I would advise making your shop as airtight as possible (best insulation you can afford, spray foam is best but pricey) and installing a good HVAC system.  A lot of what the AC portion does is dehumidification.  You could take it to another level by adding a dehumidifier to the system as well, or if you go with a heat pump the higher end ones have a dehumidification feature built in and will use the AC side to draw moisture out of the air, even when you are at or below your set temperature.  I installed a pair of large AC units in my shop last year, and I wish I'd done it 20 years ago.  It makes working on everything so much easier and it takes far less of a toll on you when you aren't sweating buckets.  Plus I noticed in high humidity paint would often not cure right.  It would end up with a hazy look to it and I'd have to redo it. 

I live in south Mississippi about an hour's drive from the gulf coast.
As nice as it would be to have A/C in my shop I only know one local guy who does, because of the expense...Not just installation expense, but also the electrical expense of running the A/C unit to keep the shop cooled. 
Everybody else I know that have shops (including me) just insulate them to keep them from causing condensation and dripping from the ceiling.  Honestly, even though it still gets really humid, rust stays to a minimum except for bare metal, which will flash rust pretty quickly.

Bolted to Floor wrote:

Depending on your proximity to the coast, a hurricane or tropical storm and the aftermath that goes with them may cause more damage than humidity.

Very true.  Even an hour inland from the Gulf Coast, Hurricane Katrina leveled hundreds of homes around where I live back in 2005 (hard to believe it's been that long).
 

A tight insulated building will slow the temperature change inside down quite a bit which will help eliminate a lot of condensation. Just don't open the doors when the temps are a lot different. Especially if it is cooler inside the building and you flood the building with warm humid air you will have a lot of condensation all over everything. I even get drops of water forming on the concrete floor. 

When I lived in Charleston, SC ......August-September-October..gave a new meaning to the word Humidity! ( a "humid day" is defined as...when the humidity exceeds the temperature by 20 points! ex. temp=75*....humidity=95%)
I worked on my Mustang in one side of a two car garage year round with no/mirror rust/dampness issues. No AC! Too expensive to get it cool enough to do any good!  Open the doors....take off most of your clothes....run as many fans as you had! (Drink beer....switch to menthols !!)
Seriously... you won't have any issues  with your "toys" if the concrete floor has a vapor barrier and the walls are insulated. Both of which are required by code.
Your floor IS concrete, right?!!  Those Florida builders????? ( ;
6sally6

I've never seen condensation on anything in my shop, and I've been up there plenty of mornings where everything outside had condensation on it.  Not sure why that is, as I said its not terribly thermally efficient, and I'd be surprised if it even had vapor barrier under the slab.

Speaking of which, most vapor barrier is 6 mil polyethylene.  Fine for the first 5-10 years, but having demolished many an older building I can tell you that the stuff becomes brittle and fails in fairly short order.  There are better options now (Stegowrap for example) that are more costly, but will not break down over time, ensuring the vapor barrier integrity lasts.  Like I said, if I could clean sheet a new shop I'd do a lot of things differently. 

Curious everyone keeps saying AC is too expensive, but has anyone actually tried it?  I had that misconception initially too, but knowing what I know now I wish I'd done it a long time ago.  I got the units for free (had some cost in removing them from the building they were in and installing them in my shop, all told about $700).  In terms of cooling they would take a 90 degree shop down to 70 in a hour, plus removing a ton of humidity in the process and making it much, much more comfortable to work. 

TKOPerformance wrote:

I've never seen condensation on anything in my shop,

Curious everyone keeps saying AC is too expensive, but has anyone actually tried it?  

Where is your shop located? Location has a lot to do with initial and operating costs.
Thank God Cali doesn't have much humidity. But in California is not the humidity, is the stupidly.
 

Last edited by rpm (4/13/2017 12:13 PM)

rpm wrote:

TKOPerformance wrote:

I've never seen condensation on anything in my shop,

Curious everyone keeps saying AC is too expensive, but has anyone actually tried it?  

Where is your shop located? Location has a lot to do with initial and operating costs.
Thank God Cali doesn't have much humidity. But in California is not the humidity, is the stupidly.
 

I'm in Delaware.  We've already seen a couple days in the 80s in April.  In the summer its not uncommon to get weeks at time in the 90s, and we do get some brutal humidity.Thankfully it not every summer, but every couple of years we will get a heat wave where the temperatures are close to 100 for a week or more and sometimes they top 100.  During those times a heat index of 105 or more is the order of the day.

Hey TKO I've been up in Delaware Built a power plant in Dover a few years back, but the only humidity I had to deal with was white, Must'a been wrong time of the year LOL, Any way I live just north of Biloxi/Gulfport Mississippi say about 14 miles north of the beach and its 98% humidity 98 deg. no rain in sight, AC would be nice in the shop but it cost me around $350 per month to keep the lights on and my head cool in a 2000sq ft. house. I do believe you have a more gentle Utility than we do.

thanks to all of you!  sounds like it starts with proper construction, proper insulation, and small openings.  at least i didn't see any horror stories, other than working on the car without clothing, lol!  And I agree, the proper beer at the proper temp would certainly help!
Regarding Texas, I had to cross it off the list (although it's our type of political climate) after I walked across the parking lot in South Padre at 7 am.....and needed to dry off before getting into the car.  Wow!!