blocking a catflap

[johnnyneuro]

I have a catflap (well, a tunnel really) passing through a double external wall that I want to close up permanently, although not so permanently that a future owner couldn't reopen it.

Here's the plan:

On the outside screw an aluminium cover plate, with a line of sealant to keep out the rain. Fill the tunnel with loft insulation. Use a bit of plasterboard to make good the internal wall.

How does that sound? Am I missing anything? Is there a better tunnel filler (expanding foam, for example)?

Thanks.

 

[JohnD]

if you can fit a large airbrick on the outside, it might blend in with the wall better.

 

[johnnyneuro]

Hmmm..an air brick. I hadn't thought of that, although the hole is one and half bricks wide and about the same height.

In general, should I provide some ventilation to the tunnel, or seal it?

Thanks

 

[JohnD]

seal the inside, allow a little ventilation from the outside - this will prevent warm damp air from indoors condensing on the cool wall.

If you see any advantage to increasing ventilation to the room, you could fit a hit-and-miss vent on the inside.