Green Building Forum - Fixings into EWI post-installation Tue, 23 Jun 2026 12:52:59 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215039#Comment_215039 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215039#Comment_215039 Thu, 11 Dec 2014 12:56:45 +0000 RedDoor Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215040#Comment_215040 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215040#Comment_215040 Thu, 11 Dec 2014 13:03:42 +0000 DarylP http://www.fischer.co.uk/PortalData/10/Resources/support/sales-documents/documents/9.Insualtion___Facades_No_Bleed_18.12.12sml.pdf]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215044#Comment_215044 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215044#Comment_215044 Thu, 11 Dec 2014 13:26:05 +0000 Mike George
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]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215089#Comment_215089 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215089#Comment_215089 Fri, 12 Dec 2014 08:46:39 +0000 RedDoor Mike, I can't do anything about it now but what are going to be the effects of timber inside the insulation?]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215090#Comment_215090 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215090#Comment_215090 Fri, 12 Dec 2014 10:17:57 +0000 Ed Davies 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.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215098#Comment_215098 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215098#Comment_215098 Fri, 12 Dec 2014 12:20:14 +0000 RedDoor The timber is approx 50mm and then covered over with polystyrene.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215099#Comment_215099 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215099#Comment_215099 Fri, 12 Dec 2014 12:29:58 +0000 Viking House Posted By: Mike GeorgeTimber should not be used behind or within the insulated zone of EWI systems - EVER! Why not?]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215105#Comment_215105 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215105#Comment_215105 Fri, 12 Dec 2014 14:41:33 +0000 rhamdu Posted By: DarylPFischer FIDs
http://www.fischer.co.uk/PortalData/10/Resources/support/sales-documents/documents/9.Insualtion___Facades_No_Bleed_18.12.12sml.pdf" >http://www.fischer.co.uk/PortalData/10/Resources/support/sales-documents/documents/9.Insualtion___Facades_No_Bleed_18.12.12sml.pdf

Daryl, I think your answer (FIDs) is right, but I believe that is the link for fixings that hold the insulation to the wall. FIDs are corkscrew-looking things which will fix into insulation with or without render.

Where there is a render system I have found that very light items (e.g. TV cables) can be fixed using Rawlplug Uno plugs. Standard cable clips (with steel pins) can be tapped lightly into the plug and will grip OK, no screw required for this application at least.

Waiting to see whether those fixings last... and also, what happens in the three places where we used timber grounds. It certainly seems to be standard practice in the insulation industry.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215109#Comment_215109 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215109#Comment_215109 Fri, 12 Dec 2014 16:26:17 +0000 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]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215110#Comment_215110 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215110#Comment_215110 Fri, 12 Dec 2014 16:29:30 +0000 Mike George Posted By: Ed Davies
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.

Yes, I wasn't really talking about Trusses, which have protection other than rendering anyway.

I was talking about wooden grounds used to facilitate the fixing of anything a homeowner decides to try and fix to the finished external wall - satellite dishes; washing lines; light fittings; pipes; etc etc

As per the OP's query]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215111#Comment_215111 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215111#Comment_215111 Fri, 12 Dec 2014 17:15:33 +0000 Viking House 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.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215112#Comment_215112 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215112#Comment_215112 Fri, 12 Dec 2014 17:34:22 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215115#Comment_215115 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215115#Comment_215115 Fri, 12 Dec 2014 18:05:17 +0000 Mike George
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]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215118#Comment_215118 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215118#Comment_215118 Fri, 12 Dec 2014 19:04:27 +0000 bot de paille Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215119#Comment_215119 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215119#Comment_215119 Fri, 12 Dec 2014 21:07:14 +0000 Mike George
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.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215121#Comment_215121 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215121#Comment_215121 Fri, 12 Dec 2014 21:51:08 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215123#Comment_215123 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215123#Comment_215123 Fri, 12 Dec 2014 21:58:00 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215124#Comment_215124 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215124#Comment_215124 Fri, 12 Dec 2014 21:59:08 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215125#Comment_215125 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215125#Comment_215125 Fri, 12 Dec 2014 22:01:27 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215126#Comment_215126 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215126#Comment_215126 Fri, 12 Dec 2014 22:03:40 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215127#Comment_215127 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215127#Comment_215127 Fri, 12 Dec 2014 22:07:06 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215128#Comment_215128 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215128#Comment_215128 Fri, 12 Dec 2014 22:08:04 +0000 SteamyTea Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215129#Comment_215129 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215129#Comment_215129 Fri, 12 Dec 2014 22:10:20 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215130#Comment_215130 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215130#Comment_215130 Fri, 12 Dec 2014 22:12:54 +0000 n2e4ewi Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215132#Comment_215132 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215132#Comment_215132 Fri, 12 Dec 2014 22:44:35 +0000 Mike George Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215133#Comment_215133 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215133#Comment_215133 Fri, 12 Dec 2014 22:57:01 +0000 Ed Davies Posted By: SteamyTeaand a *.jpg or *.bmp (I think)..png also works fine.]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215140#Comment_215140 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215140#Comment_215140 Sat, 13 Dec 2014 10:50:48 +0000 Viking House 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!]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215143#Comment_215143 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215143#Comment_215143 Sat, 13 Dec 2014 11:00:14 +0000 Mike George Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215145#Comment_215145 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215145#Comment_215145 Sat, 13 Dec 2014 11:06:55 +0000 Viking House 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!]]> Fixings into EWI post-installation https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215147#Comment_215147 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12884&Focus=215147#Comment_215147 Sat, 13 Dec 2014 11:25:50 +0000 Viking House Posted By: Mike GeorgeBuild them like what? Externally insulated Timber Frame http://www.viking-house.co.uk/kilcloon-passive-house.html]]>