I just looked at a potential job from a previous customer (I sided her detached garage). She lives in the upper level of a 4 plex. The house was built in the 1910s, but the condo conversion was fairly recent. There is a small closet that houses the furnace and water heater for her unit. It is in the peek of the roofline with no vertical walls, attic space really. Problem, it is a hot roof (no ventilation) – just 2×4 rafters stuffed with fiberglass. As you can imagine, the insulation is not enough to prevent ice dams, and the room gets so hot the fire marshal previously made her install a sheet of durock on the rafters over the water heater. The adjacent space is the master bedroom. Why anyone thought a 2×4 hot roof was adequate is beyond me, and then to put a water heater and a furnace in a tiny closet inches from the roofline, who knows.
Anyway, I’m fishing for ideas. Goal is to cool the closet and eliminate the fire and ice dam danger.
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Forgot to mention, this is in St. Paul, Minnesota. Cold winters, hot summers.
Remove and discard fiberglass batts. Install 2x4 interior strapping on 2x4 rafters. Install 5 inches of closed-cell foam. Cover foam with 1/2-inch drywall.
Martin Holladay, senior editor
http://www.greenbuildingadvisor.com
Thanks for the input. I was thinking spray foam would be the answer. Would Icynene be appropriate here? Or is closed cell the only way to go? There's only room to add 1"of material to the bottom of the rafters, including for drywall. Fortunately, the existing rafters are a full 4" deep. So, I could get 4.5" of foam in there.
Foam can also introduce fire safety issues
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurmanhttp://rjw-progressive.blogspot.com/
Closed-cell foam has a higher R-value per inch (6.8 or 7) than Icynene (3.6 or 3.7). Even at R-7 per inch, you'll only get R-31 in 4 1/2 inches -- which I imagine is less than the minimum code requirement in Minnesota. Really, these days, you want your roof to be R-40 to R-60. Let's face it -- furnaces and water heaters don't belong in attics.
I with you. Some of these historic home to condo conversions get pretty ridiculous.
>>Let's face it -- furnaces and water heaters don't belong in attics.I agree....
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurmanhttp://rjw-progressive.blogspot.com/
We just purchased a 104 year old triplex with 2 of the A/C units in the attic. Old 2X6 rafters. One the top of the list (and it is a long list) will be to spray closed cell foam to the underside of the roof. It makes my mind spin that building codes require R-34 above the ceiling and then allow R-7 insulation around the A/C duct work that is above the ceiling insulation.
What's the ventilation/air supply like?
You need 1 sq in unrestricted/free air space for every 1,000 BTU - (plus some additional details) (a 10" x 10" opening with a register cover is NOT 100 sq in free vent space - rule of thumb - 50%....)
Look at the top of the water heater, below the flue draft hood (I'm assuming gas) If you see heat stains (usually brown), there's a big air supply and draft problem.
Look also at the top exterior of the flues - if there are rust stains, there's also likely an air supply / draft problem.
Draft problems are often associated with very high levels of carbon monoxide, so this stuff can be serious.
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
http://rjw-progressive.blogspot.com/
This is in Minnesota. I've attached a photo of the closet taken from the door and a photo of the heat detector that the homeowner unplugged because it is always going off. The fire marshall had her install a sheet of cement board and a piece of sheet metal on the rafters over the water heater. Apparently, he's satisfied with the situation as is. Oh, he came because the neighbors mechanical closet (same deal) started on fire several years ago.
>>Apparently, he's satisfied with the situation as is. Unfortunately, some FMs aren't as aware of combustion air requirements as they might be.And, human nature bing what it is, sometimes folks focused on one issue don't even think about others.
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurmanhttp://rjw-progressive.blogspot.com/
Also, if they are gas and off te master bedroom, there are fire safety issues for the access panel/door.
Where are you located?
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
http://rjw-progressive.blogspot.com/