mangling PHPP if you choose to.

OK maybe check out the Schiedel ICID Plus flue brochure - there should be something there that works. Also possible to get the twinwall in black I think.

Not really It's an existing ditch that runs behind 3 properties in the countryside which we want to link up to. This was turned into a piped culvert about 10 years ago. I think this kind of 300mm twinwall pipe is the first thing that farmers/countryfolk think of when they consider culverts & ditches & rainwater. BTW in my twinwall travels I discovered this chart (below). The pipe is reputed to have an 1:80 gradient suggesting 1.8m/s & 150l/s. So, yeah, theoretically enough for 75 SuDS compliant houses if it was laid correctly and if the other houses used attenuation (they don't and one neighbour says it wasn't).

Thanks, but that's the Naylor stuff - I think this must be older or more obscure. There are some wacky rubber seal fittings to clamping sum close sizes together tho.

Anyone? I'm thinking, even though it was apparently installed less than 10 years ago, that the ~275mm id / 380mm od must be some old imperial size or old design. As far as I can see, the 300mm twinwall versions by Naylor, Polypipe, JFC, Wavin and Cherry (and probably Brett Martin) are all fairly compatible ... and not the same size as the pipe that is installed.

... I'm trying to join (as measured) 303 mm id / 352 mm od to ... 275mm id / 380mm od. The first one, is an Accesso inspection chamber, the 2nd unknown as yet. Just one of life's little challenges, grrr.

Maybe put in a small IP box, carefully spray paint that and the camera to match your eaves or whatever.

In the UK I might take the twinwall all the way to the stove to make life easy. You’ll almost certainly need a telescopic section anyway and this is most useful just above the stove. V important to ensure the stove/twinwall join is airtight, of course. Does that work for you?

>>> can't select a sd=7.5m VCL BTW you can creste your own materials in ubakus.