I posed this question in Breaktime but wondered if anyone here might have faced this.
I live in the Ft Myers, FL and set up my shop in my two car garage. It’s too hot and humid to work out there except for the cooler Winter months. I plan to aircondition the space and feel that I may need to insulate the interior side walls to avoid condensation build-up when the cool A/C hits the cement block walls. I have insulated the attic over the ceiling and plan to insulate the metal garage door.
Any thoughts and if insulation is needed how would you suggest going about it? I thought about installing pressure treated studs with ridgid foam panels in between covered with moisture barrier and finally drywall???….not difficult but a lot of work!
Thanks for comments/suggestions. This is a great forum and I’ve learned a lot.
Bruce
Replies
You don't want a moisture barrier on top of the studs--you'll be creating a cavity that traps any moisture coming in through the concrete. I think in your climate the best bet is to cover the wall with rigid foam insulation, sealing all of the cracks with low-expansion foam sealant, then build a wood stud wall in front of that. For extra insulation, you can fill the spaces in the stud wall with unfaced fiberglass, etc., and then finish off with drywall and/or wood panels.
Everything you want to know about insulation, moisture control, etc. can be found at http://www.buildingscience.com/. But be forewarned that there is a lot of information there, and it takes quite a while to go through.
-Steve
Steve: Good point about the barrier. Thanks for the site. I'll check it out.
Bruce
Bruce, up North, here in Tampa, I've been comfortable all summer in my gar..., er, studio.
The one thing that helped the most was having a LOT of insulation blown into the attic space above the garage. The guy who was in charge of the insulation crew was a woodworker, and, after seeing my tools, told me that they would blow a few extra bags into the attic, just to make sure I was comfortable.
I have also added foam panels to the garage door, and that does some good, particularly during the months when the sun beats on the door. I run a 12,000 BTU window unit, with a floor box fan to keep the air moving, and that keeps the place livable all summer. I have not had any problems with moisture condensation on the walls.
Regards,
Dick
Dick: I did have insulation blown in the attic but didn't think about the insulation on the garage door. Wish now I'd installed an insulated door to begin with. Did you use construction adhesive to fasten the panels in the door?
Unfortunately I don't have a window in my garage and I looked at the freestanding type of portable A/C units but with that I'd have to cut a hole in the side door of the garage to vent it to the outside. A more expensive option (but perhaps better in the long run) would be to have a separate small a/c unit like I have for the house central air system. Best bet would be to talk to an a/c company I guess.
Glad to hear that condensation has not been an issue on the walls.
Appreciate the response. Thanks.
Bruce
>>Dick: I did have insulation blown in the attic but didn't think about the insulation on the garage door. Wish now I'd installed an insulated door to begin with. Did you use construction adhesive to fasten the panels in the door?I, too, now wish for an insulated, hurricane rated garage door. However, I'm not going to replace what I have for now. I used 3M spray adhesive to attach the panels. I had one panel that insisted on coming loose, and I used some construction adhesive on him. Everyone stayed in place this summer.Regards,
Dick
Dick: My garage door faces South and a lot of the heat build-up in Summer comes from there. I'll try your suggestion with 3M spray but definitely feels that's causing a lot of the problem. Ceiling is well insulated already. Thanks.
Bruce
I'd move to Arizona where the humidity is no bad at all!
I LOVE the heat but NOT the Humidity.. I can feel for ya!..
WillGeorge: Thanks. Moved here 7 years ago from NH and still am not used to the Summer heat...but then I think about the long Winters up North...hmm.....maybe FL in the summer ain't bad after all.
Bruce
Bruce,
Where 'bouts from NH? I'm WWWAAAAAAAYYYYYYYYY up north near Canada.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
OK, I guess it all depends on what you are trying to do. Are you trying to insulate the place to save energy or just to stop condensation? If the latter you could try the following.
Take some treated plywood (3/4") rip it into strips about 1 1/2" wide screw these to the wall on 16" centers. Then pick up 3/4" foam, cut to fit between strips (cut them first and put up one strip then use the foam to space the next, repeat until finished) if you use the tap con screws you may be able to screw into the wall with out predrilling, I normally predrill. Use const. adhesive to secure foam. then cover with Gyp bd. If I was in Florida I would spend the extra and get the gyp bd made to resist fungus (I think it does away with the paper, but it may just treat it I am not sure. )Remember to use short screws and const adhesive to secure the gyp to the furring strips.
This should stop any condensation issues. And will not give fungus anyplace to grow. Wont do much for insulation (if you get the good foam it will be I think R5 or R6) but it should help. Big thing to keep the heat out is insulating (and venting) the roof space. Most of your heat gain will be in that area. The insul in the ceiling will keep the heat from coming down into the space, and the venting will stop it from building up TOO much heat.
Doug
Doug,
insul in the ceiling will keep the heat from coming down into the space
Heat rises so I don't think that would be a problem. As cool/cold air drops then this would preclude any coming down from above. I think the insulation in the ceiling will act more as a sound deadener than an insulator in this application.
