Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Rondar on July 11, 2012, 02:58:08 PM
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Probably frivolous but I'm getting older and I want a little comfort. Thinking about airconditioning one bay in my garage. It is 11x25 and a sloping roof from 8to approximately 12 feet high. I would be mainly in it of an evening. I can't hardly work with door open as the bugs just get terrible. Uninsulated of course.
Would.say 15 to 18k btu do it? Speaking of a window type unit.
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if i figured right(and honestly, i probably didn't), you've got 3300 square feet to cool. that range should work for that.
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I was going to say around 16,000BTU should do it, but it depends on how many windows there are and the Sun exposure to them.
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if i figured right(and honestly, i probably didn't), you've got 3300 square feet to cool. that range should work for that.
Cap1 just so you know that size floor space is only about 275 square feet. Height x Length = Square Footage
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Since you mentioned this is for the evening use, you may want some type of vent with a fan on a switch installed way up top near the roof, quickly get rid of the hottest air and it might be perfect for when its uncompfy but not hot enough for the AC. Turn it off before turning on your AC.
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Cap1 just so you know that size floor space is only about 275 square feet. Height x Length = Square Footage
DOH!! i was doing height x length x width. :bhead
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DOH!! i was doing height x length x width. :bhead
Save that to impress the ladies in the bedroom, it doesn't apply in the man cave.
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The initial cost is a bit more, but heat can also be added and if you ever remove it, you don't have to fill a huge hole in the wall. Have you considered a split system?
http://www.us.sanyo.com/HVAC-Single-Split-Systems-Wall-Mounted-Air-Conditioners/Wall-Mounted-Air-Conditioner-18KS72-18KLS72 (http://www.us.sanyo.com/HVAC-Single-Split-Systems-Wall-Mounted-Air-Conditioners/Wall-Mounted-Air-Conditioner-18KS72-18KLS72)
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I looked at some of those on home depot website Dragon. It was double what window units going for. My garage is an old barn that was used for some grain storage, so no windows for my half of barn, and other half of it was milking stalls. I sectioned off 3 parts of the grainery part inside for cars, storage, workshop etc. so no windows and the whole barn has a metal tin corrugated roof. But that half is ventilated well.
What I had planned to do was just to cut a hole inside my part and mount a/c inside with the condenser part sticking out into the ventilated part. Not sure I need heat as I have one of those kerosene powered jet engines, er a 155,000 btu space heater. Oh yeah it heats it up in a hurry when its 0 out. But dadgum, the thing is so noisy you cant think when its running, so maybe some heater/A/C unit is the ticket.
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Not sure when it happens, but when you get to a certain size of a/c, you will need a 220 plug. Anything over a ton?
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You want a 220 unit anyway. A 110 will use a lot more electricity.
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Cap1 just so you know that size floor space is only about 275 square feet. Height x Length = Square Footage
.
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Cap1 just so you know that size floor space is only about 275 square feet. Height x Length = Square Footage
actually, it just hit me.........i DID do it right. you're figuring a surface square footage.
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While you're at it, adding some insulation might help a lot. Better yet, rough finish the work space. Insulate (or not) the walls, throw up some drywall or even some plywood (if you want to hang stuff from the walls), add a ceiling (maybe with some blown insulation on top as an option) and you won't be cooling the area under the roof and will cut the heat transfer through gaps to a fraction of what it is now even if you don't use any insulation.
The side of the garage that gets direct sunlight in the late afternoon would probably be the highest priority for insulation, if your problem is too much heat. The thin insulation just on my west-facing garage doors kept my garage 10-15 deg cooler than outside air temps even throughout the late afternoon.
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I know this is extreme, especially if not new construction, but if possible get it spray foamed. I just converted my covered patio into a shop and doubled the floor slab area. I hired a professional foam crew to spray a 1.5" minimum overall coat. It's like having a custom sprayed ice chest. Their big point is continuous coverage. No gaps. Every surface above the slab is coated with at least 1.5 inches of foam. Temps inside are easily warmer or cooler (in my favor) than outdoor temps and that's without having any HVAC in the shop. When it's 105 outside, it's 90 inside my shop.
