Welcome to the battle against ponding water, when puddles of water remain pooled on your commercial roof for more than 48 hours. Chronic ponding may be an indicator of existing damage to your roof. If left untreated, it will only cause more distressing issues later on, such as unwanted plant growth, water leakage, damage to the insulation, erosion, or deformation of the roof membrane, to name a few.
Different types of commercial roofing systems are naturally going to have varying strengths and weaknesses. Thankfully, there are several distinct characteristics to look for in a new roofing system, plus preventative measures to implement to your existing roof, to address ponding water specifically. Let’s explore these ten characteristics of commercial roofs that help to contend with ponding water.
Table of Contents
1. Slope
Flat roofing systems are not parallel to the ground. They ought to have a positive slope of at least a fourth of an inch per foot. This gradient allows water to drain smoothly off the roof to one side. If ponding occurs, then the roof’s slope may not have been adequately designed during the construction of the structural frame or roof deck. If this is the case, your roofing contractor may recommend replacing your entire roof.
2. Drainage
In addition to slope, your commercial roof’s design and construction should have also included a drainage system. Scuppers, drains and gutters help minimize ponding water by providing a direct outlet from the edges and other vital areas of your roof. Your roofing manufacturer or roofing construction contractor will know the most effective places to install these elements on your roof. Afterward, it’s your responsibility to schedule biannual gutter cleanings and roof maintenance visits to keep your drainage system in tip-top shape.
3. Tapered Insulation System
Let’s say you undergo your regular roofing inspection and maintenance, and you find that your roof does not have an adequate slope. Water is ponding on the rooftop with nowhere to drain, and now you need a roof replacement. At this point, you’re probably hesitant to purchase the same type of roof that leads to this problem. In this case, your building may be an ideal candidate for a tapered insulation system. With this design, the insulation underneath the roofing layers shapes the slope. Tapered insulation utilizes one, two or even four slopes to drain water from different areas and directions simultaneously.
4. Crickets
Also known as chimney saddles and chimney diverters, crickets are most commonly used to redirect water from gathering at the base of a chimney and send it away down the roof. In commercial roofing, crickets are installed up-slope of any roofing equipment or in-between drains to steer the water toward the drains or safely off the edge of the roof. Usually made from wood topped with metal flashing or asphalt shingles, crickets are like miniature slopes incorporated around specific structures to optimize water flow.
5. Membrane Thickness
Depending on the material, roofing membranes can measure from 30 mils to 100 mils. Most membranes are going to fall in the 45- to 60-mil range. Membrane thickness is crucial for ponding issues because its polymer will erode over time due to water exposure. The thicker your roof’s membrane, the longer it will last before it completely deteriorates and allows water to penetrate to deeper layers.
6. Reinforcement
Unless you are imminently preparing for a full roof replacement, it is likely too late to change your roofing membrane’s thickness. Despite this, reinforcement may still be an option. Add a layer of polyester to the spots on your roof with ponding water. This will help fortify the membrane in those problem areas, preserving the membrane thickness’s longevity and preventing water from seeping inside.
7. Specific Gravity
Specific gravity is a fancy phrase referring to your roofing material’s density compared to that of water. A denser material will have an easier time letting water roll off. A material with less density may have a higher porosity, which will cause water to adhere to the roof. Talk to your roofing materials manufacturer about which high specific gravity roofing substances they recommend to prevent ponding water. It may be too much to afford such material for your entire rooftop, but you can at least use it to reinforce the smaller areas of ponding water.
8. Color
The color of your roof may play a role in how much water is left to sit for days. White and lighter colors are effective heat reflectors, which tremendously help your HVAC unit in the summertime. On the other hand, the inability of light colors to retain heat also means that less of the ponded water will heat to the point of evaporation. By contrast, dark colors hold onto a higher degree of heat, which spurs on the evaporation process. By this logic, keep an eye out for patches of grayish or lighter colored parts of your roof. These spots will be more likely to fall prey to ponding water.
9. Seams and Penetrations
Ideally, a roofing membrane should be one cohesive piece that stretches across your entire roof. Realistically, however, your roofing system will require some seams around certain features or equipment. As necessary as these penetrations may be, the downside is that they present a weak point for water to infiltrate into deeper roofing layers. Proper installation by expert roofers should minimize this threat as much as possible, but a break in the material will never be perfectly impenetrable. A combination of reinforcements and crickets, as discussed previously, will help prevent sitting water around these vulnerable spots. Otherwise, construct a seamless roof in the first place when given the option.
10. Maintenance
Roofing experts of all kinds highly recommend and encourage regular maintenance. It goes without saying that the more you strive to preserve and clean your roof, the longer it will last. Maintenance inspections will help to recognize problems, including potential and existing areas of ponding water, and to diagnose a strategy addressing these issues before they become severe. Additionally, regular maintenance will guarantee that your drainage systems are cleaned and working properly.
As soon as you see ponding on your rooftop, call your roofing contractor and deal with the problem immediately before it causes more serious damage. When you catch sight of the problem early on, you will be able to apply preventative measures such as reinforcement, installation of crickets or drainage systems, or reparation around seams and penetrations. Perhaps you are already in talks with your local roofing professionals for a full roof replacement. Remember to ask them about slope versus a tapered insulation system, membrane thickness, specific gravity and color of the roofing materials. With these features in mind, chronically ponding water will soon be a problem of the past.