I need ideas to help lower the humidity in my shop building. It's a 30X30 metal building on a concrete slab located in south Alabama. The building is insulated very well on all sides and top. It has one walk-in door on side and a big rollup door on end. It's located in my back yard and used to store boats, tools, etc.. and can be closed up for days without being opened up. I put a humidity sensor in a few weeks ago and haven't seen it below 75% and lots of times in 80's. Also this past summer I noticed some mold around in different places. I'm not on a unlimited budget so anything I do I'll have to keep cost in mind. After reading several threads on here my thinking is to put 2 ceiling fans spaced apart mounted to center beam and also install some type of self draining dehumidifier. Those of you with success using a dehumidifier can you share some tips on brand and location you would put it in my shop?? If there's a better solution than fans and humidifier please share it. Thanks in advance for all your advise and any small bit of information could be helpful to me so please share.
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30 X 30 Metal Building Humidity Problem
- Thread starter mgnic
- Start date
nsula_country
Well-known member
I feel ya on the humidity inside. One of the reasons I am installing a full forced air heat pump system in our shop.
Have little experience with dehumidifiers.
CT
Have little experience with dehumidifiers.
CT
finn
Well-known member
What’s the normal outside humidity?
No soffit or ridge vents, and no windows, means no air exchange, which is, I suspect, part of the problem.
No soffit or ridge vents, and no windows, means no air exchange, which is, I suspect, part of the problem.
readhead
Well-known member
There has to be moisture in the building to condense. Was a vapor barrier installed under the concrete? Are you leaving any windows open? It looks like a minimum insulation was used. My guess is most of the dripping is coming from the purlins because there wasn't enough thermal break between the purlins and the sheeting.
Fixing the building is probably not practical so now what? Options. Reduce the moisture, dry the moisture or alter the dew point. You could dehumidify, cool the building, try moving the air or put more insulation on the secondary framing, i.e. purlins and girts.
Don't recommend the builder. He may have done a neat job but he doesn't understand metal buildings and your weather.
Fixing the building is probably not practical so now what? Options. Reduce the moisture, dry the moisture or alter the dew point. You could dehumidify, cool the building, try moving the air or put more insulation on the secondary framing, i.e. purlins and girts.
Don't recommend the builder. He may have done a neat job but he doesn't understand metal buildings and your weather.
readhead
Well-known member
Finn, think that through. It's a metal building. That type of venting doesn't work in a metal building. In a high humidity location the worst thing you can do is have holes in the building to introduce more moisture. The fundamental problem with this building is a lack of thermal break and I suspect no vapor barrier under the slab. Whoever sold this building doesn't know what dew point is and how it affects the building.
readhead
Well-known member
That uninsulated coil door isn't helping either. Those leak like a sieve. A lot of the moisture is coming in along the edges of that door. Replace it with an insulated sectional door. Again, a bad salesman looking for a quick commission.
Notgrownup
Well-known member
Do a moisture test on the concrete... you know the one where you tape a piece of plastic down on the concrete, you would be surprised when you dig into it what a crappy job building companies do.
Looks like you have no ventilation at all...
Looks like you have no ventilation at all...
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readhead
Well-known member
Keep in mind that ventilation can hurt as much as can help. In this case to vent the interior air you have to supply make up air which is coming from outside. If the outside air has high humidity all you are doing is bringing it inside.
My point originally was that there has to be excess water inside to condense. My guess is that it is coming through the concrete and the leaking coil door.
My point originally was that there has to be excess water inside to condense. My guess is that it is coming through the concrete and the leaking coil door.
