# Best method to dehumidify a garage wood shop?



## jnovak (Apr 12, 2019)

I live in Minnesota and there are some weeks throughout our summers that get real humid. This particular summer I have a lot of projects I want to work on but it's been consistently high humidity….and I'm wondering what is the best method for dehumidifying my 2 car garage wood shop?

I have an overhead gas heater that covers my late Fall, Winter, early Spring times of year but would like to work out there in the summer months but worry about expansion/contraction of my wood projects if I can't control the humidity.

Thanks for any feedback!


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## Scap (Aug 7, 2018)

Mr Slim mini split should do the trick.


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## Unknowncraftsman (Jun 23, 2013)

I think I'm in the same boat as you.
I select my projects carefully during the summer months for the reasons you mention. I'm on the fringes of the low desert 30 + temp swings with high humidity one week and bone dry the next.
I'm mostly doing maintenance on my machines right now it feels productive.

Good Luck


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## jnovak (Apr 12, 2019)

One thing I forgot to mention is the size of my garage/wood shop. It's a standard 2-car garage at about 500 square feet. Mr Slim looks like it'd work for a much bigger space but not sure I want to go through that much expense. Definitely keeping it as an option though.


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## furnman487 (Feb 17, 2019)

I live in Alabama and yes, we have humidity! My shop is in a basement garage and about a week after moving in the house I knew I had to find a solution or everything metal was going to rust away. Bought a dehumidifier at Lowe's and installed it in the corner near the garage door. Keeps the humidity at 50% or lower and no more rust on tools. You'll need to run a drain hose to the outside or constantly be emptying a bucket. Been working great for about 5 years now.


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## WhyMe (Feb 15, 2014)

Use a dehumidifier as suggested by furnman487. I have a 70 pint one in my shop and it keeps it at 50% with no problem. Obviously you need to keep the shop closed up and not open and close the garage doors more than needed.


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## jnovak (Apr 12, 2019)

Thanks folks for the insight. Next question….my garage work shop is only a little over 500 sq feet. The dehumidifiers I'm looking at cover 1500, 3000 or 4500 square feet. Do I get one of the larger ones (3000 or 4500) so it doesn't cycle on and off all the time? Or the 1500 sq foot one…which based on the square footage coverage seems overkill already….but I know they can be overrated as to what they actually cover sometimes (and much of it is dependent on the humidity as well). Thoughts?


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## wapakfred (Jul 29, 2011)

I'd get the largest one you can find…typically that's the 70 pint model. Remember your garage will leak more outside air in than a residence….plus, those ratings are about as accurate as the 6.5 HP your shop vac has.


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## WhyMe (Feb 15, 2014)

Depends on just how humid and damp it is in your garage. My 70 pint is used in 720 sgft garage. I'd say you want at least a 50 pint. I don't think cycling is an issue like for AC units. My 70 doesn't short cycle but it does run alot.


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## controlfreak (Jun 29, 2019)

A mini split would be the bomb. I opted to put a small window unit through the wall in my shop and is seems to be doing okay. I bought a humidity gauge but keep forgetting to read it. A dehumidifier that cycles on and off will also do well but the temperature will increase.


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## PeteStaehling (May 3, 2015)

I went with a portable AC unit. Rather than use the included window hardware I vented it through a small hole in the wall. It was a lot cheaper initially than a mini-split, but is less efficient. It has modes for heating, cooling, and humidification. I over-sized it a bit for the rated area and have been happy with it.

At the time I bought it I thought I might be moving soon, otherwise I might have invested in a mini-split. The better efficiency of the mini-split would have paid for itself in just a few years.


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## craftsman on the lake (Dec 27, 2008)

Ah,,, a dehumidifier. They dehumidify.
Seriously though, I've got one in the cellar. You can make it as dry as you want. Hook it up to a drain, or a floor drain, or even outside and you won't have to empty it every day. Many of them have a drain plug on the side of the water collector in case eyou want to do that. They really work good. Be sure to size one for the need so It just runs an appropriate amount of time.

My AC also removes most of the humidity but you don't want to leave that running all the time if you're not there.


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## theoldfart (Sep 9, 2011)

I went with a mini split. Never looked back. A two car garage size shop. Insulated to the nines.


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## bmerrill (Mar 14, 2018)

Mini Split.
Cools in the summer
Heats in the winter
Very efficient to operate.


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## furnman487 (Feb 17, 2019)

I would vote for the mini split too, but it wasn't practical for my space. Humidifier works great and much less expensive.


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## HorizontalMike (Jun 3, 2010)

YEP! After ~15yr in south TX without AC, I ended up with a 20.5 SEER Mini-Split AND LOVE IT!

