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The bottom of a shed is the ventilated gap between the shed floor structure and its supporting base. The tricky part is protecting that space from damp, draughts, and animals without restricting airflow. Here’s what you can do.
What Can and Can’t Go Around the Bottom of a Shed
These materials are considered safe and can help deter animals while still allowing ventilation:
- Galvanised steel or open-weave mesh for perimeter edge
- Timber bearers or treated sleepers to define the base
- Gravel strip for ground-level drainage and airflow
In contrast, what you should avoid at ground level includes:
- Solid boards
- Bricks stacked tightly
- Plastic sheeting that seals the perimeter
Wooden sheds rely on air movement underneath to reduce moisture build-up. Blocking that space can trap damp and lead to rot in floor joists.
How to Keep the Ground Clear Around Your Shed Base
To ensure your shed stays well-ventilated and rot-free, the perimeter needs to be kept completely clear of blockages.
- Clear the gap: Regularly rake away dead leaves, weeds, and built-up soil from the edges of the shed. The gap between the bottom of your shed and the ground must remain visible and unobstructed.
- Grade the ground away: If the soil around your shed has shifted, don’t just level it flat. Instead, shape the soil so it slightly slopes away from the shed walls. This ensures rainwater naturally drains away from the base rather than pooling underneath the floorboards.
- Check for sinking: Walk the perimeter and look for soft, sunken patches where puddles form after heavy rain. Fill these specific dips with compacted soil or gravel to prevent water from sitting stagnant near the timber.
How to Stop Animals Getting Under a Shed Without Sealing It
Your best bet is to fix a wire mesh or galvanised netting around the perimeter, buried far enough below ground level to stop a determined rat, fox, or rabbit (6 to inches down). Hold it close to the shed frame to prevent animals from getting under the loose edges. Bend the buried portion 90 degrees away from the shed so that any digging animals hit a floor and give up.
Moisture Control Around the Shed Base
This is where gravel strips along the base come in handy. Their purpose is to drain water away and stop soil from holding moisture against the base. During heavy rains, they can also help reduce mud splashing onto timber cladding.
It can work alongside mesh wire, but note that they’re not the same. Mesh is a physical barrier for access, while gravel is for drainage and ground condition control.
If the shed is close to a garden space, keep plants and soil away from it. This limits moisture sitting against the timber and allows air to move more freely around the base.
Shed Base Support Options for Stability and Airflow
Timber bearers or treated sleepers create a raised frame for the shed to sit on, keeping it level and allowing air to move through the gap. They also spread the weight across the ground without the floorboards sitting directly on damp soil.
Installing or adjusting bearers or sleepers may require lifting the shed to reposition the support underneath. Use temporary blocks to place the structure there temporarily.
This is usually a two-person job for a small shed, but the more hands, the better, especially if it’s a large shed.
In case you need to make some serious changes to your base, here is a step-by-step guide on how to move your garden shed.
Should Shed Skirting Boards Be Used Inside or Outside?
Use skirting boards inside the shed, not outside. Internal skirting is fitted along the wall base to cover the floor edge and seal off small gaps inside the shed. It doesn’t interfere with the airflow below, making it a safe addition, although it’s optional.
In contrast, skirting around the outside of the shed isn’t recommended. You can imagine how disruptive it could be for ventilation and how it might even change how moisture behaves around the base, but let’s steer away from that.
That’s pretty much what you can put around the bottom of a shed and how to apply them.
When it’s time to upgrade to a new shed, shed kits are usually the most convenient option to go for. There are plenty of shed options available to suit your storage needs:
FAQs
Do you need airflow under a shed?
Yes, airflow is crucial, the same as an air gap for shed insulation. To maintain it, the space underneath is meant to stay open, not sealed. Otherwise, the underside of the timber stays damp for longer, especially after rain or changes in ground temperature. If overlooked, this can lead to quicker deterioration over time.
What issues start at the bottom of a shed?
Moisture, followed by damp building up under the floor. Next is uneven ground, where the shed can settle unevenly and put strain on the frame and doors. And eventually, gaps around the base, allowing water and debris to collect.
How often should I check the bottom of a shed?
Do so at least once or twice a year, and after periods of prolonged wet weather or noticeable ground movement. These are the times when gaps, soft ground, or moisture build-up are most likely to appear and affect the base.
How can I maintain the bottom of a shed?
Clear debris, leaves, and soil build-up from around the base to keep moisture at bay. Don’t wait for gaps to widen or the base to shift. Top up and compact any low or soft spots that develop over time to prevent movement. When adding any barrier, make sure it doesn’t seal the space completely.
