# Dealing with a slightly damp double garage.



## MontyVeda (21 Mar 2021)

My mother has kindly invited me to move my workshop out of my kitchen and into her double garage, but it's a little bit damp in there. 

It's not so damp that mould is forming anywhere, and apart from around the big plastic doors, the breeze blocks are all bone dry... but it is damp enough to delaminate carboard after a couple of years, and my Dad's hand saws always went rusty after a year or two in there.

It's uninsulated, open rafters, concrete floor, no plumbing or heating. 

Question is, does such low level damp need dealing with? 

...and if so, How? 

I guess the options would be heat, a dehumidifier, insultation or a combination of. 

Or alternatively, just keep all my tools out of the open (boxed) when I don't have a project on the go.


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## bikingdad90 (21 Mar 2021)

You need a source of ventilation, will the garage door adjust slightly to give you a mm or two of gap for air to flow through? If not, can you retrofit a vent on the plastic doors?

If the floor is concrete then paint it with a barrier paint and consider fitting a flooring.


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## fossyant (21 Mar 2021)

A dehumidifier would be a start - one with a drain, so you can pipe it under the door so excess moisture is dribbled out of the garage - otherwise you'll be empying it everyday.


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## shep (21 Mar 2021)

As mentioned airflow is your friend.


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## jowwy (21 Mar 2021)

As shep has stated, ventilation is key for an uninsulated garage..........


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## MontyVeda (21 Mar 2021)

bikingdad90 said:


> You need a source of ventilation, will the garage door adjust slightly to give you a mm or two of gap for air to flow through? If not, can you retrofit a vent on the plastic doors?
> 
> If the floor is concrete then paint it with a barrier paint and consider fitting a flooring.


the doors are regular up&over garage doors and not very close fitting at the top, sides or bottom; probably a good 10mm at the top and bottom. There is a double glazed window on the side, maybe keeping that open on 'vent' will be enough to give it a bit of through draught?



fossyant said:


> A dehumidifier would be a start - one with a drain, so you can pipe it under the door so excess moisture is dribbled out of the garage - otherwise you'll be emptying it everyday.


Yes. There was a dehumidifier in there for 6 months after it got flooded. Not sure it made much difference after the garage had dried out, but still needed emptying daily 'til Dad got bored of doing that and turned it off. Dribble pipe is a good idea .

I guess finding out what the actual humidity is in there would be a start


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## Archie_tect (21 Mar 2021)

Difficult to create a comfortable habitable space without intervention... any introduced heat would be wasted heat- best you can do is vent out any excess humidity created by working in it as suggested by opening the window for a cross vent.


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## Profpointy (21 Mar 2021)

ventilation helps, but in a garage I'm not sure I'd bother with a dehumidifier as it might be a forlorn battle to try and dry out the whole of England. I think DHs are quite costly to run - no doubt someone can confirm. The other thing I'd donis be very diligent in making sure all your tools are wiped down with an oily rag before putting away


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## lane (21 Mar 2021)

My garage is damp because the garden levels surrounding it are higher than the DPC. As far as I can see not much to be done.


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## ColinJ (21 Mar 2021)

Profpointy said:


> ventilation helps, but in a garage I'm not sure I'd bother with a dehumidifier as it might be a forlorn battle to try and dry out the whole of England.


I was thinking that. I used a dehumidifier in the house when I was drying washing indoors and it was sucking several litres of water out of the air every day.


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## MontyVeda (21 Mar 2021)

Ditto the thoughts on the DH... it's a big space so a little domestic one wouldn't be up to the job and a big one would be costly to run (and buy).



lane said:


> My garage is damp because the garden levels surrounding it are higher than the DPC. As far as I can see not much to be done.


Just raise the level of the DPC to match the surrounding gardens 

you're welcome


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## Tail End Charlie (22 Mar 2021)

If you do decide to put something on the floor, I can recommend the two part finishes (I got mine from Resincoat). It's much better than floor paint (although much more expensive) with a wide range of colours. It can be tricky to put down as once you've mixed the two parts you've got to put it down pretty quickly (the one litre pot was fine, but I could have done with an extra pair of hands when mixing and painting from the 5 litre one). Extremely tough finish, oil, petrol resistant etc. I do also have some mats where I usually stand, but that's for comfort and warmth in the winter. 
I used Resincoat as I was a bit worried about water coming in to my garage via the walls and floor.


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## battered (23 Mar 2021)

First off, solve any leaks or seeping damp. Unless you stop water getting in, you are on a hiding to nothing. Next up is ventilation. Get these right and you will have the place dry enough for most uses. At the moment you clearly have some damp around the doors. Unless you resolve this no amount of dehumidifiers etc will solve it. There is a hierarchy in place, unless you get the top items right the lower items will not fix it. It's like mopping the floor when the roof is leaking. The hierarchy runs - fix leaks and damp ingress - ventilate - insulate - dehumidify - heat.


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## berty bassett (23 Mar 2021)

Plus 1 for the resin
Good chance they didn’t put polythene under the concrete on a garage so damp would come up
Good way of seeing is the put a box on floor., leave it there for a week and when you lift it , see if it looks damp under it
Resin will seal it but will be dear
Also why not just put a fan extractor in
Can even get them that are triggered by humidity
If garden is above damp - then at least dig a french drain - or just dig it lower
If it’s an up and over door and an open ceiling then really don’t thing it’s a no ventilation issue - the wind would be rattling around in there


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