Words: Steven Fechino
Flashing is an integral part of every job we build. Challenges can occur because of all the different veneer designs, material options, cavity clutter, and grade changes that make a simple membrane placement difficult.
One of the typical phone calls I receive about common flashing conditions regards “step down” or “step-up,” when the grade changes rapidly, and the footing has either 8-inch or 16-inch drops or rises. First things first, you will have a heck of a time flashing a step-down, but an easy time flashing a step up. This is because the veneer, use brick, for example, needs to be laid into the rise of the footing.
Install an end dam (using sealant) at the corner of the lower brick shelf and the rise of the footing. You do not need to flash or waterproof the rise (vertical leg) of the footing that steps up, which will be flashed when you flash the next level. Here is where it becomes easy- lay the brick up to the next level of brick shelf. You will continue your flashing at this level anyway.
When the course of the brick you just laid is level to the bottom of the stepped-up footing, install the flashing as normal. However, be sure to extend the flashing over the flashing below 18-inches and terminate the end of the membrane into an end dam. This is an easy way to keep your bricklayers productive, without them having to do a bunch of unnecessary flashing steps that have little value, but add a big expense to your project.
Lipped brick is common when large shelf angles are installed on multi-story structures. In lipped brick, the face of the brick is the full dimension, but the bed of the brick (modular, for example) has only but 5/8-inch height by ¾-inch deep rectangle at the face of the brick remaining. The brick is typically laid on the shelf angle with the small tab of the lipped brick in front of the shelf angle to conceal the steel and maintain bond going up the wall.
Buildings have been built this way for a long time, but once drip edges became very popular in the late 1980s, the drip edge then needed to be bent to accommodate the lipped brick detail. This is a cost factor for the mason. The drip edge that was designed functioned perfectly because it had two additional bends before the drip that would drop the thickness of the shelf angle, then extend to the face of the wall.
This then gave the mason a smaller bed (bearing surface) to lay the first course on the shelf angle, slowing production and creating an opportunity for movement once the brick was placed. This is why a modular brick is 3 5/8-inches wide when you subtract the portion of the brick that makes it lipped, 2 7/8-inch, (your brick has bearing only area that is removed), and in some cases just shy of that.
The more cost-effective way for a mason is to lay out the lipped brick from the bottom up, which is exactly the same for bond and strength. However, the top of the lip is at the same level as the top of the shelf angle. The reverse of the lipped brick allows the metal drip edge to be standard (reduces an additional ordering task) and allows the brick placement to be full bed depth of 3 5/8 inches. The bottom line, you get a better job, and your bricklayers are more productive with better quality.
Freeze-thaw is not an issue when the drip edge is installed with a bead of sealant under the metal because the drip edge completely covers the tab of the lipped brick, eliminating the opportunity for water to saturate and create freeze damage.
Piers or pilasters are common in the geographical locations where brick is common. Piers are typically only decorative and not reinforced or grouted solid. When drip edges are required for a job with piers, you can eliminate time-consuming precutting at your office on multiple miters, sharp edges, and short pieces that can get mixed up between the office and the site. Mortar Net Solutions has designed a single piece of drip edge up to 10-feet long that can be precut to the necessary dimensions, with both inside and outside bends to accommodate the pier.
The corners are solid, with smooth edges, and installation can be as quick as two minutes per pier. With the drip edge in place, Mortar Net Solutions can also precut the flashing that has the term bar, drainage weeps and mortar collection made into the piece. This would extend from the substrate to the face of the brick in a larger dimension to eliminate any cutting or slicing by field personnel.
Piers become something that do not add additional time to your wall production, and with the many options available, it can make your bid more attractive to the evaluating general contractor or construction manager.
Arches are just as easy to flash as a step-up. Today many people use bent or curved steel arch templates (basically a curved lintel) that remain in place. Others still build traditional arches with the removable templates. Either way, they flash the same. Projects that use the curved steel as the support for the curved masonry material do not require that the radius steel be flashed with small repetitive pieces of flashing, similar to rake step flashing.
