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The Solution to Flat Roof Ponding

Commercial and industrial buildings are commonly covered by “flat” roofs. Keeping flat roofs properly drained can be tricky. In fact, while such roofs are often referred to as “flat”, they should not be completely flat — they need to have a gentle, yet well-planned slope. Should you happen to find water sitting on your roof for days after a rain, it’s likely due to inconsistent slope, or no slope at all. Moreover, the water wears away at coatings, and eventually creeps through the roofing material and underlayment, weakening the roof and possibly compromising the space below.

In cases where a roof is totally flat, or the slope is inconsistent and causes water to pond, we are able to use roof insulation products that are specifically made to add sloping.

A quick background on flat roof anatomy, and popular insulation products:

Elements of a Flat Roof

There are three major elements that make up a flat roof structure…

More About Insulation

There are various types of insulation available for flat roofing:

An Elegant Solution

As you can see, there are a lot of elements that go into a flat roofing structure. If any one of these elements is not properly planned or installed correctly, you will often end up with inconsistent sloping and drainage problems.

Thankfully there is a solution called “tapered insulation”. Tapered polyisocyanurate (or “tapered iso” for short), is a foam material created in sheets of several different thicknesses. Rather than making the sheets of insulation flat, they are intentionally made with various taper measurements - often 1/8” or 1/4” per foot. The various height sheets lock together and create a gentle slope that causes water to move downhill on what would otherwise be a flat roof surface. The taper can be designed to move water toward roof drains, scuppers or gutters.

Tapered iso has great insulating properties, guides to show which sides lock together, plus it is easy to install. While it shouldn’t be used for high-traffic areas (unless properly protected), it is a great option to help shed water from flat surfaces. Best of all, it can be designed for all roof dimensions.

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