ICF or shuttered concrete?

[Ed_]

Its been asked before, but not for a number of years so i'd like to see if there are any updates.

 

I have a walkout basement, only needs to be waterproof on 2 sides, other 2 will be above ground, approx a 10x 10m box.

I have initial quotes from an ICF contractor and a shuttered concrete contractor to do essentially the same thing (slab, 200m thick waterproof concrete walls, 2nd waterproofing, insulation etc) and the price for each is basically the same.

If it was a full basement, i'd probably go shuttered concrete for the ability to inspect the pour quality, but as its walkout and will be free draining i'm not too concerned about waterproofing.

 

Are there any reasons to pick one over the other?

[Mr Punter]

@Conor did a walk out basement in ICF.  

 

[Conor]

The advantage with ICF is that you just continue the same build method from the bottom to the top. I'd you do shuttered concrete, you need to think and detail how you change from that method for the two walls to the rest of the structure.

[Ed_]

Unfortunately I'm cheating and getting Dan wood to put a house on top of my basement, so continuity is a worry but not a determining factor.

[Nickfromwales]

5 hours ago, Conor said:

The advantage with ICF is that you just continue the same build method from the bottom to the top. If you do shuttered concrete, you need to think and detail how you change from that method for the two walls to the rest of the structure.

I came across this on a 4-storey dwelling with a walk-out basement job that I was associated with a while ago. ICF, and a few steep learning curves for all professionals around it (including the 'architect'.....). This had the "change" between poured and laid products, and the results were the sum of zero joined-up thinking.

 

There are so many ways to avoid issues whilst the job is still on paper, just choose well the folk who you trust to advise you and what their ACTUAL experiences are. Needles to say the basement leaked, at the change in disciplines, simply because those closest to the client didn't appreciate how water moves (hydraulic something or other, it's late) but it finds a way trust me!

 

Mixing shuttered concrete and ICF needs a wise head on experienced shoulders. I tried to advise, but was shot down by the 'almighty' as I'm just a plumber.. Good job my pipes didn't leak like the basement did, lol. Was painful watching 2' of water getting pumped out whilst they figured it out.

[Nickfromwales]

2 hours ago, Ed_ said:

Unfortunately I'm cheating and getting Dan wood to put a house on top of my basement, so continuity is a worry but not a determining factor.

Check out @Bitpipe's content  

[saveasteading]

8 hours ago, Nickfromwales said:

This had the "change" between poured and laid product

A joint between civil engineering and building.

You're right. This sort of thing goes wrong through lack of forethought or understanding of the power of water to get past an obstacle.

Easily designed out but difficult to put right after the event.

Then someone wants to cut holes through it.

Was expensive tanking the solution?

 

[Nickfromwales]

22 minutes ago, saveasteading said:

A joint between civil engineering and building.

You're right. This sort of thing goes wrong through lack of forethought or understanding of the power of water to get past an obstacle.

Easily designed out but difficult to put right after the event.

Then someone wants to cut holes through it.

Was expensive tanking the solution?

 

Drilling the joint and pumping in a ‘grout’ under very high pressure, iirc. I’d left by that time as we were pretty much done.
 

The plasterboards and OSB / cables etc were stripped off the wall for investigations a few weeks prior to our departure, to see where it was coming from and allow various professionals to discuss. IMO the architect was clearly to blame for not spotting (or having any such experience to know) that this was going to be an issue, but when you saw how insanely over “budget” they were at that stage I guess the cards were already on the table with regards to how he’d not ever actually built any of his drawings.
 

I did a huge amount of problem solving for the client, architect and SE, for little to zero thanks, but with the basement I left for them to point fingers with, not my battle, but could have been so easily avoided just by relocating the transitions. 🤷‍♂️🤦‍♂️. 
 

It was already tanked, btw, and the water breached that too. 

[Ed_]

Thanks for the good advice.

 

I suppose that one thing in favour of the shuttered concrete is that they will make a waterproof sealed box, including "lid" (my GF), which will be above ground, then Dan Wood will come along and put a DPC down, so there isn't really anywhere for the water to go. I hope!