Chetter
Well-known member
I would definitely do a couple of ceiling fans to keep the air moving which is one of the things I did in my garage, which is a pole style building but with wood and vinyl siding. Concrete slabs will allow moisture to wick up through it during different seasons and I put down a plastic tile, and prior to putting it down I rolled out some 30lb roofing felt paper. It helps keep the tiles from being noisy and stop the humidity from coming up through the concrete, that covers the area where my Camaro sits. On the rest of the floor where our daily drivers are parked, I had nature type stone installed 2 years ago. I noticed a real change in the garage and it stays reasonably dry even during the warm/cold cycles of winter. The fan was the last piece of the puzzle to keep air moving and it runs on low 24/7, my tools stay rust free and the Camaro with it's chrome and polished aluminum pieces stay clean with no moisture building up on them. These things worked for me over the last couple of years and I don't feel a need to do anything else, as you can see in my sig pic, the concrete is still visible throughout my garage. You have a nice looking building, put some ceiling fans up as a start and go from there. Good luck...
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These seem to pop every 30 days....All the garage/shop excessive humidity concerns all the same solution:
Get control of the building climate. Heat and cool as needed.
Get control of the temperature.......it’s impossible to control humidity if you don’t have some control over the temperature. Relative humidity it related ( linked, relative) to temperature.
Lower air change rate.......seal the building.
Lower the temperature swings ..........insulate.
Location maters:
Summer in the south AC might be needed but a dehumidifier from a big box store can easily handle 1000-3000 sqft if the other steps are done.
Winter in the south a slight amount of heat might solve all the humidity again if the the other steps are done. In the north slight amount of heat often resolves humidity issues in the winter.
If the building is cold below 40-45* a dehumidifier will not work.
Moisure through the slab is rarely a concern or problem if the other steps are done.
Fans do not remove moisture........they just mix the air. They are NOT a solution unless the other steps are done. They help slightly with condensation.......but the humidity will still be high. Sustained Humidity above 70% is where bad things are noticed.
Get control of the building climate. Heat and cool as needed.
Get control of the temperature.......it’s impossible to control humidity if you don’t have some control over the temperature. Relative humidity it related ( linked, relative) to temperature.
Lower air change rate.......seal the building.
Lower the temperature swings ..........insulate.
Location maters:
Summer in the south AC might be needed but a dehumidifier from a big box store can easily handle 1000-3000 sqft if the other steps are done.
Winter in the south a slight amount of heat might solve all the humidity again if the the other steps are done. In the north slight amount of heat often resolves humidity issues in the winter.
If the building is cold below 40-45* a dehumidifier will not work.
Moisure through the slab is rarely a concern or problem if the other steps are done.
Fans do not remove moisture........they just mix the air. They are NOT a solution unless the other steps are done. They help slightly with condensation.......but the humidity will still be high. Sustained Humidity above 70% is where bad things are noticed.
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roadrunner255
Well-known member
I have a 36' x 40', metal building 14'3" at the peak and live in central texas.
Started out with 2 reversable 60" 3 blade fans in one bay.
Tried several 70 pint dehumidifers, ended up purchasing a Whynter 70 Pint Elite D-Series Energy Star Portable Dehumidifier with Pump at Costco.
Does a good job getting humidy down during non summer months (35%).
Ended up getting 2 @ 1.5 ton mini splits, dont need dehumidifer running when using mini splits.
Mini splits also have just a moisture setting.
Also found when using ac, fans would move hot air down from peak, so i turn off fans when using ac.
Building has 4" insulation in walls and 6" in ceiling, 6" stone on 3 sides and 3/4" plywood on interior walls.
Good luck!
Sent from my SM-N950U using Tapatalk
Started out with 2 reversable 60" 3 blade fans in one bay.
Tried several 70 pint dehumidifers, ended up purchasing a Whynter 70 Pint Elite D-Series Energy Star Portable Dehumidifier with Pump at Costco.
Does a good job getting humidy down during non summer months (35%).
Ended up getting 2 @ 1.5 ton mini splits, dont need dehumidifer running when using mini splits.
Mini splits also have just a moisture setting.
Also found when using ac, fans would move hot air down from peak, so i turn off fans when using ac.
Building has 4" insulation in walls and 6" in ceiling, 6" stone on 3 sides and 3/4" plywood on interior walls.
Good luck!