I can't believe I did without for so long!... 8-( 
Now, I am a Happy Camper!


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## YankeeFan (Feb 10, 2020)

Ditto for the above!!! I am retired, very small pension and S.S. therefore, I watch my pennies. Just my worthless 2 cents.


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## HorizontalMike (Jun 3, 2010)

Just a note for those who still wonder about mini-splits. They are BEST for open-area spaces such as a shop. Not so much for multi-room floors/houses that are/have many rooms.

Granted, my 24'x30' shop only has a 1/4in fiber-glass/solar-radiant barrier, but that is more than enough to allow me to use the shop in the hottest part of the year, until 2pm or later. Sure, it eventually runs me back into the house, but if I get started early say 6am, I can still have and ENTIRE day of shop-time. And at 68yr old, I can sleep-in and wait to get out there at maybe 8am or so, AND STILL GET A FULL 6-HOURS. Being an old fart, that is more than enough for me… 

PLUS, the bonus is that this mini-split KEEPs my wood/projects stable and dry for when I need them. Also minimizes strain on my air-compressor drain valve ( and yes, I check it 2-3 times a week). Oh, as well, all my cast-iron steel machines love it!... NO Rust! My collection of SARGENT Bench Planes also require much LESS attention to keep them rust-free.


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## ibewjon (Oct 2, 2010)

My mini split from LG is rated at 28. Extremely efficient and cheap to run. Also will heat down to -10 degrees. Older heat pumps stopped working about freezing. A dehumidifier drys the air, but puts the heat back into the room. If your shop gets hot, you won't like the dehumidifier.


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## Lazyman (Aug 8, 2014)

I am using a potable unit that cools, heats or dehumidifies. The dehumidify setting uses almost as much electricity as the AC setting so I rarely just run it on dehumidify. I vent it through the garage door using some exhaust ports designed for mechanics. When this old unit dies, I don't have a good place to put the inside unit on the wall so I may do something like this:


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## david2011 (Apr 1, 2008)

If you choose to air condition your space you might want to seal the doors off from air exchange. Living where you do, that might already be done. Home improvement stores sell some vinyl seals that attach to the door trim and have a soft lip that seals against the door. It's proper name is garage door stop molding.

I live just off of Galveston Bay and our humidity rarely drops below 60% so I feel your pain. My weather instrument said it was 93 degrees today and 78% humidity for a heat index of 103. It's humid here year 'round.


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## Redoak49 (Dec 15, 2012)

The biggest question is how well sealed your garage is and if you open the garage doors. It will be like trying to pump out A leaky boat.

A dehumidifier gives off a lot of heat and a closed shop will get hot.

I think a mini split is the best idea.


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## Blindhog (Jul 13, 2015)

For far too long, I worked out of a 10×12 unconditioned shed and it was challenging at best. I live in central Texas so we have heat and humidity to deal with.
When I retired, I took a 3 car garage and walled off one bay for my metal shop and the other two are for woodworking. I installed s/r on the bottom of the trusses and blew in 10" of fiberglass, used fiberglass batts in the walls and applied s/r over that. Installed window unit with heat strip and have not looked back. Unit keeps the shop cool even when it's 100+ outside and the humidity is under control. Having the ability to work year round is a big plus in my book and well worth the effort and expense. Not to mention the stable environment for my tools and wood.
Good luck with your project!


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## Lazyman (Aug 8, 2014)

> If you choose to air condition your space you might want to seal the doors off from air exchange. ...
> 
> - david2011


+1. This made a huge difference for me. The portable AC was sucking hot or cold air around the sides and top, and $10-20 of garage door weather stripping immediately improved the temperature by at least 10° on the hottest and coolest days. Here in the DFW area they don't always insulate the garage door so adding insulation to the door was something I did 20+ years ago, mostly because my garage door faces west and the door can get over 140° in the afternoon. The most recent thing I did is add some Coolaroo patio shades to keep as much sun off the door as possible. This also helps in the times of the year when the weather is nice enough to have the door open by blocking the glare from the sun and reflections on car windshields in the drive.


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## Mosquito (Feb 15, 2012)

I know I wrote a lot, but it's how I approached the dance question myself. I'm in MN as well and can sympathize… The short answer is dehumidifier with a built in pump. You don't mention anything about shop temperature, or controlling that as well, which leads me to believe that's not a primary concern.

