Another: How do I cool my garage? thread!

[reinhardt]

I've got a 14x20 attached garage, for a total of 280 sq ft. The garage shares 2 insulated walls w/ the house. The side wall is un-insulated currently, and the front wall has a 9 wide x 7 high insulated door, leaving about 2.5 ft of uninsulated wall on each side of the door. Overhead has no insulation either. The entire garage is drywalled, including the ceiling which is 9 ft high. Concrete slab for a floor.

Now for the proposed cooling.
1. Plan on cutting 1 ft of drywall all the way around the top of uninsulated walls to blow insulation down inside walls. Then blow insulation in attic for ceiling, not sure how thick tho.

2. My brother gave me 2 window a/c units, a 5050 btu and a 8000 btu. Install those in side wall hanging out into yard.

3. No more dragonflys in the garage while working.

Now the long list of questions:

1. How thick to blow the insulation in the attic?
2. Is blown insulation acceptable for inside walls? Should I pack it down some, or let is lay loose?
3. Will one 20 amp 110 circuit w/ 12 gauge wire feed both of these units? The 5050 btu calls out 4.7 amps and the 8000 btu calls out 7.5 amps.
4. Can I build a 2x4 frame between studs to support the units?The studs are 24 inches on center and the widest unit is 19 inches.
5. Do the units NEED a support from back of unit to wall, or will the 2x4 frame support the units?
6. How do I finish the vinyl siding around the new holes to avoid leaks?
7. I was figuring on a 1" pvc pipe as a drain with both units y'ed into it ran to the driveway. Does this sound sufficient? Should I run the drain to the curb?
8. Any other suggestions?

Thanks! Btw... I did do a search before posting, and this is the ideas I came up with based on the search.

ben

 

[Motofixxer]

The pic shows how I framed for my A\C. Best would be to just frame like a normal window opening. Find 2 stud bays and cut drywall out at height you want, or to the floor depending on how you frame it. Then you can put 2 long cripple\queen studs all the way to the floor plate. Then set your horizontal 2x4 on those studs. Then I laid treated plywood on that horizontal 2x4 a little bit smaller than the a\c unit for it to actually sit on. Install your short vertical cripple studs on the sides then a 2x4 header with cripple studs going up to bottom of top plate. Make your opening larger than the a\c unit and insulate around the unit. Run your drywall right up to the a\c for a nice fit\finish. But if you ever had to change the unit, the rough opening is bigger to accommodate. On the outside cut the siding back about 3 1\2" from your A\C unit dimensions. Then fill rough opening gap with sheathing etc. Or if you measured and cut correctly you wont need any additional sheathing. The sheathing only needs to be cut to fit the a\c unit through. Cover the area with Tyvek overlapping correctly. Or use tar paper or the door and window sealing tape. Then use treated material or cedar to make trim boards around the a\c unit. The trim boards allow you to custom size the a\c unit without messing with siding later etc. Just trim the trim boards for the fit. Install your siding channels. Install the trim boards and caulk the siding to the trim boards and trim to the a\c unit.

1. Don't cut all drywall. Use holesaw of proper size then use round piece as patch. For blowing ceiling, decide how much R value you want\need. What is code for where you live and start from there. Talk to a local insulation Co. and get estimate. I have heard its about the same to have it done, as to buy the insulation and do it yourself. Do any additional lighting\wiring before the insulation. Remember to add 1 or 2 240v circuits with at least 10ga for compressor or future use. Even if you don't use it now. Get wiring in place. Maybe get some coax in for tv.
2. Talk to local professional about what's available and used locally for insul. Get estimate from them.
3.The single 8000btu should be able to cool that space enough.
4, 5. Refer to description and pic as 1 option. The other option is just attaching blocks on the inside of the 2 studs then put a horizontal 2x4 on the blocks. That won't give proper support for everything. But it's an option.
6. Covered in description
7. Don't worry about a drain. I never have. The window units have a drain designed to just drip outside.
8. The overhead can be insulated with Styrofoam. Best to use the foil backed for highest R value. And buy or borrow tablesaw to cut it with. Plain construction adhesive would work fine or maybe the foam adhesive to adhere it.