Sent from my SM-N950U using Tapatalk
Thanks for everyone's input!!!
It's funny how some suggest more venting and others suggest no venting at all. LOL!!
Please don't take that the wrong way because I don't know and certainly am asking for suggestions.
The only place I seem to have noticeable air input is around rollup door. When it's night and dark I can walk around shop and only place I see light from inside is around rollup door in some places. Not completely down both sides but in several areas on it. Not really looking to do a complete door replacement so unsure what can be done to help correct those areas??
I keep reading concerns about the moisture coming from concrete floor also. It so can I put some type sealer on concrete floor that might help? I was looking to clean and put some type coating on shop floor this summer anyway.
I totally agree that if inside of shop was kept at constant moderate temperature all year long chances are the moisture issue would go away.(no different than your home) It's really hard to do that here in the south unless you want to add some type air conditioner unit as some suggested and leave it on all the time. Some of you professionals could tell me but I would guess that's a $50 to $75 minimum add to your electric bill every month.
Again thanks for all your input and if anyone else has anything to add please do.
It's funny how some suggest more venting and others suggest no venting at all. LOL!!
Please don't take that the wrong way because I don't know and certainly am asking for suggestions.
The only place I seem to have noticeable air input is around rollup door. When it's night and dark I can walk around shop and only place I see light from inside is around rollup door in some places. Not completely down both sides but in several areas on it. Not really looking to do a complete door replacement so unsure what can be done to help correct those areas??
I keep reading concerns about the moisture coming from concrete floor also. It so can I put some type sealer on concrete floor that might help? I was looking to clean and put some type coating on shop floor this summer anyway.
I totally agree that if inside of shop was kept at constant moderate temperature all year long chances are the moisture issue would go away.(no different than your home) It's really hard to do that here in the south unless you want to add some type air conditioner unit as some suggested and leave it on all the time. Some of you professionals could tell me but I would guess that's a $50 to $75 minimum add to your electric bill every month.
Again thanks for all your input and if anyone else has anything to add please do.
nsula_country
Well-known member
I need ideas to help lower the humidity in my shop building. It's a 30X30 metal building on a concrete slab located in south Alabama. The building is insulated very well on all sides and top. It has one walk-in door on side and a big rollup door on end. It's located in my back yard and used to store boats, tools, etc.. and can be closed up for days without being opened up. I put a humidity sensor in a few weeks ago and haven't seen it below 75% and lots of times in 80's. Also this past summer I noticed some mold around in different places. I'm not on a unlimited budget so anything I do I'll have to keep cost in mind. After reading several threads on here my thinking is to put 2 ceiling fans spaced apart mounted to center beam and also install some type of self draining dehumidifier. Those of you with success using a dehumidifier can you share some tips on brand and location you would put it in my shop?? If there's a better solution than fans and humidifier please share it. Thanks in advance for all your advise and any small bit of information could be helpful to me so please share.
I am in the same climate and same region. Same building construction, same doors (3x), same insulation.
I do not have a humidity issue to the point of condensation or sweating floors, but its higher than I'd like. I do have 4, 60" commercial ceiling fans (Emerson Fan) that i leave on low speed 24/7. When I'm heating I put them on medium speed.
Attached to my signature is my current project. Installing a complete, ducted HVAC system consisting of a 5 ton heat pump. Your building could probably get by with a 2 ton mini split or package unit (easier than mini split). My intentions are not to run the system full time like a residence, but cycle the heat pump enough to control humidity.
Temperature swings and high humidity climate. The only way to combat in an enclosed area is to dehumidify. Either through a dehumidifier or AC/heat pump.
CT
DTE
Well-known member
I run a dehumidifier in my shop 24/7 . It runs constant @ 50% humidity setting and pulls 54 pints of water every 24 hours. That is unless it is really dry out. This is a 26 x 30 block building with r38 in the ceiling and two 9 x 8 insulated doors. I would have to look at the brand. I have no issues with rust or dampness , the shop stays closed and is at 50% humidity. I run a Pro-Fusion 7500 watt electric heater when I am in there working.