-----

The longer version of my thought process is this:

I run a 70 pint dehumidifier, with built in pump. I run the little tube for the pump out in the bottom corner of the garage door /jam seal, and never have to empty it. Highly recommend the pump. My shop is 672sqft and the 70 pint is more than sufficient. I buy the smallest one with a built in pump. But of note is that my shop is free standing (detached), sealed up and insulated pretty well.

Something to note, is that a stand alone dehumidifier is going to do a better job at humidity control than an ac unit in the shop, unless it's consistently also warm enough to warrant running the ac all the time.

I know it's oftentimes the unpopular opinion, but not all climates really need AC often enough to justify the expense of a mini split, as nice as they are. Are you going to run the AC when it's 60 outside but really humid because snow is still melting? Or when it's 70 and raining all fall? A dehumidifier is better for that than an air conditioner even with a "dehumidifier only" mode.

The caveat is how warm your shop actually gets. With my slab, the shop often stays fairly cool. Without the dehumidifier, it would usually stay below 70 almost all summer, and running the dehumidifier would usually bump that up to around 74-75 on the warm days. (until this year lol). Even with the ridiculous summer we've had so far, it would top out around 80 if I was out there and working, 77-78 if I wasn't out there.

For the climate, unless the shop is poorly insulated and not well air sealed, I would try just a dehumidifier first, unless it's also usually consistently 5+ degrees warmer in the shop than you would want to air condition it to. Otherwise the AC likely wouldn't run often enough to really control it that well. If temperature isn't a huge factor for you yet, I would try just a dehumidifier for now and see. It might just save you a grand or more… That's what I did for 4 years.

All that said, if you can justify the cost and think you'd use the air conditioning often enough to make it worth it, a mini split would work well. Try to avoid one with heat of you can, since no matter what people say about a mini split heat pump, you are better off with your gas heat lol

This summer, I did break down and buy a small *dual vented* portable AC, (dual vented being important) because it's been stupid hot and always humid. While the dehumidifier did fine with humidity control, the night time lows still in the upper 70s wasn't letting the shop cool down at night. I run the portable AC for maybe an hour a night when it's above 85 outside, otherwise I rarely have run it since early July. It is enough to bring it from 78 down to 72 or so, which is more than enough for me.


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## farmfromkansas (Jun 16, 2019)

I have an old central AC and furnace I use a little. When we had the units on the house replaced, I moved the old ones to the shop. The AC is ok, but I do not use it a lot during summer, as I still farm. If I give up the farm, plan to install a mini split system, and remove a overhead door for a place on the east wall to install it. Want it on the east wall, so during the hot part of the day the AC unit will be in the shade. I have 2 overhead doors now, and can get by with one. My shop is a little bigger than average, 26×66, it is an old pole building that was here when I bought the place, and thought it was too good to take down. That was 40 years ago, probably would have been better off taking it down, reusing the lumber to build a wider building. 36' wide would make a much better shop arrangement. Oh well, hind sight is 20/20.


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## rwe2156 (May 7, 2014)

> YEP! After ~15yr in south TX without AC, I ended up with a 20.5 SEER Mini-Split AND LOVE IT!
> 
> I can t believe I did without for so long!... 8-(
> Now, I am a Happy Camper!
> ...


How big is your shop? How big is the mini split and if you don't mind me asking what did it cost you?

I'm thinking about a standard heat pump for my shop it's app 2000 sf.


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## ibewjon (Oct 2, 2010)

Gas heat is great. But if using electric resistance heat, an efficient mini split heat pump is cheaper to run. I have the meters on mine to prove it.


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## ArlinEastman (May 22, 2011)

Either a Air Conditioner or Mini split. I live in Iowa which is the same as MN for weather and wish I had the funds for the Mini Split but got an air conditioner and two 2400 tower heaters of which I mostly use one in the winter and either turn on the other to get it warmer quicker or when it gets below 0 have both on to a temp of 60* so the metal equipment does not get cold to bad.

Mike

Where did you get your Split and how much did it cost????


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## BurlyBob (Mar 13, 2012)

One thing I can tell you for certain is that an epoxy floor coat will greatly reduce humidity in you shop. After I put mine down I could definitely feel the difference in the air.


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## ibewjon (Oct 2, 2010)

Mine is an LG, bought it from Supply House.com. There are many suppliers. Shop around. I don't remember the price, but the size you need will be different. I only have a 16×22 x 10' ceiling shop. 6" insulated walls, 12" ceiling insulation.


