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Yep, volts is key here, low volts mean big amps and big cables. So if your battery is 48v dig deep in the pocket, it won't be cheap. Have battery and inverter close.

Where does that definition come from? I must have done 250,000m2 at 10% using steel. It didn't feel flat when walking on it.

OK so it is rather flat. Metal will have to be very well detailed and built as water will drive uphill in strong wind. That needs serious thought and close supervision. Screwed panels are OK, despite what some people say IF done well with top quality screws Hilti etc. I've known more problems with felt/ fibreglass as it's often done badly.

Yes, no, as long as possible, yes. It is a "tell-tale" I think glued is preferred as it doesn't twist.

Should I use one of these, before I involve a local structure engineer? 1) can I glue it, rather than screw? 2) will they want to supervise the installation? 3) how long is useful for a device like this to be in place? 4) will a structural engineer find this helpful or not.

Better picture of the roof being replaced. Apart from it becoming one roof our planning only allows this height so we can't raise the higher side for angle or reduce the lower side as limited head room inside.

WE are vey slow building, think Pocster 🙂 So, although temp for storage realistically it needs to last probably 2 year. this shows how the roof was done previously when built in the 60's. We will be using the same roofing sheets, but the wood is pretty much knackered. We just want to replicate this as cheaply as possible for dry storage, the roof material is very light as just rain cover. This is all held together with joist hangers but we were hoping to do wall plates and joists. The issue is that roof one (not there in this picture) is 4.2m including the walls and roof 2 is 5.4m. For what we need we are happy to 'join' joists to make the spans from 3.6m sections, but that means for the phase we are doing we will need 64 joists plus wall plates which potentially might not survive being left for years. Phase 3, which is the bit you can see until the blue barrel behind the wheelbarrow will not have a temp roof. Once that is finished then the whole lot will be done properly with the posi-joists.

This is replacing the previous barn roof which was in situ since built in the 60's. That was metal and drained fine, albeit lots of water when it rains due to the size. Very much flat. It is being replaced with one roof covering both sections seen below. In this picture we have already removed gutters and part of the lower roof. It won't be this profile of sheets. It is facing south so I was hoping to put solar on top. the dead trees are long gone so nothing to stop light. Picture taken from other end, but this is what it looks like now.

Agree with @Nickfromwales, but if you do still want an 'interim' solution what about the longest 50x50 sawn you can get - probably 4.8 or 5.1 x 2 with ply or OSB between, as 'quasi I-beams'? 2 x 2 will come in useful in its own right or glued and screwed as 4 or 6 x 2.

As my MVHR unit is loft based, I constructed a small floor to ceiling cupboard in my sons room for shoes and the like. At the back of this is a 300mm*500mm void which I pass a bunch of ducts and an SVP stuffed with sound insulation as best i could. All through egger ontop of posi's. Personally I wouldn't cut each hole individually. Edit, All this is within the heated envelope of the house.

Gradient Degrees to Percentage.pdf

A roof is classed as a flat roof up to 10 degrees. I am currently working on a small area of roof on my place and although it is 11 degrees, I'm treating it as a flat roof, for covering material. https://ikogroup.co.uk/news-advice/what-is-flat-roof-compared-to-pitched-roof/ https://en.wikipedia.org/wiki/Flat_roof

It’s important not to have panels too horizontal - I think 10 degrees is the typical minimum - in order water drains off the edge and doesn’t pool, reducing performance as dirt is left behind. Maybe some glass only bifacial panels avoid the slight edge lip so allow for shallower angles.

So. I went around checking the pipes when I started this thread. For some reason one of the cisterns had a screwed on plastic cover behind the flush plate instead of a plastic twist like the other ones have. I didn't check that one as I couldn't be bothered getting a screwdriver at the time. Of course that one blew two days ago. Luckily I got up really early and heard it. It was dripping through the ceiling, but just needs repainted. I think it had maybe only blown half an hour before I got up. Of the nine of these that I have, I have replaced four, another four seem fine and I need to check the one today in my daughter's bedroom. Two of them would probably have blown within the next year. We have stopped leaving Toilet Duck in the cisterns, I will report back in a while to see if this has stopped the corrosion. I also, however, have to replace three or four of the connectors between the inlet valve and the pex pipework in the house. I am hoping that now I have figured out there is slack in the pex, I can just pull it through into the cisterns to change the flex pipes over. But I suspect it won't be that simple as the pex often comes up from below and the hole in the cistern is in the top, so the pex won't bend enough to come through the small holes and I will have to cut the holes bigger. I have ordered nylon coated flex pipes for this, so that they cannot corrode in the wall unseen.

Hi, I’ve got my MVHR designs but wondering about coming up through the floors deck (above posi joists). I have one section where all of my upstairs ducts will come through as o 7 ducts each with 75mm diameter. I’m wondering whether I should cut a rectangular section and add noggins around the edges of deck or individual circular holes or something else? Thanks

The battery wouldn't care if the inverter is 5 or 100m away but your wallet would when you buy the connecting cable. Our battery comes with 50mm2 cables for a 1.5m run

Sorry I wasn't clear. They don't normally need to be close though some of the sleek all in one type obviously do! This was in the context of a long DC cable run from panels to inverter (and battery) There was a suggestion about putting the inverter next to the panels and running the underground cable in AC. If we used AC coupled batteries they could then be at the house connected via AC But a hybrid connects to the inverter over a DC line so if the batteries are to be at the house i'd need a DC line from the inverter by the panels to the house alongside the AC line from the inverter to the house! Which defeats the object of putting the inverter by the panels (to avoid a buried DC cable) in the first place 😁

If your proposed future roof needs parallel chords of a posi joist, at lengths like 6m, then you have zero chance of running a 4x2 for that distance, singularly, as nobody stocks them afaik; they’d be too weak also. For my current client I have had to sister 2x 4x2’s to get beyond 3.6m; single 4.8’s are possible, but are weak and useless. For s roof, forget it basically. Posi joists are cheap enough, so wasting time, effort, money the way you propose is a bit ‘non cost-effective’ and methinks wholly impractical.

Your choice is a), over-mitigate with AS basin traps on top, or b), add them later if they’re needed. If you're going to buy a trap anyways, fit an AS one on both first as last; buy good quality ones from the likes of McAlpine.

If this is the case then the aav doesn’t need to be at the furthest point? Is the basin gurgling fear mostly avoided by using the AS traps?

Time for a day off the internet for you.

No magic flap is inedible. It may stop them walking, won’t stop them gnawing through it; they get through concrete for context.

It does? That is info that has passed my by. Im unclear why the battery would know or care if the inverter is 5 or 100m away? Whilst theres no batteries in my immediate future, longer term its likely.

As long as air can get into the pipe that drops vertically, it matters not one single bit where it comes from.

So would you recommend using 2 x 2” aav’s at the furthest point nearer the bog in the ensuite and not bother with an aav in the family bathroom?