Removing Heat

[matt151617]

I'm looking for the most economical way to remove the excess heat from my unfinished detached garage. There's no insulation anywhere. I added a static vent, but it's still very hot in the summer. I thought about finishing the ceiling and insulating, but it isn't cheap, and I would need 24" wide insulation. Also, I want to keep the rafters open for storage. A ridge vent is another option, but again not so cheap because of the price of shingles.

Would a power vent in the roof work well? This seems to be the cheapest option.

 

[koditten]

Without insulation, you will never remove enough heat to be able to work out there.

Is there an upstairs window that you can put a fan in front of and blow the hot air out?

Refering to your last line you wrote. Is there any kind of roof venting? The vents in the ridge or stand alone vents are not there just o help you keep cool. Those vents are to help your roof last longer.

 

[matt151617]

There's no windows or anything else. It's a hip roof so there's not a ton of slope. Plenty of ventilation... windows, soffits, and the main door, but nothing up top. Heat gets trapped and builds up until it starts pressing down into the work area. Cross ventilation doesn't help because the heat is up higher.

 

[Falcon67]

Just looking on HD's web, GAF ridge vent pieces and a bundle of hip shingles to run 20' would be around $100. If that's too much, you're stuck with a fan. The best option is to spend the $$$ to insulate the ceiling. Lots of 24" wide fiberglass around. Do a little framing and leave yourself a few 24" x 48" panels for access to the rafter storage.

 

[anthony666]

 

[matt151617]

Insulation plus drywall/OSB is the most expensive option. At 625 square feet of ceiling to cover, it hardly seems worth the cost for an unheated space. A fan runs about $70 plus the roofing supplies needed. Looks like that is the cheapest option.

 

[Steevo]

You have to let the heat out, since you have no way to keep it out.
Since heat rises, it will only exit via the highest exit.
Ridge vents or a couple of turbine vents near the peak would keep it moving upward.

 

[Gary S]

Just insulate. If you don't let the heat get in there, you don't have to remove it.

 

[ssentt]

I have a 30'X48' uninsulated shop/garage with a ridge vent that runs across the whole roof with vents under the eves.....and its still hot. I usually run a barrel/barn fan in the doorway that will tilt up towards the ceiling to move the hot air out. Takes about a 30-45mins to cool it down then I angle the fan to blow across the shop. Also have 4 slider windows across one side that I open to. Sometimes I will open a garage door too. A power vent would probably help you....but thats how I do it, a big fan.

 

[ADSR]

This won't work if you have roof vents. This will just **** from the vents and not the soffit.

 

[dirtydogintex]

This won't work if you have roof vents. This will just **** from the vents and not the soffit.

In theory yes but in R/L that usually is not the case.... at least in the Houston sauna area.

Ridge vents don't allow enough air flow to really be viable in the OP's app.
Money would be better spent on roof mounted wind driven turbines and non-solar AC powered ventilators (fans).

Considered a reflective barrier
attached to either
the underside of the roof rafters exhausting to a ridge mounted 'plenum' which in turn is exhausted by roof mounted ventilators)
or
as a false ceiling?
Seems like an ideal app....

 

[tylernt]

I have a suggestion: a Whole House Fan. It's installed in the ceiling and draws air from the garage (crack the rollup door and open windows) and blows it into the attic, where it's exhausted out the soffit vents. This will pull in a breeze in that blows on you (cooling you), and keeps the attic cooler too (two birds with one stone).

I strongly recommend a belt-drive WHF, as the direct-drive units are rather noisy and often low-quality.

They are a bit energy-hungry so I would probably only run it when I was actually in the garage, or put it on a timer to only run during the hottest part of the day and perhaps also for an hour before sunrise (to "pre-cool" the building against the coming heat of the day).

 

[BigWil]

I'd start with two cheap gable vents, and see if that helps.

 

[RCStocker]

The only think you can do is pretend you are a pionier and live with it. I can't believe you need to ask the qauestion.

AC was invented over 100 years ago. Insulation has been around for centuries and they did not even know it.

Other than rood air vents and a huge fan there is nothing you can to.
If you refuse to insulate the celing and walls then why bother ask the question.

If you use the attic of the garage for storage make sure you have large enough celing joist to support the load you put up there. You can add beam in the grage to give it more support.

I would insulate the entire place and drywall the ceiling and walls. I would put in a fold down ladder ad sheet the attic for storage. Then I would put a window AC unit in. Anything short of that is not going to birng you any comfort. It will ad value to your property. I dry walled a garage I rented years ago. I got the drywall free. I did not insulate it but with a window AC unit it did the job for the short time I needed it.

 

[matt151617]

It would be close to $1000 to insulate the walls/ceiling and finish with drywall or OSB. Why would I spend this kind of money on a non-conditioned, non living space? I'd like it to not be super hot during the summer, and what the cheapest option would be. Sounds like the attic fan.

 

[ADSR]

It would be close to $1000 to insulate the walls/ceiling and finish with drywall or OSB. Why would I spend this kind of money on a non-conditioned, non living space? I'd like it to not be super hot during the summer, and what the cheapest option would be. Sounds like the attic fan.