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My only concern with the spray foam is leaks.
I was a big proponent of the spray foam until my neighbor had it done. A few years later his roof had rotted to the point of collapsing. Indeed, a hail storm poked holes through the effected area, which is how he found out about it.
The foam did such a great job it prevented water from dripping through which hid the area where the leak was.
The real kicker was his insurance company would not cover the damage citing it was owner created.
Just be careful with the spray foam and check with your insurance company about liability in case of damage.
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Sounds like he had a bad roof starting out. The foam is a thermal insulator, not a weatherproofing tool. Granted, I was more or less new bare metal construction, but there were no leaks in my exterior. I was spraying on a bare all metal construction. I wouldn't advise using spray foam on any pre-existing wood construction. The foam is a waterproof and continuous surface. Any absorbency or seepage by the exterior construction material can only lead to disaster.
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Sounds like he had a bad roof starting out. The foam is a thermal insulator, not a weatherproofing tool. Granted, I was more or less new bare metal construction, but there were no leaks in my exterior. I was spraying on a bare all metal construction. I wouldn't advise using spray foam on any pre-existing wood construction. The foam is a waterproof and continuous surface. Any absorbency or seepage by the exterior construction material can only lead to disaster.
No leaks when it all started. A hail storm facilitated a new roof the year after he had the foam installed. The new roof leaked. No way to know until it was too late. Damn shame too. It does a great job of insulating, but there is no way I would use on any home in our area of the world. Hail storms are an annual occurrence for us.
The only option is to rip out the foam, if you get a new roof, and then have to blown in again once you are comfortable the new roof is not leaking.
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Another option for the spray foam is to use a second roof covering. Spray on the foam and then put up another roof on top of it, to protect the foam.
One of my grandfather's neighbors had an old-style flat roof (tar/gravel) and he sprayed on about 4 inches of foam on top. It was great until the foam cracked and started letting water run around inside the foam and collect on the old tar roof. Those tar roofs degrade over time so after a couple of years, the collecting water under the foam met a small crack in the tar, and the roof started leaking. The problem of course is that with both the tar roof and the foam covering, the inside evidence of the leak may be nowhere near where the actual roof leak because the water will run all through the cracks until it finds the final intrusion spot. So you can pour all the tar or foam sealant) into the cracks over the spot where the water is coming into the house, but the real leak may start in a tar or foam crack dozens of feet away.
The solution of course is, like all tar roofs, to re-tar the roof every few years and tear it all up and re-do the whole thing every decade or two. Once you add the foam though, you're pretty much hosed. Again, the "solution" to that is to put up a slanted tin roof up above the old roof, to minimize how much water ends up on the original foam and tar roof. That way even if some water gets onto the old roof through the tin roof, it usually isn't enough to leak through or collect enough to cause rot.
And of course all that is $$$, and doesn't even account for the fact that roofs and walls are designed to breathe to a certain degree, to avoid moisture buildup and mold throughout the house. Seal up the walls or roofs with additional treatments and you might trap moisture inside the house and cause any number of problems. It's the same sort of thing people find when they add radiant barriers inside their attics... Sure it drops attic temps and lowers heating/cooling costs, but the energy radiated back out the top of the roof can easily melt composite shingles and sealing tar, causing the roofing materials to fail much earlier than expected. The best solution I've seen is a double-roof structure that simply works as a second sun shade over the original roof, which remains the primary weather barrier. The second roof is pretty much open at the ends to allow ventilation between the layers and must be built to be easily removeable if/when the original or primary roof needs repair or replacing. The good news is that the top layer can be designed to help reduce hail damage on the primary roof and be easily repairable. Downside of course is cost, plus some insurance companies freak out over adding a roof on top of an existing roof if it isn't done exactly according to their specifications and that might make the house uninsurable or cause premiums and deductables to go way up.
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Saw an experimental roof using that concept eagl.
There was the normal composite roof with a suspended roof above it.
