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GARAGE APARTMENT – I plan to build a freestanding 24’x24′ two car garage on slab with guest apartment overhead in a cold climate and would like some advice. Do I need to put in a frost barrier for the slab? Since the apartment will only be used occasionally I do not want to heat it at all times. The garage is located 50′ from the well and 25′ from the house. Should I run the water off the house’s pressure tank? Is there a simple way to set up a way to drain the pipes when not in use? The main house has a propane Aquastar instant hot water heater (which is GREAT by the way), but I am considering the installation of an instant electric one for the garage apartment because it does not have a coil and could be kept in an unheated space. The only concern I have is that the electric one draws 80 amps when in use and the house only has 150 amp service. The house has a very low electrical draw as most appliances are propane, but I was wondering if anyone has experience with the electric instant unit (I think its called powerstar?, but it’s not related to aquastar and is built in the U.S. not France)? The apartment space will be used occasionally in the winter so I was hoping to devise a simple way to protect the pipes that come up through the slab. Any advice will be appreciated.
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If you are going to heat hte garage, I'd put some foam under the slab. If you are only going to heat the upstairs, then don't use foam.
Note that there are code requirements about the wall between garages and living spaces such as double 5/8's sheetrock and fire-rated self-closing doors.
It's going to be cheaper to run a water line 25' from the house than to create a new system in the garage.
No, there is not a simple way to drain pipes. You can blow them with compressed air to get most, but all the water out. You can slope lines to a drain valve in a vault, but unless the vault is sealed and insulated, you'll create a cold air trap and more potential problems. Or go deep (my water line is at 11', and 13' feet under the plowed driveway) and/or lay insulation over the pipe run. Or run heat trace. I'd place a remote temperature sensor at the highest, most plowed portion of the pipe run to be able to track the worst case temperature. But then I'm somewhat of a process-control geek.
If the instant electric pulls 80 amps of 240 volts, it will allow 1.8 gpm with a 70F tmeperature rise. That's a pretty weany shower. I'd put in a 50-gallon electric tank and, if concerned about the electrical draw, put smaller elements in it. Set it to "vacation" when not in use. -David
*Thanks for your thoughtful response, David. From the shores of Mt. Desert Island on the coast of Maine.
*Pat: to be more complete, if you are subject to building codes, you'll need double sheetrock (or single sheetrock plus a thicker plywood subfloor above) on the ceiling/floor between the garage and apartment. Talk to your inspector now about lighting fixture boxes and any other pentrations. My inspector was fine with regular plastic electrical boxes, but a friend got hung up on a plastic drain pipe which penetrated his garage/kitchen wall.For occasional use, I like the electrical tanked water heater. I'm usually opposed to them if there is any way to burn fuel, but without any flue, it will have much less heat loss in vacation mode than a propane water heater. Since electrics have lousy recovery anyway, if you're up against some amperage limits, you can use 1500 watt elements (<15 amps of 110 volts). by evening the tank will be hot again.A caution on heat trace: It would be worth the peace of mind to spend some time draining down the pipes (maybe not the water heater) rather than use heat trace. Heat trace can start fires when the wires overlap, get worn, or malfunction. Use with great discretion.Sounds a lot like our garage with apartment, except we heat ours (a -25F car is a terrible thing to wake up to). So ours is radiant-floor heated. (With cheap natural gas). -David
*I'd also encourage you to think about the movement of carbon monoxide in the structure; I've come to think of bedrooms above garages as a fairly stupid idea.Everyone knows high CO can kill, but chronic exposure to lower doses can cause disabling health problems, as well. Cars produce huge amounts of CO when they're first started, and even if the car is immediately pulled out of the garage, significant amounts of CO can stay in the structure and linger for hours.I would expect a heated area above a garage to be a great vacuum because of the stack affect.
*Thanks again, David. The Powerstar electric hotwater heater is actually an instantaneous one, so no water remains in the unit. They cost more than a standard tank (about $425), but you have unlimited hotwater and they are great space savers. Our rural town has no real building codes except that you can't build over 40' because that's as high as the volunteer fire departments ladder will go!
*hmmmm...thanks for the note of caution, Bob. Maybe I'll push the car out before starting it!