Depends on how much time you spend in there. Is it just for hobby, or do you make some cash out of there?

 

[CNGsaves]

It would be close to $1000 to insulate the walls/ceiling and finish with drywall or OSB. Why would I spend this kind of money on a non-conditioned, non living space? I'd like it to not be super hot during the summer, and what the cheapest option would be. Sounds like the attic fan.

Quite a few replies don't realize HOW FAR NORTH you really are . . . ie UPPER New York state.

Looked up your average summer temperatures and here is data:
http://www.weather.com/weather/wxclimatology/monthly/graph/USNY1143
. . . May . . avg High 67 / avg low 46
. . . June . .avg High 76 / avg low 56
. . July . . avg High 81 / avg low 61
. . . Aug . .avg High 79 / avg low 60
. . . Sep . .avg High 71 / avg low 52

Thus this "heat" in your Plattsburgh, NY garage can't be that much!!

Few poor man's "air conditioning" will work fine for your wonderful summers:
a) gable vents at each end of roof
b) put down plywood on rafters to "close-up" attic (keep heat up there)
c) hang a box fan inside next to gable vent (run fan when attic is hot)
d) each night run box fan next to downstairs window to pull in cool air (also run attic fan to get that space as cool as well) - - keep pulling in cool air til maybe 10 am, then close up everything and shut off fans

 

[koditten]

I agree the heat isn't that bad compared to other parts of the country. I live in Michigan, so the summers are similar. my shop was uninsulated for one summer. My shop was useless between the hours of 11am and midnight.

If you just insulate the ceilings the shop will be immensely more useful. Keep the heat in the attic and the floor will be much more comfortable.

You only pay for insulation once. You pay for heat and cooling forever.

 

[Motofixxer]

To control the heat, the number one thing you need to do is seal off the attic space. The radiant heat from the roof will make it unbearable. The temps will reach 140-150 deg easily. At a minimum Throw some plastic up on the ceiling after building one if needed. Then put up some drywall and insulate if you can. Bottom line is seal it off first then insulate if possible. Only then will you gain some control. Same goes for when its cold. Even if the walls aren't insulated which shouldn't be done unless you finish the interior completely. It won't take much to heat to reasonable if its closed off. The other bonus you will get is better light reflection. A couple gallons of white primer will make a noticeable difference.

You would be amazed what a difference just some 6mil plastic makes for temp control.



.

 

[CNGsaves]

Watching a home improvement show I noticed company called TamTech was advertised for attic fans. Did a little research and they have whole house attic fan for $579 (free shipping) for their low-end HV-1000 which is 1 speed and moves 1150 CFM.
http://www.tamtech.com/

Whatever method you could use to close up attic (ie full sheetrocked ceiling, plywood, heavy plastic stapled to slats, etc) coupled with attic fan would be great method to push out hot attic air through gable vents.

Last year helped roof my BIL 2 story house and he added a gable vent that had passive shutters that closed when no air was being forced out by whole-house attic fan. Thus flaps stayed shut during winter on gable vent, but in summer when attic vent running the hot air was easily pushed out. It's really worked for him as poor man's A/C to pull in cool air to house through windows and push out hot attic air at same time.

 

[matt151617]

I have a hip roof, so there's no gables. Attic cubic footage is minimal due to the style and low slope of the roof. If I put insulation up there, I won't have any room for storage. With 8 foot ceilings all that heat from the shingles on a southern exposure makes it over 100 at head level and over 125 at roof deck level.

Amazon/Home Depot have an attic fan with a thermostat rated at 1000 CFM for $75. My garage is 25x25, so 5000 cuft, another 1000 for the attic area. I will be turning over all the air every 6 minutes or 10 times an hour.

 

[Highbeam]

You would be amazed what a difference just some 6mm plastic makes for temp control.

6mm and 6 mil are way different. 6 mil is a heavy poly sheet. 6 mm is a quarter of an inch. Just an FYI, I'm sure moto knows this.

 

[pitterpat]

I have the same type of situation in my detached VW garage, 16' x 22' with a hip roof same as Matt. My ceiling is also not insulated and I am in the process of insulating the walls. I do have one of those turbine vents that I could install. If I install the turbine vent and then close off the attic how will the turbine vent draw out the heat?

 

[blackz26]

Dude you live in new york, you have no excess heat! Neither does Michigan, Ohio or any other surrounding states. If the heat is too much for ya, give the card up... lol

 

[koditten]

There are a couple "sac sticking hot" days to deal with on occasion up here

KO

 

[blackz26]

There are a couple "sac sticking hot" days to deal with on occasion up here

KO

Ya but nothing unbearable. I open the car door and the man door, and this air movement graces the enclosure! Usually 5-10° cooler inside on a 95° day with 100% humidity.

 

[matt151617]

Go sit on an asphalt roof in June through mid September and tell me there's no heat here!

My 13,000 gallon pool goes from a frozen block of ice to 80 degrees in about 6 weeks... that's some powerful UV.

