Screwing into exterior insulation

[FishAreFriends]

Hey there. Im looking to build a sheltered area between my back door and the back gate. I'd need to attach battoning to my wall, however it is covered in external insulation, and sounds hollow all over. Has anyone done anything like this and is there anything specific I need to do? My main concern is the load bearing on the insulation, there is a rail attached to the front of the house and that's using 120mm wall plugs, and seems stable enough.

 

[JohnD]

The external insulation I have seen is expanded plastic foam slabs clad with cement board cover and render.

None of this has any strength.

You need to drill through into the wall behind and use a strong enough bolt that it will not bend downwards under load.

 

[FishAreFriends]

That was my fear. Are the foam boards attached directly to the wall, or is there a stud frame (like in normal interior walls) do you know?

 

[freddiemercurystwin]

There is no frame to fix to, there are specialist brackets/fixings you can buy designed to overcome the issue from the likes of Swifix or fischer (£££) or you will have to be inventive, back in it's infancy the EWI fitters would fit a timber block the same depth of the insulation behind what ever they wanted to fix eg RWP or whatever to create a solid spacer though that's not so great as a retrospect fixing.

 

[FishAreFriends]

There are specialist brackets/fixings you can buy designed to overcome the issue.

Would you happen to know what they are called?

 

[freddiemercurystwin]

see edit above

 

[JohnD]

What is the house made of?

How old is it?

 

[opps]

Have a look at Corefix

Corefix Metal & Plastic 120 Heavy Duty Dot & Dab Wall Fixings 10mm x 95mm 24 Pack - Screwfix

Order online at Screwfix.com. Corefix 120 heavy duty steel-reinforced fixing for dot and dab (plasterboard over blockwork) walls. Suitable for all brick and block types, including lightweight blockwork. Ideal for securing deeper fixtures of between 10mm and 30mm thick such as timber battens...

www.screwfix.com

The plugs have a metal insert that will distribute the load from the brickwork. See the image in the link. Not cheap though. I have only used them once and they worked as promised.

 

[FishAreFriends]

What is the house made of?

How old is it?

It's a red brick house from the 50's/60's, council stock, with external insulation and white render over the top.

 

[FishAreFriends]

Have a look at Corefix

Corefix Metal & Plastic 120 Heavy Duty Dot & Dab Wall Fixings 10mm x 95mm 24 Pack - Screwfix

Order online at Screwfix.com. Corefix 120 heavy duty steel-reinforced fixing for dot and dab (plasterboard over blockwork) walls. Suitable for all brick and block types, including lightweight blockwork. Ideal for securing deeper fixtures of between 10mm and 30mm thick such as timber battens...

www.screwfix.com

The plugs have a metal insert that will distribute the load from the brickwork. See the image in the link. Not cheap though. I have only used them once and they worked as promised.

Cheers Opps, I'll give them a shot.

 

[opps]

Cheers Opps, I'll give them a shot.

Just check the diagram to make sure that the metal sleeve will be sufficiently long enough before you but a whole box.

I have seen people use the external insulation and I got the impression that it would be thinner than dot and dab 9.5 mm plaster and a 2mm skim, plus up to 5(?)mm of dot.

I am happy be corrected though.

Before buying anything, my advice would be to drill a single hole until you see red dust. Then determine the depth and see if the metal slieve is sufficiently long enough.

Additionally, if screwing a lump of timber to the wall, make sure that the supplied screws are long enough. Again, the image in my link will advise you accordingly.

 

[freddiemercurystwin]

If we're talking about the staandard retrofit external insulation it's around 120mm thick, I can't see how those corefix fixings could ever work.

 

[FishAreFriends]

If we're talking about the staandard retrofit external insulation it's around 120mm thick, I can't see how those corefix fixings could ever work.

I think you might be right. Do you know of anything that might be long enough, or would i be better making it a freestanding structure using something like fenceposts bolted to the path?

 

[freddiemercurystwin]

I already added my two pennys worth.

 

[StephenOak]

Do you know of anything that might be long enough,

Resin and threaded rods. I recently used

Rawlplug R-KEM II Styrene-Free Polyester Resin 300ml - Screwfix

to fix

Easyfix BZP Steel Threaded Rods M6 x 300mm 5 Pack - Screwfix

to my walls.

You can get threaded in thicker diameter if you need a stronger support.

That tube of resin was enough to fix four threaded rods, two other things I needed to fix in a wall, to fill a few holes I saw and there was some (fifth of the tube?) left over.