Cooling Metal Workshop Cost Effectively

[Krispy]

I will be moving to a house soon that includes a detached metal building as well as an attached garage.

The metal building will primarily be my workshop, and car storage for the "toy" car. I plan to spend considerable time here, working primarily in the spring and summer as most of my hobbies are fair weather toys (boats etc).

The building is small, all steel construction 20'x24' with a man door one one side, and a window and a 8' wide roll up door on the adjoining side. Ceiling height is about 12' in the center and 7'-6" on the sides.

I am looking for a good way to make this a workable space year round. I live in Georgia where the summer temps can soar into the upper 90's regularly and winter temps drop below freezing.

I place priority on keeping the building cool in the summer, over warm in the winter as I can always add more layers of clothes.

Ideally I would like to be able to cool the building to 80F in the summer and warm the building to 60F in the winter. I don't mind waiting some time for the temperature to change, for example if I knew I was going to spend an evening in the shop, I could turn on the heat/AC a couple of hours before returning home (via home automation software) and have it ready to work for 4-6 hours.

What are my options?

I am looking for a comfortable place to work, but I don't want to break the bank with expensive HVAC and insulation, I guess I am looking for the most effective solution that is to say the ratio of performance to cost is the greatest.

I will post a picture of the shop shortly for reference.

Thanks to any and all help!

 

[Krispy]

Pictures for reference.


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[Falcon67]

IMHO - You'd have to insulate the inside and roof. then about a 12K BTU window unit would do what you want. They all have timers. Leave the shop at 10PM, set the timer for 18 hours and it will come on again at 4 PM the next day. If you don't have some sort of insulation, I'll bet that metal reaches 120~135F easily in full sun. You'd need a hell of a AC unit to fight that kind of heat radiation, and have to start it running in the morning on days you'd be out there. Only a big unit would have any chance of catching up on a hot afternoon.

I cool twice your space with 19K BTUs. I have only R-13 in the walls and ceiling. The west wall (24') outside temp runs 130F in the summer. Underside roof temps on the back of reflective decking run 120F.

And in GA, you're going to have to deal with condensation because it's pretty humid, so that's another consideration. Last time I was in Atlanta - last year - I thought maybe I was in Houston.

 

[theoldwizard1]

IMHO - You'd have to insulate the inside and roof. then about a 12K BTU window unit would do what you want.

Insulation is the key !

You could have 2 of those units and not be able to cool it in the middle of summer !

 

[pseudorealityx]

Insulate to min R-13 and a 1 ton heat pump will meet your needs. Window shaker if you want to save some cash on first cost vs. operating cost.

 

[Bib Overalls]

I have three tips for you. Insulate. Insulate. Insulate.

The shop/garage building you are acquiring was not designed "insulation friendly." Doing the job will require some creativity.

Friend of mine has scored some ridged foam board off Craigslist several times. Seconds and most recently, from a poultry farm that was going out of business.

Good luck.

 

[Krispy]

Thanks for all the tips guys!

I am torn on the insulation. My landlord (renting till we close on new house tomorrow ) seems to think cutting and placing foam board is best, but I had a summer job once with a company that sprayed foam insulation. The spray foam is nice, but expensive and not very aesthetically pleasing. Is there a happy medium?


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[Tigwldr]

I just framed walls and insulated with r-13 roll insulation for half the price they want to spray it directly to the metal walls.Spray insulation is probably nice at some point but your talking 2500.00 or more to spray a building that size.

 

[DEnd]

Insulation and air sealing.

Spray foam is nice but you pretty much have to cover it with something (drywall basically). which means you still need to add structure, but it should (if you use closed cell) take care of your air sealing, as well as your insulation. You could go with a flash and batt type system to get R-value fairly cheap and "easy" air sealing.

I want to throw out a couple of cautions here. #1 you will likely need to be inspected, so check to make sure everything is proper (prior inspections, electrical to code or better, etc...)

#2 you are sealing up an area with very high levels of VOCs (Volatile Organic Compounds). Without A/C and heat this isn't much of a problem as you will likely work in there with the door open. When you add A/C and heat the space tends to stay closed up, this will cause the VOCs to build up over time.