 

[blackz26]

Thats an asphalt roof! Not them inside of a garage that has shade and big doors going to it
Lol

 

[matt151617]

Doesn't matter. All that heat has to go somewhere: that somewhere is radiating down into the work space of the garage. Plywood and tar paper aren't a very good insulator.

 

[blackz26]

So if its not a good insulator... where the problem? I'm still lost as we live in the same climate...

 

[matt151617]

They're not a good insulator of stopping the radiant heat.

The big problem, I've established, is no ventilation whatsoever in the roof. Radiant heat comes in, stays trapped, and heats up the garage so much it's uncomfortable. Outside temperature is 80 but inside the garage is 100+. Air is moved through the windows/doors fine but that does nothing to stop the heat radiating down from the hot trapped air mass in the trusses.

 

[blackz26]

I'm sorry I'm still lost.. I'll just move on now...best of luck in your heat dome.

 

[egnorant]

Transporting hot air from point A to point B. Gonna need to go though the roof or around it so pick your path!

If you pick through the roof shingle work will be involved so that is step 1.
Then you pick what to put in the hole...I might pick a reasonable powered vent that might even include a thermostat. Definitely one that I can seal over in the winter to prevent the heat I want from escaping.

Around the roof involves ducting of some sort.Pull the hot air down and pump it out. Fun method because with a simple vent cover you can have it pump hot air down and into the shop when it is cold outside.

From there you can start looking at methods of keeping the heat out or stabilizing the inside environment.

Bruce

 

[tylernt]

a gable vent that had passive shutters that closed when no air was being forced out by whole-house attic fan. Thus flaps stayed shut during winter on gable vent,

Actually, you want to maintain attic ventilation (not necessarily gable, for example soffit-and-ridge) even in the winter. Warm moist air rising from the living space will condense on the cold wood surfaces in the attic, providing a nice environment for mold to grow when attic temperatures are above 32°F.

 

[rieferman]

Previous page, someone suggested radiant/reflective barrier under the rafters, along with creating a "plenum" (basically a passage way) near the peak. In that passage way area, a powered vent.

You will be amazed on how much heat doesn't get past a reflective barrier. Combined with the vent, it will help considerably.

This option isn't free entirely, but it's extremely easy to setup, very inexpensive, and leaves your truss storage open as desired.

 

[BFBOB]

I'd start with two cheap gable vents, and see if that helps.

Hip roof. No gables.

 

[ddawg16]

It would be close to $1000 to insulate the walls/ceiling and finish with drywall or OSB. Why would I spend this kind of money on a non-conditioned, non living space? I'd like it to not be super hot during the summer, and what the cheapest option would be. Sounds like the attic fan.

Not sure where you are getting your numbers....unless you plan to pay someone.

Assuming you did your own work....

Insulation $150

Drywall....$175....+ $25 for screws, mud and tape.

You would be amazed at how much difference putting in insulation and drywall makes. My garage is only drywalled....and it's still cooler and warmer than the old bare garage....big difference.

And...it's a lot easier to control the dirt.....

And....your lighting will be significantly better.....

And....it will be a lot quieter....less noise going in....less coming out....it means you can work later at night and not bother people....

And....it will be a lot warmer in the winter....

So...you can try some half ***'d ways of trying to get the heat out, or you can do it right and insulate/drywall. Anything else is just a hack....

 

[CNGsaves]

Last year helped roof my BIL 2 story house and he added a gable vent that had passive shutters that closed when no air was being forced out by whole-house attic fan. Thus flaps stayed shut during winter on gable vent, but in summer when attic vent running the hot air was easily pushed out. It's really worked for him as poor man's A/C to pull in cool air to house through windows and push out hot attic air at same time.

Actually, you want to maintain attic ventilation (not necessarily gable, for example soffit-and-ridge) even in the winter. Warm moist air rising from the living space will condense on the cold wood surfaces in the attic, providing a nice environment for mold to grow when attic temperatures are above 32°F.

You're right about winter ventilation - - it is still necessary. My BIL house that I was talking about above had that "passive gable vent" way up high on south side of 2 story house that was having problem of strong winds blowing right into attic (ie he thought too much inflow of air, preventing outflow, per his reasoning). It wasn't that fancy a gable vent anyway . . more like an oversize dryer vent with those floppy slats! It seemed to be doing what he wanted, as other end of house had another gable vent . . AND . . top of roof had those cutout vents, thus actually plenty of venting.

 

[matt151617]

What about a reflective barrier on the underside of the roof sheathing? Would that be enough to stop the heating coming through?

 

[Stuart in MN]

While it can be useful in the south, radiant barrier insulation is generally considered not worth the effort in northern climates. There was an article in my local newspaper about this just the other day: http://www.startribune.com/local/205029061.html?refer=y

If it were me I'd look at putting an exhaust fan in the back wall, and then turn it on when I was working out there. with an open garage door it will pull fresh air through the garage. It's not the ideal solution but it's relatively inexpensive, and it should keep the temps inside the garage pretty close to outside temps.