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Hello all, My husband and I are in the process of buying a plot of land with outline planning permission on it in Leicestershire. Just checking in here and introducing myself before I get to the point of bombarding all you knowledge-wealthy people with questions. I am doing lots of reading and price hunting at the moment. We are meeting our architect on Monday to discuss our brief and our initial ideas, and we can't wait. Looking forward to 'working' with you all in the coming months, maybe years! Sally

I did all the first fix plumbing in Hep20, and I've never done any plumbing before. We have a manifold system and it really is pretty easy. Watch a few of the videos and mine this site. Lots of information. I think the trickiest part was arranging the runs in the ceiling void. As we have four bathroom/en suites and single pipes to each fitting I tried to avoid tangling the pipes and they need supporting properly at regular intervals. Also if you have posi joists the metal edges can be quite sharp so need to take care when pulling the pipe through. Our ceiling above the manifolds looked like Clapham Junction!

A critical point that is often ignored! I keep harping on about the lack of dynamic modelling in "standard" interstitial condensation risk models, but I do so because it's important. Once water vapour has condensed in a region inside the structure that can be prone to damage induced by organisms that thrive on damp, then it takes a LOT of heat energy to cause that water to undergo a phase change back to vapour and be able to escape from the structure. In effect, you can have a sort of "one-way valve", where vapour enters under a certain combination of short duration conditions and condenses inside the structure. Insufficient heat energy ever reaches the area where the water vapour has condensed, so it stay there, and build up every time a dynamic condition exists that allows more vapour to condense. Some of these dynamic conditions can be of short duration - for example a cold, still, wet, night, followed by a hot and sunny windless morning, where the air immediately around the external structure and in any cavity could easily reach high water vapour concentration levels, and some parts of the internal structure may well be just below the local dew point for a time. The fact they get above the local dew point later in the day may not be enough, as there may still not be enough heat energy available to convert the condensate back to vapour.

OK hold on. It’s a 1950’s house with what will be most likely a 50mm cavity on average (it might go up to 70mm in areas like mine does due to wobbly blockwork) and dense concrete blocks so no lightweight or ACC blocks. You’re not going to have the house up at 90% humidity for long in an old draughty house unless you fit a sauna or steam room in your bedroom. Any humidity from cooking or a long shower(s) will quickly dissipate. I don’t think you’ve anything to worry about here BUT as it’s a 1950’s house you could consider putting in an airtight membrane internally and create a service cavity with 25mm battens and fix plasterboard to this. This is what I did to my 1970’s detached house along with 150mm external EPS insulation but I did it to improve my airtightness and reach the Enerphit Passive House standard. The airtight layer also acts as a vapour check reducing any interstitial condensation risks.

the meter monkeys round here just seem to use a white sharpie and don't always get it right

I'll get some at the weekend and post them up.

That version of BS 5250 is now out of date and BS 6229 is more specific for flat roofs. Calculation method for condensation analysis now in BS EN 13788. Remember these standards/methods are basically steady state rather than transient conditions you can however change internal/external conditions to asses greater/lesser risk.

We also have a Miele. They're fairly compact and pretty indestructible and maintain good suction even when the bag is almost full. Treated ourselves to a new one when we moved in but the old one (must be pushing 18 years old) is still going strong and is now the basement / building vacuum. However, I couldn't resist posting this... http://newsthump.com/2017/03/29/dyson-begins-work-on-new-10000-watt-vacuum-cleaner-for-proud-brexiters/

Be careful not to confuse confidence with blind enthusiasm