Fixing into expanding foam

[churchilldog]

I am in the process of installing a cat tunnel through a cavity wall.

Pictures here: //www.diynot.com/network/churchilldog/albums/3515

As you can see from the pictures the hole is slightly bigger than the lining, and there is one more lining piece to go in on the outside of the tunnel before the flap is installed.

In order to give the best seal, I propose to fill around the final liner piece with a low expansion foam. Once this has set, been cut to shape etc, will it be enough to fix the flap into this (and if so, how should I do this, screw directly or drill/ plug and screw) or should I come up with a different method, like securing some wood either side of the tunnel then securing into that?

I've already foamed the inner piece of the tunnel and think that this will work out well once it has cured, indeed the foam seems to be holding it without screws, but I would rather get a mechanical fixing it, especially on the outside of the property!
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Untitled

• churchilldog
• 17 Aug 2009
• 1

Untitled

• churchilldog
• 17 Aug 2009
• 1

 

[^woody^]

You cant fix into the foam, so you will probably need some long threaded rod and a bolt each side, or use a timber dowel (broom handle) and screw into that from each side

 

[r896neo]

as woody says you cant fix into foam but if you let it go off and then chop it out to 3 inches deep, then fill this with mortar and push your plug in while its still wet it'll give you enough grip to keep the thing quite well on. It won't be strong enough to resist someone yanking at it but will be more than enough to hold your screws and give it a bit off grip.

 

[ColJack]

gripfill round the gap and screw into this.. hardens like plastic..

 

[churchilldog]

Thanks for all the suggestions. Picked up gear tonight to pass threaded rod through to each side, with nuts, washers and plastic caps. Will add photos when I do the job tomorrow.

 

[foxhole]

You will need to cut back foam externally to make good with mortar mix to avoid damp entering, mechanical fixing will not then be required [the foam holds like glue] or you could use Fischer Window & Door Frame Fixing Foam for a very secure fixing.