The Truth about Ponding Water Roof Coatings

For decades roof coatings have been an effective repair and restoration option for a variety of roofing substrates. They are durable, economical, and if applied properly, they can transform a troubled roof into an energy-efficient, leak-resistant asset. However, before executing a roof coating project, it is important to conduct a comprehensive inspection of the pre-existing roof to determine its overall condition. If any surface areas are compromised, the coating may not fully adhere and could merely cover up a serious underlying problem.

For instance, applying a coating over an area affected by ponding water can lead to numerous challenges down the road. Ponding or standing water can occur from insufficient drainage or a number of other reasons. One common cause is water damage to the substrate or insulation board; persistent leaks can cause these materials to eventually break down or settle, creating a place where water can accumulate into stagnant pools.

When coatings are applied over areas containing trapped moisture, the following issues can ensue:

• Deterioration of the substrate
• Rusting of the fasteners
• Adverse effects on roof insulation
• Rusting of steel decks
• Buckling and warping of plywood
• Breakdown of seam adhesive on some single-ply roofs
• Added weight to the roof assembly
• Blisters or other coating problems
• Freeze and thaw damage
• Adhesion failure

Locating Trapped Moisture

One method roofing professionals can use to help identify trapped moisture is an infrared roof scan. Utilizing infrared technology, roofing specialists can identify temperature differences that may indicate areas of moisture that are invisible to the naked eye.

During the day the sun’s rays warm the roof, and at night the roof radiates that heat back into the atmosphere, a process called radiational cooling. Wet insulation can retain heat differently than surrounding dry materials. Infrared imaging can reveal these temperature differences and help identify areas that warrant further investigation. Once moisture is confirmed, saturated materials can be removed and the affected area repaired using dry, compatible materials.

There are many advantages to using a roof coating system; however, thoughtful preliminary preparation should never be underestimated. Critical steps taken before the coating process can determine the outcome of the entire project.

Roof Coatings for Ponding Water

Can silicone roof coatings withstand ponding water? Many silicone coatings are formulated to tolerate prolonged exposure to standing water when properly installed. However, a coating should not be viewed as a substitute for correcting the underlying cause of a drainage problem.

Compared with acrylic coatings, silicone coatings can also have some disadvantages depending on the roof and application:

• Higher initial material costs in some applications
• More involved application and cleanup
• Can pick up dirt and debris
• May have lower resistance to abrasion in high-traffic areas
• Future recoating generally requires a compatible product and proper surface preparation
• Can be difficult to remove from an existing substrate
• Reflectivity can decrease as the surface becomes dirty or ages

Again, though, ponding water can indicate a larger roofing or drainage issue and should be properly addressed rather than simply covered.

Advantages of Acrylic Roof Coatings

There are many roof coating products on the market today. Acrylic coatings remain a popular option for commercial roof restoration because they can provide a seamless, reflective and flexible protective surface when installed on an appropriate roof.

Some potential advantages include:

• Durability — A properly installed coating system can help protect the existing roof from UV exposure, rain and other weather conditions.
• Cost performance — Restoring a suitable existing roof can cost considerably less than a complete tear-off and replacement.
• Energy efficiency — Highly reflective acrylic coatings can reduce the amount of solar heat absorbed by the roof, which may help reduce cooling demands in some buildings.
• Life-extending capabilities — A liquid-applied membrane can reinforce and protect an existing roof and extend its useful service life when the roof is a good candidate for restoration.
• Easy cleanup — Many acrylic roof coatings are water-based, making application equipment easier to clean than with some solvent-based products.
• Elastomeric properties — Acrylic elastomeric coatings are designed to expand and contract as roof temperatures change.

The exact performance of a roof coating depends on the product, existing roof condition, preparation, installation and ongoing maintenance.

Determining the Root Cause of Ponding Water

Regardless of the formula, roof coatings should never be an excuse to ignore ponding water issues. Commercial roofs should be designed and maintained so that water drains properly. Water that remains on a roof for an extended period after rainfall can indicate a problem that deserves further investigation.

A roof inspection may reveal blocked drains, depressions in the roof surface, damaged insulation, structural issues or inadequate slope. Once diagnosed, the problematic areas can be properly repaired so the roof is ready for a coating system if restoration remains an appropriate option.

The Advantages of Roof Restoration

When a roof is old or damaged, the default solution may seem to be replacement. However, not every aging commercial roof needs to be completely torn off and replaced. When the existing roof is structurally sound and otherwise suitable for restoration, a roof coating system can provide a cost-effective, life-extending alternative.

Acrylic coatings are liquid-applied over the surface of an existing commercial roof. When properly installed and cured, the coating forms a seamless, fully adhered protective membrane over the prepared roof surface. Roof restoration can extend the useful life of an existing roof while helping building owners avoid many of the costs and disruptions associated with a complete re-roofing project.

Depending on the existing roof and project requirements, potential advantages can include:

• Lower labor costs than a complete tear-off
• Reduced tear-off requirements
• Reduced landfill and disposal costs
• Less disruption to normal business operations
• Simpler future maintenance and repairs in many applications

Roof restoration is not appropriate for every commercial roof. Wet insulation, structural problems, severely deteriorated materials and other conditions may need to be corrected before a coating system can be considered.

Interested in a Roof Coating System and a Proper Install?

A participating Choice Roof Contractor Group member can inspect your commercial roof to determine whether it is a suitable candidate for a coating system. The roofing contractor can evaluate ponding water, drainage concerns, wet or damaged materials and other conditions that may need to be addressed before restoration begins.

Choice Roof Contractor Group is made up of independent commercial roofing contractors serving businesses throughout the United States. Participating members perform their own inspections, recommendations and roofing work.

For more information or to contact a participating member, please call (800) 670-5583. We look forward to speaking with you!

Written by: Cami Cox

Cami is one of the main writers at Choice Roof Contractor Group. Leveraging her unique background in the space and more than a decade of professional writing experience, she has written countless articles on the various aspects of commercial roofs and has gained the respect of building owners and contractors across the country.