 

[Falcon67]

>3.The single 8000btu should be able to cool that space enough.

What he said. I would not try to use both. If you think the 8K isn't enough, go buy a 12K unit and that certainly will take care of it. 12K works fine in my 20x24. Mine is framed in like the pic above. 8Ks are window units, so you may need some 1x2 trim inside the hole to make it more like a window mount. The 12K and up units slide out of the case. You can then mount the case in the hole and then install the guts.

 

[ghnl]

Before remodelling we had a 22'X22'X12' garage. 3 1/2" fiberglass insulation in the walls and 6"-8" in the ceiling. I bought a 12K BTU casement window A/C and mounted it in the wall. The reason for buying the casement unit is because it is 14.5" wide - it fit between the studs with no need for fancy framing.

The 12K unit cooled the garage nicely even during NC summers.

 

[reinhardt]

i'm picking up what u all are laying down as far as the units i have arent ideal. but... the price is definately right. upon further research, and u all's input, i think the 8000 btu unit will take care of the garage. i know a wall unit would be easier than making this window unit fit. but.... i have 2x4s, i have some aluminum angle iron to make brackets to attach unit to 2x4s. have to modify the siding either way i go, and have to add a circuit either way. so i think the only down side here is it will be a more difficult install. i think i can make it look just as good installed, so the only expense is my worthless time.

lets pretend for a moment that the 8000 btu unit wont keep up w/ my needs, and i have to step it up to 12000 btus.... other than the looks of 2 units in the wall, whats the big deal of using these 2 versus 1 12000 btu unit? again, the cost is my motivation for the question.

so, i'm still unclear on the blown insulation down the walls... something about vapor barriers or something..... what are they for, do i need them?

 

[Motofixxer]

I doubt you will need any more than just that 8000 unit. I personally would just go with that. I have used a 10,000 for my house. That was adequate except in the bedrooms down the hallway during the late afternoon sun. So that little 8000 should work fine. Price is right go with it.
I'm unfamiliar with blown insulation in the walls. I know it is done in older houses. Obviously a vapor barrier is extremely important if your working from the ground up. But with what you have now its not really possible without removing all the drywall. I would consult a local insulation pro and have them come give you an estimate, pick his brain a little bit. Then either do it yourself or pay them to do it.

 

[mo2872]

Blown-in for walls is used around here quite often. They call it "BIB's"....Blow In Blanket....personally think it makes a place more "snug"...... www.bibs.com for more info on it.....parents had a house with it, wish I'd done mine that way.

 

[pcmeiners]

Agree use a hole saw, large enough hole to send the hose down the stud space, pull up the hose as the blower bogs down, couple feet at a time, which will pack sufficiently; without some compaction, cellulose will settle too much. Make sure the cellulose has borate or other fire retardant. Don't skimp on the ceiling cellulose thickness, in my house I have 12", after it settled.

 

[Falcon67]

Your "cost motivation" for running two units is that you will easily use twice the power of a single 12K unit. The larger units are more energy efficient. However, in your space you'd only need the other once in a great while, if at all - so it may not matter.

 

[reinhardt]

ok.... i think i'm settled on using the single 8000 btu, we can stop beating that horse. onto the next horse, why cut a round hole instead of cutting the top foot of drywall all the way around? i figure it would be alot easier to cut a 4x8 sheet of drywall into 1 foot x 8 foot strips and screw that in place, tape, mud, sand. rather than dealing w/ a circle, trying to re-attach approx 10 of them and tape, mud, and sand each one. what am i missing here?

 

[MScott]

I think the problem would be trying to fill that last 1 foot without the blown-in insulation falling out. If you really prefer to cut the strip, my suggestion would be to fill the cavity level, then use an appropriately sized fibreglass bat to fill the final area.
As to the lack of vapor barrier, you can get a vapor barrier paint that, while not as efficient as plastic sheeting, can provide some resistance to moisture.

 

[Motofixxer]

Reason for the holes as opposed to cutting a long strip is Simple. 1 little 3-4" patch for each one. Rather than 14'+ 20' of seam to mud or whatever the dimensions end up being. Plus the extra sheets of drywall and all the extra mud, and tape= More time and more material. But if you want to cut along the top, it's your garage and your doing all the extra work. We are just telling you the quickest, easiest, and simplest approach to get the job done in a reasonable manner.