Edited 9 hours ago by Ed_

[Nickfromwales]

43 minutes ago, Ed_ said:

Thanks for the good advice.

 

I suppose that one thing in favour of the shuttered concrete is that they will make a waterproof sealed box, including "lid" (my GF), which will be above ground, then Dan Wood will come along and put a DPC down, so there isn't really anywhere for the water to go. I hope!

What tanking measures and insulation will be put in place?

[Ed_]

Waterproof concrete, bitumen paint to outside.

Insulation either inside or out. I'd prefer outside but thinking inside might work better for the detail at the ground floor where it goes to the timber frame, otherwise the insulation will just end at the ground level and then step in to the timber frame?

 

In case it isn't obvious, I haven't started the detailed design yet, i'm just wary of being herded down whatever is the architect/ structural engineer's preferred route without having a decent understanding of the pros/cons myself first.

[Nickfromwales]

11 minutes ago, Ed_ said:

Waterproof concrete, bitumen paint to outside.

Insulation either inside or out. I'd prefer outside but thinking inside might work better for the detail at the ground floor where it goes to the timber frame, otherwise the insulation will just end at the ground level and then step in to the timber frame?

Ok, great. FYI, on a 'huge' basement we recently quoted for I also recommended installing a layer of 75mm or 100mm EPS around the whole thing after the tanking was done; a), to provide some resistance to the static ground temps, but b), more importantly, to protect the external tanking solution from mechanical damage (a stone / other reducing effectiveness or causing a failure) as I really didn't want to ever have to revisit this for the sake of a couple of £k worth of (seconds) sheet material.

 

2 birds with one stone afaic, and a good place to invest in a second or third set of belts & braces.

[Nickfromwales]

19 minutes ago, Ed_ said:

might work better for the detail at the ground floor where it goes to the timber frame

Yes, and one to consider if sitting the sole plate across the top of the uninsulated concrete in the frost zone? Me personally, I'd rather some externally and then less internally (but defo both) so the GIA doesn't then suffer too big a loss internally to get to BRegs levels.

 

Marmox breakers may be a big help here of course.

[saveasteading]

4 hours ago, Nickfromwales said:

tanked, btw, and the water breached that too. 

 

46 minutes ago, Ed_ said:

Waterproof concrete, bitumen paint to outside.

The tanking needs to be outside or it will be forced off. Unless using Newtonite which catches the water inside ....but that's for a tunnel not a house.

Waterproof concrete works for dams, pipes and tanks, keeping water in, not out. But it is not damp-proof. We don't see the dampness because it evaporates

It requires a huge amount of small diameter reinforcement to make the cracks tiny.

I wouldn't trust bitumen paint as cracks could form or widen.

For complete water exclusion I used an expensive membrane that was wrapped under and around the concrete, and allows for future movement.  Worked really well.

And the concrete must extend above ground, leaving  a very simple, non tech, interface. And any drainage be pumped out and over the concrete.

[Big Jimbo]

Just a thought. has anybody seen the spray on rubber ? I believe that it has been used in basements in the USA. It is quite stretchy so, does not crack with movement.

[Nickfromwales]

2 hours ago, Big Jimbo said:

Just a thought. has anybody seen the spray on rubber ? I believe that it has been used in basements in the USA. It is quite stretchy so, does not crack with movement.

Would need BBA approval for use here, or an acceptance from the BCO and warranty providers that the certification and intended use qualified.

 

I quite like the Zip products for going in around window and door openings a-la the USA / Canada etc, but the UK is only now adopting (stealing and copying) these “modern construction methods” so we’ll be the last to benefit from them I guess.

[Tom]

15 minutes ago, Nickfromwales said:

I quite like the Zip products for going in around window and door openings a-la the USA / Canada etc

 

I haven't watched Grand Designs in years, but I do like watching "This Old House" which is a US build/renovation show - they use a lot of these Zip products, self-sealing membranes etc. and it's really interesting seeing how they do things over there. It's quite good for a laugh at the American-ness of it all, but the skill level of one of the guys on the show is amazing and the way he explains what he is doing makes it all very accessible. Worth having a look if you can find it.