Garage built in hillside sweating

[rickyb01]

Looking at buying a home that has a 24x20 garage built into a hillside. It has double barn doors and a 36" walkout door in the front. The floor is concrete, the walls are cement block and the ceiling is about 12" of poured concrete with real heavy gauge steel roofing covering the concrete on the ceiling. The whole garage is in the ground except for the front. When I walked into it today it had water from condensation dripping off the metal roof. Any idea's on getting rid of condensation. I would like to store tractor and four wheelers in this space but don't want to invite rust. Outside of keeping the doors open it has no ventilation so maybe a whirlybird on top would help. Any other idea's. Thanks Ricky

 

[Ed of all trades]

I would try the whirlybird, I would think that it would help a lot. Ed

 

[dieselcrawler]

I agree, ventilation is key. Been helping a friend design an addition to his house, and the study of vapor barriers and condensation is complex.

 

[RedNeckRacin]

Agreed, warm air and cold surface = condensation. Get some ventilation going and you should be fine. It sounds more like a bomb shelter than a garage!

 

[KennyG]

With a poured ceiling, how much ventilation can you get? I agree that's the way to go but the key is probably that the walls are not well insulated. You can't do much about that now and it will probably take several vents.

 

[B7510HSD]

Dehumidifier leave it run 24/7

 

[buickanddeere]

Should have been insulation under the floor and outside of the walls.

 

[Deere Dude]

Sounds like a nice Obomba shelter. Just throwing something out here on top of some good ideas about venting, but I would consider insulating the whole inside with 1" blue-board or Styrofoam. Studding the walls, the same thing.

 

[Gary Fowler]

Sounds like a nice Obomba shelter. Just throwing something out here on top of some good ideas about venting, but I would consider insulating the whole inside with 1" blue-board or Styrofoam. Studding the walls, the same thing.

That isn't going to be cheap but should be effective. I would first just try putting a fan or two inside to keep the air moving and see how that works. If you have to insulate, I would rent a stud welding gun and shoot some stud nails onto the sheet metal, then you can hang your insulation very easily. The CMU block walls will be a challenge to put studs on. A construction adhesive is what I would use to stick the Styrofoam to the walls. I doubt that you would need to insulate the concrete walls if you get the ceiling done. The adhesive would need to be compatible with the Styrofoam.

 

[Snobdds]

Need a couple of vents in the lower section of the walls and either gable end vents or roof vents. Need cool air coming in the bottom and hot air leaving through the top. Right now you have warm moist air trapped at the top. A roof vent will work, but you need something to break the negative pressure in the building, hence the lower wall vents.

I would use spray foam for insulation.

 

[GPintheMitten]

I'm having a hard time picturing the building with a concrete ceiling and metal roof dripping condensate into the building. I understand it being built into a hillside but can't figure out the ceiling and roof configuration.

 

[Billrog]

A roof vent is not going to stop the condensation in this case. I think Deere Dude has the best answer & since it's under ground the ceiling may only have to be done. To vent out you would also have to have air vented in lower down. If the barn drs. were sealed heating the space would be the best answer to eliminating the condensation. By the explanation it sounds like the metal ceiling was put in over the forms to hold the concrete until they were taken out ?

 

[rickyb01]

Ok guys I really appreciate your comments. Pictures are worth a 1000 words but I don't have any. I have a offer on the home but have not heard back from my realtor. I have no way of knowing how this bomb/storage shelter was built. It looks like they dug into the side of a steep hill and poured the slab and blocked up the walls. Your guess is as good as mine on the roof but everything is covered except the front which has two swing out barn doors and a metal front door beside barn doors. The barn doors are not sealed very good. On top of shelter they have a fire pit and chairs and it looks out over a river. I don't know how I would get a hole thru concrete top for whirlybird? How would I get vents on bottom? I really want to utilize the space and if I get the property. here are some off the internet

 

[ruffdog]

I have lived in a underground home. Never ever open it up on a warm and humid day. If the concrete is cold and you let that humid air in, it will sweat just like a cold glass on a hot humid day. Even my Steelmaster building that is on a slab will sweat the floor on the wrong days. Nothing wrong with it, you just have to know when to open and when to keep it closed.

 

[Tractor Seabee]

Unless you are going to heat the space, insulation is a waste of time and money. You need forced ventilation operated by a humidistat. A blower at the ceiling line on the door end, ducted out through a back-draft damper with another inlet grill with back-draft damper at the floor line. For the size you need to run a duct along the ceiling with several inlets to assure full circulation. Fan and duct sizing is a mechanical engineering solution I will bow out of lest I mislead someone. Those using shipping containers for storage have the same problem

Ron

 

[2458n]

I have owned a garage built during world war 2. It is in the ground on three sides with two 9ft. garage doors. 10 to 12 inch thick concrete roof with slope towards the back. I have painted the inside with white water block paint. Have used fans and heat. Might have done more, but everything did not work. It is a rust pit. Snap on boxes ruined. tools ruined. TV and stereo ruined. Car and motorcycle ruined. Kubota has set outside under cover for 34 years. Do not buy this property at any cost. A good dry barn would have saved me thousands. I am in Ohio so the weather changes daily.

 

[Howling]

I have lived in a underground home. Never ever open it up on a warm and humid day. If the concrete is cold and you let that humid air in, it will sweat just like a cold glass on a hot humid day. Even my Steelmaster building that is on a slab will sweat the floor on the wrong days. Nothing wrong with it, you just have to know when to open and when to keep it closed.

My shop is concrete slab on bedrock and partial concrete walls. Stays naturally cool way in to the summer. But the outside hot and humid air cause condensation and rust on everything in the shop. Now I keep it closed up and starting late spring/early summer leave air conditioner on low to to keep the humidity down. The electric bill is cheaper than the water/rust damage to my tool and equipment.

 

[GPintheMitten]

Well, you could still buy the property but store something in there that likes humidity. Maybe grow mushrooms. Seriously.

But may want to plan on building a new outbuilding.

 

[KennyG]

Property looks great even if the storage unit turns out to be useless. I would start out by cutting vents in the bottom of the doors. Is the front wall poured or frame with stone facing? To vent it at the top, I think you are looking at concrete work, but that's not a killer if you rent the right tools. I would suggest cutting a good size hole in the top/deck and buiding a small stone or brick pedestal. You can open the sides of it as vents and put a top on it that would become kind of a permanent table.

Humidistat fan as recommended could be used in the top vent. Do you have power there?

Oh, yes, and build a big pole barn somewhere else on the property. We love pole barns.

 

[ruffdog]

The ground is cool in the summer and warm in the winter. That is why people built earth homes. If you think you can pump enough air through that boathouse to make it dry on a humid day, your nuts. The moisture comes from the air that you want to pump through it. You will never warm the earth around it enough for it not to sweat on a warm spring day with the doors open. Keep an eye on the outside humidity and temp and learn when you should or shouldn't open it up. Work with it instead of fighting it.