You may have noticed that some homes have vents virtually at ground level but they are not a form of window to allow light into a basement. These vents are a form of subfloor ventilation and a crucial ingredient for many homes.

Why Subfloor Ventilation?

The gap under between your floor and the soil is to reduce the risk of damp and other issues. Damp builds up in the soil, particularly after heavy rain. This damp can then rise through the foundations of your home and into the floors and walls, potentially causing a health issue.

Ventilation is designed to allow air movement under your home, the flow of air pushes damp air out by bringing in dry air, effectively stopping the damp from getting into your home.

Considering the dampness under your house makes it more attractive for many pests, such as termites, it’s a good idea to get rid of the damp.

Types Of Subfloor Ventilation

There are two main types of subfloor ventilation systems, both work to remove the damp.

  1. Natural flow

This type of system has vents on both sides of the house. The idea is that this creates a cross breeze which will ensure the air moves and pushes damp air aware from your home.

However, you have no controls over this type of ventilation, it is just as easy for the damp air to flow through overnight, making the area under your house damper than it needs to be.

  1. Fan operated

This is the best option for subfloor ventilation. A fan is used to pull air in under the house, effectively forcing the damp air out. You can also use the fan to push air out which effectively draws dry air in.

This type of system does need power, ideally, the fan will be on a timer so that it runs during the day when the air is driest. In fact, it’s a good idea to run it from a solar panel, this will ensure it comes on when the air outside is dry and really help to ensure the air under your house is dry, preventing damp issues.


Providing you have a gap under your home it is very easy to install either type of ventilation system. All you need is to create a hole big enough to put a vent in, and a second hoe opposite this to create the natural cross draft.

You can connect your fan to a pipe that covers the vent, this will be the in, or out, point. The other vents can be simply covered with mesh.

It is important to cover the vents with a fine mesh, this will help to keep all sorts of pests out.

Once the pump is in position it simply needs connecting to your chosen power supply, if necessary with a timer.

More complex systems add pipes under the floor to encourage damp air movement but this is only as complicated as positioning the pipes, fitting subfloor heating is a simple job and one you should consider having done.