Russdl

Well, I have a standpipe. My first dabble with blue MDPE and plasson fittings - a bit like massive Lego, I feel like a builder, and I will now stride around in my Dunlop Safety trousers with a new feeling of self worth. Being generous my standpipe is producing 15 litres of water a minute - but most importantly, it's not leaking! Now for the pressure test, I'll call the water company first...

@Nickfromwales I woke up thinking about an accumulator!! I think need to arrange for some more interesting dreams ? I presume the blue connector that I need to use, with the 7mm internal diameter, will have no effect on the static pressure? I also presume it will have an effect on the flow?

@Nickfromwales I'll be doing that in the morning, so ? @ProDave Probably not. The water is turned off at the meter which is on a road about 50m from the property. I found the main in the corner of our plot and a straight line from that hole to the meter would be under the 2 neighbours back gardens (green line in the image below). I suspect they wouldn't want me digging up their gardens (but I haven't asked the question yet. To replace the main, I suspect the only viable option would be to route it up the gravel track (red dotted line below). I'm hoping Nick will be right and the flow from my piddly little main will be sufficient.

It turns out we have a 3/8" Alkathene water main. Is 3/8" big enough to produce the goods when it comes to connecting to the new house? To set up a temporary standpipe I've got a Plasson 90° elbow (with a blue adapter) the internal diameter of the blue adapter is about 7mm. Does anyone know of alternative connectors that don't restrict the 3/8" Alkathene, I'm guessing that 3/8" is too small and 7mm is way too small?

@CC45 that’s been our best guess up to now, pretty heavy duty earth though! @ProDave we have the electric DNO on site in a couple of weeks so I’ll get them to peer down the hole.

Thanks Nick. It's definitely sub 20mm external diameter, no more than 17.5mm, should there really be a 2.5mm tolerance? The plan is to have a standpipe off the main at that location as a temporary supply and then, when the build is complete, run the main from that point to the new house. I was thinking of a 90° elbow up to the standpipe and at a later date, replace the 90° elbow with and in line join for the new supply. Are there massive flaws in that plan?

Well, a friend bought his mini digger round and we've found the water main... It's not iron or lead, it's black poly (is that the correct technical name?) We also unearthed a steel cable buried around the same depth, can anyone tell me what that is for? Should I hide it quick? The water main itself is externally just shy of 3/4" and internally it's pretty much bang on 1/2". So, have I got a 3/4" or 1/2" black poly main? I'm assuming it will be imperial as I suspect it's been there for decades (in new money, externally it's 17.5mm).

Wouldn't that be fun!

@Onoff. Thanks, thats just the kind of practical advice I was looking for ?

(Minor thread drift). I know where my water meter is and so I can make a pretty good guess as to where the supply enters the plot around 50m from the meter. I want to set up a building supply prior to demolition so I dig down and find the supply pipe... And then what? It's probably a sixty-ish year old pipe. Are there special techniques, tips and tricks to cut it and fit a standpipe and how do I connect a standpipe to the supply pipe? What bits do I need (apart from a mini digger).

Wow. Good luck Vivien, @ProDaves comments make for pretty scary reading. I hope a simple (and cheap) solution is forthcoming.

We are planning on using Tata, MBC say it should be laid on OSB and the OSB should be on battens for the air gap. Can you give me a link to the Aussie/US stuff?

Great news ?. You seem to have everything under control. I’m looking forward to seeing the photos as well, and hopefully I’ll pop along when MBC are there.

That is really interesting because the main player using the I beam construction would appear to have many more certified passive house's out there than MBC using (what you would consider) an inferior construction method to achieve it, that's reassuring as MBC is our company of choice. I didn't realise you'd done that. As my design has concealed gutters I think I'll be stuffed on the eaves but should be able to get a bit in the ladder frames.

Yeah, I guess I was trying to cheat the system! I've changed it to 55 W/mK and reduced the % of nail plate due to all the holes in them. As you predicted, the impact is minor. The last PHPP expert I spoke to suggested replacing the nail plates with OSB webs (which the manufacturer has agreed to do at no extra cost) but I have to say it seems like complete overkill and I suspect I won't bother doing that. I suppose the bottom line is that I have more faith in @JSHarris's U value calculations than the PHPP expert I spoke to, and I'm starting to feel inclined to ignore the PHPP expert (which means that was an expensive conversation!)

@JSHarris Certainly can, off to look at windows now ? The nail plates in my model have very little impact but they are not as accurately modelled as yours.

@A_L Some very interesting observations there and thanks for the attachment, and yes 'twin stud' construction.

@JSHarris I've modelled the nail plate over the central 122mm noggin (it would of course extend either side of that, as per your CAD drawing) but I found that an easy way of modelling it. I didn't consider the fact that it's full of holes but I guess I could just reduce my % of metal in the frame to account for that.

@JSHarris I've no doubt that is accurate, and much different to the figure I've achieved in my PHPP. Can you see any glaring errors in the data I've put in to my spread sheet that has resulted in my U value of 0.137?

Wow! ? I should have guessed! I'm just scratching the surface, clearly!

We're planning to use the same timber frame as @JSHarris (and many others) and if I enter the wall construction into PHPP with a U value of 0.12 I get this: If I then add the % of timber frame (6.4%) and nail plates (0.016%) in the wall (as explained to me by a PHPP expert) it changes the U value a fair amount and pretty much everything else on the verification page: The difference between those 2 verification screen shots is purely down to the 6.4% timber frame in the wall construction and the 0.016% of metal nail plates, I find it quite amazing the changes that produces and, as I said earlier, I've not even started on modelling the roof construction into it's component parts. Has anyone else modelled a timber frame wall construction in such fine detail? Is this going over the top or a useful exercise?

In case we had to get shot of it before we popped our clogs is the main reason. Or maybe lack of faith in me getting it right ? Probably the latter. Probably justified, time will tell.

Still on the fence, but falling towards 'not' (if permitted, we all know the rules) I've loved and loathed messing with the PHPP in equal measure. My geo-located Sketchup model has probably guided me more than the PHPP as you can produce the sun/shadows for any time of the year/day and it really reinforces that gut feeling. It's around 190m2 and may look something like this.

I think you've hit the nail on the head there. The thing is Mike, mine looked like that (without any shading) but I'd made a mistake in the data, which wasn't spotted by my second PHPP expert (and his credentials put him right up there - expert that is), and when I corrected my error it was 10% 'frequency of overheating'. I'd always planned on shading for the SE and SW elevations because I reckoned it would need that by just 'eyeballing' it. After fixing my error and putting the shading back in I'm down to 0% overheating. I think. That's what my PHPP says at the moment anyway.

Out of interest @Dreadnaught are you going for certification? I was on the fence but very happy to use PHPP to guide me. The better half was/is very keen that we get certified but after our last meeting We are now not so sure.