I did some more looking last night and found where alot of the air/moisture in coming in shop. The rollup door has a rubber seal at top that goes all the way across so when the door is closed it seals. Well after looking the seal is perfect against door about 2 foot out on each side and then has a 1 inch gap all the way across from one side to other. Basically same as leaving door opened 1 inch all the time.
What is the fix for this issue? Is door adjustable or different seal available that would eliminate seal not touching door? Not looking to replace the roll-up door with a sectional door as Redhead suggest. I'm going to contact the contractor that installed door next week and talk to him about it also.
I ordered two fans last night to move some air around and also help make things more comfortable this summer while I'm in shop.
Hampton Bay Industrial 60 in. Indoor White Ceiling Fan with Wall Control
Also ordered a dehumidifier while I was spending money to see if that would add to the solution.
Toshiba 70-Pint 115-Volt ENERGY STAR Dehumidifier with Continuous Operation
Function
My long term plans are to install some type mini-split unit to help. Is a Mitsubishi 2 ton unit too big of a unit for a 30x30? I briefly looked at them online but haven't done much research yet. The mini-split unit will be alittle later on and not at this time.
Thanks for everyone's comments.
What is the fix for this issue? Is door adjustable or different seal available that would eliminate seal not touching door? Not looking to replace the roll-up door with a sectional door as Redhead suggest. I'm going to contact the contractor that installed door next week and talk to him about it also.
I ordered two fans last night to move some air around and also help make things more comfortable this summer while I'm in shop.
Hampton Bay Industrial 60 in. Indoor White Ceiling Fan with Wall Control
Also ordered a dehumidifier while I was spending money to see if that would add to the solution.
Toshiba 70-Pint 115-Volt ENERGY STAR Dehumidifier with Continuous Operation
Function
My long term plans are to install some type mini-split unit to help. Is a Mitsubishi 2 ton unit too big of a unit for a 30x30? I briefly looked at them online but haven't done much research yet. The mini-split unit will be alittle later on and not at this time.
Thanks for everyone's comments.
readhead
Well-known member
The seal needs to be repositioned or replaced. I think the mini split will be the best solution. In the meantime keep as much moisture out of the building as you can.
nsula_country
Well-known member
I did some more looking last night and found where alot of the air/moisture in coming in shop. The rollup door has a rubber seal at top that goes all the way across so when the door is closed it seals. Well after looking the seal is perfect against door about 2 foot out on each side and then has a 1 inch gap all the way across from one side to other. Basically same as leaving door opened 1 inch all the time.
What is the fix for this issue? Is door adjustable or different seal available that would eliminate seal not touching door? Not looking to replace the roll-up door with a sectional door as Redhead suggest. I'm going to contact the contractor that installed door next week and talk to him about it also.
I ordered two fans last night to move some air around and also help make things more comfortable this summer while I'm in shop.
Hampton Bay Industrial 60 in. Indoor White Ceiling Fan with Wall Control
Also ordered a dehumidifier while I was spending money to see if that would add to the solution.
Toshiba 70-Pint 115-Volt ENERGY STAR Dehumidifier with Continuous Operation
Function
My long term plans are to install some type mini-split unit to help. Is a Mitsubishi 2 ton unit too big of a unit for a 30x30? I briefly looked at them online but haven't done much research yet. The mini-split unit will be alittle later on and not at this time.
Thanks for everyone's comments.
I have 3 roll ups. 2, 12x14 and a 8x8. Have the seals, never installed. Central Louisiana, basically same climate. I run 4 ceiling fans on low 24/7.
Have never had condensation inside. Outside under the 30x60 lean, it will condensate and drip off purlins.Soon will have Heat Pump to further control humidity.
CT
olgreyhair
Member
I didn't see in your post the age of the concrete. Our new concrete floor (3months), is putting out alot of moisture. We did a vapor barrier before the pour but the concrete itself will take a very long time to fully cure.