# Garage Condensation



## Ant21 (Oct 12, 2013)

After some help / advice please! 

Just moved in to our new house last week which came with a brick built double garage :argie:

The garage is single skin brick with a concrete floor and pitched tiled roof with 2 single doors.

Now I've not had a garage before, nor have I ever stored my car in a garage for any period of time. 

Whilst moving in, I've literally just dumped all my tools in there and also parked up the car. However I'm getting really bad condensation. My tools are all slightly damp and the car seems to be really bad, rust starting to form on the discs and even droplets of water under the exhaust 

I plan to get the car out of there tomorrow morning to try and prevent any long term damage, however I'm after some advice please.

What can I do to try and prevent condensation on the inside? There's ventilation from underneath the doors as I've not placed any weather stripping down yet.

The actual shell of the garage was built about 3 months before we moved in so I don't believe it's coming from the structure. 

I did park the car straight in there after driving it about 10 miles, so I don't think that was wise. 

Anything would be great, even if it's really stupid stuff like don't park a hot car in a cold garage! 

Thanks for getting this far if you have


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## lofty (Jun 19, 2007)

If it's only 3 months old the garage floor will still be damp, concrete hardens quickly but takes a while to dry out properly, especially over the winter. Try and open the door when your at home to vent it, it should be fine once the weather warms up and it starts to dry out properly.


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## dholdi (Oct 1, 2008)

Why don't you think its the structure ?
Its single skinned so I presume there is no insulation ?
Is there any insulation in the roof ?


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## Jack R (Dec 15, 2014)

Concrete takes 24hrs to harden, 28 days to fully cure and 3 to 6 months to dry out depending on weather, bearing in mind that is dependent on if a damp proof course which might not of been installed if that is the case then it will never dry out.
Also what is the ground conditions like? Is it wet and are the gutters working properly?


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## uggski (Jun 29, 2016)

JR1982 said:


> Concrete takes 24hrs to harden, 28 days to fully cure and 3 to 6 months to dry out depending on weather, bearing in mind that is dependent on if a damp proof course which might not of been installed if that is the case then it will never dry out.
> Also what is the ground conditions like? Is it wet and are the gutters working properly?


I read somewhere that while concrete hardens quickly it takes about 28 days per inch of concrete to dry out. So depending on how thick the base is it's going to be a while.


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## JordanE (Jun 26, 2013)

It's also single skin so will always be damp/cold
Best thing you will ever do it board it out properly and seal the outside brick work with some weather shield to stop driving rain. 
Then you can get some Heaters in there and have a great man cave


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## Jack R (Dec 15, 2014)

uggski said:


> I read somewhere that while concrete hardens quickly it takes about 28 days per inch of concrete to dry out. So depending on how thick the base is it's going to be a while.


Sounds about right, so assuming it's 4 inches thick (standard slab) it could be dry in a month :thumb:


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## Ant21 (Oct 12, 2013)

lofty said:


> If it's only 3 months old the garage floor will still be damp, concrete hardens quickly but takes a while to dry out properly, especially over the winter. Try and open the door when your at home to vent it, it should be fine once the weather warms up and it starts to dry out properly.


Good man, I have been trying to keep the doors open whilst I'm there, but given they are still building I'm conscious of prying eyes on all my tools.



dholdi said:


> Why don't you think its the structure ?
> Its single skinned so I presume there is no insulation ?
> Is there any insulation in the roof ?


Nope, no insulation at all in the garage. I don't / didn't think it was the structure as it's been up for around 3 months already so would have presumed it was dry. However now I'm thinking it still needs time.



JR1982 said:


> Concrete takes 24hrs to harden, 28 days to fully cure and 3 to 6 months to dry out depending on weather, bearing in mind that is dependent on if a damp proof course which might not of been installed if that is the case then it will never dry out.
> Also what is the ground conditions like? Is it wet and are the gutters working properly?


There is a DPM thankfully. 
Gutters are working good apart from one join which they are coming to sort next week.

Hopefully it just needs more time to dry out.

I did put a large fan in there earlier for a good few hours as I'm reluctant to add heat as when it cools off it's just going to get worse.


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## Ant21 (Oct 12, 2013)

JordanE said:


> It's also single skin so will always be damp/cold
> Best thing you will ever do it board it out properly and seal the outside brick work with some weather shield to stop driving rain.
> Then you can get some Heaters in there and have a great man cave


I do plan to board it out at some point and eventually epoxy the floor.


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## Mikesphotaes (Jul 24, 2016)

Don't get upset at rusty discs though, they all do that!


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## Jack R (Dec 15, 2014)

Don't use heat, to dry only use fans and a dehumidifier but that's pointless anyway in a garage. If it was me I open the window and doors as much as possible just to keep the air moving freely (also the cheapest option).


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## Ant21 (Oct 12, 2013)

Mikesphotaes said:


> Don't get upset at rusty discs though, they all do that!


I'm not bothered about that. Just would have thought that in the garage it would be fine.

I'll take her out for a drive tomorrow anyway to clean them off.


