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How to damp proof your shed

6th February 2017

Damp proofing your shed helps to stop moisture from damaging the fabric of the building and destroying your tools and equipment.

Here we cover routine maintenance, insulation, ventilation, heaters and dehumidifiers, and more. Everything you need to know to keep your shed dry and damp-free.

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At a glance

  • Take stock of your shed – repair and maintenance helps keep the weather out
  • Install insulation
  • Ensure adequate ventilation
  • Heat and / or dehumidify
  • Effective storage solutions

Water ingress and condensation create a damp atmosphere in your shed which promotes rust and corrosion. To avoid damage to expensive tools and equipment, and to stop your shed rotting, it’s vital to make sure it’s water and damp proof. Here’s how to do it.

Regular maintenance

Check the roof

Your shed roof takes the brunt of all weather - ensure it’s maintained between seasons
Image: Shutterstock

When was the last time you gave your shed a good once over? Check the roof first – many sheds are covered with roofing felt or felt shingles. This bitumen-based product is cheap and cheerful, but deteriorates over time. Pay particular attention to potential stress points like the ridge line and eaves.

Patching a felt roof is straightforward: use gutter sealant to secure patches in place and to repair minor tears in roof shingles. When the time comes to replace the felting, you may wish to consider going for EPDM, a rubber sheeting solution which is made to measure and lasts for many years without maintenance.

Walls, doors and windows

Windows are susceptible to damp and rot - ensure you treat them routinely with wood stain
Image: Shutterstock

Apply wood treatment every year. Even if you’re buying a new shed which comes with a guarantee against rot, it’s very important that you give it a coat of wood stain every year. Stopping rot before it starts is by far the best way to stop your shed getting damp and moldy.

Check your windows and doors for damage and decay and repair as necessary. Over time, wood can crack and shrink, so make sure you apply filler as necessary and have adequate draft exclusion. You don’t want rainwater blowing through gaps.

Install insulation

Keeping heat in will fight damp and make your shed more useful in the winter months
Image: Shutterstock

The dew point is the temperature at which humidity in the air condenses. Without insulation, cool surfaces like windows and metal tools get wet when the temperature drops, and soft furnishings, wood and paper grow damp, swell and become the perfect growing medium for mold.

Even without heating, if you install insulation, you’ll trap any available heat inside your shed, helping to keep the temperature more stable. Basic insulation like silver backed bubble wrap will help, but if you can, go for a really effective insulation product like Kingspan or Celotex – solid foam insulation available in a range of thicknesses.

Keep the air moving

Positioning small vents on opposite walls of your shed will keep the air moving
Image: Shutterstock

Stop moisture buildup by making sure your shed is well ventilated. Even opening the door and windows every few days will help keep moisture levels down. That’s because moving and replacing the air in your shed stops damp building up.

To get the air flowing, you need a minimum of two vents, ideally installed into opposite walls.

For smaller sheds, a couple of static vents are all you need, but for sheds over 12’ by 8’, consider installing a solar or mains-powered vent. To stop bugs setting up home among your tools, make sure that any vents are mesh backed.

Heat sources

Electric heaters will help to keep damp at bay
Image: Shutterstock

Along with ventilation, heating your shed works wonders for keeping damp under control. If you have mains power to your shed, it’s worth thinking about buying a tubular heater which you can wall or floor mount and set to emit background heat to help keep the temperature above the dew point.

Even if you don’t have a 240V electricity supply, you can still install a heat source. A professionally installed wood burner is one option, a solar powered air heater is another – but avoid paraffin and Calor Gas heaters because as well as producing heat, they pump out moisture – just the thing you’re trying to eliminate.

As well as a heater, you might want to install a dehumidifier, particularly if your shed is located on damp ground, if you live in a particularly rainy part of the country or you’re near the coast.

Quality storage solutions

Lock away your tools and equipment to protect them from damp
Image: Shutterstock

If despite your best efforts, your shed still suffers from damp, invest in quality storage boxes, cupboards and drawers and there’s every chance you can still prevent your tools and equipment corroding.

Anything left lying around deteriorates, so always put your tools away after use – preferably in sealed containers with a silicon gel sachets inside to keep them dry and undamaged ready for the next time you need them.

A shed which is left shut up, is unheated, or which leaks, will quickly grow damp and moldy. But with regular maintenance and by paying attention to insulation, ventilation and heating, you can make sure your shed stays warm and damp-free this autumn and winter.

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