House wrap

[Firsttimer]

 

[Firsttimer]

This makes good sense to me. Especially with timber cladding.  Happy to be convinced that it's unnecessary (which appears to be the perceived wisdom).

 

Has anyone got any thoughts or advice ? If you did timber cladding did you use a membrane ? 

[Nick Laslett]

Beware USA centric building information. It can be really useful, but things like Building Regs, BBA certificates, NHBC and manufacturer materials will cover the requirements in the UK. You can of course do whatever you want if building controls will sign it off. Lots of videos about ICF in USA because it is more popular there, if you research deep enough you will find in some regions ICF has a problem with termites and needs special treatment in those regions.  

@Russell griffiths who has an ICF Nudura build recently posted about render coating ICF here. 
 

 

Edited September 11 by Nick Laslett

[liammcl]

In my mind it should be treated the same as a timber frame building once outside the ICF block.

 

- As in you need membranes & trays to act in the same way. It amazes me its not addressed more clearly on the manufacturers websites.

[Firsttimer]

11 hours ago, liammcl said:

In my mind it should be treated the same as a timber frame building once outside the ICF block.

 

- As in you need membranes & trays to act in the same way. It amazes me its not addressed more clearly on the manufacturers websites.

I'd not really got as far as thinking about drip trays yet. I'm still pondering about how best to do the external window seals.

[Nick Laslett]

12 hours ago, liammcl said:

In my mind it should be treated the same as a timber frame building once outside the ICF block.

 

- As in you need membranes & trays to act in the same way. It amazes me its not addressed more clearly on the manufacturers websites.

ICF in the UK doesn’t really need membranes and trays or to be treated like timber frame. But you do need a water shedding strategy with render, cladding, brick or some other facade. The concrete is your water proof layer. You could scrape all the eps off, if you didn’t care about the insulation and the concrete would behave like any concrete structure and give you decades of water proof, rot free performance. ICF is nothing like timber frame, and should not be treated in a similar way. If it wasn’t for the UV in sunlight slowly eroding the EPS, you could leave the bare EPS walls uncovered for many, many years and not see any degradation. EPS is not a new material, there are decades of evidence showing how it performs. ICF is not a new build method and has been around for over 50 years. 
 

Watch some Building Science videos with Joe Lstiburek, where he describes the “perfect wall” and what you need to do to prevent water ingress, this starts a the 30 minute mark, but the whole video is worth watching. Every building needs a good strategy for shedding water as this is one of the most damaging environmental effects. 

 

 

https://buildingscience.com/documents/enclosures-that-work/high-r-value-wall-assemblies/high-r-wall-icf-wall-construction

 

[Nick Laslett]

There are a lot of extensive papers on testing ICF. The two I have read are specifically regarding windows. Did also read a few sound test papers. 

 

https://www.bchousing.org/sites/default/files/rcg-documents/2022-04/ICF-Wall-Test-Modeling-Lab-Report.pdf

 

https://www2.bchousing.org/sites/default/files/rcg-documents/2022-04/ICF-Field-Test-Report.pdf

Looking at the Amvic manual it recommends a membrane behind timber cladding. 
 

The Thermohouse manual says to do what the cladding supplier recommends.

 

The Nudura manual defers to building regulations and manufacturers requirements. 
 

These are the 3 ICF manuals I have on hand. 
 

NHBC doesn’t require a membrane behind cladding. 
 

https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/6.1/external-finishes-to-insulated-concrete-formwork.pdf

 

 

 

 

Edited September 26 by Nick Laslett

[Nickfromwales]

On 26/09/2024 at 23:27, Nick Laslett said:

There are a lot of extensive papers on testing ICF. The two I have read are specifically regarding windows. Did also read a few sound test papers. 

 

https://www.bchousing.org/sites/default/files/rcg-documents/2022-04/ICF-Wall-Test-Modeling-Lab-Report.pdf

 

https://www2.bchousing.org/sites/default/files/rcg-documents/2022-04/ICF-Field-Test-Report.pdf

Looking at the Amvic manual it recommends a membrane behind timber cladding. 
 

The Thermohouse manual says to do what the cladding supplier recommends.

 

The Nudura manual defers to building regulations and manufacturers requirements. 
 

These are the 3 ICF manuals I have on hand. 
 

NHBC doesn’t require a membrane behind cladding. 
 

https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/6.1/external-finishes-to-insulated-concrete-formwork.pdf

 

 

 

 

I made some suggestions to the technical director of Nudura a while back regarding this weakness in most suppliers strategies …..she said that it was a better methodology than they proposed at the time……didn’t get done……not much has changed methinks. Life goes on in the absence of anyone wanting to ‘do better’.

[liammcl]

My only concern is if there's scope for water to creep in the seams of the external eps behind where window or doors are mounted then it needs a membrane lapped over trays etc. to prevent this..