The top layer/panel was comprised of aramid fiber using a vinlyester resin, coated with a UV stabilize silicon rubber coating and backed with butyl rubber. The panels were affixed to aluminum rails attached to the roof using the ends of the existing rafters so no punctures of the existing roof was done. The panels were bonded to the rails with a 3M panel bond adhesive.
The rails suspended the protective roof panel 8 inches above the original roof. Not a cheap solution in the short term, but long term they were optimistic about the costs being less than a normal roof.
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I'd definitely add insulation if I were going to add heating or cooling to the space.
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my garage is 24x24, totally unfinished. when i used to do side work out there, it would take a single propane heater about 20 minutes on high to bring temp up to comfy.....then on low/med to maintain comfy temp. i never had anything more than fans to keep air circulated out there when i was working in the summertime.
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I live in Phoenix Arizona. Normally we have low humidity. If you have low humidity you should seriously consider an evaporative cooler. Sized correctly an evaporative cooler pumps in enough air to change out the entire volume every 2 minutes. If you only want to cool it while you are in there this is a good option as it will take an air conditioner much longer to "catch up" if it has been off. You have a fairly high heat load to get rid of with the tin roof and poor insulation as it is. Add to that, everything in the barn will have to be cooled also, so as those items radiate heat it must be expelled also.
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there is no way I would use on any home in our area of the world.
I was spraying on a bare all metal construction. I wouldn't advise using spray foam on any pre-existing wood construction.
In case you missed that part.
I also wouldn't advise a composite roof on any construction in Texas. It's 1 hailstorm away from leaking and we never have hailstorms in Texas.
Metal roofing, on the other hand, is good for 25+ years.
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Cap1 just so you know that size floor space is only about 275 square feet. Height x Length = Square Footage
he meant cubic feet.
semp
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In case you missed that part.
I also wouldn't advise a composite roof on any construction in Texas. It's 1 hailstorm away from leaking and we never have hailstorms in Texas.
Metal roofing, on the other hand, is good for 25+ years.
I did not miss it.
Not all composites are equal. Several years ago I had to replace my roof due to a hailstorm. I went with a good Class 4 shingle (most residential areas do not have codes allowing for a metal roof) and it had survived four good hail storms before I sold the house. When I sold it, the roof still looked new and was leak free.
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(most residential areas do not have codes allowing for a metal roof)
And that is just plain crazy. It's just like HOA's that require wooden shingles on all homes for a uniform look, then blame the kid with a bottle rocket when the neighborhood burns down on 4th of July.
Sorry, I'm just prejudiced to metal roofing. It outperforms almost everything else on the market, it's fireproof and it's easy to install.
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I did not miss it.
Not all composites are equal. Several years ago I had to replace my roof due to a hailstorm. I went with a good Class 4 shingle (most residential areas do not have codes allowing for a metal roof) and it had survived four good hail storms before I sold the house. When I sold it, the roof still looked new and was leak free.
Most locals don't have ordnances limiting or restricting its use either... very strange.
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Most locals don't have ordnances limiting or restricting its use either... very strange.
Not strange in the Dallas/Ft. Worth area here. Most, if not all, the cities do not allow metal to be used for roofing in residential. It is allowed for commercial properties.
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Not strange in the Dallas/Ft. Worth area here.
True. Just ask the people in Plano and Highland Park who's houses burned down a couple years ago. Cedar shingles are much more aesthetic.
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Save that to impress the ladies in the bedroom, it doesn't apply in the man cave.
CAP1 made the mistake and used the formula for the TMI Scale.
ack-ack
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My only concern with the spray foam is leaks.
I was a big proponent of the spray foam until my neighbor had it done. A few years later his roof had rotted to the point of collapsing. Indeed, a hail storm poked holes through the effected area, which is how he found out about it.
The foam did such a great job it prevented water from dripping through which hid the area where the leak was.
The real kicker was his insurance company would not cover the damage citing it was owner created.
Just be careful with the spray foam and check with your insurance company about liability in case of damage.
Don't think you ever want to coat the underside of you roof/shingles with foam. You want all the insulation on the top side of your ceiling. Let the attic ventilate.