Mounting fixtures to externally insulated wall?

[gremlin_95]

Hi all,

I have to mount a few air temperature sensors for the heating system and
my weather station on the North facing external wall - the wall was
previously plain brick but it has now been insulated externally with
90mm EPS board and finished with a lightweight render.

Is there anything I should watch out for when mounting the sensors?
Also, it is likely that we will be fitting a security light to the wall
too so is there anything special needed to mount the lights on an
insulated wall?

 

[gremlin_95]

Much depends on how strong the render is...

Is there a test I can do? Perhaps involving an angle grinder?

 

[Bill Wright]

Is there a test I can do? Perhaps involving an angle grinder?

In my domestic aerial installing days I learnt that fixing cables to
render of the sort done by cowboy builders on recently purchased
ex-council houses was a bit of a problem. Sometimes a tap with the
hammer would result in a resonance that told me that the whole area of
render had detached from the wall. A serious attempt to knock in a cable
clip might result in area of render a yard by a yard falling onto the
pavement.

Bill

 

[Jeremy Nicoll - news posts]

The other option is to go for the 5" screw and drill right through the
insulation and into the original brickwork. Then put a plug on the end
of the screw and tap it through the render and the insulation and into
the wall, before tightening the screw. Take care not to over tighten.

So you end up with a screw that goes into brick by only about an inch, with
3-4" of shaft running through the EPS & render, then the item you're hanging
on the wall attached at the outer end of the virtual lever. Wouldn't it
tend to flap around a bit?

Small items being hung will probably only have small mounting holes, but
this 5-6" screw is likely to be a #8 or #10, which might present a problem.

If the render is reasonably strong, could one glue/mastic some sort of board
onto it?

I wonder if there are fixings, a bit like those used for hollow doors, that
one could use that would pierce the render and a little of the EPS behind,
then spread out to grip the EPS?

I think I'd be inclined to try to fit a wooden batten/spreader onto the
wall, then mount objects on that. Drawback with a batten/spreader will be
rot, and fixing a new one in due course might be tricky, especially if you
tried to use the old screw holes/plugs.

If I needed the mount to be able to take a reasonable weight I don't see any
reliable method other than piercing the render and removing a core of EPS,
then filling that void with a 3-4" deep wooden plug or something screwed
firmly into the brick, then one could scrrew the item onto the plug.

Perhaps the OP should ask the insulating company? They'll know if there's a
reliable method. I suspect they'll say such mounts should have been planned
before the wall was insulated.

 

[Dave Liquorice]

... it has now been insulated externally with 90mm EPS board and
finished with a lightweight render.

One assumes that there was some form of (metal?) mesh support fixed
over the EPS board to provide some form support/key for the render?
And that this mesh was fixed to a frame work of some sort fixed
through the insulation to the original brick wall. If so a suitable
depth hollow wall anchor that spreads onto the back of the
render/mesh will probably do for sensors and small things.

What do you mean by "weather station"? A 10 m long ali scaff pole to
support and anemometer/wind vane or something a bit smaller?

 

[Jeremy Nicoll - news posts]

Depends on how thick the EPS. If its 2"...

OP said 90mm...

 

[gremlin_95]

One assumes that there was some form of (metal?) mesh support fixed
over the EPS board to provide some form support/key for the render?
And that this mesh was fixed to a frame work of some sort fixed
through the insulation to the original brick wall. If so a suitable
depth hollow wall anchor that spreads onto the back of the
render/mesh will probably do for sensors and small things.

I will have to ask someone who was home when the rendering was
completed, I was not at home.

What do you mean by "weather station"? A 10 m long ali scaff pole to
support and anemometer/wind vane or something a bit smaller?

No it's just something similar to this:

http://www.amazon.co.uk/DB-Tech-Wir...r_1_4?s=kitchen&ie=UTF8&qid=1376174355&sr=1-4

 

[gremlin_95]

I will have to ask someone who was home when the rendering was
completed, I was not at home.

Okay, I remembered I have some pictures, there does appear to be a mesh
fixed over the EPS before the render.

EPS fixed:
http://i363.photobucket.com/albums/oo71/david938/03072013505_zps1e70b212.jpg

Initial layer of render/base:
http://i363.photobucket.com/albums/oo71/david938/18072013535_zps6d7f2bfe.jpg

Completed finish:
http://i363.photobucket.com/albums/oo71/david938/image_zps88aa0b3d.jpeg

If you tap the wall from outside, it feels hollow.