To address this issue you should at the same time add ventilation. Preferably you would add something that can run at a low-ish rate when unoccupied to help combat VOC buildup and then run at a higher rate when occupied. I would use something like the Broan ZB80m bathroom exhaust fan, it can run continuously at 30 cfm then will bump up to 80 cfm for 5-60 minutes when movement is detected. That's not a product recommendation just an example of a product that will work for your application.

ASHRAE 62.2 recommends a minimum ventilation rate of 30 cfm, however this really isn't a residential living space. The minimum cfm requirement for a parking garage according to ASHRAE 62.1 is 0.75 cfm/ft² that's 360 cfm for your space. That would result in a complete air change in less than 15 minutes, which is probably a bit ridiculous for a home garage. That number however is likely to deal with the exhaust gasses, which you won't have to deal with as long as you only run the car with the big door open, and not for long periods of time. I am not an expert by any means but I would be comfortable with something like 20-30 cfm continuous ventilation bumped up to 50-120 cfm when occupied.

As it is a garage I would go with exhaust only ventilation. For you the type of ventilation (exhaust, supply, or balanced) does not really matter, however for attached garages I think exhaust only is essential so as garage gasses don't get pushed into the house by a pressure differential. Exhaust only ventilation is also the cheapest so there is that too.

 

[Highland doc]

I just finished having the same building installed in central Florida. My plan is to go with rigid foam board that is covered in a metal skin from lowes. I'll use metal studs in front of this and cover with 1/4" plywood from the ground up to 4' then pegboard above to the roofline. The studs will be for securing the ends of the panels, as the tube studs in the building are on 5' centers. I think this will give me the most bang for the buck. Spray foam would be twice as much $. I'll be watching this thread for any other ideas.

 

[pseudorealityx]

Insulation and air sealing.

Spray foam is nice but you pretty much have to cover it with something (drywall basically). which means you still need to add structure, but it should (if you use closed cell) take care of your air sealing, as well as your insulation. You could go with a flash and batt type system to get R-value fairly cheap and "easy" air sealing.

I want to throw out a couple of cautions here. #1 you will likely need to be inspected, so check to make sure everything is proper (prior inspections, electrical to code or better, etc...)

#2 you are sealing up an area with very high levels of VOCs (Volatile Organic Compounds). Without A/C and heat this isn't much of a problem as you will likely work in there with the door open. When you add A/C and heat the space tends to stay closed up, this will cause the VOCs to build up over time.

To address this issue you should at the same time add ventilation. Preferably you would add something that can run at a low-ish rate when unoccupied to help combat VOC buildup and then run at a higher rate when occupied. I would use something like the Broan ZB80m bathroom exhaust fan, it can run continuously at 30 cfm then will bump up to 80 cfm for 5-60 minutes when movement is detected. That's not a product recommendation just an example of a product that will work for your application.

ASHRAE 62.2 recommends a minimum ventilation rate of 30 cfm, however this really isn't a residential living space. The minimum cfm requirement for a parking garage according to ASHRAE 62.1 is 0.75 cfm/ft² that's 360 cfm for your space. That would result in a complete air change in less than 15 minutes, which is probably a bit ridiculous for a home garage. That number however is likely to deal with the exhaust gasses, which you won't have to deal with as long as you only run the car with the big door open, and not for long periods of time. I am not an expert by any means but I would be comfortable with something like 20-30 cfm continuous ventilation bumped up to 50-120 cfm when occupied.

As it is a garage I would go with exhaust only ventilation. For you the type of ventilation (exhaust, supply, or balanced) does not really matter, however for attached garages I think exhaust only is essential so as garage gasses don't get pushed into the house by a pressure differential. Exhaust only ventilation is also the cheapest so there is that too.

While I 'get' why this is your solution, insulation isn't going to be enough to maintain the temps the OP is looking for.

If you're really concerned about VOC's, open the door/window each night and let it air out. VOC's will disperse. I'm sure the main doors will be open/closed pretty often since you'll be playing with boats. Could add a screen door to the man-door to allow ventilation, but avoid the bugs and critters.

