How to Prevent Condensation in Your Metal Shed

A metal shed.
  • 2-4 hours
  • Beginner
  • 40-100
What You'll Need
Damp-proof membrane
Timber base

A metal shed is great for storing items or can be used as a workshop. It requires very little maintenance and, unlike wooden sheds, it is not necessary to stain or treat the outside. However, the one issue that occurs with these sheds is condensation. There are steps to take to ensure as little condensation occurs as possible. Much of this condensation will occur near the foundation. It is important to think about condensation when putting in a shed. It is much easier to prevent condensation when installing a shed rather than changing the shed after it is standing.

Step 1 - Check the Foundation

The size and composition of the foundation will contribute to condensation problems. If cement is being used, then ensure that the foundation is only an inch or two wider than the shed on each side. It is also very important for the cement to cure properly. If the shed is installed too early, then the water in the cement will enter the shed and begin cycles of condensation. A damp proof membrane can also be installed in the foundation. This should be done at least 2 inches above ground level.

Step 2 - Create a Raised Timber Base

If the shed and foundation have already been installed, then creating a raised timber floor will allow for air circulation under the shed. This can dramatically reduce condensation. When installing this type of floor, the shed will need to be secured to the floor using wood screws. Also, apply a mastic seal to the interior of the shed. Make sure that water cannot pool underneath the timber floor as this will counteract the benefits of air circulation.

Step 3 - Apply Sealant

A mastic or silicone sealant applied to the exterior of the shed is important. This sealant should be applied where the shed meets the concrete base. The function of this sealant is to allow for water runoff on the outside of the shed and ensure that the water does not enter the shed at its base.

Step 4 - Add Insulation

Condensation forms because the shed is not properly insulated. Apply rigid foam to the interior of the shed. Also, cut holes through the insulation to allow for ventilation. The vents should be about 6 inches in diameter. Once the insulation is in place, apply a plywood wall. Make sure that the walls and the roof are properly insulated.

Step 5 - Add Vents

Circulation is important as it is necessary to move the moisture out of the shed. Most of the time, moisture will enter the shed form the base or bottom. Therefore, it will be necessary to have a vent towards the top of the shed. The air inside the shed is warm so it will exit out the top and draw more air in through the bottom. This way with a vent up high constant air circulation is occurring.

Step 6 - Use a Dehumidifier

If there are still major condensation issues then a dehumidifier can eliminate much of the moisture in the shed. This will be a more expensive choice as the dehumidifier will run on electricity and need to be running constantly. Try insulation and ventilation before installing a dehumidifier.