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:eek: could you at least tell me why i have done wrong. @^woody^ is telling me to put a membrane down which “stops weeds” but it is the same material as dpm. but then i’m told i don’t need a dpm as it is a timber raised floor. just tell me what i need to put down instead of the reg lingo...

So can you just respond with YES if this is right: sand blinding, dpm to resist “moisture and plant growth” ( this will be butted up against the blockwork not connected to the dpc), then 50mm of concrete goes on top of this dpm, which then i will leave a 150mm gap so i can have a suspended...

sorry @^woody^ exposed the crucial detail that the membrane is for weeds not damp.

ah i see i see. isn’t polyethylene a dpm material though, so i still need to lay this, and i’m guessing i can butt it up to the brickwork as i don’t need to join it to the dpc. also see diagram below: if i didn’t lay this membrane which is the same material as a dpm, could damp come up from...

So you do have to lay a membrane????? which one?

timber ground floors. so a floor with timber, raised or non raised

Timber ground floors: Timber used for suspended ground floors should be treated or naturally durable, in accordance with Chapter 3.3 ‘Timber preservation (natural solid timber)’, and the ground below the floor covered with: 50mm concrete or fine aggregate on a polyethylene membrane laid on...

so just 50mm blinding sand and then concrete underneath? why wouldn’t i need a dpm as damp could rise couldn’t it? would there be any harm in putting one and butting it to the brickwork instead of connecting it to the dpc? is there a diagram you can point me towards?

four screws then, either way i’m asking about penetration of the dpm.

Also you say here that the dpm and dpc are not linked for a suspended timber floor??

ok i understand this. but as i said earlier when the dpm goes up the wall can i penetrate this now and again with 2 screws for joist hangers? if not how else am i going to keep the joists in place?

what if i didn’t. as outside is being rendered.

where would my ventilation go?

in a suspended floor why are these not linked (going up the wall to the dpc). you will still have that small bit where water can get across.

i have added to my diagram shown below. so i know i need a 150mm gap from concrete. my floor level will most likely be around the height of the dpc. is the diagram correct? also say i was going to put joist hangers to the wall, would it be ok the penetrate this with maybe two screws for every...

extension. will have footing then 3 blocks flat on footing, then will have 2 blocks upright going to dpc. my question is that once i have put 50mm of sand then my dpm on the floor, when i get to the blockwork can i cement this into the nearest mortar joint. i was thinking of putting a few blocks...

this is hypothetical. but i now understand there is no need for the extra mcb as there is already over current protection at main cu.

ah i understand. IR testing whole circuit isn’t possible due to rcd and neon indicator, take both legs out of rcd test them individually, do the same with neon indicator and they should be all pass. also rcd doesn’t mess with r1+r2 readings do they? this makes sense now, i don’t have to take...

so you are saying i could have a small cu with only a 30ma rcd and nothing else? and i’m guessing they put the 40a mcb in with it as if you were tapping into the tails or main switch as you said? how would you write down the tests on a form as how would you split the cable and put in down as on...

i am a little confused about mostly testing of sub circuits this is what i get so far and i am basing this off of a shower sub circuit that has a shower cu with a 30ma rcd and a 40a mcb ;; also at the original board there is also a 40a mcb.: you have to test ze at origin of board, then you...