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## grunty-motor (Aug 11, 2016)

Are you sure there is a DPC under the concrete floor? 

my garage was always damp - the 2 sources were up through the concrete floor (very thin) and dew from the roof

when i got it extended i got the floor dug out and a DPC put in and new concrete. I also had a metal roof with anticondensation laid on plywood over the joists. Damp is gone. (floor was laid in winter and never had any drying out issues - certainly 3months should see it dry)

do you only have tiles on the roof? no vapour barrier or sarkin?


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## Ant21 (Oct 12, 2013)

grunty-motor said:


> Are you sure there is a DPC under the concrete floor?
> 
> my garage was always damp - the 2 sources were up through the concrete floor (very thin) and dew from the roof
> 
> ...


From memory when we were looking at it being built there was a DPM under the floor, I know there definitely is in the walls, but I can always ask the builders tomorrow.

There is some form of vapour barrier, it's the same one that's on the house roof too.


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## grunty-motor (Aug 11, 2016)

Ant21 said:


> From memory when we were looking at it being built there was a DPM under the floor, I know there definitely is in the walls, but I can always ask the builders tomorrow.
> 
> There is some form of vapour barrier, it's the same one that's on the house roof too.


you've exhausted my limited knowledge then.

I will say i can park my wet car in the garage and see pools of water on the floor and yet have no condensation on anything.

if its new build then there should be adequate ventilation already (building regs).

what you can try is put plastic/impervious material on a bit of the floor and lift it the next day. if its got condensation underneath, then you will have identified one source!!!!


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## Ant21 (Oct 12, 2013)

grunty-motor said:


> you've exhausted my limited knowledge then.
> 
> I will say i can park my wet car in the garage and see pools of water on the floor and yet have no condensation on anything.
> 
> ...


Interesting.

I've just read on Pistonheads that road salt can also attract moisture, maybe that is part of it given I haven't washed the car in a while and they love gritting round here!!

Good shout on the plastic on the floor trick, I'll try that tomorrow :thumb:


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## DouglasH (Jul 18, 2007)

Now this may sound strange, but the way I cured the condensation in my 8' x 6' Shed and also the underside of the small Boot in my Mx-5, was to remove every container, tin and bottle that held liquid, in cold weather conditions, condensation forms on the outside of all liquid containers, that condensation then drips onto shelves and floors especially if the Shed or Garage is unheated.


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## Ant21 (Oct 12, 2013)

Update:

So there doesn't appear to be any moisture coming up from the floor. Everything that's been down (cardboard and plastic) is bone dry.

Took the car out today and left her outside for a few hours to cool before parking back up in the garage. So far it seems ok, but it is a bit warmer today.

Also left the door open for a few hours whilst I was in there and will continue to do so.


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## Rhys (Aug 28, 2006)

I also got a new build garage and had this happen once. Since I have put garage door draft rubber strip down and also insulated the door. I have also put a dehumidifer in there and so for so good. Though I would like to insulate the roof!


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## macca666 (Mar 30, 2010)

Have you got any air bricks for ventilation? If not this might help if you could retrofit them.

My garage is partial brick and concrete block and i've no insulation. I've quite a few air bricks and I also leave my window very slightly cracked open and I don't have the issues you're having.


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## percymon (Jun 27, 2007)

I keep a 25kg bag of salt near the main door of mine and , yes, you can on some days get droplets of water on the floor near it, like summer dew.

I also use the garage to spray RC models and one of the weathering techniques involves masking with table salt - if there is any overspill of salt on the floor this is the first area to show any dew like droplets

I suggest you give the underside of the car a good blast off at the local jet wash (let them have the salty wash off) and then see how you go the next few days - warmer weather and plenty of rain the next few days so that should also wash the salt remains off the roads too.

In fact, thinking about it, it may be worth putting a table spoon of salt over a 2' x 2' area of the floor and monitor it over a week or so ?


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## Ant21 (Oct 12, 2013)

Another update:

Took the car out the other day and upon returning let her sit outside for a while to cool off.

Left the garage locked up for 2 days without going in there and so far so good. No moisture, no rust on the discs, no droplets on the exhaust. Nothing.

Hopefully it was just one of those things, but I'll be keeping an eye on it along with ordering some of those door weather strips to help out.


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## Ant21 (Oct 12, 2013)

So far so good. No more condensation issues. Guess because the weather has warmed up.

I'll be getting a garage thread up soon


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## Ant21 (Oct 12, 2013)

Quick teaser


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## vsideboy (Sep 1, 2006)

If it's condensation on the roof and dripping on everything and you don't want to insulate/false roof etc. I used a product called grafotherm on the metal roof of my sheds 6 years ago and it's working well still, product says it changes the dew point temperature then absorbs any moisture and then allows it to evaporate quickly rather than generating condensation. I now only get a few drips in extreme circumstances. Not sure if it would work on vertical surfaces or not?

I'm not affiliated with this at all btw. http://www.grafoproducts.co.uk/index.htm


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## Guest (Feb 1, 2019)

If that,s the DPC (arrow)..the DPM under the slab is not united with the DPC in the brickwork.There will always be a path for moisture.
As said,the key to reducing condensation is ventilation...air bricks.
A single skin wall will always allow moisture to pass through.


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