Repair hole in cavity wall

[Lionel_Smith]

Got a positive input ventilation unit in the hallway of my apartment. The contractor, or somebody working for him, bored a new 100mm hole out through the gable wall of the apartment building. The wall consists of 44 centimeters of concrete block, and then a cavity, and then red brick. There's no external cover of any sort on the hole in the red brick because it's completely inaccessible from the outside. There's another building just a few inches away. The hole is about 7 feet off the ground. It's a ground floor apartment.

The problem I have now is that rats can gain access to the cavity from the outside and have free rein to run around the walls and ceiling. Also, my quick Google research tells me there should be a fire sleeve or something in there as well. Don't don't know if this is correct.

How would you even begin to fix this? Filling the 100mm hole through the concrete seems doable but what about the red brick on the outside? Getting at the red brick wall when your only path to it is a hundred millimeter hole through a 44 centimeter wall seems impossible.

 

[Murdochcat]

Why was the 100mm hole drilled and then not utilised

 

[Lionel_Smith]

Why was the 100mm hole drilled and then not utilised

It is being utilised. Given that it's not authorised by the management company, I want to get rid of it completely.

 

[Murdochcat]

Stop beating around the bush and post a photo with more detail because if it’s allowing rats or mice into block that isn’t great

 

[Lionel_Smith]

Stop beating around the bush and post a photo with more detail because if it’s allowing rats or mice into block that isn’t great

That's two unhelpful replies from you. Haven't been on this forum before so don't know if rudeness is the norm. I don't have a photo with me. Just imagine a round 100mm hole going through a concrete block wall, and on on the external side of a cavity, a hole in a redbrick wall that can't be seen or photographed. There's plenty of detail in my first post.

 

[Murdochcat]

That's two unhelpful replies from you. Haven't been on this forum before so don't know if rudeness is the norm. I don't have a photo with me. Just imagine a round 100mm hole going through a concrete block wall, and on on the external side of a cavity, a hole in a redbrick wall that can't be seen or photographed. There's plenty of detail in my first post.

It’s not unhelpful

You said “it’s being utilised” so to enable people to give constructive replies a photo would show exactly what you are describing AND why not get the work done by the person who asked for it to be done ?

 

[Deluks]

Cut a small flat piece of board, slightly smaller than the diameter of the hole.

Ply would work, cement board or plastic better.
Drill a hole in the centre and tie a piece of string through it.
Post it through the hole to the outside, then pull the string tight.
The board then mostly covers the hole, you tie the string off to something and squirt expanding foam in.
Mortar and a cut piece of block on the inside. (Or just use up the rest of the foam)

 

[Lionel_Smith]

Ok, I get you. I'll see if that will work. And foam is ok for the concrete block part, with little or no mortar, so that's good to know, thanks.

 

[Murdochcat]

If the expanded foam is accessible on the outside, rats will make short work of getting through that

 

[endecotp]

So you have or will decommission the ventillation unit?