Replies

1. 
   Robert Riversong | Nov 25, 2009 05:28pm | #1

   What kind of foundation do you have? Is it waterproofed - is it damp?

   Vinyl siding is very open to moisture unless foam insulation is installed behind it. Describe the "bead-board panels" more thoroughly. What is it made of - is it wood boards or manufactured panels?

   What do you mean by "Insulation is believed to be sandwich along the woods studs"? Are the walls insulated between the studs? Was insulation changed or added during renovation, and what kind of insulation material?

   It seems you might have "rising damp" from the foundation that was showing up in the lower walls, and then rising to the second storey walls after the thermal envelope was made more vapor tight and less breatheable. But I need more information to make an educated guess.

2. GBA Editor
   Martin Holladay | Nov 26, 2009 04:24am | #2

   Mike,
   You need to determine the source of the moisture and the condensing surface.
   Robert has hypothesized that the source of the moisture is the foundation. Considering your climate, it is also possible -- perhaps probable -- that the source of your moisture is warm humid exterior air.
   We need to know:
   1. Is the building air conditioned?
   2. During what season does the condensation occur -- summer or winter?
   3. Are the walls fairly airtight? Has the building ever had a blower door test or any work to reduce air leakage?
   4. Does the HVAC system put the building at a positive pressure or a negative pressure with respect to the outdoors?

3. 
   Mike Silvestre | Nov 30, 2009 09:55am | #3

   I really appreciate your comments.
   We are not sure if the walls were properly insulated, we assume ther is batt insulation. We had made attempts to seal the wall system as tight as possible, but once this is done, moisture started affecting the areas that did not seem affected from before.

   The building is air-conditioned and after the problem was recognized, a dehumidifier was installed and run 24/7. The condensation is predominantly visible during the warmer seasons. The walls are fairly airtight and we have not done a blower door test. It appears the AC system puts the buikding at a positive pressure. There is a bathroom inside the exterior wall and it's exhaust fan is ducted to discharge on this wall facing the south. We also observed the vent to be reactive to both negative and positive pressure, in other words, exhaust from the bathroom opens it as well as wind blowing from the seaside.
   Thanks again, I appreciate your help.

4. 
   Mike Silvestre | Nov 30, 2009 10:09am | #4

   I also failed to mention, the bead board panels are pre-manufactured plywood panels made to look like bead board. These were painted during the renovation but are now peeling-off. In some parts, the paint separates from the wood in in wosrt cases, you can see the wood components peeling in layers.

5. GBA Editor
   Martin Holladay | Nov 30, 2009 11:05am | #5

   Mike,
   If the condensation happens during the summer, then it's pretty clear that warm, humid exterior air is somehow contacting your cold interior wall panels. Running a dehumidifier indoors will never solve this problem.

   The first step is to install an effective air barrier to separate the exterior air from your interior wall panels. This can be done from the interior (for example, by stripping all of your interior wall panels and spraying your stud cavities with spray polyurethane foam) or from the exterior (for example, by stripping your siding and installing carefully taped rigid foam on the exterior of the building before reinstalling the siding).

   This work should only be performed by a contractor familiar with air leakage problems and air sealing. I would strongly advise hiring a home performance contractor to conduct a blower-door test before proceeding.

6. 
   Mike Silvestre | Nov 30, 2009 02:13pm | #6

   Thanks Martin for your suggestions.
   We instructed the contractor to install a vapor barrier on the studs facing the exterior side. We also had instructions to fasten nailer strips in regular increments on which to fasten the vinyl siding. We wanted to create a breathing air space between the vapor barrier and the siding. We will do the blower door test to attain mor info and hopefully be able to solve the problem. Thanks again.
   Mike Silvestre

7. GBA Editor
   Martin Holladay | Nov 30, 2009 02:25pm | #7

   Mike,
   Some vapor barriers are air barriers, but many are not. What product did you use?
   As you may know, exterior vapor barriers may lead to wall rot during the winter.
   In a mixed heating and cooling climate, the wall assembly details must be carefully considered.
   You really need an air barrier -- not a vapor barrier.

8. 
   Mike Silvestre | Nov 30, 2009 04:15pm | #8

   Since we were not initially the architects for the renovation, we will suggest and request permission form the owner to open up the wall and investigate. We will carefully assess and incorpoarte the above suggestions based on how it is applicable. Thanks