Dog proof material around the walls

[otolith]

Currently, the back of the house has a foot wide strip of gravel between the house wall and the patio.

Actually, that's not quite true. That's what it used to have. Now it has a small recreation of the Somme, circa 1916. The mutt keeps trying to excavate the house. There's a pipe under there carrying rainwater from the roof to the drain. I know, I can see it.

What can I put down that will be dog-proof, but won't cause problems down the line?

[otolith]

I've been thinking about that, but he's a fairly large dog, I think he'd just pull it up.

[otolith]

Gazzab said:

Cover the ground in chilli powder :-) or don't leave him outside and unattended and bored?

I only need to turn my back for a minute and the bugger is at it again! He just thinks digging is the best thing ever.

[otolith]

I think the dog would be the least of my worries after the wife had trodden on that!

[otolith]

What I'm wondering is whether that surface needs to be permeable - would it cause damage if I put a thin skim of concrete over it?

[otolith]

Yeah, that's exactly the kind of concern I had.

[otolith]

Although googling "French Drain" suggests that it's a porous or perforated pipe in a gravel trench - this is just a solid walled pipe which happens to run along the side of the house under the gravel.