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: 1558

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

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Jim Gunshinan commented on Jim Gunshinan's blog post Energy Upgrade California—Up Close and Personal
"I had a revelation while attending Bruce Manclark's session of duct leak testing at the Energy…"
12 hours ago
George J. Nesbitt commented on Jim Gunshinan's blog post Energy Upgrade California—Up Close and Personal
"Blower Door; the 2007 test was a depressurization test, and the 2014 a pressurization test, which…"
12 hours ago
George J. Nesbitt replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"Plan, plan, plan, plan. The 1st step to is to understand the house, how it's built, the…"
12 hours ago
George J. Nesbitt posted an event

High Performance Windows - A Panel of Experts at Pyramid Alehouse`

April 26, 2014 from 3pm to 5pm
Join a lively panel discussion on high performance windows. We'll cover some basics, as well as…See More
13 hours ago
Kaushal Bharath Raju replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"Hi David, Thanks for pointing out Martin Holiday's article. I do not wish to engage in the…"
13 hours ago
Profile IconAdam Penberthy, Scot Davidson and j jarvella joined Home Energy Pros
14 hours ago
David Eakin replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"More food for thought on this subject - read this (fairly) recent blog by one of the most respected…"
19 hours ago
Curt Kinder commented on Christopher Morin's blog post 5 Things New Energy Efficiency HVAC Contractors Need to Know
"You left out air distribution...Without at least a passing glance at how much air moves through the…"
yesterday
David Eakin replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"I mis-spoke - I was referring to the Midori House in Santa Cruz. Have an in-depth discussion with…"
yesterday
Kaushal Bharath Raju replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"Hi David & Bud, $400/sqf > $300 sqf. The latter is the minimum cost of new construction in…"
yesterday
David Eakin replied to Kaushal Bharath Raju's discussion Affordability & Deep Energy Upgrade/Passive House Retrofit in Berkeley, California.
"Kaushal, There was a deep energy retrofit upgrade project (to Passive House standards) in San Jose…"
yesterday
Kim Tanner updated an event

Beyond Residential Testing at The Energy Conservatory

May 14, 2014 to May 16, 2014
The Energy Conservatory (TEC) is hosting a Beyond Residential Testing event. In addition we are…See More
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service