Which ICF method should I use?

[Russell griffiths]

Not an expert so I will take the salesman's word for it, 

 

why on earth would you do that,

have you heard the saying DONT ASK A BARBER IF YOU NEED A HAIRCUT. 

 

[Indy]

5 minutes ago, Russell griffiths said:

why on earth would you do that,

have you heard the saying DONT ASK A BARBER IF YOU NEED A HAIRCUT.

 

No comeback to that ?

 

I would be interested to hear more about your experience and why you don't like Durisol that much. Does that extend to all woodcrete products or is it durisol only?

[scottishjohn]

13 hours ago, JohnMo said:

Still don't understand the hate people seem to have for Durisol.  Other than 12mm OSB screwed (directly into the woodcrete) at corners, lintels and cut blocks, that's the only bracing you need.  No blow out on my build or two other I know about near me.  

 

Easy enough to do yourself, without a lorry load of bracing other systems seem to demand.

 

Durisol has been around for 70 to 80 years, tried tested and worked easily enough for me.

 

A downside is it's not airtight, so that's an extra job to do, but it is vapour open and can give a breathable building.

the only thing I can say comparing durisol to isotex  is that the durisol blocks are a little variable in the thickness --so decide at start which side you want perfectly flat and accept there could be  a variance in the other  side of maybe 0-5mm  block to block - no big deal but something to think about  and if hard plastering  no problem at all on inside  or  indeed for a parge coat on the outside if you build it flat  on the inside , then batton and PB

for DIY I think both systems are good   if you going to be stop start and if worried about bonding of one layer of concrete to the next -- just drop some rebar in where you stop .

I am not saying anything bad about poly systems as you could do the same with them if you wanted ,and you would only pour  one storey at a time with those ,even if blocks are built to eves in one go .

even poly systems require to be have a water proof layer of butyl type stuff rolled on if  building below ground for a basement 

all the systems work if done correctly of that I am sure 

 

Edited February 25, 2022 by scottishjohn

[JohnMo]

36 minutes ago, BotusBuild said:

 The question I always ask is, how do you get to the top of the wall to pour the concrete? Surely some scaffolding is required. So, OK, no bracing, but you've got to put scaffold up. Now read on....

 

I used Nudura (EPS) with the Nudura bracing - this bracing includes a platform level (you have to put scaffold planks on it of course). We did it DIY. The first floor took myself and my wife 5 days to put it all up ready to pour.

Yes you use scaffold, the same scaffold as you will need to erect to allow the roof structure and covering to be installed.  So scaffold up, do final rows of blocks, pour, move on to roof.

[Russell griffiths]

1 hour ago, Indy said:

 

No comeback to that ?

 

I would be interested to hear more about your experience and why you don't like Durisol that much. Does that extend to all woodcrete products or is it durisol only?

I’m not really sure how you can compare durisol with anything else really. 

It doesn’t have a continuous insulation layer, just blocks oddly wedged inside the woodcrete. 

How can they tell you that has the same insulation value that a continuous sheet of insulation would. 

Very poor block manufactured, the dimensions are all over the place, 

does not have a solid core of concrete just a lattice work. So if your block is inherently porous then you could use the concrete core for some element of keeping stuff out, water etc, oh but you can’t because it’s not continuous. 

 

[Nick Laslett]

Just drilling the screw holes for my windows and hit a void today, 60mm into the concrete. Whichever system you choose, the execution is everything. My ICF wall could be littered with air pockets, very hard to tell after the fact. Pretty difficult to remedy. During the wall pour I observed them using the poker, but I guess you still have the issue with voids. Perhaps they needed to leave the poker in that area for 30 seconds more, seems like a very hard judgement call. 

[markc]

12 minutes ago, Nick Laslett said:

Just drilling the screw holes for my windows and hit a void today, 60mm into the concrete. Whichever system you choose, the execution is everything. My ICF wall could be littered with air pockets, very hard to tell after the fact. Pretty difficult to remedy. During the wall pour I observed them using the poker, but I guess you still have the issue with voids. Perhaps they needed to leave the poker in that area for 30 seconds more, seems like a very hard judgement call. 

Leaving voids is easily done, using a poker is one of those tossy half-hearted jobs that rarely gets done properly. The nature of an ICF wall (high and thin) puts more reliance on proper poking than foundations or similar bulk fill pours.

[JohnMo]

8 hours ago, Russell griffiths said:

I’m not really sure how you can compare durisol with anything else really. 

