Getting the garage temps to a more comfortable level

[The Lazy Destroyer]

Hey guys! Another question. I have a 40x22 outbuilding that is currently not heated/cooled, nor is it insulated. I understand that without a good AC system (or heat in the winter) it's never going to be the "perfect" temperature in there, but with the way the GA heat has been lately it gets pretty brutal in there by afternoon. Outside might be 95°+ and my thermometer inside the garage is about 90°. It'll stay pretty warm in there until it's well into the night, but eventually falls to where it's comfortable again.

I'm hoping with insulation I can bring these temps down to a more bearable level, 80° or something. At least to some point where I can get more fans in there. But at the temps now, fans don't feel like they do much.

Here are some pics:

Building faces southwest. With the trees it feels really good in there in the morning, because it is all shade. Noon will get the sun on most of the roof and it starts to heat up. Afternoon, the sun is full on the front and the inside really starts to cook up.

This is how the inside is:

I've already did the Owen Corning insulation kit for the door. I've also installed a gable vent fan which exhausts at the front side. Both helped a little I'm sure but not very noticeable.

I'm wondering what the temps may change to if I add a ceiling and insulated both the ceiling and walls.

Insulating the walls seems pretty straightforward, just get batts and mount it up. They are 2x4's on 16" centers.

I'm not really sure on the ceiling, I guess mount drywall or OSB or something mounted to the bottom of the roof trusses? Then insulate on top of that? The bottom chord is about 14' or 15' high. Because of the garage door a drop ceiling is probably out of the question. Does the ceiling height being that high pose a problem with temperatures? Trusses are on 24" centers BTW.

I would assume that all this would keep the temperature extremes from being really bad but would there be a significant change? I will probably eventually get to a proper heating and cooling rig for out here but really don't need it at a perfect temperature for now, just trying to take the brutal edge off of it now.

Thoughts?

 

[The Lazy Destroyer]

Also, for the ceiling, what is the best way to get the boards installed, would a drywall lift be the only way to get it done?

This one seems pretty affordable:

http://www.discounttommy.com/Shop/Control/Product/fp/vpid/3445588/vpcsid/4550507/SFV/32282

Wondering if I should snag it up for that price, free shipping as well.

 

[78Bird]

insulate... and add that ceiling. The heat the roof absorbs can be cut off from the main area and with good venting, it doesnt come down to heat you up...

Those 2 things will make a big difference. Especially if it cools off at night, it'll keep cooler much longer by resisting the suns heat.

 

[John in OH]

78Bird is correct ... do the ceiling first. I'm sure when the GA sun beats down on the shingle roof, the roof sheathing radiates the heat downward into the your work area.

So step one is to eliminate that radiation by installing a ceiling. Even if you left it un-insulated you would see an immediate improvement, but it should be insulated. You could install Kraft-faced insulation bats then install a ceiling, or install a ceiling with a vapor barrier (top side of ceiling) and then blow in insulation.

Ceiling material is a good question. Drywall will work but it's heavy, awkward to install, and the joints have to be finished. Another possibility that I'd consider are white steel liner panels. These are similar to the long steel panels used for roofing, but the liner panels are usually lighter gauge material and made for interior use. Material is probably more expensive than drywall, but lighter in weight and NO joint finishing required! Working the panels around existing electrical fixtures and anything already installed on the ceiling will be somewhat tricky.

By the way, you can rent a drywall lift for reasonable cost ... but I don't know if they are available for such a high ceiling.

Final step will be to insulate the walls and finish however you want. Lots of opinions on this board regarding the best wall materials for a garage.

 

[Charles (in GA)]

Make absolutely sure all of your wiring is run and boxes mounted, or be prepared to use surface mounted conduit in the future, and get the ceiling done and insulated, then the walls. It will be like nite and day the difference. Be sure and consider some ceiling fans. Good in both Winter and Summer, You have the height, that is GOOD, will be cooler in the summer, but harder to heat in the winter, but that is where the ceiling fans come in, to push heat back down.

Charles

 

[paris_tj]

I insulated my metal building here in dallas area, with R24 in walls, and R38 in attic. Then covered with 1/2" Ply and so far, 82 degrees is as hot as it has gotten in side. I do run a dehumidifier, and keep it at 50% and with a fan running, it is quit nice with all the doors shut.

