How do I systematically trouble-shoot water in the exterior wall? It has appeared where one external wall meets another.
Water penetration issues can be very tricky things to pin down. For example, in some cases water can enter from more than one point or may leak only when the rain is wind driven and from a specific direction.
To be as accurate as possible in pin pointing the leak, it is often necessary to open the wall or ceiling where the damage is greatest, cut carefully through the vapour barrier (it must be repaired and made air-tight) remove insulation and perform a water test with the goal of recreating the leak. Have someone inside watching the area while another runs water from a hose. The one on the hose must run the water from the lowest point possible at the leak area and work slowly up the wall concentrating on each area for at least a minute. If it hasn't leaked for some time, it can take the water a while to track its way through the wall. So, one must be aware of the possibility of residual water.
Once the leak has been pinpointed, make sure that the correct caulking product is used. Remember for example,that most silicone formulas are un-paintable if this is a visible area. I tend to favour acrylic latex or elastomeric formulas for wood/siding issues and urethane products for concrete.
If there is no obvious entry point (such as a rotten wood frame window for example (replacement is then likely)) it is possible that the building paper and or flashing have been incorrectly applied. It would be best to call in a professional under these circumstances. Once you are confident you have found the leak,(never be TOO confident!) it is generally best to wait out the weather until similar conditions occur before you finally make the internal repairs.
There's my two bits.
Keith Benross Home Services Ltd.
Hi JM, Keith is right about tracking down the leak from the inside. If the water is appearing in a basement, you should also check the grading and ensure it is sloped away from the house. Check and clean your eves troughs and put in downspout extensions to ensure the water is not going down against the wall or the foundations. I have experienced a full eves trough overflowing over the house side and into the soffit. A good, detailed, close up inspection of the exterior walls may actually pinpoint the problem(s) without tearing anything down inside. All of the caulkings that Keith mentioned are excellent choices and will do the job.
This leak sounds fairly recent so you should also look at any changes you have made to the exterior that may be causing it.
The project manager at the last Habitat for Humanity build that I worked on kept saying "THINK LIKE WATER!!" while the volunteers were installing windows and doors. It all made sense when he explained the details of the membranes, house wrap, and flashing.
That's what you have to do if you want to figure it out yourself!
If you need help, post your project requirements on the site so contractors can get in touch with you.
Kettleby Handyman Services
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