Posted By: Shevekwhats the advantage of putting it on the outside?

No drainage channels or sump or pump inside.

Posted By: Shevekjust let it drain by gravity.

Ah, now I get it, yes I agree a channel is a good idea, so will keep this in mind when doing the final design.

I have to defer to others greater practical experience in these matters but to me it seems an inane thing to do, to construct a new wall that you expect will leak and then go about devising complex runoff channels etc.. Why not dig the hole a little bigger put the watertight membrane/layer on the outside tied into the floor membrane and save yourself the mess. I've seen loads of cellars constructed on the Continent and all were tanked in one form or another, on the outside.
We build floors with only concrete, insulation and a sheet of heavy duty polythene between the occupants and the soil, they don't leak so why make a fuss about walls.
Triassic's right IMO, to want to put the membrane on the outside and then backfill with French drain.

This how we do it over here. Very rare to have damp problems

I've used the Delta material in the UK but that was always for renovations, usually a Victorian era basement where you couldn't access the exterior. On a new build theres no reason not to put it on the outside as long as you install adequate drainage.

People used to use Vandex type tanking systems or very a very strong cement render, but it never really worked so the switch was made to cavity drainage systems where it was accepted that damp would penetrate but it would be allowed to drained away behind the decorative finish.

Same system on all new builds in Italy (says he generalising!), except they don't bother with the outermost 'fines' membrane - I have myself 'melted on' a good few m2 of 4mm bitumen onto new concrete walls. 'De rigueur' as Mr French would have said.

https://en.wikipedia.org/wiki/French_drain

"These may have been invented in France[3] but were described and popularised by Henry Flagg French (1813–1885) of Concord, Massachusetts, a lawyer and Assistant US Treasury Secretary, [4] in his 1859 book Farm Drainage"

Only one company helps you completely waterproof concrete. See some certificates here.
www.waterproofconcrete.co.uk/certificates.html

It will also supervise to help you do your work perfectly.

There are a number of good reasons here not to use ICF.
www.basementexpert.co.uk/waterproof%20concrete%20basement%20construction%20gallery.htm

However if you want simplicity and all the other benefits of ICF without any of the disadvantages, look at this page.
www.basementexpert.co.uk/waterproof%20basement%20construction%20gallery.htm

Finally, don't plan internal drainage. If you try to build waterproof you could not possibly need a pump that removes a fifth of a cubic metre each week. Waterproof concrete can be repaired. But if the work is done well your basement will be dry.

Concrete is the material you use first. Do it properly and you won't need anything else, so at least try.

Willie.McLeod and Orangemannot had an interesting discussion earlier.

Orangemannot thought he was the only person who cares about concrete and concreting. He and I should meet! We would each have a friend at last. "Phil your killing me, for God's sake put in some more water"

Yes, concrete always cracks. That is one reason why it is reinforced with steel so that when there is a crack (as the element cools and shrinks faster on the surface than it does inside) the steel that was at rest inside is suddenly under tension and if it can resist that tension the crack is held very thin. The concrete will therefore crack elsewhere as well. If crack widths are restricted by enough steel then the concrete can heal completely (autogenous healing).

The blended cement also heats up much less and shrinks less so it is less prone to cracking, but flyash is in short supply now and you probably cannot make truly waterproof concrete with flyash or GGBS either.

When talking about water cement ratios you must quote the cement type. Pure OPC with only 0.40 water would suffer from carbonation, a problem sometimes called a concrete cancer, whereas if the cement was 30% replaced by flyash then 40% of total cements is 57% of OPC.

I have found by experience that basement floor slabs need 0.25% steel by area in both directions. Wall height can shrink unrestrained so 0.25% vertical steel. But 0.35% horizontal steel at least in basement walls with fully waterproof concrete, preferably in front and rear faces and 100mm centres vertically.

And don't use ICF. You cannot see the concrete, just leave your formwork on for 3 to 7 days (depending on weather), then take it off and admire your good work and sleep soundly knowing you saw all cracks heal themselves.

I have tonnes of detail on my waterproofconcrete web site, too much probably, but that's passion for you.