The Money Pit

I have pole building ( two car detached garage) that I'm fixing up to store the Vette. Two years ago it had a dirt floor, bare rafters and no interior, but now it's coming together pretty nicely. Before I restored the interior, the car sat for about a year, and got a bit of mold on the interior, I gutted it, and it's all new now, but now I'm concerned about the mold coming back.

The building is cut into a fairly steep hill, the rear of the building faces the uphill slope, and the overhead doors are on the down hill side. I plan to dig a French drain across the back, and curb any water away from the new slab, and also some sort of moisture control.

Got my eye on a shutter fan, not sure how big a fan I need to do the job, or a dehumidifier. The fan would be cheaper up front, and to run 24/7 so I'm leaning towards the fan.....Looking for words of wisdom.

Kelly.s

My shop is a pole building. We put a concrete floor in with vapor barrier, insulated ceiling and walls 6",sheet rocked walls and ceiling, south facing doors used double wall green house plastic, and propane ceiling shop heater set to 60. Costs about $200 a year for propane. I'm in Oregon and the way we know it's summer is because the rain is warmer.

Rescue Rogers

I run a dehumidifier in the basement to keep the moisture down to protect the tools. It has a stone floor. I also did the french drain and it helped alot. If you're looking for winter storage I would get one of those car cocoons to use inside the garage if its that humid.

If you you want to work on it, get the dehumidifer for the winter and section off the vette side of the garage to make the space smaller. It will help with heating it too. I think a fan is just going to move air, not dry it out.

My dehumidifier didnt run too much during the winter. Barely filled the 5 gallon bucket 4 times over the 5 months. The summer time weather fills it every other day. I may set up a sump pump this summer.

You can also buy reusable dessicant packs that absorb moisture. You just bake
them in the oven to dry them out, then place them inside the car. Use a wireless weather station and place the remote in the car and you will know the temp and humidity in the car. When it starts to increase or at regular intervals, bake the dessicant.

turbojet

Put a box fan in front of the car in the summer and plastic over the concrete. Stagnant air is the worst. And as said if you can a dehumidifier.

Sunstroked

Move to the desert!. 7-8% humidity for about 90% of the year.
Short of doing that, a vapor barrier, a very well sealed garge and de humidifier.

jnb5101

Assume it's a warm day with relative humidity of 60%. Outside air will enter the garage and cool when it contacts the concrete floor. The cooling will raise the relative humidity to a much higher level, and cause even more problems. Be sure to make the garage as air tight as possible and use an effective dehumidifier.

The Money Pit

This morning I went into the garage to get something, and when I opened the overhead it felt like a sauna. Not hot, but steamy. ( It has been raining for days ) In a minute the air seemed much less humid, so I am really thinking a fan pushing the air out through the wall could help. If nothing more it will pull some heat out during the hot summer.

I can't help but think about all those hundred year old barns that don't have any fans or dehumidifer.....Guess they were pretty drafty with all the cracks and spaces between the wall boards.

Move to the desert?.....There's a thought. Just bought a Kodiak ATV and plow because my driveway is 450 feet long, and this winter we had that blizzard. Plowed for 8 hours with the old ATV and only got half the driveway done. Desert.............

OK, the garage is 24x24.....how big a fan or dehumidifier would work? It is not yet insulated, but is sealed pretty well both walls and ceiling. Overheads a bit loose. No windows or man door.

skytop

Paint the floor with a moisture barrier paint, be sure you have a compliant rubber gasket on the bottom of the garage door, a outside vinyl seal on the sides and top of the garage door. install a dehumidifier and you are set. Try to get moisture level below 55%. Of course, lower the better.

Rescue Rogers

Carport correct? Metal roof maybe? Any vents in your roof? Adequate venting will keep thair from heating and that sauna effect from happening.

What did you do for flooring? Is it concrete now? Some concrete garage floor paint (expensive, but good) will help seal the floor.

What is your relative humidity outside now? If its low circulate the air so it doesn't increase inside. If its high you need to decide how much of a space you want to work on your vette and enclose that space so a dehumidifier wont have to be really big and run alot to keep your space dry.

If you want to use the entire space maybe rig a fan up near the ceiling to keep it from getting really hot up there and that will help you dehumidifier too.

The Money Pit

The roof is metal, no ridge vent but soffits are open, and the gable ends are not closed. I think that should be OK. I put double bubble insulation stapled to the bottom of the roof trusses to create a ceiling, and just recently put vinyl soffit up as a ceiling. I wanted to seal the rafters in an effort to later insulate and heat the space, while at the same time knowing I had a moisture issue, use a material that did not matter if it got wet. You can not hurt plastic.....event if it goes under water.

The floor is still just raw concrete. Not sure what I'll do there once the moisture issue is resolved.

I figure the space to be around 4500 cubic feet, and if I get a 3000 cfm wall fan, the air would be evacuated once every minute and a half. The fan I have in mind is a three speed fan, and on low it pulls 1000 cfm, so air change would take 4 minutes or so...No stagnant air for sure. Assuming outside humidity eventually drops...the inside of the garage should eventually dry.

Rescue Rogers

Cement is pourous and attracts moisture. Moisuture can travel down through it as well as up. So it can be causing a moisture problem for you. If the ground is wet it will come up as a vapor through the concrete.

ScottBlack11

Installing an exhaust fan will necessitate the installation of a supply damper sized in accordance with your exhaust fan. Otherwise, the air evacuated will be replaced with air infiltrating under and around your doors and windows as well as every crack and orifice in your building. This will create an extremely dusty environment that you won't be happy with. Spring pollen will be your worst nightmare. The utilization of a supply damper will permit the use of filters to keep your air somewhat cleaner but you'll need to keep a close eye on them or as they become clogged you will start to see air infiltration, and the dust that comes with it, around your doors and windows. The use of the fan will also prevent effective temperature control whatsoever. I would highly recommend taking the advice of those recommending the use of a dehumidifier solution. Talk to a professional.

13611

Bite the bullet and invest in a good dehumidifier. I too always weigh costs and "other" ways but why risk it. You asked for our opinions so here ya go. All of your other ideas are good but fan vs. dehumidifier... dehumidifier. You've got a lot to protect in there. Good luck.

The Money Pit

Never thought about the dust and pollen being pulled in....good point.

I have a dehumidifier in the basement now I could toss in and try for a while to see how much it helps. Might give that a try while I work on that French drain.

crisko

Try the humidifier I put one in my garage a few years ago.Best thing I did If it does work using your existing one go out and get a good one Was an easy fix for me

crisko

Sorry meant dehumidifier

Dirty Dalton

I think a dehumidifier will give you the biggest bang for you buck.

In my shop and underneath garage I laid a floor consisting of 3/4" ply sleepers on 12" centers, with 3/4" dense foam insulation between, overlaid with plastic, overlaid with 3/4" underlayment.

The shop has heat and dehumidifier, the underneath garage only a dehumidifier. Big improvement. I've not yet had a car in the underneath garage, so I can't attest as to how that floor will stand up to such static weight. I'm thinking it will need 2x10 'runways' to further distribute the load.

dobeluvr

My setup seems to be backwards from yours. Off the hiway, down to the garage doors down further to the rear. There has been times I have had a river running thru the pole barn. French drains to catch runoff on sides, a little lip to get into garage and so far I have made it since late last summer with no water inside. A de-humidifier is the way to go hands down. I have it partitioned off and heated as well.