How To Prepare A Commercial Roof For Single-Ply Installation

Posted on: 8 June 2023

Single-ply roofing systems are popular for commercial buildings. However, installing a single-ply roof requires proper preparation and attention to detail to avoid common problems compromising its performance and longevity. 

Understanding Single-Ply Roof  

A single-ply roof is a flat or low-slope roof made of a flexible membrane of synthetic materials, such as thermoplastic polyolefin or ethylene propylene diene monomer. 

How to Prepare Single-Ply

Remove any debris, dirt, grease, oil, or other contaminants from the existing roof surface that can interfere with the adhesion or performance of the single-ply membrane. Remove any loose or damaged materials, such as shingles, tiles, metal panels, or old membranes, that can create unevenness or punctures on the new roof.

If the existing roof has severe damage or deterioration, you may need to take it down to the steel deck or concrete substrate and replace it with a new one.

How to Install Single-Ply

Install a layer of insulation board over the existing roof deck or substrate to provide thermal resistance and support for the single-ply membrane. Different insulation options are available, such as expanded polystyrene. Attach it with screws, plates, or adhesives according to the instructions and building codes.

Unroll and position the single-ply membrane over the insulation and cut it to fit the dimensions and shape of the roof. You must then attach the membrane with screws to secure it to the insulation board regularly along its edges and seams. This method is suitable for roofs with high wind loads or irregular shapes.

Attach the membrane with a layer of solvent or water-based adhesive to the underside of the top of the insulation board and press them together. This method is appropriate for roofs with smooth surfaces and low wind.

What Can Go Wrong 

If you prepare your commercial roof properly for single-ply installation or follow the manufacturer's guidelines and industry standards, you may avoid some common problems.


Blisters are bubbles trapped between the membrane and the insulation board or substrate. They can reduce the adhesion and strength of the membrane and create weak spots that can leak or tear.


Wrinkles are folds or creases on the surface of the membrane that can result from improper tensioning, alignment, or cutting of the membrane during installation. 


Punctures are holes or tears on the membrane caused by nails, screws, tools, or debris, during installation or maintenance. They can allow water to penetrate and damage the insulation board or substrate and cause leaks or mold growth. 

Seam Failures

Seam failures are gaps or openings along the edges or joints of the membrane. They compromise the water tightness and integrity of the roof and lead to leaks or membrane detachment.

How to Prevent These Problems 

Hire a roofing contractor who can follow the best practices and standards for single-ply installation. A professional roofing contractor can inspect and maintain your roof regularly and fix any issues before they worsen. 

Speak to a contractor today to learn more about commercial metal roof systems.