 

[DEnd]

While I 'get' why this is your solution, insulation isn't going to be enough to maintain the temps the OP is looking for.

If you're really concerned about VOC's, open the door/window each night and let it air out. VOC's will disperse. I'm sure the main doors will be open/closed pretty often since you'll be playing with boats. Could add a screen door to the man-door to allow ventilation, but avoid the bugs and critters.

I was assuming he was going with A/C and heat of some sort. If he had enough insulation and air sealing he could theoretically just do night time flushing to keep his temps down, but I'm not sure that with a garage door he could get enough air sealing. Since I was assuming he would be using A/C and heat he would want to keep the door closed as much as possible, so some ventilation would likely be needed.

 

[pseudorealityx]

I was assuming he was going with A/C and heat of some sort. If he had enough insulation and air sealing he could theoretically just do night time flushing to keep his temps down, but I'm not sure that with a garage door he could get enough air sealing. Since I was assuming he would be using A/C and heat he would want to keep the door closed as much as possible, so some ventilation would likely be needed.

The idea being that at night, it cools off enough that you don't need the A/C, and can just open the door.

In the winter, yeah, doing that will make it cold, but it will also flush the VOC's pretty quickly if there really is a build up.

And hopefully the OP knows that he shouldn't seal himself up while sniffing fiberglass resin, lacquer thinner, paint, oil, and anything else that is bad without some ventilation.

 

[Steve in Louisiana]

That type of metal building is simply a carport cover with sides. There is not enough of a structure to properly insulate. The walls could be insulated by building self supporting stick built walls to hold insulation. Then the ceiling could be done with spray foam. Beyond that, I would tear down carefully, sell the unit for the most I could get and build a typical metal building.

There is one more option I know of that would be to use the adhesive blocks with stickers and caps. Basically a 3"X 3" plastic with a spike. You put them up as a grid and place the insulation on top. You put caps at the end of each spike. That would do the walls cheaply & then just spray the ceiling.

I just spent over year trying to solve the same problem in Louisiana. I tore down & rebuilt.

Also, a misting system on the roof using a rainwater reservoir, capturing and recirculating the water will knock down the temp really quick. Cheap to do. This is what we did while insulating my shop ceiling last August. Otherwise you could only stay on the scaffold about 20 minutes.

As to an earlier post saying all you need is 120 CFM for ventilation, please note that is not correct by a looooooooooooong shot. A muffin fan on a PC puts out 100+ CFM.

 

[minytrker]

A friend has a building just like that. He added rolls of double sided silver insulation to the ceiling and walls. It helped out alot but is still not as good as the add on with real insulation.

 

[TheEquineFencer]

A friend has a building just like that. He added rolls of double sided silver insulation to the ceiling and walls. It helped out alot but is still not as good as the add on with real insulation.

With the Foil/Bubble/Foil or Foil/Foam/Foil insulation you need to understand how it works. It reflects heat, you need to give the heat a place to go. If this were my building, doing it on the cheap, I'd just get some furrowing strips, screw from the outside in to hold the wood up sort of like a studded wall and staple the F/B/F or F/F/F insulation to it. Or use thin metal tubing the same as the building is built with and lag it to the bottom and top. If you do it this way you need to put a vent in the wall to let the heat that builds up between the insulation and metal vent to the outside. If you wrap the entire inside with it, seal the seams with the foil tape and the building will be air tight. The neat thing about doing it with this type of insulation is the foil backing reflects the inside light back. With the strips screwed to the wall, later if you want to you can sheet the walls in OSB or something. http://www.insulation4less.com/ is where I got mine from, I got it in 4 ft x 125 ft rolls.

 

[DEnd]

As to an earlier post saying all you need is 120 CFM for ventilation, please note that is not correct by a looooooooooooong shot. A muffin fan on a PC puts out 100+ CFM.

For ventilation, not temperature control, it is likely plenty.

Human oxygen demand is 0.042 CFM while walking 4 mph (1) to replace that oxygen we consume we only need to add 0.2 CFM (oxygen is 21% of air) per person, even if we up that by 10 times to account for the fact that we are only exhausting the diluted air thus not the full volume of CO2 exhaled that would still only be 2 cfm per person.

