Friday, December 5, 2008

What Lies Beneath?

Do you ever wonder "What's behind my siding?" Most people don't, but maybe they should! Most people only notice the condition of their exterior paint and only take action when they notice rot or other damage. Unfortunately, by the time they notice the problem the damage is done.

On most homes in our area, the only line of defense to water intrusion is caulk. Caulk is necessary to keep air and water out, but it's something that needs to be maintained. I can't tell you how many homes I have looked and worked on that have not been flashed properly or have inadequate or missing caulk. Water is a very tricky substance. It can get into places where you least expect it and causes all sorts of damage.

Here's a look at a "naked" house. Click on the picture for the full size view.

It had Masonite lap siding on it, but no water resistive barrier; not housewrap, tar paper, nothing! It's very east to see where the water was getting in. A good portion of the sheathing was damaged and had to be replaced. The flashing above the window caps was holding water and the caulk around the windows had shrunk. Both allowed water to get in. If water can get in, so can air! The insulation around the windows was inadequate as well.

Installing windows is really an art these days. In addition to being installed plumb, square and level, drainage must be factored into the equation. Installing the right size flashing and properly installing the housewrap can make or break a proper installation. When choosing a window or siding professional, make sure they know what they are doing!

On this particular project, had housewrap been installed, the water would have stopped there and drained out at the bottom of the siding. The sheathing would have been dry and not had the chance to rot.

Improperly installed housewrap can also be a problem! I've seen a project where siding was installed by one of my competitors where the top layer did not lap over the bottom layer, it was the opposite. When some of the caulk joints failed water ran down the housewrap but was directed inside the wall. Once the drywall was removed, the problem was apparent. The only option was to remove the siding and start from scratch. I'll explain WHY the caulk joints failed in another post.

I guess the moral of the story here is to make sure you check your caulking on a regular basis. Look at the metal flashing over your windows and doors. Does it actually go the entire length of the trim board? If not, you are probably getting water beneath your siding.


JOCOeveryman said...

Bill, this blog is way to informative and proper. Thanks for reading and commenting on my blog. I appreciate it.

Bill the Painter said...

Thanks! That's the way I intended it! Hopefully it will help others in preventing similar issues.