# Outdoor Workshop and Ventilation



## amossbur (Apr 23, 2016)

Hey all, just joined and was hoping for some help in finding a solution to my exes heat problem I'm having.

Just had a shed built about a year and a half ago. Its 16ft x 15ft x 7ft and is just studs and T1-11 siding. The height i listed does not take into account the roof space. The shed is not insulated, but does had soffits, a ridge vent, and a window. I use this shed for both storage of all outdoor equipment, as well as all of my tools, workbench, and as a workshop. I'm in Northern VA and the summers can get pretty hot and humid. Temperature during the summer inside the shed is about 20+ degrees warmer than outside.

I've been looking at what to do to get it cooler in there for the summer months. I've thought about a gable vent fan, but don't really know what size to get or if I would have enough intake ventilation to balance. I've thought about insulating it, but don't really know how to go about it on my own. I'm trying to keep it as low cost as possible.

Any thoughts or ideas would be greatly appreciated, thanks!


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## HerbC (Jul 28, 2010)

When I was in St Mary's, GA I had a shop in an old external garage. It had tin roof, 2X4 framed walls with lap siding and there was no shade. It was suffocating hot in the summer time. I found that setting up a water sprinkler on the roof of the shed would quickly cool the shop down.

Don't know if you could make it work, depends on your water supply cost…

Good Luck!

Herb


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## kajunkraft (May 7, 2012)

I applied heat-reflective paint to my metal roof which really made a difference. I also use a large fan facing out to exhaust the heat, which creates air flow as well. Don't know how hot/humid it gets where you are, but south Louisiana is brutal.


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## Redoak49 (Dec 15, 2012)

I think a roof vent and or gable vents plus a fan.


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## amossbur (Apr 23, 2016)

Thanks for the input. The siding is already painted white and the roof has shingles. There's already a ridge vent and soffits but it really does nothing. Would installing a gable vent and fan help?


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## mojapitt (Dec 31, 2011)

I work from a dirt floor pole building. Whether it's -20° or 105° outside, it's the same in my shop. I feel your pain.

Welcome to Lumberjocks


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## JeffP (Aug 4, 2014)

Some way to shade the whole shed would make the biggest difference. The fact that it is 20 degrees hotter than the ambient air tells me it is all about the sun.

Is there some way to rig up a tarp a foot or two above the roof to shade the whole building?


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## dhazelton (Feb 11, 2012)

If the shingles are dark that's a problem. Light ones reflect heat and actually last longer.


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## amossbur (Apr 23, 2016)

Ya, can't do anything about the shade. Shingles are dark unfortunately because they were overstock from another customer's order so I didn't have to pay for them (I'll take free any day).

I'm guessing rigging up a box fan to hang from the ceiling and then blow out the door may have to just work here, lol


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## Cooler (Feb 3, 2016)

> When I was in St Mary s, GA I had a shop in an old external garage. It had tin roof, 2X4 framed walls with lap siding and there was no shade. It was suffocating hot in the summer time. I found that setting up a water sprinkler on the roof of the shed would quickly cool the shop down.
> 
> Don t know if you could make it work, depends on your water supply cost…
> 
> ...


My father used to tell me about that method for cooling factories in the 1930s. The problem with it is that condensation forms on the interior of the roof and causes the wood to rot. But it was very effective in cooling the factories. In fact they had a mist over the roof and the roof never really got wet as the mist would evaporate as soon as it hit the hot tar.

The other thing they would do was to "paint" the roof with white wash (not paint). The white was would rinse off over the summer and the roof would be black again in the winter.

I suppose that if you have enough air circulating (lots of fans) you could minimize that but it is a concern. Also a concern is the water dripping onto the floor (or equipment).

I think I would add insulation to the roof at the very least; or fully insulate the shed and put in a window A/C. It is a pretty small room and should cool quickly.

You could also add a "tropical roof" a second roof over the first with 2" x 2" spacers so that there was a 1-1/2" of open space and a large ridge at the top. That would allow the hot air to escape, effectively putting the shed under the shade.

Here is a Landrover with a tropical roof: http://13252-presscdn-0-94.pagely.netdna-cdn.com/wp-content/uploads/2014/10/1964-Land-Rover-Series-IIA-88-Station-Wagon-Front.jpg


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## clin (Sep 3, 2015)

The answer is INSULATIION!

Here's some background for those that are interested.

IF, a structure where shaded, not insulated, and we ignore the heat transfer to/from the ground, no major heat source inside, and there were free airflow around it, It would have an average internal temperature equal to the average outdoor air temperature.