So do some good insulation, it is worth it in my opinion.

 

[W650Mike]

Insulation is always the first step. Money spent keeping the heat out (or in) has the best ROI. Fans are cheap and make a huge difference. Ceiling mounted would be best but consider their placement relative to where you will be adding your lift! With that height a lift is a must.

Make friends with a local A/C contractor and have him keep an eye out for a decent used 5 ton unit. The older ones are not as efficient as newer but being a shop, it doesn't run near as much as a house so the operating cost is reasonable.

My steel 30x40x14 has steel siding and top, 3" rolled bats, and a 5 ton that I scrounged. Copper, vac and freon ran $285, a few beers and a couple racks of ribs. Monthly (separate meter) runs $75 ±5 in the TX summer. Without the A/C, my shop would be useless after work when temps are 100+.

 

[The Lazy Destroyer]

I insulated my metal building here in dallas area, with R24 in walls, and R38 in attic. Then covered with 1/2" Ply and so far, 82 degrees is as hot as it has gotten in side.

That was the other thing I was wondering about regarding insulation. R13 seems standard for the walls, but for the ceiling... the bottom chord on the truss is a 2x4 I think. Is it normal to use a thicker insulation between a smaller 2x4? I would think it wouldn't matter and that running thicker stuff would be okay, but my only concern was if I needed to get into the new "attic" for any work on the gable fans or inside of the roof or whatnot. Wouldn't the thicker insulation make laying a few sheets of plywood (when I need to get up there for any work) difficult?

Or is there an easier/simple solution to that that I may be missing?

I'm assuming R13 for the ceiling would not be good enough. R23 okay for an outbuilding/workshop?

 

[Cryptic1911]

it doesnt look like there's enough room up in the ceiling to be doing much of anything anyways, I'd jam some r30 or r38 up in there and call it a day, then do the walls with whatever the highest r value is you can find. The difference in price between r values isn't a ton, so do it right

 

[mastiff0]

I went throught this process in Houston last summer, starting with a garage similar to yours. First, roof insulation (along with appropriate roof venting) is most important. You need a second room (an attic) which traps the hot air from the roof and vents it back out. There are tables that give recommended R value ratings for your attic depending on your location, but I think a R value of 38 would be your minimum. Yes, this will be thicker than your 2x4's, and the cheapest and easiest method is to use that DIY blow in insulation from Home Depot. Much cheaper and easier than rolled batting.

If you absolutely need access to your attic, you can have localized areas with less insulation so you can make floors, but your ceiling joists are big enought to carry much weight, so definitely no storage up here. In fact, you will need to do some estimates to see how much weight per square foot the addition of your ceiling will be. Don't want to make your roof sag.

With the ceiling insulated and vented, your garage will be shielded from most of the suns rays that hit the roof. See how this feels. If its still too hot, the next step is the wall insulation using the rolled batting. At this point you've done enough where you can add and A/C and run it without a crazy electricity bill. Even if you have no intention of going with an A/C now, this is the route you want to take- insulated attic, then walls.

 

[NUTTSGT]

If you check out my thread in my sig, you can look at what I did for my garage refurb. Last year and the previous years, my garage got hot in the summer. It wouldn't cool off at all and made it miserable out there.

I dropped the ceiling and added R19 insulation. I could have went with a a higher R value but in the winter with the wood burner, it's fine.

Temps in the past have been the same out side up until 4-6 pm, then it was hotter in the garage then it was outside. This year with the new ceiling, it's 12-15 degrees cooler in the garage. It was money well spent.

If you can swing it, with the high ceilings, maybe some windows just below the ceiling would help keep it cool, if you don't use AC. I'd put two on the back wall, crack the garage door about 4" and it should flow some nice air.

Your ceilings look to be atleast 16' if not 18. I'm not sure if a drywall lift will go that high even with a extension. If would probably be easier to hang some metal siding with some scaffolding and two buddies.

 

[bigdav160]

Perhaps ya'll can convince people there is no reason for A/C in their homes.

Just add insulation!

It' 95* outside and it's 80* inside with just insulation!

Right



to the OP, if you want to cool off that building you'll need A/C. You want a radiant barrier installed to shield the afternoon sun. This will help with the heat gain. Insulation after the A/C will help with the energy usage. Insulation without the A/C is just going to hold in that hot moisture laden air.

