26 replies to this topic

[Gaz66]

Ive just painted the garage floor, big mistake as its taken ages to dry!
Anyway its done and now the floor is damp with condensation.
Talk about one extreme to the other, dusty to wet!
Rather than having a dehumidifier running all the time what would be the best option to keep the place dry, more ventilation or more air tight?
Cheers
Gaz

[IronmanG]

I have always found ventilation is best
It wasn't wet at all before you painted the floor?

[Gaz66]

I have always found ventilation is best
It wasn't wet at all before you painted the floor?

No, bone dry
I reckon any condensation or damp in the air was being soaked up by the dusty concrete before.

Edited by Gaz66, 12 December 2021 - 11:28 PM.

[Tornado99]

Cold floor with damp air means condensation....if floor is now fresh/sealed paint, water will pool on surface rather than diffuse into concrete. Put a little heat into garage if possible, will lower the relative humidity which it what determines when condensation occurs. Other than that, use a passive vent or fan driven vent.

Edited by Tornado99, 13 December 2021 - 12:56 AM.

[Spider]

It may seem a dumb question, but what's the source of the moisture ?

Is it just atmospheric, coming up through the floor (not likely now) or coming through the walls ?

[IronmanG]

Is it a concrete garage? I've seen all sorts of damp problems there. Brick less so
Connected to the house?
Separate block?

[Gaz66]

It may seem a dumb question, but what's the source of the moisture ?

Is it just atmospheric, coming up through the floor (not likely now) or coming through the walls ?

Its atmospheric.
Concrete base and single skin brick walls detached from the house.
We are also in a valley next to a river (200m) which wont help at this time of year.

Edited by Gaz66, 13 December 2021 - 12:17 PM.

[MatthewsDad]

I've mentioned this on the forum before but I lost my beloved golf GTi to rust after longish term storage in a poorly ventilated garage. I'm surprised that you have the condensation you describe unless there is particularly poor ventilation? Is it possible to ventilate even temporarily to see what difference it makes? Even just a few air bricks to allow air to flow rather rather than stagnate?

[IronmanG]

You can get extractor fans that recirculate what warm air there is. I fitted 1 on a job where there was extreme damp and mould. They haven't called back in 4 years so I guess it worked

[Gaz66]

The garage is pretty much sealed with a roller door and a composite side door.
There is a toilet, well when its installed in the corner which has 2 air bricks but that is enclosed with a door too so airflow is limited to that area only.
The roof is tiled open trusses with vents in the soffits but there is no airbricks low down in the side walls.
Maybe low down air bricks will promote better all round air circulation?

[IronmanG]

So the roof is pitched with vented soffit. And that's open to the garage?

[Gaz66]

So the roof is pitched with vented soffit. And that's open to the garage?

Yes, pitched with vented soffits and open to the garage partially as there is storage access of maybe a third of the ceiling space.

Edited by Gaz66, 13 December 2021 - 03:59 PM.

[Gaz66]

Ive just been in to the garage and things seem a bit dryer. Maybe because the temperatures are stabilising?
Still no good though as it will happen again at the next temp drop.

[Quinlan minor]

The garage is pretty much sealed with a roller door and a composite side door.
There is a toilet, well when its installed in the corner which has 2 air bricks but that is enclosed with a door too so airflow is limited to that area only.
The roof is tiled open trusses with vents in the soffits but there is no airbricks low down in the side walls.
Maybe low down air bricks will promote better all round air circulation?

Definitely!

Start with four, front and back, both sides, ideally at floor level.

[panky]

Try a desk fan in one corner to get the air circulating, I put one on a timer and it cured the condensation dripping from the plastic roof on my garage extension.