Because the structure provides some insulation, even if not insulated, the interior temperature swings, from the cool to heat of the day, will be less than outside.

Now, if you insulate this, it will have the same average internal temperature, but the temperature swings will be much narrower. This means it won't get nearly as hot at the peak of the day. It will be significantly cooler than the outdoor peak temperature. Similarly, it will be warmer inside during the coolest part of they day.

Now, this is with a shaded structure. Since that is not common, we have to consider what happens from the sun hitting it. Basically this just exposes the structure to a lot more heat. This is especially significant for small structures that have a lot of surface area relative to volume.

Without insulation, the interior will get very hot. Usually much warmer than ambient air temperatures. This is a worst case situation.

If the structure is well insulated, the thermal gain from the sun can be greatly reduced and the structure will behave similar to being shaded. Obviously sun reflecting surfaces (white paint), is helpful.

Now, if you ventilate this can help or hurt, depending on what you are doing.

If you have no insulation, but the structure is unshaded, lots of ventilation can at least keep the interior near the ambient air temperature.

Ventilation will pretty much negate the advantages of insulating, though you won't need as much ventilation because the insulation keeps out most of the solar heat.

If you want to keep it as cool as possible, with nothing fancy, INSULATE, and DON'T ventilate. This has the other big advantage of keeping dust and dirt out.

Note: If you insulated the ceiling, then vented the space between the ceiling insulation and roof (equivalent of attic venting), this would remove some solar heat and may provide some advantage if condensation were an issue.

If you wanted to get a bit fancy, insulate, but have active venting that is turned on during the COOL of the day. Basically draw in outside air any time that outside air is cooler than the inside. But be sure this venting seals up when the outside gets warmer than the inside.

I have a storage shed that I insulated. It's interior peak temperature, in summer, is about 10-15F cooler than peak outside air temps. And of course very much cooler than the hot box it would be without insulation. Even though this shed is only used for storage, these much lower temperatures are much easier on the more delicate items we store.


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## amossbur (Apr 23, 2016)

This is great information, thank you! What did you insulate with? I would like to keep the area in my slanted room there because this is where my lights hang and I have some storage. Would I be able to insulate the ceiling and leave a gap behind that insulation for warmer air to escape?

I'll get some pictures loaded tomorrow when the sun comes out so you all can get a picture of what I'm dealing with.

Thank you all again, I'm glad I found this forum, its been the best help yet!



> The answer is INSULATIION!
> 
> Here s some background for those that are interested.
> 
> ...


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## clin (Sep 3, 2015)

I insulated with common R19 batting for both walls and ceiling. Mine again is just a storage shed. As always, more insulation is better in the ceiling when possible.

I have no ceiling ventilation. If you have a ridge vent and soffit vents, then you could leave a gap between the insulation and roof sheathing. But this will probably not help that much with heat removal. The space would be too restricted to get significant airflow. However, this is a common thing to do to avoid condensation build up. But this is probably not much of an issue for you since you won't have large moisture sources like a kitchen and bath. Of course just breathing puts moisture in the air and you can also get moisture coming up from the ground.

If it is a tight fit, consider rigid foam board for the ceiling insulation. If you leave a gap for ventilation, get the type of foam board with a silver foil side. Put thus foil side toward the roof, but again, keep a space. The foil only helps reflect radiant heat and does no good if it is touching or the gap is real small.

Also, while foam board is available to fit between common framing spacing, you could lay it across the framing and let the framing define the ventilated gap. This will of course reduce your overhead clearance.

If you use common batting for walls or ceiling, be sure to then cover it with some sort of paneling. This will protect it, and the paper backing on batts is a bit of a fire hazard. I used thin hardboard with a white side, just to keep the inside of my shed as lightly colored as possible. For a shop space, I'd probably use plywood thick enough to support shelving.

Bottom line, cover the insulation with something to protect it.

Also, you could also add on a low cost window AC unit. Either in a window or cut a hole in a wall. Cheap and might really make a difference on those really hit days. Again, insulate first.


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## wormil (Nov 19, 2011)

Insulation is always the first answer. Second answer is anything else.


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## Finn (May 26, 2010)

I agree insulation is best but a cheaper route is to install an old furnace fan as an exhaust fan in the attic space you have. Bigger the fan the better. More than one may help. The humidity will play havoc (rust) with your steel equipment surfaces so wax them well and often.


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## amossbur (Apr 23, 2016)

Thanks for the info. Here is the space I'm using if anyone needed a visual:


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