I bought a fairly good sized garden shed end of last year. It’s pretty solid and does the job of storing bikes and the nippers go kart etc but when it gets really cold (freezing temps) it gets icey and full of condensation in there. So, I always put sheets (old bed sheets and waterproof bike covers) over the bikes and toys etc.

Yesterday morning I went to go for a ride for the first time in a couple of weeks (I know I know) and when i took the sheets off, the bikes were covered in condensation, literally dripping wet. When I took them out I noticed that the moisture had obviously been sitting on them for a long time as there were areas of pitting and rust starting to form.

So, my first question is it better to actually not cover the bikes at all? My thinking was that the because I cover them, perhaps over zealously, that it’s not allowing moisture to escape so it’s just sitting on the bare metal slowly eating away at it so it’s better to leave them uncovered completely?

Secondly, what is the best way to reduce the amount of moisture in the shed itself?

1. Don’t cover bikes.
2. Lack of ventilation.

Assuming the roof isn’t letting in water I’d think you need ventilation too so air can blow through and get some of the moisture out. Also the waterproof cover probably won’t help as it will trap the moisture.

Similar problem, but what is the best way to add ventilation?
A few holes drilled below the roof, an extracted style vent, a fan?

one of these at each end:

Cut out a suitable hole and fit these over. They’re only a couple of quid each

A much more expensive but ultimately more effective option may be to insulate the shed. I have done this-cheap 25mm kingspan insulation on the sides and roof from their seconds store via a friend who is a builder, 4mm MDF to line the shed painted with outdoor paint, leave an small air gap between the insulation and the fabric of the shed to avoid long term rot issues.

It took a few weeks to get rid of the residual damp with rechargeable dehumidifiers used in caravans etc. but for about £150 all in and a few hours work my shed is now condensation free and has been for three years. I also have one of the grills shown above but with a closing shutter on the inside and use it in the summer to help ventilate

Edit: I should say that mine has a suspended wooden floor, not direct onto concrete