Your recent stucco inspection has reported problems with your balcony or rooftop terrace. Improper drip edge. No visible balcony flashing. No end dam flashing. Balcony needs to be re-worked. What does this mean and how does it affect you?
Balconies and terraces provide a beautiful architectural feature for your home. It not only provides functionality but gives you views of our great city. Like the remainder of your home, they are not maintenance free. Failure to construct a balcony properly and failure to maintain that balcony will may result in very expensive repairs.
Where to Begin
Let’s address the most visible portion of your balcony or rooftop terraces. The surface itself. There are many options available for balcony surfaces. The most popular seem to be using slate or another natural product. The second most popular is a composite decking system. I will explain to you the common problems that we see with each of these surfaces.
Let’s talk about slate, granite, travertine and other products that are natural to the earth. These products are porous and will allow water to soak through them. Unless you are very diligent with your maintenance and properly seal not only the grout lines but the tiles as well, over time the excess water will deteriorate the protection underneath. Once that “pan” has been compromised water will enter the wall cavity and will look for a place to drain. Porous products are not a good idea for balcony or terrace surfaces.
Composite decking materials have become very popular in the Houston market. There are a number of builders that exclusively install composite materials. These materials are very good and will certainly hold up to the elements. That being said, they have to be installed properly.
The waterproofing membrane that is installed under the decking material is generally a thermoplastic polyolefin, (TPO). TPO is commonly used for flat roofing as well as waterproofing under a composite decking. It is the defense against water. As such, when installing railing posts and other items penetrate the TPO leaks will occur.
What the Experts Find
The most common problem that we deal with is that the installers of the composite decking will use furring strips to level out the surface so that the composite tile will lay uniformly. A furring strip is generally a 1”X2” wood strip. This is nailed directly trough the TPO and into the wood decking. Once this happens, the waterproofing barrier has been broken. This is why a qualified waterproofing expert should be installing balcony and terraces.
Our preferred method of waterproofing the balcony decking is to utilize a liquid applied waterproofing material. It is applied via roller just like a paint application. This material will soak into the decking providing the waterproofed surface. The joints that exist between the sheets of plywood receive a later of fabric that we use to help the waterproofing liquid to bridge the butt joints. This creates a uniform decking. Our preferred material is StoGuard. (For more on StoGuard please check out this link; https://www.youtube.com/watch?v=GUwqor_1ViE)
When we repair balconies and terraces, we insist that our customers use a porcelain or ceramic surface. There are many styles and colors available. We also like to see our client’s use of larger format tiles. The larger the tile the less grout that we have to use. This reduces the surface space that you will need to maintain moving forward.
Now, let’s discuss flashing. This is equally important as the surface material. There is more than just one type of flashing that is required. First, an el flashing that is flashing we use to marry the wall with the balcony decking. To install this post construction, we do need to cut the stucco out around the balcony and/or terrace. We use a 6”X6” el flashing that extends equal distance up the wall and decking. It is manufactured by our metal fabrication company and is a one-piece flashing broke at 90 degrees. We attached via pneumatic staple so that we do not create an excessively large hole. Once it is in place, we use StoGuard fabric and waterproofing to make certain that the edges are impenetrable from water.
The next flashing step is to add the “drip edge” to your balcony/terrace perimeter. This is an aluminum material that we purchase dye cast to a color that will closely match your wall. It extends 4” onto the balcony decking and 3-4” over the front of your completed stucco wall. At the very bottom of the flashing there is a tiny “ramp” of ½”. This piece allows water that may be under the surface to run off via the front of the wall. The “ramp” keeps water from wicking back underneath of the flashing material.
The final flashing piece that we require is a diverter or end dam flashing. This piece is used at the corners of the balcony and where there may be a column or columns in the middle of the balcony or terrace. These diverters take the water that is being expelled from the el flashing and the water that is shedding from under the surface and allow it run off over the front of the stucco wall below. It is an integral part of moving water because a proper balcony and terrace will be sloped at a proper pitch to keep water from ponding. The slope is generally 2 or 3 to 1 forward. Larger surfaces will pitch to the right and left to assist in a faster expulsion of water. Failure to install end dam or diverter flashings will allow an excessive amount of water to pour in behind your stucco wall.
After all of the flashings have been installed and waterproofed a pan flashing or membrane must be installed. Most balconies are simply to large to put an aluminum full-sized pan in. The cost will also not be conducive to your budget. A bitumen peel and stick or Westcoat peel and stick is very effective. It is installed in a ship lapped fashion and will allow water to roll over and expel itself over the drip edge.
All flashings must be installed under the pan flashing or membrane! This is why, when we do repairs, that we must remove all of the tile and balcony material. A contractor cannot properly flash a balcony without removal of the entire balcony.
It is important to note that the drip edge and end dam flashings must be 100% visible. There are many builders that prefer to tile over the flashings. This is improper and will cause the drip edge to prematurely fail.
If your balcony is cantilevered, or has an overhang, a proper drainage relief is required at the bottom. There are many accessories that are available on the market. We utilize a drip screed accessory because we find it is the most effective way for water to escape without causing cracking around it. It is very important that when this drainage relief is installed that it is not sealed over in any way. This will obviously cause residual moisture to remain in the wall and eventual wood rot will occur.
There are many types of balcony materials and every contractor has their preferred brand. We like Westcoat. The mortar bed is waterproofed cement before tiling. This coupled with the StoGuard and membrane and then the non-porous tile will give you the best waterproofing coverage available.
Maintaining Your Finished Project
As for maintenance, our balconies and terraces simply require you to seal the grout lines. Ideally it would be good to do this every 90 days. Especially if your surface has high UV exposure. To seal the grout will take you just a minute or two. Simply buy a good quality grout sealer. Then purchase a one gallon bug sprayer. Dump the sealer in the sprayer and you are ready to go. Once you have sprayed the grout lines stow the sprayer and leftover material for the next time.