Rodents in cavity walls of terrace ‘blay’ house.

[joannerooks]

Good morning,
We have been struggling to rid our property of rodents who have managed to get into the cavity walls. We finally got rid of the decking and hoped that would solve it but they are still entering. We now are considering the possibility they are entering through an air brick under the floor. We have a 1930s terrace ‘Blay’ house in sw London which has a 3 m single storey extension. We have wondered if there is a broken air brick under the floor connecting to the property next door (entry seems to be on one side) Any advice would be very helpful.

- Massive job but is it possible to lay a concrete floor throughout a property (which has a floating floor) I’m concerned about damp.

- we have a drain running under extensions. Is it possible they can enter through there? Thames water did survey with camera and no damage to pipe.

Thanks for any suggestions.

 

[JohnD]

Laying a concrete floor without curing the source problem means that it will be much more difficult and expensive to repair it later.

This is sometimes found when a leaking pipe or drain causes damp and has been concealed under a slab.

Rats need constant access to water so are fond of leaks.

The food source might be bins, bird table, drains or animal feed.

 

[RandomGrinch]

I've had problems with rats in my Victorian terrace.
There weren't any external entrance for them in my house, nor were they entering our living space.
But they were in the loft and beneath the floorboards.
The loft problem was solved by building up the firewall and blocking gaps with stainless mesh, wire wool and fire rated foam.
The underfloor problem took longer to solve - I eventually found that the rear 'extension' of my house had floor joists running into the party wall. These joists were butting against my neighbours with large gaps between our two properties.
Sometimes these problems take some time to investigate. Have a nosey under floorboards, set up cameras, get a pest controller around for a look; vermin don't just come up from the sewers, but could be entering the cavities from the loft, or elsewhere.
Good luck!

 

[opps]

A customer of mine in Chiswick had an ongoing problem with rats. After months of putting down poison, she paid about 8 grand to have the foundations backfilled with concrete. From memory, she had to move out for about 6 weeks. She calculated that it was cheaper than moving and then paying stamp duty/etc.

 

[Ivor Windybottom]

vermin don't just come up from the sewers

They don't only come up from sewers but they often do.

 

[Ivor Windybottom]

There are other big advantages to getting a concrete floor - you'll get much better insulation, so lower heating bills and more comfortable. Plus it will feel more solid.

But if there's wiring and pipes under it then it's more complicated.

 

[opps]

Rat man at her site told me that sewer rats leave black marks on skirting boards. I only ever saw one rat. I had lifted some boards and found myself having a staring competition with one. Rat man told me that it must have been a young rat. It looked clean. She did have a camera inspection of the sewers. They weren't coming from there, that said, prior to the camera inspection, I did lift the manhole cover to do a smoke test. I looked down at what looked like a white t-shirt. I then realised that it was a bloated dead rat. I refused to lean down to remove it.

She had a Polish cleaner. The cleaner told her that sewer rats sometimes come up through the loo. From that point onwards she would only use the loo in the attic conversion.

 

[RandomGrinch]

They don't only come up from sewers but they often do.

Yes, agreed, but my point is that in a terrace, the drains may be in someone elses house.

 

[Ivor Windybottom]

The youtube vid I posted shows a rat getting into the loft from a sewer pipe. They climb up the inside of the vertical pipe. If there's any flexible ducting connecting the pipe to an air vent (common on newbuilds) then they can bite straight through it.

The tracer dust used in that video looks like a very useful tool. You may be able to see their fur grease and urine trails without it, just by getting a UV torch for a few quid online.

Definitely start by working out where they're coming from. You could spend a fortune fixing the floor when that's not the actual route used.

 

[joannerooks]

Thank you for the responses. It has been horrendous and seems that if they make an entry point they seem to make others to escape etc.

Thankfully no rats have entered the property - we have only heard them in the wall and under the house. One pest control thought they were entering through the roof but we have blocked everything possible that we can see. We have fitted air brick covers to front of house aswell. I think the foundations are a really good shout - we might have to lift everything up and survey first before we can do anything else.

No issues apparently in either property next door to us (so they say)

I will also consider the pipe leak idea. This could be something we haven’t yet thought of. However the main sewer pipe had a long camera extended the whole way two houses either side of us by Thames water and they said no issues with the drain being broken or anything. But I find it hard to imagine exactly what that looks like.

We have so much wire wool everywhere. But I am concerned about fire risk with chewed cables. They really are the most disgusting and intelligent creatures.

 

[ChrisJLW]

We had a problem with rats too and they were getting in via an outside drain which hadn't been blocked up when the kitchen extension was done. We would get sewage smells in the kitchen when the bath was emptied.
Spent ages hunting for their way in, had the council pest control in, 2 drain surveys & put a £200 rat blocker in the drain which didn't work. Eventually stopped them with a £45 one way valve from Amazon, it might be worth getting one and bunging it in to see if it stops them.

 

[JohnD]

I don't know how old the house is.

Old clay gullies are usually broken

There may be a hidden and forgotten sewer vent

Water pipes usually leak after 50-100 years.

 

[sparkymarka]

We had rats in the cavity walls at our last property , they where getting in next door who still had an outside toilet ( not used ) but there was half a brick missing behind the toilet pan ( I could see the dirty mark on the wall as they had squeezed past ) blocked the hole and that was the end …

 

[Odds]

Rat man at her site told me that sewer rats leave black marks on skirting boards. I only ever saw one rat. I had lifted some boards and found myself having a staring competition with one. Rat man told me that it must have been a young rat. It looked clean. She did have a camera inspection of the sewers. They weren't coming from there, that said, prior to the camera inspection, I did lift the manhole cover to do a smoke test. I looked down at what looked like a white t-shirt. I then realised that it was a bloated dead rat. I refused to lean down to remove it.

She had a Polish cleaner. The cleaner told her that sewer rats sometimes come up through the loo. From that point onwards she would only use the loo in the attic conversion.

Who won?