Internal wall connection to ICF

[metalgear2k2]

Hi all, so I have made the mistake of pouring the ICF external walls without concidering how to connect the sigle leaf internal block walls.

 

I work in an engineering company with a large workshop so I was thinking I would get some L brakets made and concrete screw to the ICF and to the internal block.

 

I assume I'm not the only numty to do this, would any be willing to share how they came around it, detail, photos etc?

 

Thanks

 

[JohnMo]

We did ICF and the internal walls are all stud - is this an option? Ours do not touch the the ICF walls.

[Nick Laslett]

You just need the right wall ties. 
 

Something like this:

 

https://pamties.co.uk/product/wall-starter-kit-2/

 

https://www.vistaeng.co.uk/product/v63-universal-stainless-steel-wall-starter-system/

 

Cut back the EPS where the wall is going to start and treat it like you would adding a block wall to an existing block wall. 

Edited April 15 by Nick Laslett

[JohnMo]

1 minute ago, Nick Laslett said:

Cut back the EPS where the wall is going to start

Isn't that just introducing a thermal bridge? Or is the majority of the insulation on the outside?

[Nick Laslett]

Here’s a good video. 
 

 

[Nick Laslett]

1 minute ago, JohnMo said:

Isn't that just introducing a thermal bridge? Or is the majority of the insulation on the outside?

I don’t think so, but could be wildly wrong on this one. My understanding was that with EPS ICF the external insulation is all that matters, the internal EPS is entirely sacrificial, it could be removed and it wouldn’t affect the U-value of the wall.  Of course it is not as simple as that, but my understanding is that from a U-value calculation the internal EPS is ignored. 

[Nick Laslett]

@metalgear2k2 If you are worried about potential thermal bridge, you could bolt some timber to the EPS, like how you would construct a stud wall, and then use the starter bars. 
 

Like @JohnMo, most of my internal walls, are stud walls.

[JohnMo]

This is best photo I could find on how I did it.

 

Top and bottom plate joined with studs. Nothing interfering with ICF.

 

 

[Conor]

For the walls where we didn't put in steel mesh ties before the pour, I cut back the inner insulation and used galvanised L brackets approx 150x150mm at every other course. I'll put up with a minor cold bridge  with 175mm insulation on the outside, losing a strip of 75mm in the inside is preferable to a wall falling down.

[LaChab]

FWIW, our SE approved using starter bars (frame) screwed through to the core. Wouldn't dream of cutting back the inner insulation!

 

[Nickfromwales]

Time to discover timber methinks, all you masonry addicts!

 

Even load-bearing walls can be done well in timber….. why make life any harder than it already is? 😑😌

[ChrisJ]

Using Nicks comment for wood, Use an SDS drill, drill thru the stud, foam and into the concrete, epoxy/resin threaded rod in, every 600-750 starting just above the floor will be fine, once cured, square washer and a nut, snug it up add 11mm OSB typically one side is enough nail every 50-75mm on the perimeter of the sheet and 150 in the field

 

 

[JohnMo]

2 minutes ago, ChrisJ said:

Using Nicks comment for wood, Use an SDS drill, drill thru the stud, foam and into the concrete, epoxy/resin threaded rod in, every 600-750 starting just above the floor will be fine, once cured, square washer and a nut, snug it up add 11mm OSB typically one side is enough nail every 50-75mm on the perimeter of the sheet and 150 in the field

 

 

Why does anything need to attach to ICF?

[ChrisJ]

1 minute ago, JohnMo said:

Why does anything need to attach to ICF?

If need for sheer purposes, plus to prevent cracking in the corner of the plasterboard

[JohnMo]

49 minutes ago, ChrisJ said:

If need for sheer purposes, plus to prevent cracking in the corner of the plasterboard

We have had zero corner cracks in any wall and they were built in 2021 - not a single crack ever. Just dry lined.

 

Not a single wall (structural and non - structural) is attached to ICF. All internal walls are stud walls. Tallest is 3.5m. walls are just attached to other internal walls and top and bottom plates, as photo above.

Edited April 16 by JohnMo

[metalgear2k2]

Thanks all for the info, really appreciate it.

[ChrisJ]

On 16/04/2025 at 14:52, JohnMo said:

We have had zero corner cracks in any wall and they were built in 2021 - not a single crack ever. Just dry lined.

 

Not a single wall (structural and non - structural) is attached to ICF. All internal walls are stud walls. Tallest is 3.5m. walls are just attached to other internal walls and top and bottom plates, as photo above.

Awesome, sometimes you get lucky with the correct moisture content in the wood and never get a crack

[JohnMo]

1 minute ago, ChrisJ said:

get lucky

Not sure I got lucky, several different batches of timber used. All walls are solid, none attached to ICF.

[Iceverge]

What was the benefits of standing the studs off the walls? 

 

Services? 

Edited April 17 by Iceverge

[JohnMo]

58 minutes ago, Iceverge said:

What was the benefits of standing the studs off the walls? 

 

Services? 

For me less holes in the parge coat. Maybe less noise transfer, I inserted same insulation as between the studs.

 

My electrical services all ran around the top of wall, so nice easy runs for electrician.