Pocster

Ok just thought of another place under stairs - I mean where the bottom stair joins the floor - it might need fixing to the floor depending on staircase type ...

Hey all! I'm trying to work out/guess where UFH shouldn't go Under kitchen units Under stand alone fridge freezer (better not ever relocate it!) Under bath? Under toilet - I assume not as pointless and also depends on type of toilet; might need bolting to the floor In a porch? i.e. area between front door and 'inner' door What do we think?; anywhere else in a 'normal' house Cheers

Yeah. I'm probably over thinking this and maybe confusing you The problem also is different manufactures / resellers give different advice. That newton link did seem the correct stuff (for example it deals with any 'floating issues' ; something one of the sales guys mentioned ; hence his suggestion of sticking insulation to the floor). TBH as my slab is 250mm thick it's going to take some serious water pressure to come up through that. I also have an external land drain around the base. The general ideal was that it could/would fail some day. The plastic sheet membrane externally on the walls also could/would fail one day. The internal dimpled membrane (floor and walls) into drainage channels theoretically (!!!!) can't fail ....

No load bearing walls. The architect's original slab was a 'raft' ; so effectively had a 'gap' underside in the middle ; he suggested to make this 'form' to put insulation in there (non load bearing). The edge of the slab (load bearing) has foam-glass equivalent insulation. There is zero specification for drainage below or in the slab ; this is what has concerned me and hence my post. BTW you've been super helpful! Here's a link to a 'suggested' floor insulator I've been sent i.e. expensive! https://www.permagard.co.uk/newton-fibran-xps-500-c-closed-cell-insulation

Ah I see. So you are saying use the insulation in the centre to form my channels (rather than sacrificial screed). One company did suggest this; but said I had to use foam glass for the insulation - now I know; this stuff is MEGA expensive! - it would be cost ineffective. I think the problem was walking on the floor membrane would simply dent the insulation . I'll have 2 or 3 sump pumps with battery backup; don't worry about that!! p.s should I 'stick' the insulation to the slab????

So *more* insulation on top the slab?? Insulated Slab Screed to make height for drainage channel Floor membrane for drainage Insulation UFH Screed That correct??

:-) I know when you said "for me" I assume I've done it wrong ! Yes. My assumption was the UFH could end of heating 'ground water'. So with the floor membrane beneath the UFH this should be avoided. Beneath the insulation in the slab is plastic sheeting ; but I guess this can only reduce the chance of water coming up through the slab. After-all it only takes 1 hole somewhere!. Perhaps I'm going belts 'n' braces on this - but better safe than sorry!

The slab is insulated to 250mm. Whats wrong with the drawings? i.e. no viable floor??????? here's a manufacturers info; you can see the 4 suggested methods http://static.safeguardeurope.com/downloads/datasheets/aquadrain-perimeter-drainage-channel-datasheet.pdf#_ga=1.192104355.866109518.1486119729 So example 2) is what I'd end up with by adding a sacrificial screed. Actually floor spec; is just this!!! Floor Structure 50mm screed on; cast in situ reinforced concrete slab to Structural Engineer's details on; polythene on; 100mm thickness insulation on; tanking membrane on; blinded hardcore

Right! Finally got to talk to someone who seemed to understand! Easiest solution seems to be battens around the perimeter and a sacrificial screed in the centre thereby creating my 'channels'. Presumably then floor membrane ontop ; UFH and final screed. Just one question if this is the best method. The existing slab; does it need 'treating' before the sacrificial screed is applied or will that just stick anyway (obviously will jet/clean slab first)?

There! Hope that helps. I called a few of the membrane suppliers and most suggested it had to (unsurprisingly) have the channel below the floor level. But some definitely had it sat on the floor! Is my suggestion ok?. Majority of any water ingress is via the walls; but I have to assume it's possible I may get some up through the slab. Thanks p.s. forgive quality artwork!

WET UFH Will put some drawings up to help explain

Hey PeterW! Concrete pour was meant to be finished slab i.e. UFH + tiles on top My assumption was the UFH heats the slab also to act as a thermal store. "If UFH is needed and you have a decent insulation layer below the slab, why not just lay UFH on the slab and put a 50x75 up stand around and top with concrete - so two jobs with one ..? " Not sure exactly what you mean by this?. My issue is the perimeter drain would currently be above the floor rather than below it. Can you explain please? Cheers

Thanks I've got the height no wiring or plumbing is in yet ; so no issue there should I pour concrete though or pad up with insulation? Does it matter ??

BUM! My insulated reinforced concrete floor doesn't have drainage channels at the perimeter ; which are needed! To chase is out (!!!) would be a nightmare (100mm x 50mm) around 30m of it Can I cheat?. Could I bolt wood around the edge and then simply pour concrete in the middle? i.e. make a channel effectively by raising my floor? The reason for all this is as I'm below ground I have the dimpled membrane on the walls for drainage; but I'm guessing I should have a dimpled membrane on the floor that runs into the perimeter channels i.e. has to be higher than the channels. Also if I 'chase' these channels there's no way they are going to be level and neat!. Is this a good plan? Although my concrete slab is insulated I did wonder rather than put concrete in the middle why not just put an extra 100mm insulation down and then the membrane on top? (followed by UFH and screed) Advice welcome! (so dumb!; on pouring the slab I could of allowed for this with ease! )

This one did. It was an expensive fan that runs constantly and supposedly adjusts depending on the humidity. You see my concerns for this issue with MVHR.

Hmmmm ive had bathroom extractors with the flexible ducting get moisture build up in them and then sag . Making the problem worse .

So what stops condensation and moisture build up occurring in the MVHR pipework?

Yeah; it is nice!

Yeah I looked at that!. I *think* I'll ask then about the hob 'down' extractors and see what they say.

Yeah this is the type I mean. I guess Im thinking it could still create an air imbalance for the MVHR; but does that matter just for an hour of cooking? Cheers

Thanks guys. What about one of the new hobs; where the extraction is built in and at hob level??? Or does it not make any difference? i.e. any extractor must be a filter type rather than vented type?

Hey all So how do you deal with this and MVHR?. Because in theory (and I suspect practise) the MVHR could spread cooking smells throughout the house; yes? I presume you do not want MVHR vent above hob/hood? Thanks in advance! Cheers

Yeah I worked out the savings also by just not having gas. Also with PV I always think electricity is more 'flexible' i.e. you can generate hot water from it, cook, heat etc. etc. and run my mac :-)

Of course!

s24 etc. will cause a slowdown in house turnover. But supply and demand!!!. Less to rent and less to buy. House prices can for the short/mid term only go up!