I am a long time reader of FHB, and the owner of a 1932 bungalow. I have run ito a little probelm with our home that I may have created in an effort to make it more energy efficient. I recently got started on a project replacing a section of mudsill and rim joist from improperly installed steps that where placed against the house with no flashing. This project is well underway and tomorrow I will be able to start replcaing the cedar shakes. What I have found though is that the mudsill on our home is rotting out over the entire length of the house on the south side. Our fondation wall is block and it is not capped. I am wondering if moisture is coming up the wall and rotting the underside of the mudsill? I may have exaserbated th problem in 2006 I installed a radaint heating system. In the process I foam filled the rim joist cavities the thicness of the foundation. I am also wondering if I have exxcelerated the rot process by not allowing the mudsill to breath. I am not sure how I shoud address the issue of the uncapped wall. On the 16 foot section that I have reapired I have replaced the mudsill with treated lumber and palced aluminum flashing between the block and the mdsill. Now that have found more rot I am wondering if I should have the foundation filled, or if the flashing will suffice. We do live in a wet area, I have mitigated the water that used to com into the basement every spring. And even thoug the sump pump runs we have not had water in the basement in several years.
I appreciate any feedback!
Chris
Replies
On a house of that vintage and construction it's normal for the mud sill to be rotted out. I doubt that anything you did contributed to the problem to a significant degree.
Wood (even treated) in contact with a masonry foundation for that long will rot. Using some sort of moisture break (metal or rubber) under the sill is the basic solution.
Sill Rot
Chris,
There are many conditions that can affect the moisture content in our homes as well as their many components. Some of those conditions can be environmental or inherent in (deficient) building construction and some we can cause ourselves with the various renovation and maintenance projects we decide to tackle. Installing closed cell insulation in between joists can affect air and moisture flow through a structure - definitely. However, it seems unlikely in my opinion that this (or any of the other work you mentioned) is the cause of the rotting sill. The work you did may affect moisture through floor and wall cavities in a way that the basement (?) or habitiable areas are affected.
More than likely though the rot was caused, as you indicated, by a lack of flashing on the steps for the past 80+ years. Other questions: Were these the original steps? Were they ever repaired - backpitched, cracked etc.? This damage could have occurred 30, 50 years or more form a catastrohic weather occurrence or renovation etc. Or over the coure of many years sue to a condition that is not evident any longer.
Aluminum flashing is great for protection against termites - it should extend wider than the foundation, but as far as moisture I have not seen the type of moisture that would rot a localized area of a sill emanate up through block.
Good Luck and Keep Up the Good Work
Chris M