Saturday 2 July 2011

So what is causing the leak?

With evidence of mould on the drywall under the baseboard in the family room, we called around to try to find someone to fix the problem.  We finally found a contractor who specializes in leak issues, but he had other clients before us, so we had to wait almost 3 weeks before he could get started on our house.

First, he removed the mouldy drywall inside.  There was evidence of water damage inside the wall.

Mould on the back side of the drywall.

Then he did some water testing with a hose from outside.  Sure enough, water leaked in very quickly when he put a hose on the stucco just below the window.  He said that the only way to know what was really going on was to remove some stucco.  As soon as he took the stucco off, he immediately was able to tell us that the builder had done the building envelope incorrectly. 

Here are the things he found wrong:
  1. The white Tyvek paper that was supposed to come from the bottom of the window and lap OVER TOP of the black tar paper was actually BELOW.  Since stucco is permeable and some water will get through, the Tyvek and tar paper needs to be lapped correctly - kind of like shingles on a roof.  If it is backwards, it can act almost like a funnel, allowing water into your house.
  2. The tar paper looked to be very worn, and the contractor suggested that perhaps the house had sat a long time before the stucco was put on - a fact our neighbour later confirmed.
  3. The tar paper should overlap by ~4" where different pieces of it meet.  In one place it was only overlapped by 1" and in another place there was actually a gap that they covered with red Tuck Tape.
  4. The stucco was (at least over some of the house) not thick enough to meet the minimum 19mm thickness required by the 1997 Alberta Building code.
The brown tar paper is over top of the white Tyvek (outside, below the family room window).
The tar paper should be a darker colour - it is very weathered and deteriorated.

Tar paper only overlapped about 1"

The stucco should be 19mm thick but is more like 12-13mm.



The plywood of the wall under the window was so rotten that the contractor was able to just put his hand through it!  It had clearly been leaking for a long time.

The contractor took off the stucco below another window - where we did not have any apparent leaks - and the building envelope was done incorrectly there as well.

We took off the drywall inside in two other locations - below a window in the breakfast nook and the window in the living room - and found water damage and mould in both locations.

Mould in the wall under the breakfast nook window.


Mould and water damage in the wall under the living room window.

It is becoming apparent that we have a bigger issue than a leak under one window.  It looks like the whole house was papered wrong, which obviously is an error that the builder made when they built the house.  We now don't think that anyone was right when they said the windows were leaking, we think it was the building envelope all along.  Most of the time, with the amount of rainfall that we get in Calgary, the moisture was staying in the walls, so that we had no idea the problem was there.  Also, until you actually rip off the stucco, it is pretty hard to tell how thick it is, and that it didn't meet the building code.

2 comments:

  1. I’m glad you sought the help of a contractor who specializes on leaks. He was able to found out the reason behind your wall leaks. The construction of a house is very crucial. The parts that weren’t properly installed will become a problem in the long run. So, the over-all installation of roof, gutters, windows and other important structure of the house must be observed to avoid such inconvenience.

    ~Lilia Marchi

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  2. Hey, there! Too bad the mold fed on woods, especially the wet ones. I suggest that you work out on reducing the humidity as cool places are attractive for mold. You could also allow air passages to increase ventilation or air movement by opening doors and/or windows. One way to do this is to make use of fans. Allen Hoffman

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