For VOC control I agree it is really likely too low. ASHRAE recommends .75 cfm/ft² for parking garages and 1.50 cfm/ft² for automotive repair rooms.(2) The Minnesota OSHA requires 0.5 cfm/ft² for service stations.(3) OSHA requires 2,000 cfm per person welding in spaces less than 10,000 cubic feet. (4)

Like I said I'm not an expert by any means, but considering the lower exposure time and using some common sense (like welding with the door open and a fan going) I'm comfortable at the 75-110 cfm rate when occupied. To put that in perspective his shop has about 4440 cubic feet of volume, that 110 cfm means the entire air volume of his shop is changed out about every 40 minutes or so. If you were really concerned the 0.5 cfm/ft² isn't that unreasonable as that'd be something like 240 cfm for his shop while occupied.


(1)http://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-125/125-AtmosphereManagementF-M.pdf (pg. 1 table 1)
(2)https://ashrae.iwrapper.com/ViewOnline/Standard_62.1-2013 (pg. 19 table 6.5)
(3)http://www.dli.mn.gov/OSHA/PDF/directives/STD_5-1.2_Garage_Ventilation.pdf
(4)http://www.gpo.gov/fdsys/pkg/CFR-2013-title29-vol5/pdf/CFR-2013-title29-vol5-sec1910-252.pdf (pg. 671 2(c)(ii))

 

[nine4gmc]

For ventilation, not temperature control, it is likely plenty.

Human oxygen demand is 0.042 CFM while walking 4 mph (1) to replace that oxygen we consume we only need to add 0.2 CFM (oxygen is 21% of air) per person, even if we up that by 10 times to account for the fact that we are only exhausting the diluted air thus not the full volume of CO2 exhaled that would still only be 2 cfm per person.

For VOC control I agree it is really likely too low. ASHRAE recommends .75 cfm/ft² for parking garages and 1.50 cfm/ft² for automotive repair rooms.(2) The Minnesota OSHA requires 0.5 cfm/ft² for service stations.(3) OSHA requires 2,000 cfm per person welding in spaces less than 10,000 cubic feet. (4)

Like I said I'm not an expert by any means, but considering the lower exposure time and using some common sense (like welding with the door open and a fan going) I'm comfortable at the 75-110 cfm rate when occupied. If you were really concerned the 0.5 cfm/ft² isn't that unreasonable as that'd be something like 240 cfm for his shop while occupied.


(1)http://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-125/125-AtmosphereManagementF-M.pdf (pg. 1 table 1)
(2)https://ashrae.iwrapper.com/ViewOnline/Standard_62.1-2013 (pg. 19 table 6.5)
(3)http://www.dli.mn.gov/OSHA/PDF/directives/STD_5-1.2_Garage_Ventilation.pdf
(4)http://www.gpo.gov/fdsys/pkg/CFR-2013-title29-vol5/pdf/CFR-2013-title29-vol5-sec1910-252.pdf (pg. 671 2(c)(ii))

120cfm would not even be noticed in that building, that's like a bathroom fan. You need to turn the entire volume of air(like 5760 cubic foot) over several times per hour or you will stroke out in the summer.

 

[DEnd]

120cfm would not even be noticed in that building, that's like a bathroom fan. You need to turn the entire volume of air(like 5760 cubic foot) over several times per hour or you will stroke out in the summer.

How many times do I have to say this that number IS NOT FOR TEMPERATURE CONTROL. It is for ventilation only when using A/C or heat.

 

[over40pirate]

Beyond that, I would tear down carefully, sell the unit for the most I could get and build a typical metal building.
And how different would it be to insulate a "typical metal building"?

There is one more option I know of that would be to use the adhesive blocks with stickers and caps. Basically a 3"X 3" plastic with a spike. You put them up as a grid and place the insulation on top. You put caps at the end of each spike.
Any idea how 125 degrees would affect the adhesive?