Just my 2¢.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 10/27/2007 7:16 am ET by KiddervilleAcres
Bob, Trust me on this one, in a building that has limited (to no) insulation between the living spaces and the attic you will get heat transfer down into the living spaces. What happens is that the sun heats the roof, this heats the air in the attic (a LOT) the air tries to go out the vents on the top (if their are any) and pull in more air from the bottom vents (if there are any) but this is not a perfect system. So the air will not change enough to keep the attic cool.
Now we get to the biggest mis understanding. Heat does not travel up, heat travels from the hot item to the cold. (Law of thermal dynamics I think???) Hot air however travels up (being as it is lighter) this is why we (in the north) insulate the ceiling so much so that all of our hot air will stay in the house and not go out the roof. However in the summer up north we have very hot attics and with out the insulation this heat will make the ceiling noticeably hotter then the walls. This heats the air in the room (once again heat wants to average out so it will go from the hot to the cold) and one small thin layer of gyp. will not slow it down much at all. If heat only traveled up we would not put 2 to 4 inches of insulation below our basement floor in the north country. (something I have shown on almost ever plan I have drawn for a house or commercial building for the last 7 or 8 years, and something I did in my own basement)
I have a condo that was rehabbed a few years back, not much insul in the attic. And starting about 3 in the after noon it would start getting hot. (well in the summer it would this is Michigan) To the point that I noticed the difference between sitting and standing in the room. I started to insulate the ceiling, but did not get it all done, yet the half that had the insulation in the ceiling was noticeably cooler, when I got the whole thing done I all but ended the afternoon early evening heat wave.
In effect what was happening was a form of solar flywheel effect that the more solar effective houses use, but this time it was not intended and worked against me. I found that it was hottest in the house about half an hour to an hour after the sun set. As this seamed to give the heat the most time to soak into the living space before it started to cool off in the attic as the air outside (and lack of sun shine on the roof) brought the temp in the attic down.
Doug
Hi Doug,
Heat does not travel up, heat travels from the hot item to the cold. (Law of thermal dynamics I think???) Hot air however travels up
Not trying to argue with you but I'm totally confused by your stetement(s) above; just trying to understand.
Are you saying that if there is a vent on the high side of a hot room that hot air will escape through it as hot air rises? If not vented then heat will transfer to the coldest object in the room, i.e. a heat sink?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Doug said, "Heat does not travel up, heat travels from the hot item to the cold. (Law of thermal dynamics I think???) Hot air however travels up"Doug is splitting hairs a little bit there. Heat itself is a form of energy that is conducted in any medium (metal, concrete, soil, air or whatever) in the direction of a temperature difference; that is, heat flows from higher temp to lower temp. That process is called conduction.Fluids (like water or air) expand when heated, becoming less dense. Since denser fluids are heavier, the cooler air or water sinks and displaces the warmer, less dense fluid which then must rise. That process is called convection. So Doug is saying that, technically, warmer AIR is rising not HEAT. But practically speaking, the effect in our houses is the same since warm air carries heat with it as it rises, making it hotter near the ceiling than near the floor.You asked "Are you saying that if there is a vent on the high side of a hot room that hot air will escape through it as hot air rises? If not vented then heat will transfer to the coldest object in the room, i.e. a heat sink?"Yup. Assuming the house were perfectly insulated and there were no vents for warm air to escape, heat would flow from warm air to everything cooler, gradually equalizing the temperature throughout.BruceT
I was not trying to split hairs (I can but I was not at that point) I was trying to respond to the person that posted that heat in an attic would not work its way down and into the house because it travels up. Heat travels any and all directions, Hot air travels up. But if you have a ceiling between two spaces (attic and living area) then the air will not move (well not much) but the heat will flow from one to the other. So if you have a hot attic and no insulation in the ceiling then you will get the heat flowing down into the living space.
So insulating the ceiling is a good idea in Florida as well as in Michigan. In Michigan we use it both ways (to keep the heat in the attic in the summer and the heat in the house the rest of the year) while in Florida I imagin it mainly keeps the heat up in the attic an not in the living spaces.
Doug
Oops, I should first have looked back on the previous page for your complete post - and then stayed out of it. Sorry.BruceT
Not an issue, just a lot of peaple seam to think that heat only goes up. I think we (house designers/builders/diy'ers) spend so much time talking about insulation in the ceiling that we loose track of the fact that heat goes everywhere it can travel to.
Doug
Doug: Iwas concerned that if I put A/C in the garage that it might cause condensation of the walls but others that have commented say otherwise so I'm going to hold-off insulating walls. I've used tapcons and predrilled to install slot board panels and they worked great. Thanks for the comments/suggestions.
Bruce
Bob: Exeter for 15 years. Previously enjoyed building Shaker-style furniture. Loved it there and was a member of the Guild of NH Woodworkers....a great group of folks and some very serious professionals...David Lamb et al. I wish we had a club in SW Florida...maybe when I retire in a few years I can find others that may have an interest. You're location sounds beautiful. Love the mountains and went to school in N. Vermont (Norwich).
Enjoy your comments and expertise in Knots!
