Cooling down an uninsulated shop.

[Hax Planx]

My ancient detached shop/garage has an uninsulated roof and now that temps are parked in the 90's with full sunshine most days, the heat radiating from the roof turns it into an oven. Things inside (like projects) get warm to the touch and the ambient temperature soars to about 105°(40.6°C). I've had to move all glues and solvents and anything else that might be temperature sensitive into the house. As you can imagine, it makes things like brushing shellac difficult. Any ideas for a cheap remedy just for the radiating heat problem? I know I could insulate the roof, but that isn't the direction I want to go with this space. Before winter sets in, I want to frame about half of the inside of the building into a room for the wood shop and insulate that, but I didn't want to do it now. The building is about a 1000 sq/ft and the roof is over 12' high at the peak, so that isn't very practical anyway. I was thinking along the lines of maybe using a reflective coating for the roof or tacking down tarps to cut down on the heat absorbing properties of the black shingles. Does this sound practical at all?

[David]

In a word, NO! Been there, done that. I had a shed that was hotter than a firecracker when the sun came out. I painted the roof stark white and put a thin layer of insulation on the inside of the roof. The temperature drop was nearly unnoticeable. Years later I tore the shed down and built my own. fiberglass shingle roof, 2 small gable vents, thicker insulation AND I insulated the walls that were exposed to the sun. Now on a HOT, HOT day I can walk into that shed and be greeted by coolness akin to walking under a large shade tree.

If you don't insulate where the heat load is coming from you can forget about cooling your shop. Of course the dark roof is much of the problem, but the larger problem is lack of insulation.

Dave

Hax Planx wrote:

[Leon]

Snip I was thinking along the lines of maybe using a reflective

Well I am going to differ from David's view. I live in Houston. Last year I built a storage room in my back yard with no insulation. I used Radiant barrier decking for the roof and went with 30# felt and a premium asphalt shingle on top of that. The room stays closed up all day long and the inside temperature never feels higher than the out side temperature. 2 weeks ago I painted the out side a medium brown color and the inside temperature rose slightly. While it may not be feasible to re roof your building and put down radiant barrier decking there is radiant barrier paint that can be sprayed up on the bottom of the roof. They may help and be relatively inexpensive. Keep in mind also that insulation does not warm or cool a building it simply slows the temperature movement going from a warmer area to a cooler area. If the building does not cool down at night insulation is probably not going to help. IMHO the trick here is to reflect the heat with the proper materials.

Oddly the radiant barrier products face towards the inside of the building. the metallic surface on the decking faced down and the radiant barrier paint is applied on the same surface facing down.

[David]

is that room primarily or wholly in the shade, Leon? There isn't any way to be comfortable in a totally uninsulated outbuilding here during the summer if the sun beats down on it. White roof, brown roof, purple roof--makes such a marginal difference if there's no insulation in the walls/roof. In fact I've got almost the same roof on my shed as on my house and the house is hotter than the shed because of all the frickin single pane glass that I've yet to replace. Removing a wide sliding door (single pane) on the south side of the house and replacing it with a 36" triple glazed door helped tremendously to keep that end of the house cooler. YMMV--and apparently it does.

Dave

Le> I was thinking along the lines of maybe using a reflective

[Leon]

No, not in the shade at all. In fact when I painted it brown it became slightly warmer. I went with radiant barrier because I wanted to see if it really worked and it only cost me $24 more than standard decking. I was really amazed at how much it helped.

[Swingman]

It _is_ amazing how proper construction methods can keep temperatures down inside a structure.

I just walked in from checking the gas furnace line installation in the attic of a new house built with radiant barrier roof decking and ridge venting ... it was no hotter in that attic than it is outside today in Houston.

As you well appreciate, being in an attic in Houston at 11 AM on a sunny June day can be a scorching experience in the older houses. AAMOF, the shingles on this one were already too hot to install the HVAC roof vents ... I like to have that done at first light, before the sun get overhead, to keep from damaging the shingles.

Now, if I ever get the time to build that new $hop ...

