How To Look At A House

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What are the signs of stucco wall leaks?

Thursday, December 17, 2020

Small cracks may look like they wouldn’t be a problem, but a 1/32-inch crack (less than the thickness of a dime) only three feet long exposes a wall to more water intrusion than a 1-inch round hole. By the time enough water gets behind a stucco wall to be noticed inside your home, or it becomes too ugly outside to ignore, significant damage has already been done. 

    You can stop water intrusion behind stucco before it gets started if you take a slow walk around your exterior walls at least twice a year, examining them carefully from top to bottom for cracks that are just beginning. If fixed right away, it will save you the grief of an expensive, wall-opening repair later.

    Here’s what to look for:

1) Cracks -  Tiny cracks are sometimes best seen by looking obliquely down the wall, like the one running across the center of the photo below, along with more in the lower right. Can you spot them all?

   Cracks are also common around window and door openings. They can run diagonally out from the corners or along the sides, top, or bottom.

Look all the way up too.

2) Cracked or missing caulk around wall openings - The deteriorated/cracked caulk along the side of this sliding glass door is causing damage and discoloration at the bottom of the wall next to it.

3) Damp or stained areas - The discoloration and flaking paint shown below is due to water pouring off the end of a roof valley above it at a narrow overhang without a gutter. Even a light breeze pushes a waterfall down the wall in a heavy rain. A gutter would alleviate the problem before it gets much worse.

4) Bulging areas - These are caused by water collecting behind the stucco that has drained down to it from an entry point above. It’s important to repair both the bulge and locate the entry opening for repair also.

5) Flaking, crumbling, or missing chunks - This can be caused by moisture accumulation in the wall or accidental impact damage.

6) Unsealed small wall penetrations - Hose faucets, wall-mount light fixtures, air conditioning refrigerant lines, electrical conduit, and gas pipes that penetrate the wall should be sealed with caulk too. These are easy to overlook unless painfully obvious like the example below.

    Stucco that is applied over a wood frame wall is more susceptible to cracking and water damage than when it’s used on block. Concrete block is more forgiving of minor moisture intrusion, but will experience many of the same problems as the level of water in the wall increases and the moisture migrates through it. 

    Also, many concrete block houses have parts of the walls that are wood frame. Shown below is a house under construction, and the area of the tall roofed entry that is above the tie beam line is framed in wood. The change in underlying structure will not be discernable when it is all stuccoed over.

    We suggest using a sanded acrylic or acrylic/latex caulk for all but the largest cracks or missing chunks of stucco. One that’s available at the big box home improvement stores is Quikcrete Stucco Repair, and there are others that are comparable. 

    The bigger repairs, like bulges, will need a construction professional to make them disappear without a trace. Here’s an example of a well-done stucco repair by a pro before being painted over.

    Also see our blog post Why is my stucco cracking? and How can I tell if stucco is loose around wall cracks? to learn more.

• • • • • • • • • • • • • • • • • • • • • • • • • • •

Here’s links to a collection of some of our other blog posts about STUCCO:

Why is stucco that goes into the ground a problem at a wood frame house?

Do stucco walls mean a house is concrete block?

What causes raised white lines of residue on a block wall that are crusty and crumbling? 

What is the difference between EIFS and stucco? 

What is the difference between Acrocrete and EIFS? 

What is the average life expectancy of stucco? 

How can I tell if a crack in a stucco wall is a structural problem and what is causing it?

• Is the stucco on a wood frame house allowed to extend down into the ground? 

Does stucco need expansion joints?

• What are common problems with stucco? 

    Visit our EXTERIOR WALLS & STRUCTURES page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Photo of severe damage at opened wall courtesy of Mark Cramer.

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