Window Leaks are Too Common

As an Arizona Home Inspector living in the valley of the sun one would think that window leaks are not a very common occurrence. unfortunately the opposite is true.

I see more and more homes with leaks around the windows all the time.

There are several different types of windows but since I live in the desert south west and aluminum framed windows are the norm, that is what I am focusing on in this blog.

There are several reasons for it. Poor drainage, blocked weep holes and flashing issues top the list, I will cover each of these items in a little more detail.

Most windows have weep holes. these are small openings at the bottom of the exterior side of the window that allows any moisture that makes it into the window track to drain back out. Sometimes when performing home inspections I notice these weep holes are blocked by dirt, debris (dead insects) or covered by shade screens. Sometimes they have been sealed by the home owner to prevent dust from coming in the hole. NEWS FLASH That dust will not cause damage to the home, failure to allow the moisture out will cause damage, you can damage the drywall, framing, baseboards, flooring, help create a mold issue and more simply because you didn’t want to clean a little dust.

I tell my home inspection clients to use the attachments on their vacuum cleaner to literally suck the dirt and debris out of the window track. (it works well on the air return grill also)

Another reason is Arizona desert doesn’t get much rain so many contractors either didn’t install window flashing or they didn’t install them properly. The flashing is what keeps the water out if it makes its way through the stucco or exterior cladding or maybe it simply enters between the window and the siding.

The flashing should be installed so it directs water back out of the wall. So if the flashing is above the window the building wrap (Tyvek or building paper) should be on the outside of the flashing however if the flashing us under the window, the wrap should be behind the flashing so the flashing direct water from the window back outside of the flashing. This picture shows flashing under a window that is installed backwards.

When I perform expert witness work we cut into the wall to investigate the damage and the leaks. I will mark the areas that are stained with chalk then spray test the exterior of the window and see if there are leaks and if the leaks are in the same areas as the stains. This picture is of a window that was being spray tested for about eight minutes before I took the photo. You can see the chalk and even see the drip splash as it hits the bottom of the wall. This home is about 5 years old.

If you want to know if you may have window leaks in your home there are some things you can do:

  • Clean the windows and tracks, make sure the weep holes are not blocked.
  • Look for stains around the sides and bottom of the windows and at the baseboard and carpet tack strip as well.
  • Hire someone with a thermal imaging camera to inspect the home right after a rain or spray test the windows and have either thermal imaging or destructive testing performed by competent qualified contractors.

Thermal imaging is a great tool if used correctly but the operator needs to have proper training and a firm knowledge of building science before they perform the testing. If the wall is dry the camera will not show leaks, if the water is not in contact with the inside of the sheet rock the camera will not show it either. I have spray tested windows and waited over an hour before the moisture made it through the exterior cladding, insulation and came in contact with the interior surface, therefore the only way to know absolutely is to open the wall.

I understand that scares some people but some are even more shocked when I open a wall and show them what is inside.


Mold and rot in wall from window leak

Rotted wood removed by hand

If you have questions or comments about how to find window leaks, how to find a competent inspector or what to do when you have window issues please feel free to contact me through our Arizona Home Inspection Website

Be Sociable, Share!


  1. This is interesting, something I have seen over and over again too. I have even seen windows installed upside down with the weep holes at the top. I live in Oregon and people think mold and moisture is just part of living in a wet climate. I tell them that states like Texas and Arizona have huge mold problems too and they are shocked. It’s not a climate issue; it is a building construction and maintenance issue.

    You also hit the nail on the head about thermal cameras. A great tool in the right hands, but many inspectors rely too heavily on them. They human eye and knowledge is the best tool to fight this growing problem.

Speak Your Mind

Site Designed by Go Pro Local