Bruce
Hi, Bruce,
(I live in orlando.) Do you know where your greatest heat load is coming from? Start with that and don't worry about condensation on the block walls just now. I would suspect those garage doors are the main problem, both from a lack of insulation and from poor seals around them. I replaced mine with code-compliant insulated doors in my previous shop and it made a world of difference with no other insulation steps taken. As for the block walls, put your hand against them at various times of the day and see if they are contributing to the heating problem before getting into any insulation fixes. You may not need them. Is your garage a stand-alone structure or connected to the house? Is your house air conditoned? Also, especially since you live close to the water, you might find that humidity is a major part of the discomfort -- not to mention a problem for various woodworking issues -- and this is not solvable with insulation alone. It comes with not having a good seal from the outside air and can only be effetively reduced with A/C. (I don't think a humidifier is a practical solution.) Furthermore, your electric power company will come out for free and evaluate your shop from an energy point of view. Also, there are plenty of woodworkers, professional and otherwise, working in Southwest Florida who have managed to deal with the heat and humidity and you might look around -- but I bet you'll find many of them with open doors and big fans. Let me know if you're coming to Orlando and I'll show you how I've dealt with the problem.
Jimma: I'm sure its a combination of heat and humidity. Garage door is sealed well so I'll start first with insulating it. The A/c (provided I select the right system) should deal with the humidity issue. Garage is connected and the house has central air. Good thought about having the electric company come and do a survey and to check with woodworking company's in the area. There's an architectural woodworking company in Cape Coral so I'll stop by and see what they do. Don't get to Orlando very often. Thanks for the offer though.
Bruce
Good luck, Bruce. If it helps to know, my present shop is below a second story and it has cement blockwalls and large windows plus a two-car garage door. It is served by 1/2 of a split system A/C that suplies the upstairs as well as my shop, but I never turn it on as there is enough blow-by when it runs for the upstairs to cool the shop to around 78 degree most of the year. Works very well and I supplement it occasionally with a small fan. Good enough for me!
My shop is in the Florida Panhandle, a long way from you to still be in the same state but still the same Gulf Coast heat and humidity. There is no such thing as too much insulation. My 16 x 32 shop has 2x6 walls with fiberglass batts, and about 12" of blown in insulation above m 10' ceilings so it is pretty well insulated. Put plenty above you, most of your heat probably radiates through the ceiling, and also foam panels on the door will make a big difference. I don't have a garage door in my shop but when I used the garage I was amazed at how much air blows around the door, get some good weatherstripping for the door.
I used a window unit that I had to cut a whole for in the wall of the garage. Advantage was that it was cheap and lots of models to choose from at every store. Downside was that all window units are noisy, not the best energy efficiency, and lousy filters. Conventional split unit AC's are much quieter and more efficient, but are costly and require professional installation. I split the difference and bought a wall unit made for small condos or hotels. Cost was more than a window unit but much less than a split unit, plus takes up no floor space. It's quiet compared to window units. No matter what kind you get be sure to add axtra filtering and clean it often. Once those coils on any unit get covered with sawdust it's not long until it fails. I have a good duct collection system and air cleaner but I sitll spend a lot of time cleaning the filters and blowing out the coils, which is messy.
Woodwish: Good thought on the alternative to window unit using a motel-type unit. Since I have block construction vs. 2X6 its a bit more challenging. Weather-stripping is critical you're right and the side door and garage have it. Regardless, keeping filters clean will be vital. Thanks for the thoughts and comments.
Bruce
Bruce, I live in north Naples just west of I 75. We moved here about three years ago and have my shop in a three car garage. Only one car ever gets inside. I had the same concerns. I had a Fujitsu, Halcyon, split A/C system installed. The outside unit is located outside near the service door close to the whole house A/C unit, it is just a lot smaller. The inside, air handler is mounted above the service door, near the celing, in the corner of the garage the farthest distance from the dust producing power tools. The inside unit is about 13"H X 50" L X 8" D. I have a small household fan on low speed near it blowing toward the work area. The system cools the area very quickly so I only run it for about 15 minutes ahead of time. It has a remote control like a TV. Both the inside and outside units are variable speed so the operating cost are very low. I only run it when I am out there. The total cost, unit, electrical and installation was about $2,500
Don't worry about the moisture condensation on the block wals. The A/C is a dehumidifyer. You would only have that if the wall are cool and the air inside is moist and warm. Part of the space above the garage is living, air conditioned space, so that is not a problem. The rest of the overhead space is insulated. I didn't yet put foam on the overhead doors, but plan to. I don't consider them to much problem except when the sun is shining directly on them. That is not a lot because of the wide roof overhang. I agree with the need to keep the filters clean.
Go ahead and do it. The problems are small and it works great.
Florida Andy: The unit you installed is exactly what I had in mind. I work in Broward County in Weston at the end of alligator alley and we head West every Friday for the weekend to our home in Cape Coral and plan to retire there. I go past N. Naples every week (Fri.) and head back East on Sunday PM. Who did you get the system from?
Thanks very much for your thoughts.
Bruce
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