Is there any such product as a fixing for attaching (lightweight) items to the EWI itself? Something along the lines of a plasterboard fixing for screws? Or is the advice to always plan ahead and put timber grounds in where items are to be mounted in future?

Timber should not be used behind or within the insulated zone of EWI systems - EVER!

Use long stainless steel screws fixed through the insulation directly into the substrate behind
Screwfix carry 150mm screws.

There are also plastic auger plugs similar to plasterboard fixings available for lightweight goods - i will try and find a link

Posted By: Mike GeorgeTimber should not be used behind or within the insulated zone of EWI systems - EVER!

Doesn't that rather depend on what you mean by EWI? A timber Larsen truss with vapour open insulation could reasonably be used for EWI in some circumstances, for example.

Posted By: Mike GeorgeTimber should not be used behind or within the insulated zone of EWI systems - EVER!

Why not?

Posted By: Viking House

Posted By: Mike GeorgeTimber should not be used behind or within the insulated zone of EWI systems - EVER!

Why not?

I'm not even sure if you are serious..... Because EWI rendering is not completely waterproof - and grounds similer to that queried by the OP will by their nature have fixings penetrating the system - which will inevitably lead to water ingress into the zone.

What happens next?

Wet wood will rot
Warm wet wood may promote the growth of dry rot
Cold wet wood may freeze
Water expands when it freezes...leading to cracking, and further water ingress - and so on

Posted By: Mike George

Posted By: Viking House

Posted By: Mike GeorgeTimber should not be used behind or within the insulated zone of EWI systems - EVER!

Why not?

I'm not even sure if you are serious..... Because EWI rendering is not completely waterproof - and grounds similer to that queried by the OP will by their nature have fixings penetrating the system - which will inevitably lead to water ingress into the zone.

What happens next?

Wet wood will rot
Warm wet wood may promote the growth of dry rot
Cold wet wood may freeze
Water expands when it freezes...leading to cracking, and further water ingress - and so on

Can you post an example of this ever happening in real life? Have you personal experience?
We've externally insulated hundreds of houses and often put in grounds for down-pipes etc, oldest projects are 15 years old now, we've never ever had a problem like the one you've mentioned! Its very easy to drill a pilot hole and put a squirt of silicone into it before you screw in the screw.

Viking, Yes i have lots of personal experience seeing rotten timbers which have been rendered over, both internally and externally. I spent around 5 years working for a damp proofing/dry rot company where I learned to plaster... I have seen dry rot outbreaks caused by a single wooden peg originally used to hang Victorian gas lamps...

The picture below is not EWI of course but the water and vapour permeability properties of cement/ acrylic/lime even silicone renders are very similar. Unless of course you can produce published values to the contrary? (I've challenged manufacturers and others to produce such figures many times to no avail)

Anyway, irrespective of what render is used, the weather is the same; the physics is the same; It is well known and accepted that timber subjected to water or vapour can and does rot. See picture as an example.

Timber also expands and contracts disproportionately to the render with both temperature and moisture content, which again can lead to micro cracking and water ingress - again the physics is well known and accepted

No, I am not familiar with EWI on timber frame. Do you mean new or retrofit?

I would imagine with New construction there will be a ventilated airgap/breather membrane arrangement /cladding outboard of the insulation? If so perfectly safe.

For retrofit would need to be carefully specified - Like I said not seen any retrofits of this type.

And like I said previously my comment was in response to the query of timber grounds ie, timber within or just behind the insulation zone.

The photo shows a wooden block starting to cracker the render maybe due to water/ damp ingress an important point to note many system providers will say a fixing must go through the render coat through the wooden block and in to the main fabric of the building, this never gets done when did you ever see a 6 inch number 4 black jap screw.

How do I add photos from an iPad " choose photo" but not adding to post

RedDoor have a look at that website if you want to refit it can be done without affecting system warranty, which system I can tell you if approved, look for photos of a cast iron road sign this was a Permarock system where the wood was lost !!

On talking to a warranty company a big issue seems to be fence posts, damp will travel from the ground up the wood SPS Envirowall do one that allows the post to sit above ground and fixed to main fabric with EWI fixings might be helpful and no hole digging or crossing damp course.

You need to resize the picture by the number of pixels. You can do this in most packages just go to 'picture options and .'resize' The one I uploaded is 1600 x1200.

Posted By: bot de pailleOk, but do you have experience of timber frames rotting under modern EWI systems?

We used to build extensions like that 150mm Platinum EPS on OSB on a 150mm structural frame. The oldest house we built like that is 12 years for my sister, very cosy!

Posted By: Mike GeorgeViking, Yes I have lots of personal experience seeing rotten timbers which have been rendered over, both internally and externally. >

But no experience in putting timber into EWI as grounds? I have experience of putting pieces of marine plywood into EWI and plastering over it with the Acrylic type renders. I've done it over 100 times and there's no queue outside my door, so from my experience, I'd say the risk is minimal!
This thread is about EWI so there's no point putting up scary straw-man photos that have nothing to do with EWI and arguing about that!