Common Thin Veneer Install Mistakes - Pro Masonry Guide
Common Thin Veneer Install Mistakes

The 5 Most Common Thin Veneer Install Mistakes

Proper professional installation of thin veneer stone is crucial for the stone to work accurately. Find out what are the most common thin veneer install mistakes.

By Jim O’Neill

Thin veneer stone is extremely common in the building of new homes. There are many advantages to using thin veneer stone on a home, such as, cost effectiveness, light weight, and the availability of a variety of designs and colors. When installed correctly, the home will be left protected, while appealing to the eye. Proper professional installation is crucial for the stone to work accurately. And, a few common thin veneer install mistakes often are made during installation, which can affect the home in a big way.

An exterior experiencing moisture damage.

An exterior experiencing moisture damage.

  1. Among the most common thin veneer install mistakes that people may make, the first one is neglecting to inspect the water-resistive barrier, which can often affect the outcome of the whole project. The water-resistive barrier and proper integration of flashing details must be inspected prior to application of rainscreen and thin veneer. Critical areas, such as roof-to-wall intersections – which include kick outs, step flashings, weep screeds or z flashings – are one area of concern. Penetrations, as discussed prior, must be checked to insure the penetration has been flashed properly. Window flashing needs to be under the flange of the window at the sill and over the water-resistive barrier, directing water to the drainage plane. Guaranteeing all of this is done correctly goes hand-in-hand with the rest of the project.
Properly inspect the water-resistive barrier (WRB).

Properly inspect the water-resistive barrier (WRB).

  1. Another common thin veneer install mistake that is often made is improper termination of stone at the bottom of the wall when using a weep screed. A weep screed is extremely useful, because it flashes bulk water out of the wall and stops moisture from wicking up from the ground. In order to work effectively, the weep screed needs to be installed no less than 1inch below the foundation plate line. It should be located 4 inches above the earth and 2 inches above paved surfaces or minimum ½ inch (12 mm) above exterior walking surfaces, which are supported by the same foundation that supports the exterior wall.Ideally, the leg of the weep screed should be flashed, and then the water-resistive barrier and rainscreen will lap over the flashed leg of the weep screed. This will allow the water to drain correctly from behind the stone.
Weep screed properly installed.

Weep screed properly installed.

  1. Lack of ventilation space is the third major thin veneer install mistake regarding moisture issues behind siding. When moisture gets behind the wall, it needs space to drain and dry to prevent problems, such as mold and decay from occurring. A proper airspace gap of ¼ inch needs to be ensured throughout the entire backside of the thin veneer cladding, to create enhanced drying capability. Installing Keene’s Driwall Rainscreen, for instance, allows all the flashing details and drainage areas such as drip caps and weep screeds to function better. This can greatly reduce the risk for moisture related issues.

 

Driwall Rainscreen is installed on full wall.

Driwall Rainscreen is installed on full wall.

 

Shown is a close-up view of Driwall Rainscreen installed with casing bead along door jamb.

Shown is a close-up view of Driwall Rainscreen installed with casing bead along door jamb.

  1. Terminating the stone to windows and/or doors is another common mistake. Windows and doors are where you see most moisture problems, so making sure the stone is installed correctly around the windows and doors is crucial. A drip cap should be used at the head of all windows, doors and other penetrations. The leg of the drip cap should be flashed, and building paper and rainscreen should lap over the flashed leg of the drip cap. The drip cap should be extended over the casing bead and backer rod at the jambs of the penetration, allowing water to exit at the head of the penetration. The joint between the drip cap and mortar should not be caulked. A casing bead and backer rod is then installed on top of the rainscreen, down the jambs and under the sill (doors just require jambs) for expansion and to create a proper joint to be caulked.
Shown is a close-up view of Driwall Rainscreen, casing bead along a window, and metal lath installed with part of the scratch coat applied on top of the window.

Shown is a close-up view of Driwall Rainscreen, casing bead along a window, and metal lath installed with part of the scratch coat applied on top of the window.

 

From left to right, a close-up of casing bead, a backer rod, and a window, awaiting sealant.

From left to right, a close-up of casing bead, a backer rod, and a window, awaiting sealant.

  1. Lack of a proper scratch coat is the final thin veneer install common mistake. Thin veneer stone requires a scratch coat of ½ inch prior to applying thin veneer with mortar on the backside of the stone to adhere to the scratch coat. The scratch coat of mortar needs to embed into a minimum 2.5 pounds of self-furred lath. Improper installation of scratch coat can leave the metal lath exposed and subject to oxidation and rust.
Shown is a properly installed scratch coat.

Shown is a properly installed scratch coat.

 

An improperly installed scratch coat is shown.

An improperly installed scratch coat is shown.

Each of these steps are crucial when installing thin veneer. If done correctly avoiding these common thin veneer install mistakes, the final product will be much less susceptible to any issues that may arise in the future, leaving the home looking just as new as the day it was completed.

Jim O’Neill is director of building envelope products for Keene Building Products. He can be reached at jmo@keenebuilding.com.


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