 

[Old Moparz]

Definitely insulate, but you might consider an exhaust fan for the entire building if you don't want to spend the money on an a/c system yet. Like you said, if the heat builds up during the day it'll take quite a while to get the temperature inside to cool down. After it cools down outside, open a window, turn on the exhaust fan & it will pull the hot air out & draw the cool air in the window.

A friend of mine uses one for his house & it works great. Of course if it's 90+ outside, you aren't going to cool anything down with a fan.

 

[The Lazy Destroyer]

Wanted to bump this thread as I am just starting the ceiling insulation job here in a few days. Going with R-30 on the bottom chord of the trusses. Furring strips every 1 ft (trusses are 24" centers). Then eventually doing either OSB or Plywood ceiling.

Along with the R-30 on the ceiling, I had thought about doing also a foil-backed radiant barrier on the top chord of the trusses. When I asked about it to the local supplier he made it seem like it would be a waste of time if I do not have soffit and ridge vents on my roof.

Currently I have two gable vents, one on each side, one has a 1600cfm gable fan to exhaust the hot air. He said I would be better off doing a ridge and soffit vents.

Wouldn't adding ridge vents hurt the exhaust fans ability to exhaust the hot air across the whole attic area? I'm thinking maybe he thought this was for my house and not a 900 sq ft garage? He made it sound like what I have now is already inadequate so of course now I'm paranoid about it.

Any thoughts on this? Should I skip the radiant barrier and just stick w/ the R-30? I can always add the radiant barrier later but once the insulation is up I guess.

 

[NUTTSGT]

I have read before (and it made sense to me when it was explained) that soffit vents and ridge vents work together and gable vent and roof vents work together.

I'd leave what you have in place, the fan will (should) cycle the air nicely.




EDIT; I posted this before and this was the explaination I was talking about, follow the link and go to post #14. I pulled the quote from another site.

http://www.garagejournal.com/forum/showthread.php?t=105281

 

[GarageEnvy]

My climate is much different so YMMV but I did the radiant barrier sheathing on my stick frame shop. We get up to 110+ during the summer and it has made a dramatic difference. The attic with a darker comp shingle is much cooler than before with the wood shake and no radiant barrier. How much different it would be on the chords vs. the roof sheathing I couldn't say. I priced R-30 from the big boxes and had a contractor do R-38 with sealing the sill, stud gaps and wire holes for less. I have two 18' doors and an 8' door that are triple layer insulated and the garage faces west. The highest temperature I've ever seen was 89 on a very hot day. However, it's a two-way street. Once it gets hot, it will stay hot if I don't open the doors.

We have soffit and ridge venting. On a day like today (~105) I can see heat boiling out of the ridge. However, on a windy day I have felt hot air coming out the soffit vents on the east side of the house. It was entering the west vent running up one side and down the other.

 

[camarotoolman]

It will take awhile to help, but plant more trees. Its been 20 yearrs coming, but now most of my house and garage are in the shade now. Helps the cooling, and I like the look.

 

[The Lazy Destroyer]

Is it possible to say if there is enough ventilation to allow the radiant barrier as well along with the r30 in the ceiling?

 

[VANAMAL]

Thats really nice id finish up first class. Ive got a motorcycle table lift hydraulic that i recesed into the floor. Its really nice for workin on the bike and i also use it to service and repair the riding mower,water blaster,edger etc. As far as heating it up how about a pellet stove or pot belly stove? Might work good with the large area

 

[J Persons]

Saw an ad for this material the other day, it looks promising, but I have no idea of the cost. http://www.greenenergybarrier.com/index-7.html
BTW, I'm getting real tired of all the green this green that ****.

 

[BWS]

Just a note on ventilation....I'm in a slightly different situation.We're climate controlled...even got a cleanrm,well sorta.And thats being rectified with anvanced or engineered ventilation system.Which is reason for post.

Think about a whole house fan...mounted in ceiling.It isn't completly a substitute for AC....think of it as part of an overalll HVAC system.It will do a fantastic job of pressurizing the "attic"....exhausting hot air from up there will pay big benny's in the workshop.BUT,it has other,very useful uses.Do a search here....should get lots of info.

 

[darkk]

I don't think I would plywood or OSB the ceiling. I think Tin would be a better choice, it would definitely be much easier to install..

