External Wall Insulation (EWI) onto Nudura ICF?

[Mulberry View]

Has anyone here installed additional insulation over their ICF?

 

For a few reasons (and not just the u-Value), I have opted to allow for an additional 50mm of external insulation over the top of my Nudura on the upper proportion of my build.

 

Has anyone installed EWI over ICF? What did you use and what was the installation process?

 

Also, how long can you leave EWI exposed before render being applied?

 

(Pic for attention - it's come on a bit since then)

 

Edited September 5 by Mulberry View

[Conor]

We did. 100mm EPS on to Amvic blocks. Got good advice from a guy that ran a EWI and rendering supply business.

 

1200x600mm EPS70 boards. Five fixings per board, full bead of EWI foam adhesive around the perimeter, a cross on the back of the board, and the edges where it met a neighbouring board.

 

Fixings were 180mm galvanised screws. We used EWI washers and used a rebate tool so they were below the insulation, the capped off with an EPS plug. 

 

When it came to rendering, was all rasped down before starting. 

 

Was a lot of work, but really easy and light. Corners and around windows need a bit of cutting and messing around.

 

I've hundreds of caps, screws etc left over.

 

This is before we were told to recess in the plastic caps.

 

After recessing and plugging with the EPS biscuits. N.b. the treated timber grounds for lights and fittings.

 

 

After rendering.

 

[Mulberry View]

13 hours ago, Conor said:

We did. 100mm EPS on to Amvic blocks. Got good advice from a guy that ran a EWI and rendering supply business.

 

1200x600mm EPS70 boards. Five fixings per board, full bead of EWI foam adhesive around the perimeter, a cross on the back of the board, and the edges where it met a neighbouring board.

 

Fixings were 180mm galvanised screws. We used EWI washers and used a rebate tool so they were below the insulation, the capped off with an EPS plug. 

 

When it came to rendering, was all rasped down before starting. 

 

Was a lot of work, but really easy and light. Corners and around windows need a bit of cutting and messing around.

 

I've hundreds of caps, screws etc left over.

 

This is before we were told to recess in the plastic caps.

 

After recessing and plugging with the EPS biscuits. N.b. the treated timber grounds for lights and fittings.

 

 

After rendering.

 

 

@Conor That's super helpful. You've pretty much answered all my questions in one swoop.

 

Out of interest, why did you opt for 100mm?

 

Did you render straight away?

 

[Conor]

2 hours ago, Mulberry View said:

 

@Conor That's super helpful.pr You've pretty much answered all my questions in one swoop.

 

Out of interest, why did you opt for 100mm?

 

Did you render straight away?

 

100mm because we wanted to meet the passive house standard. The Amvic blocks at the time only 

 

No, was several months. EPS isn't UV stable so all has to be rasped down prior to rendering. It'll need to be done anyway to level everything off.