Also, a misting system on the roof using a rainwater reservoir, capturing and recirculating the water will knock down the temp really quick. Cheap to do. This is what we did while insulating my shop ceiling last August.
I sure wouldn't want to be pumping water with all sorts of minerals on my metal roof. I did this on a metal roof, before I thought it out

 

[stage20]

I have a 26ft with 9ft walls......up in the panhandle of florida. Temp inside today was 99.6f. I work in heat 10 hrs a day in construction. 2 big fans can't **** the heat out of it. Will give you a headache after an hour. I need to do something myself.

 

[EOC_Jason]

You can frame out the walls easy enough, that will give you an area for insulation and also to run electrical. Without seeing the roof area, you might be able to frame that out too, or use ridgid foam board / duct board and figure some way to hang it.

 

[DEnd]

I have a 26ft with 9ft walls......up in the panhandle of florida. Temp inside today was 99.6f. I work in heat 10 hrs a day in construction. 2 big fans can't **** the heat out of it. Will give you a headache after an hour. I need to do something myself.

The easiest way is to frame out the interior, and add insulation in that. If you are going to be conditioning the space 24/7 then you want to pay close attention to the air sealing, as air leaks are a major contributor to energy used to condition the space (which means you electric bill will be more expensive). Garage doors are very hard to seal well, so you want to pay close attention to the rest of your air sealing. Once you get below 5 air changes per hour at a pressure difference of 50 Pascals you pretty much have to add ventilation. I'm not sure you could get a garage down to that (due to the design of most garage doors), but due to VOCs that are in most garages it is still a very good idea.

The easiest way to air seal is to put up a layer of plywood or OSB sheathing, the prime the edges about an inch or two in then tape them with a product like Siga Wigluv. Also do this on the sill plate as well, tape from the bottom of the sill plate and wrap it around the sheathing. As well you should use a sill seal under the sill plate. Since you are doing this in a already built building the easiest place to install that sheathing may be on the interior side. If you put it on the interior side I would not run wiring or plumbing in the wall. If you have to have it in the wall one solution is to space drywall out 2" or so, that way you create a wiring chase in the wall.

 

[over40pirate]

The 31 x 30 metal building on the property we just bought has truss roof support. The lower horizontal chord of the truss, is 8' high. I plan on putting either 7/16 OSB. or metal roofing panels, on the under side of the truss, and put lots of fg insulation on top of it.
I thought about putting 1x4 or 2x4 stringers along the wall uprights, to screw the OSB to, with insulation behind it.

 

[Krispy]

Thanks for all the input and suggestions.

I would like to see some pictures of what has been done in similar situations so feel free to post them!

We just moved in over the long weekend and at the moment all my free time is spent unpacking boxes but I hope to get to working on the shop soon.

 

[Krispy]

I know reviving an old thread is sometimes frowned upon. But 6.5 years after making this thread on this forum I have finally insulated and air conditioned the shop.

I want to say thank you to all who weighed in.

I went with spray foam and a window unit, and also properly wired the shop with 220V service and a ton of 20A outlets.

I will be installing flooring this weekend and moving back in soon.

-Chris

 

[nadogail]

IMHO, the answer will be to minimize heat gain. This may be accomplished by shading your roof and exterior walls with panels spaced away from the structure. Allow an air space between the shade panels and the shed surface.

Paint the surface of the roof with a reflective paint.

The theory is that the sun will heat those panels and the air space will retard the heat transfer to the shed. Consider how Ready Service Boxes and pyrotechnic lockers are constructed on Navy ships.

 

[nadogail]

Just this afternoon I read about a new Ultra White Super Reflective paint.

It was written up in an article in the Smithsonian Magazine website.

 

[TonyinNC]

I know reviving an old thread is sometimes frowned upon. But 6.5 years after making this thread on this forum I have finally insulated and air conditioned the shop.

I want to say thank you to all who weighed in.

I went with spray foam and a window unit, and also properly wired the shop with 220V service and a ton of 20A outlets.

I will be installing flooring this weekend and moving back in soon.

-Chris

How much spray foam? Roof and walls? How big of a window shaker? Are you happy with it?

I was reading through your thread, as my shop will be built in a few months, and I'm in a similar predicament.

I'm going to insulate and probably go with a mini split (I'm 99% sure on the mini-split). I'm just looking to learn from the experience of others.

Thanks!