Damp garage, need suggestions

[homerj]

Hi folks, recently moved house, garage is sectional concrete panels with corrugated roof, slightly oversized concrete floor with potential dpm below which doesn’t go back under concrete panels, garage is watertight but floor is wet below car and underside of car was wet,
Heating hasn’t helped due to no insulation atm so currently running a fan under car which has dried things up.
Dehumidifier showed 75% this morning when turned on and hasn’t brought humidity down by much,
Is this purely a ventilation issue, no problem adding some vents but would also like to be able to get a bit of heat in there

 

[RrogerD]

Likely wet due to condensation (cold floor) rather than rising moisture. Not a lot you can do about it tbh without digging out and re-laying with insulation.
In general, garages were built to house a vehicle rather than storage things and so keeping it dry from above was the primary aim rather than having warm 'feet'.

 

[noseall]

Hi folks, recently moved house, garage is sectional concrete panels with corrugated roof,

A concrete sectional garage on a slab, with corrugated roof, is about as low end as you can get.

What are you expecting from it?

 

[Harry Bloomfield]

Hi folks, recently moved house, garage is sectional concrete panels with corrugated roof, slightly oversized concrete floor with potential dpm below which doesn’t go back under concrete panels, garage is watertight but floor is wet below car and underside of car was wet,

Is that 'wet' taken in by car, or due to flooding?

If taken in - I have a roller shutter door at the front, plus two smaller doors towards the rear. I leave the roller door open a few inches, plus a rear door, to get air flow to dry things up.

If it's from flooding, you need to work out why, and deal with that.

 

[JohnD]

Did you drive the car into the garage when it was wet with rain?

Lay a large piece of plastic on the floor, and weight it down. If there is no DPM and water vapour is rising from the floor, condensation will form under the plastic.

If the air is damp and is condensing on the floor, you will see it forming on the plastic, and the floor beneath will be drier.