I Hate My Garage

[huggy76]

I’ve got a double pre fab concrete garage and this time of year I hate it because it is so damp. Was doing a bit in there yesterday and my bikes are soaked with condensation. Not sure what to do, I normally put a car cover across 2 bikes which helps a lot . Any ideas please?

[looey]

There's been a long discussion about it on here before, I'll see if I can find the a link to the post.

Basically it's not how cold or warm it is in there, or the amount of airflow (though that will help dry stuff that has got condensation), it's rapid temperature change that causes the condensation problem. The temp has been cold ish for the last few days, so everything metal gets very cold (and holds it), then yesterday we had a warm front come over the country, so the outside temp went up, that warmer air hits everything cold and that's when the condensation happens.

Basically to avoid condensation, you need to keep the garage temperature stable, even in a sealed non heated garage, you won't get condensation until you open the garage door when the temp is warmer outside, which allows the warmer air to enter and hit everything cold

My current garage is integrated to the house but not heated. It was colder in there yesterday than outside but nothing got any condensation because I didn't open the door, if I had, I would've had the same problem as you.

It's a bummer for sure

[looey]

rdlccrazy.proboards.com/thread/42337/garage-condensation

[markhoopy]

A concrete frefab garage with steel up-and-over door has to be the most difficult to keep condensation free.
Cheap insulation on the walls, door and ceiling would certainly help, but temperature change is the cause as looey says above.

[huggy76]

Thanks looey, just read through the old posts.

Been in the garage this morning and it’s bone dry so confirms exactly what has been said.

Think some more ventilation would help but obviously not cure the problem.

[perazzi350]

Hi if you can make it more or less airtight with some draught excluder you could run a dehumidifier, this is what l have (its a shed though) then you can set the humidity to what you require I run it 24/7 removes any moisture in the air.

[looey]

Nov 2, 2019 12:24:04 GMT 1 huggy76 said:

Thanks looey, just read through the old posts.

Been in the garage this morning and it’s bone dry so confirms exactly what has been said.

Think some more ventilation would help but obviously not cure the problem.

Yeah ventilation will help everything dry quicker but also help the condensation appear quicker on everything, as it will make the temp change quicker in the garage when it changes outside.

[stusco]

My brick garage is attached to the house it has two air bricks and an inch gap under the door and I’ve never had any condensation problems so must be the ventilation,absolutely Baltic in the winter though

[huggy76]

I was thinking it might help to keep a similar temp to outside thus reducing the condensation.

[looey]

Nov 2, 2019 17:57:29 GMT 1 huggy76 said:

I was thinking it might help to keep a similar temp to outside thus reducing the condensation.

The problem is that metal objects take ages to change their temperature but the air doesn't, so once the metal objects are cold and the ambient temp around them goes up, you've had it. That's why you've got to keep the room temperature fairly consistent, at least not to change much quicker than the metal objects themselves can do the same. If the room temp can change quickly, then you'll get condensation whenever you have cold, then a fairly quick temperature rise.

[markhoopy]

Nov 2, 2019 14:40:10 GMT 1 stusco said:

My brick garage is attached to the house it has two air bricks and an inch gap under the door and I’ve never had any condensation problems so must be the ventilation,absolutely Baltic in the winter though

My shed is also brick but detached, with double-glazed windows, insulated roof and walls, no draughts whatsoever, always reasonably warm from spring to autumn and in winter I just leave a small oil-filled radiator on constantly to keep it cosy. Never had any condensation problems at all and nothing ever goes rusty.

[midlifecrisisrd]

Greenhouse heater under each bike does it for me

Costs about a pound a day to run but worth it over winter

Otherwise you need to stick them in a vac bag

Steve

[earthman]

Nov 2, 2019 18:56:55 GMT 1 looey said:

Nov 2, 2019 17:57:29 GMT 1 huggy76 said:

I was thinking it might help to keep a similar temp to outside thus reducing the condensation.

The problem is that metal objects take ages to change their temperature but the air doesn't, so once the metal objects are cold and the ambient temp around them goes up, you've had it. That's why you've got to keep the room temperature fairly consistent, at least not to change much quicker than the metal objects themselves can do the same. If the room temp can change quickly, then you'll get condensation whenever you have cold, then a fairly quick temperature rise.

This is very true, only yesterday I noticed how much moisture formed on my LC tank after I had wheeled it out of the garage. 
I had forgotten about this aspect since bike fuel tanks have been made out of plastic or hidden under fairings etc.

[spondon440]

I have a big brick built garage attached to my house and a sectional garage with a steel roof, I have bikes and cars in the brick one and a lathe, milling machine, the spondon and shed loads of parts in the concrete garage, I run a dehumidifier all the time in each garage with them draining through the wall, nothing gets condensation on it in any weather.

Andy

[martinrs2k]

I have an Ebac Dehumidifier in the garage and I am amazed how much water it collects in a week.

The garage is brick built with insulated walls and has 2 heaters to control the temperature better but the temperature change overnight when it is cold in the Winter surprised me.

[icarus001]

There are a lot of factors that can change the circumstances in your garage, but essentially you want to keep the items in the garage at a higher temperature than the dew point, so the water vapour in the air won't condense.
There are a few ways to do it, raise the temp of the items, lower the dew point, insulate the garage so the air temp doesn't increase faster than the items sitting in the garage, let the hot air out and replace it with cooler air, etc.
Google psyhrometrics.


I'm guessing that your garage gets quite humid from the concrete dumping water into the internal atmosphere. Then the external building fabric gets warmed by the sun, so the air inside gets warmed, but the items inside don't warm up as fast, so the air around the cold items cannot hold it's moisture and dumps it in the form of dew on the cold surfaces - if that makes sense.

Dehumidifying the air during the night could help, because then the air would hold less moisture and the dew point would be low, so for example, if you had air temp of 2c and you'd reduced the humidity to 40%, the cold items would have to be at about -10c to make the water in the air condense on them. The problem here is that if the sun heats the air in your garage up quickly, to say 15c, then the dew point raises to about 1-2c and if the items have been chilled to zero in the night then you'll still get condensation. So this is where it gets interesting and you need a combination of things to try and combat the problem, e.g. keep the air cool, heat the items, lower the dew point again, etc, etc.
Pick the easiest options depending on what you have.

The trick really is to always keep the surface temperature of the items in the garage above the dew point.

[huggy76]

I think changing the roof might be a good first option for me.

The asbestos roof heats up very quickly in the sun because I quite often see it steaming but I need to see what better options are available at a reasonable cost.

Luckily I think I can get rid of the old asbestos roof via a friend, hopefully for a favour.