Dreadnaught

Haha, thanks @PeterStarck. Perhaps I might, if I had your impressive ability! My problem is that my keenness is likely to overwhelm mine ?.

Good point. As @JSHarris also mentioned. That sounds like the answer. It is interesting to consider why the figures in Diagrams 1 and 2 in the Building Regs are so different. Both measure rain intensity but one is for gutter sizes and the other for underground drainage pipes. It is unclear to me why it pays to oversize gutters but not underground pipes.

Thanks @epsilonGreedy, yes please. That could help me put my home-brew numbers in a form that they might like & expect. Presentation matters!

Ah, I think you were right the first time @Mr Punter. Reading through it all, the rain-intensity figures for drainage come from Diagram 2, which also mentions "underground rainwater drainage", not Diagram 1 which is what I showed and is for roof drainage. As follows under "Section 3: Surface water drainage" … From diagram 2… So I should use 0.014 or 0.016 l/s. Now, I just need an exact measure of the roof area including the overhangs from my architects drawings. I suspect it is a bit greater than 120 m². But even if the drainage rate exceeds 2 l/s I suspect it won't do so by much so a little attenuation is all that I will need to hopefully fall into compliance and satisfy the drainage person in the local planning department. The drainage person was adamant that any attenuation device would need to be "permanently installed". I presume they have instances of a modified water butt doing the job which was whipped away as soon as their backs were turned. I am not sure what permanently installed means in this context. And she also said that a water butt would not do anyawy as it could be full on the day of a deluge and so do no attenuating. This has been very helpful. BuildHub continues to amaze! Thanks to everyone.

Thanks! When I look at the map in the Building Regs for Rainfall intensities below for "design of gutter and rainfall pipes (litres per second per square metre)", why is the intensity higher in East Anglia (0.020 or 0.022) than say Pembrokeshire (0.016) when East Anglia has some of the lowest rainfall in the country? Seems counterintuitive.

How would I calculate the drainage rate from my 120 sq.m roof area? I assume I need to find some standard figure for rainfall per sq.m in my area that will withstand scrutiny from the planners. Is that right? How then to convert that into a flow rate and a calculation for how big an attenuation tank I will would need to achieve a max flow rate into the storm-water sewer of 2 litres per second? Anyone know?

Ah good point. Thanks. You may well be right. I am sometimes too keen to try something new.

Thanks @Russell griffiths, @JSHarris . Yes, there is a lovely storm drain immediately outside may plot that drains into the river less than 40 metres away. But I just spoke to council drainage person and it seems that the new local plan requires SUDS down to 2 l/s anyway. I might be able to do it myself but am concerned about getting it right. I have a big no-dig zone so my amateur guess is I will need a biggish (1500l?) above-ground attenuation tank sited on firm footings outside the root-protection zone (as it will weigh a lot when full), like this…

I have a quote for a SUDS-drainage design for my 20m x 20m plot of £1,350 + VAT. Is that high? Any recommendations for alternatives? (The plot is located in Cambridgeshire if that is relevant. I need to attenuate drainage from 120m2 of roofing to a max of 2 l/s.)

Oh nothing extraordinary, just decent sound isolation between bedrooms that share a wall, and between utility room with a washing machine and the rest of the bungalow. By learning about thermal insulation, I have been Pavlov-style conditioned to be skeptical of buildings regs minimums. Not sure if I should be equally so for the household sound insulation. What do you think?

Oh nil expertise here, just quoting from: http://www.mullinsacoustics.com/tidbits.html. And I think I recall @nod referring to the better sound insulation properties of metal studs over wooden ones in general.

Good point. I presume that to some extent this can be influenced at the time of frame design (steels, etc.). Then perhaps the question becomes the merit of metal studs for non-structural stud walls. Are they worth bothering with?

