There are different types of rat flaps, which vary in price and skill required to install. The first thing to ensure is the rat flap has a single stainless steel flap, to prevent the rats coming up the drain pipe.

The next step is to identify the size of the pipe leading from your property to the drainage system. As a simple guide:

  1. Residential properties – 110mm sewer pipes
  2. Commercial properties – 150 mm sewer pipe

N.B. you may have more than one pipe leading to the drainage system. To determine which sewer pipes lead to your property, we recommned lifting the lid and then asking someone to flush each toilet from inside the property.

The next step is to determine where you can install a drain non return valve. The easiest place to start is to look around your property for an inspection chamber, and lift the lid. If you are unable to remove lid yourself, please contact a drainage expert to help you. If you have an inspection chamber, count the number of in pipes into the chamber and assess the size of each pipe. In this case, you can install a retro fit non return valve. No tools are required and can be installed in minutes.

If you do not have an inspection chamber, then you will need to install an inline non return valve. The type of inline non return valve will depend on whether you are preventing storm or saline water. Although inline non return valves operate with a single flap like a retro fit non return valve, the issue is they require expertise to install. The works may involve digging down, cutting the pipe and installing the valve.

Alternative Entry Points

Another area where rats and mice can enter your home is via Air Bricks. Air bricks are a designed to ventilate your sub-floor void under your property to prevent dry and wet rot. However, mice can squeeze through the gap in the air brick and enter under the floors. We would recommend investigating whether you have any air bricks, and consider an air brick cover.

Given mice can squeeze through a hole the size of a pencil, you may also have cracks in your brickwork. We would recommend inspecting the pointing around your property and sealing any holes.

Can Rats Chew through Drain Pipes?

Yes, rats can chew through drain pipes and that is why we recommend a rat flap rather than rat poison. Rat poison dehydrates the rat, causing them to search for water and become anxious. This leads them to chewing through your drain pipe and leading to potential damage and leakage. This can be costly to rectify. A rat flap allows the rat to leave your property humanely, and will protect from them coming back up the sewer pipe.

If you have any questions about rat flaps, contact us on 01484 505509.