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Appreciated, that makes logical sense to me. Will wait and see if anyone disagrees.

Yes this is a slab resting on insulation and the ground (not suspended). Conventional wisdom seems to be you need a decent layer of sub base whether thats graded MOT, stones or just rubble to spread the load and prevent settlement, although my uneducated self never fully understood this (the...

As summarised in my other thread about a separate issue I have broken up and removed a concrete ground floor slab in a house, which was sitting on top of about 200 mm of loose stones (with the DPM separating the two layers). These stones are just that, with not much in the way of graded finer...

I have decided that I won't use these stones on the mix without passing them through a 25 mm sieve at least and if that turns out to be not worth it I will just stick with the ballast. Ivor your point about the sub base has led to some more questions but these probably belong in another thread...

I have done exactly this, the ground floor internal wall was perpendicular to a (quite exposed and windy) gable end wall and I left a buttressing nib of 2 brick lengths. What reassured me was that after removing some plaster but before I demolished the brickwork, I saw the mortar joints had...

Not sure exactly what you mean by oversite slab. The old floor consisted of (top to bottom): 50 mm screed, 100-150mm concrete, DPM, approx 200 mm loose stones, stony compacted earth (?) I havn't dug below this, level of the top of the footings. The new floor was going to consist of (top to...

Jeds and Ivor, perhaps I should clarify the stuff I was proposing to use as aggregate in the new slab were the loose stones originally underneath the broken-up slab, (actually underneath the DPM) not the remains of the slab itself. As I said these are mainly natural-looking flints similar in...

It wouldn't want to have to make it any thicker than 150 mm. If I have to make it thicker than this just to re-use the 'free' aggregate then I would probably stick with purchased ballast and 100 mm slab. The stuff I dug up has rounded edges, but mostly not to the extent of 'balls' or 'eggs'...

I have broken up a solid concrete ground floor and excavated the underlying material (to a depth of around 200mm, level with the footings), to install under-slab insulation. The excavated material appears similar to beach shingle consisting of slightly rounded, mainly flint stones. The largest...

Come to think of it the push fit for mitigation of expansion and settlement make a lot of sense in a long run outside where the pipe is just buried in an earth trench, but shouldn't be as much of an issue underneath the building slab where the consequences of a leak are also that much higher. Is...

I see, any advice on how to ensure that the joints will never fail or need to be accessed?

Hi, not sure if this is should be in the plumbing or building forum. I want to install a new ground floor toilet which involves teeing into the existing soil stack below ground level. I have already cut a 4 metre long trench through the floor slab and dug out enough material to install the pipe...

Good explanations, cheers.

There is quite a widespread opinion that concrete blocks are as strong as or even better than brickwork, or at least that was the impression I had. Is this a myth? Also it is certainly possible to produce high strength concrete with compressive strength up to 40 N/mm2, so why aren't blocks with...

There is something don't understand about concrete block strength vs brick. Most of the blocks on sale are advertised as maximum 7.3 N/mm2 (occasionally I see 10 N/mm2 but rarely more). This goes for the dense, hard to handle blocks as much as medium density or even aerocrete. I am no expert...

I want to install an extraction vent in the ceiling of the shower cubicle: Is this a done thing/recommended in general? If I use an inline extractor fan which is installed in the loft as shown above, does this count as a non-classified area (DIY fair game)? Are there any kits for this type...

See below diagram, earths omitted for clarity.

I think I understand, so the use of junction boxes is really just for practicality in case the light fixtures don't have enough space in them? Explaining the wiring a bit more, since it seems to have not been very clear: The top 4 lamps are zone A, bottom 4 zone B. The 4 lamps in each zone...

Hello, I want to install some downlights in a grid pattern with 2 independent zones. I was thinking I could do it as shown attached, is this OK? Online resources seem to suggest junction boxes are required. Can't the connections just be done in the light fitting terminal blocks?