Is there merit in ordering a timber frame but without the stud walls included? Reasoning: @nod has persuaded me of the superiority of metal studs. And YouTube videos make them look easy and DIY-able. No resilience bars needed with metal studs for acoustic insulation. I assume that metal studs will have less (no?) drying shrinkage. Less need to fix plaster cracks and repaint, at least for stud walls (would still need to fix cracks in the exterior wood panel walls). Seems to be a big benefit. I hope that the frame supplier would reduce my frame quote accordingly, although I suspect the stud walls won't represent a large part of the total. [Specific benefit to me] less on-site storage needed for the studs during frame assembly. (I have a very cramped plot.) What are the flaws in my reasoning please (I assume there are many)? Any other advantages of metal studs? (Context: new build. Will be ordering my timber frame as soon as I get planning approval, maybe in 6-weeks or so. MBC is my current favoured supplier. Frame will be 140mm open panel with U-value of 0.11).

For studs (and maybe only studs), @JSHarris's trick with little neodymium magnets?

Do inverters have a cooling fan?

The planners are considering my revised planning application. They have asked that I get an "in principle" confirmation from Anglian Water that I can connect to the storm-water drain in the unadopted road immediately in front of my plot, otherwise the local drainage department will start talking about soak-aways, attenuation, and SUDS, etc., which I am keen to avoid as I have no space on my plot for any of that. In the Anglian Water online application form for a new connection, it asks for a discharge rate in litres per second for surface-water drainage. What can I put for a two-bed bungalow of 120 sq.m?

Very possibly yes. Ceiling height will will be in excess of 3m at the peak of the vault. I am assuming that when I get that far my timber-frame designer and my M&E expert (now selected) can come up with ideas for where to put internal duct runs. The MVHR in its plant room will be at the central corner of an L-shaped building so I fundamentally have two runs to think about. One will be easier than the other: the one to the bedrooms has a corridor which can have a false ceiling. The tricky one is the other wing, getting a supply vent to the other end of a large open plan vaulted room, with exterior walls on both sides. The following might work. A low level duct run extending initially through a bathroom beneath a bath and then into the kitchen, under kitchen units and then finally continuing out into the open, underneath some built-in furniture might be one idea. If it is important for the supply vent to be higher up, I might even then be able to run the supply duct up inside a shelved room divider made by a cabinet maker which I plan to have. Having said that, I have heard @jack mention that he has (some?) low level vents (I am not sure if they are supply or extract) and they work fine for him. Good point. I do recall that German example. However I am thinking more about the internal ducting runs after the MVHR unit rather than the inlet and outlet to the outside. The outside connections fortunately should be straightforward as the MVHR unit will be on an exterior wall.

Hard hat on. It is possible to run MVHR ducting through a passive slab? I am starting to think about ducting runs from my bungalow with vaulted ceilings. As a bungalow, there are no joists to take the runs. Passive slab not poured for another few months at least.

When I was reviewing timber frame suppliers, I looked at MBC (Ireland and Gloucester), PYC (in Wales near Welshpool) and Touchwood Homes (Hertfordshire). Eden (Cumbria) was on my long list but I did not approach them in the end.

Thanks @MarkA. Looks like great progress! Very interesting to see. No apology necessary. Please count me in for a visit, if it won't inconvenience you.

Fascinating. I read that DU also has an usual physical characteristic helpful for munitions: self sharpening on impact, related to the sheer characteristics of the material. I wonder, can you confirm this?

For what its worth, I have a digital shower in my current place (I think its an Aqualisa model; it has the characteristic start/stop & boost buttons). It came with the house. And I don't like it. And in my new home I shall be choosing a non-digital shower. Reason being that, in the event of pausing the shower mid-way for any reason (for example for hair washing) then, on restarting the water flow, the shower hunts through the temperature range again providing an extended dose of cold water onto your head; rather unpleasant! The motor is also unpleasantly noisy: a high pitched whirr as the valve moves at the start, in the middle, and at the end of each shower. Just my tuppence worth!

A left-field comment. If in your build you will have MVHR then that requires a ventilation gap under each door to allow air to circulate between rooms. One build I visited in Hampshire decided to put those gaps above the architrave at the top of the doors instead and leave the doors without their gaps beneath. I thought it was quite a good idea. An option for you while you're doing it?

A poll strikes me as a good idea, as someone who will be choosing a window supplier in the coming months.

I love BuildHub! Not only is it a source of great knowledge… but it guards against any risk of procrastination. Thanks guys, I will get right on it!