 

[reinhardt]

Reason for the holes as opposed to cutting a long strip is Simple.

please forgive me sir for my ignorance. what u find simple, i find baffling. if i found it simple, i wouldn't bother asking the question. if u want to enlighten me as to how to put a round piece of drywall back up, i wouldn't mind listening.

i work in ship repair. if it were steel i would weld it back in, unfortunately this is drywall and i don't know how to make a circle of drywall stay in place w/ some mud and tape. sorry to bother u with my stupidity.

 

[Motofixxer]

Don't worry, it's easy, and it's no problem. We have no idea the background of people posting. So me personally I will give an overview, then if more info is needed, the questions will get asked, then answered.
Using a holesaw cut the proper sized hole which will leave a round blank cutout. That you will reuse. Once you are ready to patch. Cut a piece of plywood or wood block about 1 1\2 to 2" wide and 3" longer than the diameter of your hole. Place that piece on the inside of the hole holding to the back of the drywall. Zip a couple screws through the drywall into the block on the outside of the hole. Then place your drywall circle cutout back in the hole and screw it into the block. Then use a wide drywall knife and put 2-3 coats over the hole filling the cut lines. Sand as needed. Repeat as needed for other holes. No extra drywall needed, or tape. If you need more info you can find videos on Youtube etc for drywall hole repairs. Different ways of doing it. But this is simple and easy.

 

[BirdRacer]

Also, it will be a much smoother patch if you cut the holes at a 45 degree angle, like below:

 

[reinhardt]

thanks u all. i like the 45 degree cut. will have to use that in the future, but i do not think i can get a hole saw to cut on a 45.

thanks tho.

p.s. u didnt cut a hole in your wall just to show me that did u? i appreciate the dedication, but i wouldnt want u to have to explain to the wife.

 

[BirdRacer]

thanks u all. i like the 45 degree cut. will have to use that in the future, but i do not think i can get a hole saw to cut on a 45.

thanks tho.

p.s. u didnt cut a hole in your wall just to show me that did u? i appreciate the dedication, but i wouldnt want u to have to explain to the wife.

Anything for the cause, bro.

No, I stole the pic off the 'net. LOL

As for the 45, use one of these:

 

[55chevr]

If you cut the hole at 45 degrees or near that and mark the piece, you can replace it into the same spot ...

 

[green.bubbly]

FYI, many window unit air conditioners do not drip water. In fact for them to function properly, the water is picked up by the outside fan and sprayed across the coils to aid in heat dissipation.

One other tip. Cut and frame the hole in the wall larger than the actual unit and fill in with wood trim or filler boards. This way when the unit dies and you have to replace it, you may not find a unit the same size and you can just replace the filler boards rather than trying to enlarge the hole in the wall.

 

[HVAC Phil]

Use a hole saw to cut out holes. Save piece. Blow in insulation. Put backer board in from behind in hole you made. Put saved piece back in. Simple.

 

[rackeu]

Don"t want to hijack a thread but how would you get insulation into a drywall ceiling?

 

[Tymscholl]

Do you have an attic access? Lay fiberglasbatting or blow in some insulation through the attic access.

 

[darkk]

The pic shows how I framed for my A\C. Best would be to just frame like a normal window opening.

Is that a water pipe in that outside wall? Living in WI. I'd be afraid of it freezing in the winter.

 

[ishiboo]

FYI, many window unit air conditioners do not drip water. In fact for them to function properly, the water is picked up by the outside fan and sprayed across the coils to aid in heat dissipation.

One other tip. Cut and frame the hole in the wall larger than the actual unit and fill in with wood trim or filler boards. This way when the unit dies and you have to replace it, you may not find a unit the same size and you can just replace the filler boards rather than trying to enlarge the hole in the wall.

This depends greatly on your location. Where you are, "swamp coolers" are used frequently. Here, air conditioning is typically conventional and it is desirable for the water to condense and drip or be pumped outside, as the removal of humidity from the air is desired and you definitely don't want the A/C adding to it!