[skeezics]

here in n.c. it gets pretty hot in the summer months. do you have vents at each end of the building? if so, you could put a large fan blowing out at one end. my shop is uninsulated also exept for the foam sheating under the siding. nothing in the roof. it is under a few shade trees and 2 story so i am sure that is helping. my shop stayes cool up till around 4 pm in the summer. after then i go to the house. if you dont insulate then ventilation and air flow are the key to keeping cool. on days i want to work in the late afternoon i set a fan blowing in downstairs and one or two blowing out upstairs. seems to work ok. i have a window a c unit that suposedly works. havent ever pluged it in so i cant say weather it does or not. you are welcome to it if ya want to haul it home. maybe it willl make it cooler to work in there but might be kind o exspensive. lol.

skeez

[no(SPAM)vasys]

I'd start with a gable mounted vent fan.

[TheNewGuy]

How about actively removing the heat: a gable-mounted exhaust fan, with or without a thermostat control. Depending on the CFM, you'll need a certain area of "inlet" into your shop of fresh air - got a screened window?

The collateral benefit to the exhaust fan is it moves out the fine dust too.

-Chris

Hax Planx wrote:

[Leon]

It is amazing. My wife and I have been looking at new homes and Ryland is guaranteeing that heating and cooling costs will not be over about $50 per month on average for a full 3 years. This is on homes ranging in size from

2,000 to 3000 sq feet. IIRC they are using radiant barrier plus that new blown in wall insulation that is made up of old newspapers like on TOH.

That is the way my store room is. You can almost touch the decking and it is no warmer.

Where are you planing on putting that new shop? LOL

[David]

Are we really arguing?? :) Isn't a radiant barrier a form of insulation?

Dave

Le>>is that room primarily or wholly in the shade, Leon? There isn't any way

[Leon]

No, not really by definition, although its purpose is pretty much the same. It reflects the heat rather than stops its movement into a cooler area. Insulation pretty much absorbs heat.

[Leon]

As a P.S. to my comment. My supplier was very insistant that knew to lay the radiant barrier decking with the foil side down as some of the installers put it with the foil side up and the roofs only lasted 4 or 5 years. Radiant barrier IIRC does nothing to keep a house from getting cold in the winter.

[Dhakala]

What about a swamp cooler?

[John]

Spray isocythene insulation would be a solution. Also something like the foil/bubble/bubble/foil insulation would be easy to install (just need a staple gun and the time) and I did that a couple years ago on a addition (quasi-garage) we built with BOTH the foil/bubble/bubble/file AND fiberglass bats in the wall studs, and it is noticeably cooler in there than outside util be open up the garage doors at both ends, then it equilabrates to the outside temp

I totally agree, without adding insulation/radiant barriers, you are not going to accomplish any significant temp reductions

John

[Pat Barber]

$50 a month for heating and cooling ??? They must have figured out a brand new way to heat water for the laundry or dish washer.

At the VERY cheap rate of .08 per kwh, that works out to 625 kwh per month for heat or cooling.

I don't think my home would be that low if "nobody" was living there.

I assume these homes are NOT total electric ???

Le>

[Robert Bonomi]

There are a few 'cheap' solutions.

1) a large 'barn fan'. venting to the outside. this will help pull the 'inside' temperature down to 'approximately' what it is outside. 2) "water the roof". Intermittantly -- just enough to dampen it, and let it evaporate off. As long as the ambient humidity isn't excessive, your water costs are reasonable, and you don't have excessive amounts of minerals in the water, this can be suprisingly effective. If tap water quality is suspect, or expensive, build a cistern to capture the rainwater from the roof, and 'recycle' it. :)

[Tom Banes]

I cobbled a swamp cooler together to use in my garage here in the Dallas area. Box fan with a mister in front of it, water feed from a 2 gal jug. Not fancy but it helps. As outside humidity rises, it becomes much less effective, but below 40% relative humidity it drops the temp about 15 degress if ambient temp outside is >85 degrees F. It does, obviously, raise the humidity in the garage a bit.

Regards.

[Hax Planx]

Water is an interesting idea. I'll have to try that.

[Hax Planx]

For 1000 sq ft?