*Pat: I'm familiar with instant hot water heater, both gas and electric, and like them for many reasons. But my point (not clearly stated) was that Americans are often more attached to unlimited FLOW of hot water than they are to unlimited TIME of low flow hot water. If you can accept the style of euro-showers, then it does sound like a good way to go. For just a bit more $, you could get an instant propane-fired unit, allow a higher flow rate and have lower energy costs than electric. If someone wants a long shower, just send them out the garage. (P.S. I really like cold AND HOT hose spigots outside. Lets you deice the car or wash the dog in warm water.)I agree with Bob that CO is a concern. I'n not sure that an apartment over a garage is inherently more hazardous than a garage attached to a house as so many are. You want a good vapor barrier (whether polyethylene sheeting or good drywalling taping and painting and tightly sealing lighting fixtures) and great door seals. And to mantain lower pressure on the garage side. In a top/bottom situation, that means keeping the garage colder than the apartment and/or exhausting from the garage. In a typical attached garage, why doesn't anyone exhaust from the garage or at least check the pressure differential? When you run the range hood, you'll be sucking in garage air.I wouldn't bother with the $39 P.O.S. Carbon Monoxide detectors without digital readout at Home Depot. Slightly better is the Kiddie Nighthawk with readout ($50), better yet is the AIM Safe-Air Products Model 935 Low-Level CO Monitor ($75) which avoids the damnable UL requirement that CO detectors not tell you about low levels of CO. (Fire Departments were getting too many calls back when units were more sensitive). I'd like to know if any detectable CO is there and see the concentration; that is very helpful in tracking down the source and route of CO. The first time I had a CO detector go off, I felt that it had been money very well spent.Here's a link with a lot of info on CO detectors:http://www.avweb.com/articles/codetect/ It has an aviation prespective - pilots are very concerned about CO, because they can't just step outside when the alarm goes off. -David
*David,I 'd like to second your discussion of CO alarms: the AIM 935 is the way to go.I don't know if an apartment over a garage is more dangerous than an attached garage, but suspect that it could be.I wonder if heating the air in the second story will create a stack effect, potentially depresurizing the second story relative to the first. Also, CO is lighter than air, (actually, one of the lighter components of air) and the testing experts (esp, Jim Davis) stauchly maintain that it will congregate/collect at ceiling level. I've wondered about that, since it's not that much lighter, but it's hard to argue with the guy with the experience. (I don't often run into homes with significant CO, the few times I have I've had mixed results testing high v. low.)Assuming it does collect high, any air leaks between the garage and apt could lead to leaks into the apartment. Very hard to quantify, though.FWIW, there was a pretty bad CO poisoning case in the Cleveland area a few month's ago of an older man above a commercial garage.
*Bob: I wonder about the stack effect as well. I am tempted to put a Magnehelic differential pressure gauge across the floor/ceiling between the garage/apartment after we finish separating the two spaces. And then play with maintaining different temperatures upstairs and downstairs and exhausting the downstairs to assess whether the chimney effect can be controlled. Seems if the building is fairly tight and the two spaces heated seperately, you could have cooler air stay low (downstairs in the garage) and warmer air stay high (upstairs)As we discussed previously in http://webx.taunton.com/WebX?128@@.eeb15fd , I've got a good theory based on my caving experiences and from having studied diffusion and separation as a Chem Eng (air temp predominates and density differences are too small to overcome mixing by air movement) for why CO is found high as do you (lighter air components such as CO go up and heavier ones like CO2 go down) for which there is certainly a driving force and that your CO guru supports. And I think we both acknowledge that we, personally, haven't done enough testing and measurement to nail it down for sure.In addition to having the highest per capita number of airplanes, cell phones, drowning deaths, and plane crashes, Alaska has a tremendous number of CO deaths. People living on the edge, heating little cabins with unvented heaters. Don't. Get a CO a detector. A good one. Vent appliances properly. Get periodic inspections. Rules to live by. -David
*CO can be a problem. I would suggest that there be no access to the apartment from inside the garage. Use an outside stair and seal the floor very well.
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GARAGE APARTMENT - I plan to build a freestanding 24'x24' two car garage on slab with guest apartment overhead in a cold climate and would like some advice. Do I need to put in a frost barrier for the slab? Since the apartment will only be used occasionally I do not want to heat it at all times. The garage is located 50' from the well and 25' from the house. Should I run the water off the house's pressure tank? Is there a simple way to set up a way to drain the pipes when not in use? The main house has a propane Aquastar instant hot water heater (which is GREAT by the way), but I am considering the installation of an instant electric one for the garage apartment because it does not have a coil and could be kept in an unheated space. The only concern I have is that the electric one draws 80 amps when in use and the house only has 150 amp service. The house has a very low electrical draw as most appliances are propane, but I was wondering if anyone has experience with the electric instant unit (I think its called powerstar?, but it's not related to aquastar and is built in the U.S. not France)? The apartment space will be used occasionally in the winter so I was hoping to devise a simple way to protect the pipes that come up through the slab. Any advice will be appreciated.