20 July 2023 · Sharon Winson
Do concrete garages get damp?
They can — but damp in a concrete garage is almost always preventable. Here's where it comes from and how to stop it.
Concrete garages can get damp, but they don't have to. Damp usually comes from condensation, poor drainage around the building or moisture rising through the base — not from the panels failing. With good ventilation, working gutters, a damp proof membrane under the base and anti-condensation roof sheets, a concrete garage stays dry year round.
Why do concrete garages get damp?
Concrete is a porous material — it contains microscopic pores and capillaries that can let moisture through — so where damp appears, it's usually one of four causes:
• Condensation: warm, moist air meeting cold concrete or metal surfaces, most common in winter and in garages with little ventilation. • Poor drainage: ground that slopes towards the garage, or missing and blocked gutters, letting water pool against the base. • Moisture from below: a base laid without a damp proof membrane lets ground moisture rise through the slab. • Construction problems: gaps, poor sealing or a badly laid base letting weather in.
In our experience, condensation is by far the most common of the four — and the easiest to fix.
What problems does a damp garage cause?
Left alone, persistent damp causes three kinds of trouble. It can damage the structure over time — cracking, surface spalling and general deterioration. It encourages mould and mildew, which are unpleasant and bad for anyone with allergies. And most immediately, it ruins whatever you're storing: tools rust, boxes soften, fabrics smell. If the garage is protecting things you care about, it's worth getting damp under control early.
How do you stop a concrete garage getting damp?
Six measures cover almost every case:
• Start with a properly built garage — sound panels, sealed joints, well fitted. • Keep water moving away: gutters and downpipes in working order, ground graded away from the base. • Ventilate: air movement through eaves vents stops moist air sitting inside and condensing. • Put a damp proof membrane under the concrete base when it's laid. • Seal or coat the inside of the walls if you want extra protection. • Choose roof sheets with an anti-condensation coating, which hold moisture until it can evaporate rather than letting it drip.
Get the base and the roof right at the start and the rest is light maintenance.
A dry garage starts underneath — our concrete base laying service includes a damp proof membrane as part of a properly prepared base. If you want a warm space as well as a dry one, read how to insulate a prefab garage, or compare our concrete garage ranges and prices.
Is damp a design fault in concrete garages?
No — damp is almost always about the site and the setup, not the building. Condensation, blocked gutters and bases laid without a membrane cause the vast majority of problems, and all three are preventable.
What causes condensation in a garage?
Warm, moist air touching cold surfaces — typically the roof sheets and walls in winter. Ventilation and anti-condensation roof coatings deal with it in most garages.
Will my things rust or go mouldy in a concrete garage?
Not in a dry one. Keep air moving, keep water draining away from the building and make sure the base has a damp proof membrane, and a concrete garage is a perfectly good store for tools, furniture and anything else.
Do Nucrete garages come with anti-condensation roof sheets?
Anti-condensation roof sheet options are available across our ranges — tell us how you'll use the garage and we'll recommend the right specification. Call free on 0800 849 9036.