garage insulation/ventilation

[Roger P.]

Re: garage insulation/ventilation

Mark:
As Kenny mentioned, every state has different Building codes. However, every garage does need low vents through the exterior wall for carbon monoxide vapors. Of course, these will also provide some ventilation for the room without excessive cold or heat gain. I took for granted that these vents were existing, so yes, you should definitely restore them. With regard to the venting of the water heater, if it is enclosed in its own closet, then you would not be relying on combustion air from the garage. In Florida, the Code requires a high vent near the ceiling and a low vent near the floor that both penetrate an exterior wall - plus the exhaust flue from the water heater which typically exits through the roof. There are "direct-vent" water heaters that only require one double-lined flue (or two separate flues) that bring outside air into the unit while exhaust air is forced out without the need for the high & low vents or a separate closet. However, I assume that you already have a standard gas water heater installed. I would recommend that you contact a local mechanical engineer for a consultation at your home for some guidance so you can achieve the cooling, heating, and ventilation results that you desire for your garage. If you are interested and live in the San Francisco area, I can recommend one of my engineers who moved there last year... just let me know.

Best regards,
Roger (50141)

[Tom L.]

Re: garage insulation/ventilation

OK, this company does offer Inverter technology. IF you have an Inverter unit, oversizing will not be a problem. In this case the unit is smarter than we are.

If not then the input you have gotten about having ventilation (not a bad idea) may offset the load issue because you will be continuously adding warm, humid outside air, an additional load. Good luck!!

[Kenny C.]

Re: garage insulation/ventilation

Mark
Okay lets look at the ventilation issue. The rule around here is that the opening square inches should equal 1/3000 of the total floor square feet. So for your 660 SF garage floor space you should have at least 198 square inches of opening. you have 2 vents 12x7 that's a total of only 168 square inches so you are short on opening. Keep in mind that this requirement is a "Bare Minimum" for a "Storage" garage and that additional opening is better. Also that if that garage was a "Work Shop" the requirement would be much greater and based on actual usage possibly requiring a powered vent system. So my advice would be to add two more of the same sized vents similar to what are presently installed. FYI in my area a typical 3 car garage would typically have 4 base vents installed. This also helps to produce a convection effect and increases the air change to roughly 6 times per hour. Keeps the fumes in the garage to a minimum and smelling better to boot! As for the lost energy efficiency of the HVAC system I cant give you an actual calculation without a real survey but I will tell you that it would be a fairly low amount in terms of dollars and cents. Personally I would be far more concerned about the safety of my home and my family's health than the extra 50 bucks a year to heat and cool my garage.
Best Regards
Kenny

[Mark P.]

Re: garage insulation/ventilation

I now have two 7" X 12" vents and no more wet car issues. A bit more drafty but the garage still stays pretty warm (i.e. if it is 45F outside it is 60F in my garage with no heating turned on).

Thanks for all your help guys.

[William F.]

Re: garage insulation/ventilation

What kind of combo AC/heat units can be safely used in a garage without possibility of igniting gasoline fumes? Any specif requirements?
Thanks,
Bill Ford 50517

[Kenny C.]

Re: garage insulation/ventilation

William
Depending on the size of the garage you can use a through the wall heat pump style a/c or as has been mentioned earlier in this post a "Ductless Mini Split" system which is also a heat pump system. Cost of these systems can be very high however they are very good in terms of efficiency and performance. Wall a/c units can work very well for far less money but have the down side of being much louder. If the garage is very large say in the 1200 square foot range then a conventional system either roof or split type would be better. So there you have it many choices depending on the space, budget and tolerance of sound levels. Basic safety consideration would be no open gas flame appliance should be used in a floor mounted application where combustible fumes are present.
Kenny

[John H.]

Re: garage insulation/ventilation

Bill -

I have a 42,000-BTU Mitsubishi ductless mini-split A/C system in my super-insulated 2600-sq. ft. garage, and it has no problem maintaining 75*F in mid-90's summer weather (and it's scary quiet, both inside and outside). I already had heat, so I didn't need that feature. It's worked flawlessy for five years. Photos in the link:

http://img.villagephotos.com/p/2002-2/13522/1411059

[Steven B.]

Re: garage insulation/ventilation

Bill -

I have a 42,000-BTU Mitsubishi ductless mini-split A/C system in my super-insulated 2600-sq. ft. garage, and it has no problem maintaining 75*F in mid-90's summer weather (and it's scary quiet, both inside and outside). I already had heat, so I didn't need that feature. It's worked flawlessy for five years. Photos in the link:

http://img.villagephotos.com/p/2002-2/13522/1411059

John, what do you have for garage doors? Insulated with what? Metal, wood, FG?

Thanks!

Steve

[Harry H.]

Re: garage insulation/ventilation

Mark, I am in the mold, virus, bacteria business and agree to whoever said not to put the vapor barrier up where you did. You are in for a mold problem first, and this will not do your car any good either. I am in southern CA and if you need any info, PM me and I will give you my website and phone number.

Harry

[Stewart A.]

Re: garage insulation/ventilation

I would of thought a steel garage door would cause a problem as well. In winter they are very cold and can hold moisture. In summer they can be red hot to touch. This is nearly the largest wall in your shed ! If you were worried you should of ran slab heating with water flow or electric. I have this heating in my shed and never have a problem with moisture. If you drive your chrome bumper stuff in the wet you should always dry them with a good quality chamois when putting them in and never put a cover on a wet car. The exposed concrete floor will always keep the cars cold and keep wet for a long time. I have covered mine with a linoleum floor and has changed the temperature feel of the garage straight away without the heating on. You should never leave your concrete floor exposed. Seal it with polyurethane, epoxy or some type of tile that's got warming properties to it. just by doing that you will change the air moisture content in your shed. BILD0767.jpg
Stewy

[Stewart A.]

Re: garage insulation/ventilation

Also what we call wurly birds, those round spinning galvanized domes on top of a roof also help pull heat out of the ceiling area. Not sure if they help moisture but it lets the area breath. Stewy

[John H.]

Re: garage insulation/ventilation

John, what do you have for garage doors? Insulated with what? Metal, wood, FG?

Thanks!

Steve

Steve -

They're custom-made 18' x 8' sectional doors, 1-1/2"-thick steel/foam/steel sandwich, with tubular seals between the sections. Had them made by Taylor Door Co. in West Branch, Michigan, ten years ago when we built the house.