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## HorizontalMike (Jun 3, 2010)

> Either a Air Conditioner or Mini split. I live in Iowa which is the same as MN for weather and wish I had the funds for the Mini Split but got an air conditioner and two 2400 tower heaters of which I mostly use one in the winter and either turn on the other to get it warmer quicker or when it gets below 0 have both on to a temp of 60* so the metal equipment does not get cold to bad.
> 
> Mike
> Where did you get your Split and how much did it cost????
> - Arlin Eastman


I have a Mitsubishi 20.5 SEER M-Series, $4,400 (installed 2017) rated at:


Cooling 22,400 Btu/hr 
Heating 27,600 Btu/hr
Shop = 24ft X 30ft X ~11ft(avg) or 7930 cubic feet (aka 720 sq ft)
Shop ceiling starts at 10ft and slopes to gable crown at 12ft.

BTW, I never actually see any large increase in the electricity usage… ~$30-$40/month in Summer months at my Latitude of 30 degrees North in the middle of Texas.


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## Mosquito (Feb 15, 2012)

I'm curious to find out what you decide to go with. I haven't run my portable AC in the past month… seems since I got it, the temps subsided a bit, so it's just been my dehumidifier that runs, and the temps have been rolling from 67-72 with 50% humidity setting on the dehumidifier :-D


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## clin (Sep 3, 2015)

I'll throw this out there concerning AC. If you oversize the AC it won't dehumidify well. The reason is it cycles too quickly; basically making a little bit of really cold and dry air. To dehumidify, you need to move a lot of air so that you get a lot of dry air. ALso, an AC that is just big enough is the most efficient. Oversized AC is common and the reason people get that cold clammy feeling.

Most mini-splits have some form of a variable speed compressor. This is great because it allows them to run nearly constantly and low power. This is the most efficient way. Like running a 4-cyclinder car on the highway. Get it up to speed and just let it cruise.

I've got a mini-split in my shop and a few other rooms in my house. I can't recommend them strongly enough. However, mini-splits are best running 24/7. They are not designed to take a space and cool it down quickly and by the same logic would not dehumidify quickly. If your garage shop is dedicated to being a shop and you don't open the big door often. I.E., don't keep your car in there, then you're all set.

Or of course, if you are disciplined enough and can remember that you want to work in the shop on Saturday, be sure to turn it on Friday night so it has time to cool things down and draw off the humidity.

BurlyBob mentioned sealing the concrete floor and I think he's spot on there. Concrete is like a sponge and if the ground is moist under the slab, it will just keep wicking moisture up from the ground. While no doubt an epoxy finish will do this, I believe there are other ways to seal as well that may fit your needs better.

Along the same lines and also mentioned by others, I'll restate, insulate and seal as best you can. Get things well insulated and sealed and it won't take that much energy to keep it cool in the summer and warm in the winter.


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## ibewjon (Oct 2, 2010)

+1 on that. Do not oversize an ac of any kind. Even a mini split needs to be sized correctly. The compressor running on a vfd is a major help in saving money. I only have a 16×24 shop, but I never turn the AC off. It costs about 25 cents a day to keep the shop at 70 degrees.


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## HorizontalMike (Jun 3, 2010)

> If you choose to air condition your space you might want to seal the doors off from air exchange. Living where you do, that might already be done. Home improvement stores sell some vinyl seals that attach to the door trim and have a soft lip that seals against the door. It s proper name is garage door stop molding.
> - david2011


Here is how I sealed the large 16'x8' overhead door. It is like a stranded brush strip and flexes as the door moves up/down. Works great. The sides did not need additional sealing as they were nearly light-tight to begin with:


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## NatalieM (Jan 6, 2013)

> A mini split would be the bomb. I opted to put a small window unit through the wall in my shop and is seems to be doing okay. I bought a humidity gauge but keep forgetting to read it. A dehumidifier that cycles on and off will also do well but the temperature will increase.
> 
> - controlfreak


I am contemplating a Mini-split for my 750sqft shop, but I'm wondering about dust. I have a dust collection system, but I wonder if a mini-split has any kind of filter on the air intake?


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## NatalieM (Jan 6, 2013)

> I ll throw this out there concerning AC. If you oversize the AC it won t dehumidify well. The reason is it cycles too quickly; basically making a little bit of really cold and dry air. To dehumidify, you need to move a lot of air so that you get a lot of dry air. ALso, an AC that is just big enough is the most efficient. Oversized AC is common and the reason people get that cold clammy feeling.
> 
> Most mini-splits have some form of a variable speed compressor. This is great because it allows them to run nearly constantly and low power. This is the most efficient way. Like running a 4-cyclinder car on the highway. Get it up to speed and just let it cruise.
> 
> ...


I am contemplating a Mini-split for my 750sqft shop, but I'm wondering about dust. I have a dust collection system, but I wonder if a mini-split has any kind of filter on the air intake?


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