 

[Nowater]

My build is 24 by 36 and one window unit cools it down as cool as I want. However, my garage is foam insulated structural panels and very air tight even allowing for the single 10' door. The air conditioner was less that $400 new. (Long story about getting it, but it is re-purposed now in the garage.)

You may consider interior sheating with OSB for the increase in strength to resist hurricanes, as long as your garage is held down well. You could blow in a lot of loose insulation in the ceiling, which is where a lot of heat gain comes from.

 

[Falcon67]

My 24x40 uses TechShield radiant barrier. It helps quite a bit, but it's designed to be used as the roof and not an add on. With R30 ceiling, I don't think you'll get much out of the effort and expense to install the radiant. Maybe, but not very much. My 24x40 has R13 walls and R13 ceiling, leaky OSB on the ceiling, soffitt and passive deck vents. The attic runs about 120F and the building stays about 10~15F cooler than outside - if it's 102 outside, it'll be 88~92 inside. I have two AC units totaling 16.5K and I can get the place in the low 80s in an hour. I do not run anything in the building during the day. I'll eventually caulk the ceiling, which will help. And if the Crepe Myrtles survive, in a couple of years they will drop the west wall outside temp down from 130F+, which will help a bunch.

 

[SGKent]

we live in Sacramento and have a fully insulated and sheet rocked garage. What happens is that day time heat doesn't soak thru as fast so at 4pm instead of being 100F+ in the garage it is 80F. However at 9pm when it is still 90 outside it is 100+ in the garage as the heatsoak comes thru. At 7am when it is 60F outside it is 75F in the garage then the garage will continue to dip down until the whole cycle starts over. Opening the doors and running a big fan will drop the evening temps to maybe 5 - 10F above ambient. It is still uncomfortable even with fans on in the garage. To fix that would require a/c in the garage. I don't mind the cost so much of installing an A/C unit but the ongoing cost of electricity to run it makes it not worthwhile to work in the garage this time of the year because you have to run it a long time to keep the garage cool. Once cannot just flip a switch and have it instantly drop from 90 to 70.

 

[The Lazy Destroyer]

Thanks for the replies! I think I will stick with the R-30 and worst case if I decide on the radiant barrier I'll get back in there during winter when the temps aren't crazy. Hoping the gable exhaust fan I have will be a bit more efficient once everything is sealed up in the "attic" area up there.

 

[bluesman2a]

As a fellow Georgian, I can relate, and have gone through this in several instances in my own shop.

I agree with what many here have said. Ceiling and insulation will make a big difference, but that's only PART of the puzzle. That keeps the heat out in the summer, the heat IN in the winter (yes we do have colder winters sometimes). Winter here is easy, you just need something to knock the chill off.

Summer is a little more problematic. The first thing I see is that you have no cross-ventillation. When I built my shop I put a rear garage door for use purposes, but it's MUCH better (in hindsight) for cooling. Your gable fan is on the same face as your garage door, it won't DRAW air through the shop. Put a high CFM fan like this on the rear wall:
http://www.farmtek.com/farm/supplies/prod1;;pgcf1750_CF1760.html

Another thing is humidity. We have it in spades. You can get a decent 220V window/wall unit for under 500. You don't have to refrigerate the space, but sometimes it helps to button-up and knock some of the humidity down.

Others have also mentioned fans. Get some at least 2. If you can keep the air moving it will feel cooler and keep the bugs down. Try these:
http://www.homedepot.com/Lighting-F...Id=10053&langId=-1&storeId=10051#.UCSMLk1lRIE

 

[The Lazy Destroyer]

Others have also mentioned fans. Get some at least 2. If you can keep the air moving it will feel cooler and keep the bugs down. Try these:
http://www.homedepot.com/Lighting-F...Id=10053&langId=-1&storeId=10051#.UCSMLk1lRIE

Hah! Yep, actually I have three of these (in white) ready to be put up, it's the next step once the ceiling insulation is done.

I had thought about putting the gable fan on the back side but I knew eventually I'd be insulating the ceiling and figured it would be best to exhaust onto the hot side of the garage (and draw air from the opposite gable vent from the shady/cooler side.

When the AC in our house gets replaced I may move that unit over to the garage, or get 1 or two larger window units. But that will probably be in the distant future, year or so.