I have a customer that we dense packed the attic floor of their house and airsealed around the masonry chimney.  The problem is the red brick chimney condenses in the attic. This has caused the floor around the chimney to heave and the ceiling below to stain.  The attic is 1260 square feet and is pretty leaky to the outside.  The customer states the problem has only occurred since we did the work.  Can any one give me some ideas what would cause this issue?

Views: 3148

Attachments:

Reply to This

Replies to This Discussion

It seems to me the chimney is probably cold, being connected to the outdoors.  So the moisture is coming from the surrounding air.  If keeping moisture out of the surrounding air is not practical, I'd suggest insulating the chimney with fiberglass batts with a vapor barrier on the outside.  Does that sound reasonable?
Is the chimney lined? It could be from flue gases from an unlined chimney. Any problem with condensation on the roof sheathing?

The condensation is from the flue gasses condensing inside the chimney.  This will be increase  as the attic temp drops. ths cools down the brick which allows the flue gasses to condense out at a greater rate.  If there is no clay liner or a flexible chimney liner in the chinmey one will neeed to be installed.  

This has been happeneing before but because the attic was kept warmer do to the heat loss through the ceiling it would only have shown up when it got colder outside.  Now that the attis is seperated from the house there is not enought heat to keep the bricks warm so more condensate from flue gasses is present.  

The condensate is mildly accitic (like lemon juice)  It will turn any paper products a dark chocloate brown after a while.  This is one way to tell the difference between a roof leak and condensate.     

 

All gas furnaces produce water vapor as a by product of combustion adn need to be addressed when furnace, water heaters and such are changed out-   You will need to recommend a chimney liner.

http://oee.nrcan.gc.ca/residential/personal/chimneys.cfm?attr=4  the link will give you a explanation, even though it is canadian, they expriance the problems much more than warmer climates

RSS

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

Crosbey Archery liked Don Hynek's discussion Testing "Magic Pak" units??
9 minutes ago
Crosbey Archery joined Norm Bourassa's group
Thumbnail

Multifamily Buildings

For too long there has been relatively little EE focus on multifamily, but some new programs have…See More
22 minutes ago
Crosbey Archery liked Crosbey Archery's blog post Energy Tips - Fresh Look at Heating and Cooling the Home
27 minutes ago
tedkidd liked Luis Hernandez's discussion Airsealing an old basement ceiling
7 hours ago
Ryan T De La Rosa posted a blog post

The Clean Power Plan and What You Can Do

Last month, Jessica Hardcastle at Environment Leader described an especially non-polarizing…See More
8 hours ago
Ed Minch replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"Luis Think of it as a part of the house that is not being used, but part of the house none the…"
12 hours ago
Luis Hernandez replied to Luis Hernandez's discussion Searching for a multifamily study book in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Hey Craig!  Well, let's get serious and keep asking all our friends in the Home…"
14 hours ago
Luis Hernandez replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"Hey there Ed,      I appreciate you comments... this is an interesting case because…"
14 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service