Typically, when small pieces are used, it is flashed with rubberized asphalt held back a minimum of ½ inch or more from the face of the steel. Primers are difficult at best if even used in this application, so I recommend eliminating both the previous concept and flash it a different way. First of all, the curved steel will be hot-dipped galvanized. Therefore a slight amount of moisture will not have an effect on steel deterioration.
Second, the process we initially mentioned with the rubberized asphalt pieces is time-consuming and frustrating, and also slows down the line. An alternative way to flash an arch is to flash across the arch two or three courses above the material that is laid that turns the arch (intrados of the arch). If flashing is one course above the intrados, you may see cracking over time, that is why we recommend two courses as a minimum. The flashing extends from the keystone horizontally in each direction to approximately 1/3 of the width of the arch terminated on each end with an end dam. Another flashing is placed beneath the top flashing. underlapping it by approximately 12 inches and will extend 6 inches beyond the jamb, again, terminating with an end dam on each side.
Rain and wind-blown water that can come in contact with the material below the flashing will be held to a minimum, and depending on the elevation, it could be almost non-existent. So, why is this way better than flashing the curved steel? This method keeps your bricklayers laying flashings on flat surfaces, something they do almost daily.
Flashing penetrations have become a big issue in the restoration world recently, because the restoration performed today is historical as well as recent construction modifications and repairs. I have had a contractor ask me how we deal with Shelf angle bolts and conduits that are placed at the inside corner of the substrate and the brick shelf. When the conduit is lovingly placed at the juncture between the substrate and the brick shelf by our sometimes not-so-friendly electricians, we have to deal with it.
Dealing with the penetrations is really not a problem when the occurrences are at random locations. The first thing we need to do is clean the mortar droppings and debris around the base of the conduit. Do a dry fit of the flashing that you want to install. If the conduit is extending up the wall, a very small cut in the flashing that will allow you to slip it over the conduit (this is where the dry fit comes into play). The flashing will not be cut at the base of the substrate and the brick shelf- it will actually be cut slightly up the wall on the substrate side.
Before you get too far in snugging the flashing over the conduit, place a healthy bead of sealant around the perimeter of the conduit, but also place a liberal amount of sealant about three inches on each side of the conduit and six inches up the substrate wall. It is important to make too small of a cut and modify the cut as you place the flashing down to the final placement. You do not want an extra cut on the brick shelf portion of the flashing, as this can and likely will cause a leak. Once you have the flashing where you want it, drill the holes for the term bar screws and snug them into place. However, we will need to remove a portion of the term bar in a moment.
Complete the installation of the drip edge, complete with a bead of sealant under the metal and on the edge of the brick shelf. Now, back to the conduit penetration. You will need to add sealant to the area where the conduit passes through the membrane on the top surface of the flashing. This needs to be watertight. Then, if possible, loosen the term bar and find a scrap of the membrane, and repeat the step of the dry-fit over the conduit- this will be an apron over the base of the conduit held in place by the termination bar.
This is added protection, it does not need to be set in a bead of sealant, but should extend under the brick if possible, to shed any secondary water away from the hole that was created by our almost friends, the electricians. We all know it should have been on the wall in the first place, but that does not always happen.
Shelf angle bolts are typically jumbo nuts that have a sharp threaded bolt that is adjacent to the back of our flashing. So yes, we need to deal with it. The other day a contractor told me that the engineer wanted him to cut holes in his flashing and put a peel and stick the patch over the nut and bolt. I told him his engineer was the nut.
I have been repairing shelf angles for many years, and the easiest way to flash over the nuts and bolts is to use a piece of poly extruded insulation ripped into 8-inch tall pieces by 8- foot long. The extruded insulation is placed at the base of the wall at the juncture between the substrate and the brick shelf hardware and pressed into the anchors. Once this is done, you can install the flashing just as you would normally, with the term bar just over the top of the insulation. A piece of insulation can yield about 48 linear feet. Therefore, it is economical.