Dry mix as sub-base

[Ian-M]

Hi all - I have read the main site and various pages, and have a question. Our landscaping contractor is suggesting a concrete base for the patio, so when I questioned that and asked him about a drainage plan (per your suggestion on the main page) he confirmed it was actually a dry mix which he whacks down, as he finds it 'better' than type 1 and still allows drainage. Is that an acceptable solution? My worry is that it will still 'set' and/or will take moisture out of the full mortar bed for the slabs and thereby weakening the bedding layer. Am I right to insist on type 1 instead - if nothing else I imagine it will be cheaper. I know it's a delicate balance - I know I'm the paying customer so have a right to ask, yet I don't want to annoy the contractors by second guessing their construction methods at every turn. Advice welcome as always - it would be good to get the experts perspective as you must come across armchair sub-base experts all the time FWIW we are based in Hampshire and the guys are good/approachable - I will talk to them obviously but wanted to gauge how much I should push it I guess. thanks in advance .. Ian PS half the landscaping area is slabbed, half is self-binded gravel and he is suggesting same for both ..

[lutonlagerlout]

sub base should 99/100 be type 1
unless the ground is horrifically bad
problem is even a dry mix will set ,and potentially crack
unlikely for a patio of course
also potentially a source of efflorescence
ask him how long he is prepared to warrant it for?
LLL

[Ian-M]

Thanks LLL - much appreciated, I think that's pretty clear then ...