Hi Everyone

Hoping you wonderfully knowledgeable people can make sure I can repair holes in my eps, with silicon render.

I recently changed my internet provider and to cut a long story short I have just realised that I now have two holes in my external wall insulation through to the brick where a m8 screw has been stuck in (wiggled around a lot) and removed.

Should I just use expanding foam and cut off any that expands out the hole?


Also any recommendations for new fixings in future, on research I can see two options.

Heavy duty, drill a hole through insulation and into the brick behind insert some sort of tube to protect the insulation and then a normal fixing into the brick behind. I found the following products

tube only by swifix at the ewi store
https://ewistore.co.uk/shop/external-wall-insulation/swifix-single-tube-fitting-pack-of-10/?attribute_colour=White&mh_matchtype=&mh_keyword=&mh_adgroupid=&mh_network=x&gad_source=1&gclid=CjwKCAiAx_GqBhBQEiwAlDNAZpLww1VdfaqRNOE1fxY1w6Ga0Hh4aUwqlZcLFtxPBmXToj6uQfOXihoCoTYQAvD_BwE
Or
complete solution by Fischer Thermax
https://www.fischer.co.uk/en-gb/products/fixation-on-etics-insulation/fixing-in-substrate/thermax-8-and-10/stand-off-installation-thermax-8/45682-thermax-8-120-m6-2

They both also do a screw-in plastic grip for things like cable ties that only goes into the eps.

Has anyone used either system and got any feedback?

Important to ensure that driven rain cannot be forced into any penetration and get behind insulation.

If it helps I have a document I send out for EWI fixings suggestions.

Loadings are based on woodfibre density so need to be checked with manufacturer.

When using spiral fixings into my EWI I screw in most of the way and then apply some clear CT1 (construction mastic) around the rim before screwing fully home. It's the best glue/mastic I've ever used and no way that rain will get in. On the downside, you'll never be able to remove it again either!

The mastic leaves a permanent flexible bond and consolidates any crumbly edges in the render.


A couple of things I've learned using these nylon spiral fixings:

1) Make sure whatever you fix will cover the large plastic screw head as otherwise, it can look a bit rubbish.

2) If fixing into woodfibre EWI pre-drill with a smaller bit and use a hoover to clear the hole

3) Expect the first screw you put in the grind up the thread against the render on the way in.
Chuck it away and use another one. Never attempt to get a duff nylon fixing all the way in - they WILL jam.
They can be a right pig to get out again when they jam.

4) Buy twice as many fixings than you actually need due to point 3.