jack

One of our smoke alarm mounts has a relay that closes when any of the alarms is triggered. Our home automation system takes this as an input and... presently does precisely nothing with it! But we could use it to kill power to the MVHR if desired (and wired). Personally I don't think it's an issue - building regs don't require it and I can see arguments both ways for leaving it on and turning it off. For me the main thing is waking up and getting the flock out of the house as soon as there's smouldering. By the time any fire has got the bit between its teeth, my family and I will be long gone.

If that happens, then I imagine the pressure would completely overwhelm the MVHR fans. If you're right about pressure, then closing the inlet at this point will cause a further increase in pressure, and the smoke will therefore potentially work its way through the rest of the house seeking further exit routes as the outlet in the area of the fire (most likely the kitchen) is overwhelmed by the volume of exiting gases. I know you asked how you can achieve your proposal. I think Pete's offered one option there. But turning off the MVHR (the standard proposed approach) will do most of what you're asking. You've said that pressure increases greatly. If that's right, then nothing the MVHR does is going to make much of a difference. I'm not saying any of this is fact, because I simply don't have the necessary knowledge to do so. There are some interesting principles at play though, and I suspect there must be a reason that MVHR manufacturers recommend simply turning off the MVHR in the event of fire.

Allowed by whom? That's a good question! Our (private) building control has seen our plans including the UFH being clipped to the steels. He's happy. Several other people have had MBC houses (which all use this arrangement) signed off by building control. I believe @Bitpipe had an architect (or perhaps engineer) who wasn't comfortable with this approach, but this was in a basement with some very stringent structural requirements. Don't suppose the steel would hurt heat movement, but bear in mind that with a very well insulated slab you don't tend to use high heat levels. Our ASHP is programmed to provide 25 deg C water to the slab during winter. I programmed in a mild weather compensation curve starting at 10 deg C exterior temp, with the ASHP supplying up to 28 deg C water at a -5 deg C exterior temperature. Never felt cold all last winter. You basically keep the slab largely at the same temperature all day and night, rather than blasting heat in morning and evening like with a screed.

I looked at this before we started looking at raft foundations. I recall it being interesting stuff, but very expensive. I think it's produced somewhere in Scandinavia.

I don't know all the ins and outs of combustion, but if something's burning to produce gas, surely it's consuming gas (ie, oxygen) to do so? Is there a net increase in the volume of gas, other than via expansion due to heat?

I don't think you'll get very much airflow at all if you close the inlet and boost the outlet, as you're largely extracting against a sealed box. All you'll do is lower the interior air pressure slightly and draw in small amounts of air from around windows and doors (the main relatively leaky points in most airtight houses). That's why standard advice is to shut off the MVHR rather than boosting etc. I've seen inlets with intumescent collars, the idea being that the duct will close when the heat gets high enough. But frankly by that stage your smoke detectors should have been going off for several minutes and you and your family should have left the house. Have a look at the different types of detector. Some are better at detecting different types of fires (eg, smouldering). Given your apprehension (natural given your experiences), consider going belt and braces with both types in or just outside each bedroom, plus kitchen, utility room and anywhere else you need. Consider whether you want a sensitive smoke detector in the kitchen though - too many false alarms.

No steel? Is it fibre reinforced? I'd have thought you'd need one or the other as an anti-crack measure.

Right, gone back to source (invoice). I knew it wasn't 22mm - it's 28mm, like you were using. I can't imagine how difficult it would be to work with the JG Speedfit stuff if it's noticeably stiffer than the Hep2O!

Actually, now I think about it, it's 32mm. Forgot this was for the ASHP runs

22mm Hep2O barrier.

Is it the same thickness/stiffness? I used barrier pipe for a long run from our ASHP and it's surprisingly inflexible. It also tenaciously wants to hold onto the curve it acquired while coiled up. Perhaps non-barrier would be the same, but I didn't use any of that myself, so can't say.

Perhaps oddly, the cheapest source for our Fakro roof windows was our local Travis Perkins (who we had a pretty good relationship with at the time). Also, Fakro's sales department were very helpful - might be worth a call to them to ask about distributors and who's likely to do them for the best price in your area.

Don't do it - that way lies madness!

"Finished" is a fascinating word, don't you think? We moved in just before Christmas. Our "let's take a few weeks off to refresh" turned into several months with very little getting done. We've recently turned up the wick again and have started working through our to do list.

Yep!

I remember this bit. Everyone wanted around £1000 every time we needed anything doing (and sometimes several rounds of £1000). Wait until the next bit when everyone starts wanting £5k every time you need something doing - and then the £20k round that follows!

Welcome to the swear-filter-less future! Glad you found us.

The Brink 400+ seems like overkill for a 96m2 house. We have that model for a 289m2 house! You could go for the 300 or even the 180 model: http://cvcdirect.co.uk/Whole House Ventilation/renoventexcellen.html One good thing about the Brink units is that the filters can be vacuumed and reused. When that's no longer effective, you can just replace the filter medium yourself, as it's simply installed onto a rectangular wire frame that can presumably be reused.

I think I did about every 300-400mm on ours. Seems fine. Hmm, they didn't glue ours. Wish I'd asked them to now! It's possible that the couple of squeaks I've detected aren't actually floorboards. I've assumed so just because of how localised they are.

We screwed most, but not all, of our power-nailed 22mm OSB upstairs floors. The areas where we didn't add screws have already developed a couple of minor squeaks after a year. Thankfully it's mainly the guest bedroom, which I'll only rarely have to go into again once we move back into our bedroom when the ceiling's been replaced. We used these: http://www.screwfix.com/p/spax-flooring-screws-4-5-x-60mm-300-pack/88716 They use a special bit (supplied) that doesn't slip. They drive in very nicely with an impact driver.

Nick's sense of humour?

We have a few 50mm flex conduits running between places that might want more wiring in the future, they're just not where I need/want them (or course)!

+1 to more cables. I tried to do this and yet there are already a couple of runs I wish we'd made that we didn't. There's virtually no point trying to do this now, as the missing runs are long and would require too much disruption. Someone (Prodave perhaps?) suggested putting a "liftable" section of flooring along the edges of halls and any part of a room to where you might want to run things. It's much easier to lift that and run things through the floor, than trying to get into the walls or ceiling (especially if, like us, you don't have a loft above the insulation).

We used that stuff too - amazing it can stick to plastic like that. Tiler would have been happy with PVA P.S. - What is it with the building trade and putting bloody PVA in/on everything? Concrete, paint, plaster, as a base coat for every single thing in the build? It's like they all get given shares in a PVA factory when they join the trade!

You're probably better filling it to the brim and covering the cap with a wet towel. More fuel = less temperature rise for a given amount of heat, plus no oxygen in the tank to allow combustion. I'd do this in conjunction with the screen ideas above.