Basement - ICF vs Shuttered Reinforced Concrete

[Triassic]

23 hours ago, Red Kite said:

Hi, we are looking at a basement into a slope in clay soil - front out of the ground

I constructed our using ICF, defiantly a DIY job if your willing to get stuck in!

 

Here it is with the insulated slab

ready for the concrete.

 

 

A view part for the completed basement with interior walls. 

[Pocster]

Icf as far as I am aware you can only pour up to a certain height before risk of blowout increases more . This is what concerned me because I can’t get to the outside . So cost wise you might need the concrete pump twice . Also the icf insulation wasn’t thick enough so i’d Need to add PIR anyway . 

Edited February 10, 2019 by pocster

[Triassic]

We poured 26 tonnes of concrete  in one go, to the full height of the ICF shown (2.6m) The most important thing is the prop the ICF as per the manufacturers instructions, then add more props, for good measure.  We also chose an ICF system with a good internal matrix of cross ties, this helps stop the two sections splitting during the pour, we also used s small concrete poker and resisted the urge to over poke the concrete.

[Pocster]

17 minutes ago, Triassic said:

We poured 26 tonnes of concrete  in one go, to the full height of the ICF shown (2.6m) The most important thing is the prop the ICF as per the manufacturers instructions, then add more props, for good measure.  We also chose an ICF system with a good internal matrix of cross ties, this helps stop the two sections splitting during the pour, we also used s small concrete poker and resisted the urge to over poke the concrete.

I’m surprised at that . When I looked into icf ( some years ago ) they were adamant not to pour more than 5 or 6 levels . Guess things have changed .

[connick159]

On ‎09‎/‎02‎/‎2019 at 14:42, pocster said:

Yep !

Worked great !

Simply bed the first course then off you go . I had to add rebar in as I went . I shuttered any corners before the pour . Poured the whole lot in 1 go ! ; few minor issues but no real problems 

 

I insulated on the outside . Also land drain at base . Internally I will have membraned walls going into an internal drain then out to sump .

 

The main thing is that stepoc is an easy diy approach - Christ ; I did it so it must be ! .

 

 

hi,

Out of interest re the stepoc, what size were your ones and how much footing (width and depth) did you  to cater for to add the stone cladding?

We have to build a retaining wall that will be about 2.5m away from house and around 10m long.  It's about 1.8m high overall but I'm going to terrace it to be about 1m high first rise and then terrace back 2m and then about another 800mm up at that point.

 

Also, how far did you have to dig back behind the wall (away from house) to allow for drainage and backfill, and did you put any of the spoil you dig out originally back in as backfill?

[Pocster]

6 hours ago, connick159 said:

hi,

Out of interest re the stepoc, what size were your ones and how much footing (width and depth) did you  to cater for to add the stone cladding?

We have to build a retaining wall that will be about 2.5m away from house and around 10m long.  It's about 1.8m high overall but I'm going to terrace it to be about 1m high first rise and then terrace back 2m and then about another 800mm up at that point.

 

Also, how far did you have to dig back behind the wall (away from house) to allow for drainage and backfill, and did you put any of the spoil you dig out originally back in as backfill?

Can’t remember the stepoc size but I think it was one less than the largest .

Stone is sat on a separate footing . We had a gap between the stepoc and the lane so just did a concrete pour in the gap . Not very wide - maybe 40cm .

 

i stuck a land drain around the base outside the stepoc . Covered it in chippings to aid drainage . We had very little gap between dug hole and external insulation. Our dig out was all rock so couldn’t use to backfill 

[K78]

I nearly used precast L shaped bolt down wall sections. Big issue I had was getting a SE to do a design for less than £5k. 

 

It didn’t make sense to me as they are a bolt down retaining wall with a recommended foundation detail. In the small print it said slab to be designed by SE. Most didn’t want to know. 

 

I used concrete Lego in the end instead. 

[Thorfun]

On 08/02/2019 at 18:38, Red Kite said:

Hi, we are looking at a basement into a slope in clay soil - front out of the ground. I am trying to decide how to build it and seem to have a choice of ICF versus RC (Reinforced Concrete) - anyone any thoughts about Pro's and Con's? Here I am only considering external tanking and waterproof concrete - to my mind an internal membrane and sump is admitting defeat!

 

I like RC because you can see the concrete and any defects when you take the shuttering away - and my GW does basements like this all the time and is prepared to guarantee waterproofing for 10 yrs (not sure if that is really worth much!).

 

However I am hearing that ICF may be cheaper / quicker - and as I need to insulate anyway seems like a neat way to go. Would I need external tanking to an ICF basement?

 

I am looking at an insulated raft slab under the basement and TF above - and also having the discussion of a concrete 'top' to the basement (cast in situ / hollow core beams etc) versus an 'open box' with a posijoist type roof - again any sage advice would be welcome.

 

It would seem there is no 'best way' and the SE's I have talked to say the reinforcing / concrete for the walls is much the same for ICF and RC 

 

Any thoughts?

 

Hi @Red Kite. I see from your blog you went for in-situ RC concrete over ICF. can I ask what swayed you to this route rather than ICF? was it financial or some other reason?

 

I'm going through a similar decision at the moment.