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I have a older home with a second story addition in the Chicago area. I
have lived there for two years and have had difficulty with ice dams last winter and again this winter. During the summer months I added an excessive number of eave vents. ( 2 story house with 4 roof vents – 1000 sq ft/floor). While this has helped the situation, it has not solved the problem.
The challenge is in the leaking ductwork in the attic. The heat is routed through the attic because the second floor is an addition. Is there a special ductwork system designed for absolutely no leaks? Are there any local installers in the Chicago area?
I believe the primary leak is where the furnace discharge enters the main
trunk. I can feel air leaking, but am unable to access this joint because
it is underneath the main trunk and very close to the return duct. Attempts to seal off a small area far from the leak itself result in only moving the leak farther downstream of its original source. Of course, every connection to the main trunk leaks a little as well. Any ideas would be appreciated.
Replies
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Tough installs are tough for anyone....The comprimised space sounds like the real problem. Solve the space issue....Go to hydronic....or take space from rooms....etc....
tightly squeezed near your air stream,
aj
*Franklin. You say, "While this has helped[add[ing]an excessive number of eave vents] the situation, it has not solved the problem." Please explain. If you cannot seal the leaking ducts why not then insulate between the roof rafters.Next add 1-inch thick rigid foam board insulation (RFBI)to the bottom of the rafters, then cover the RFBI with sheetrock. Thisnow makes the attic space part of the thermal envelope. Now the ductwork will leak to the interior rather than to the exterior. TThere is leakage you can seal. Go into the basement and seal all the openings in the basement ceiling. Ideally, it is best to also seal all the openings in the attic floor. Do you have a ceiling mounted bathroom ezxhaust fan Is it exhausting to the atic? GeneL.
*Genes got some good ideas....the only other alternative is to fly Fred L out to work his magic.near the stream,aj
*Gene - I still form icicles on the edge of the eave when snow sits on the roof. However, the extent ( number and size ) of icicles is greatly reduced. Currently - only icicles are forming on the south side of the house and greatly reduced compared to last year and my neighbors. Last year - my house was the worst in the neighborhood by far.Your suggestion to insulate in between the roof rafters is an interesting one. Last winter I implemented this technique and a roofing contractor told me in the spring that this will block airflow around the roof decking and eventually cause mildew and rotten roof decking. Therefore, I tore the insulation down per his recommendation (pain in the but to install and remove) - stripped the kraft backing to prevent trapping moisture and laid it on the attic floor. Only way to work around this would be to use a styrofoam or plastic "chute" between the insulation and the roof rafters. This is difficult - as the original roofer used nails that are too long and stick through the decking - but definitely do-able. I hate the thought of having to do this again, but maybe that is what it will take.As for the bathroom fan - I do have one that vents into the attic, but we do not use it when there is snow on the roof. Again this is inconvenient, but I have not gotten around to finding an alternate solution. How do you feel about using a "dryer" vent and routing the fan exhaust outside the house that way?Franklin
*As discussed elsewhere, and in most books--Vent fans should NEVER be vented into an attic. Period. End of statement.Even Homer's palace sells both roof vents and wall vents for exhaust fans. And, yes, a dryer vent will work, but sometimes it doesn't match the piping from the exhaust fan.Also consider this: Even if you are not running the fan, air is escaping into your attic via the fan ducts. Perhaps THIS is your leaking ductwork.(I live in the Chicago area too. Fun driving to work this morning with the frost collecting on bridge overpasses, and creating black ice conditions for the motorists.)
*Who is Fred L. and how do I contact him? I just may be interested in a little magic.
*JohnD - thanks for the tip. I will go into the attic an shove some towels into the exhaust outlets. This should help - but I have been able to stop icicle formation by only sporadically running the upstairs furnace (one which routes the heat through the attic) and using the basement furnace more often. Based on this, I think it is safe to conclude that the ductwork is the heat source in the attic. Yes - is does seem like quite a bit of snow for Chicago this early in the winter.Franklin
*Franklin. The roof sheathing is the coldest part of the roof and is called the 1st condensing surface. It is the first place moisture will condense on. However, when you install continuous(from soffit to ridge) expanded polystyrene (EPS) air chutes between the roof sheathing and the insulation, the air chutes now become the first condensing surface. And unless you have pretty much stopped the warm moist air leakage into the attic (you can't completely stop it), the mosi air will condense on the underside of the plastic propervents.You say, " a roofing contractor told me in the spring that this will block airflow around the roof decking and eventually cause mildew and rotten roof decking." The purpose of the ventilation is to remove leaking moisature and heat. If there is little or no warm moist air leaking into the attic there is little or no need for attic ventilation. The first line of defense against ice dams begins in the basement with the sealing of all openings in the basement ceiling. Now seal all openings in the attic floor. What you can't get at in the attic floor will be sealed in the basement ceiling. Good liuck and happy holidays. GeneL.
*b WBA At Your Service Franklin, as far as Fred L. is concerned, check FHB #130, May 2000. He may visit here, but he doesn't post.
*Franklin, If I read your post correctly, the first joint from the furnace to the ducting system is leaking and cannot be corrected due to restricted access. Down between rafters, buried & can't get there from here. I wonder if a spray foam product (of this type) http://www.fomo.com/4comp.html could be used to fill the area around the joint to the point of eliminating the leak? Just a thought,but with a long enough tube maybe you could slowly build it up. I don't know what temp this particular foam will withstand, but maybe you could find something suitable. I believe Fred L can be reached here http://www.weatherization.com/ Joe H
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I have a older home with a second story addition in the Chicago area. I
have lived there for two years and have had difficulty with ice dams last winter and again this winter. During the summer months I added an excessive number of eave vents. ( 2 story house with 4 roof vents - 1000 sq ft/floor). While this has helped the situation, it has not solved the problem.
The challenge is in the leaking ductwork in the attic. The heat is routed through the attic because the second floor is an addition. Is there a special ductwork system designed for absolutely no leaks? Are there any local installers in the Chicago area?
I believe the primary leak is where the furnace discharge enters the main
trunk. I can feel air leaking, but am unable to access this joint because
it is underneath the main trunk and very close to the return duct. Attempts to seal off a small area far from the leak itself result in only moving the leak farther downstream of its original source. Of course, every connection to the main trunk leaks a little as well. Any ideas would be appreciated.