It doesn’t have a continuous insulation layer, just blocks oddly wedged inside the woodcrete. 

How can they tell you that has the same insulation value that a continuous sheet of insulation would. 

Very poor block manufactured, the dimensions are all over the place, 

does not have a solid core of concrete just a lattice work. So if your block is inherently porous then you could use the concrete core for some element of keeping stuff out, water etc, oh but you can’t because it’s not continuous. 

 

Don't have a continuous insulation layer - wrong, it is thermal bridge free, the continuous woodcrete thickness and the mix material layer (woodcrete, PIR and concrete) have the same thermal resistance. U value of 0.14, thermal bridge free out the box.

 

Block dimensions are acceptable to get a straight vertical wall

 

Funny that the lattice work concrete/woodcrete doesn't require the same amount of rebar required for a polystyrene block.

 

The porous nature allows a high slump concrete mix, which can settle more easily without air pockets, the porous nature allowing the concrete to dewater.

 

Funny how leaky the blocks are, never had any water in the house after the roof went in.  Behind timber cladding you have a breathable membrane, same as most buildings.  Stone slips directly bonded to woodcrete keep other water out.  And the porous nature of the block is vapour open, for a breathable building.

[Bitpipe]

On 24/02/2022 at 22:00, Nickfromwales said:

@Bitpipe for one, used a stand alone basement contractor and then built a timber frame atop ( MBC Timberframe ). They're in Gloucestershire iirc. Options are available for 'mix n match'  

 

11 hours ago, markc said:

Leaving voids is easily done, using a poker is one of those tossy half-hearted jobs that rarely gets done properly. The nature of an ICF wall (high and thin) puts more reliance on proper poking than foundations or similar bulk fill pours.

 

11 hours ago, Nick Laslett said:

Just drilling the screw holes for my windows and hit a void today, 60mm into the concrete. Whichever system you choose, the execution is everything. My ICF wall could be littered with air pockets, very hard to tell after the fact. Pretty difficult to remedy. During the wall pour I observed them using the poker, but I guess you still have the issue with voids. Perhaps they needed to leave the poker in that area for 30 seconds more, seems like a very hard judgement call. 

 

 

This was the main reason I went with cast in situ concrete (i.e. shuttering) for my basement vs ICF.

 

Due to a low water table, SE signed off on a single waterproofing barrier, the concrete, so it needed to be executed perfectly. We have a warranty from Sika as the contractor used their system (admix, jointing strip & hole plugs) but the work needed regular inspection & sign off by the Sika rep.

 

It does add significant labour cost and is not a DIY option but we were very happy with the result - the crew were rigorous with the pour and powering and we could see the quality when each panel was struck, no voids and no 'marshmallow' finish.

 

I applied 200mm EPS 70 to the front face of the concrete using LE foam before backfill, the slab was cast on 300mm of EPS 200 so we had a contiguous insulation layer that the passive frame above could tie into.

 

GRP light wells from MEA came with their own 200mm XPS insulation collar & adhesive and were quite easy to fit - just needed to cast a suitable aperture in the wall and pop a window in afterwards.

[Indy]

Isn’t pouring of concrete on site for any form of ICF considered in-situ? Trying to understand what the difference was in your approach so we can avoid the same. 

[Nick Laslett]

13 hours ago, Indy said:

Isn’t pouring of concrete on site for any form of ICF considered in-situ? Trying to understand what the difference was in your approach so we can avoid the same. 

With a traditional shuttering method, the shuttering is removed after the pour so you can see the finished concrete. My staircase was a traditional in situ concrete pour using plywood for shuttering. With ICF the EPS is the shuttering and this isn’t removed. 
 

 

[Happy Valley]

On 25/02/2022 at 21:18, Nick Laslett said:

Just drilling the screw holes for my windows and hit a void today, 60mm into the concrete. Whichever system you choose, the execution is everything. My ICF wall could be littered with air pockets, very hard to tell after the fact. Pretty difficult to remedy. During the wall pour I observed them using the poker, but I guess you still have the issue with voids. Perhaps they needed to leave the poker in that area for 30 seconds more, seems like a very hard judgement call. 

 

We didn't use pokers but hammer drills with a block of wood and vibrated the side of the polystyrene ICF - you could see the concrete drop when looking over the top when someone was vibrating the walls below. Worked a treat for us as there was a lot of (unnecessary) rebar inside the core making a poker very difficult.