A Primer on Roofing Adhesives for Commercial and Industrial Buildings

Roofing contractor applying roofing adhesives to commercial building.

Did you know that choosing the best type of roofing adhesives and application method for each project is critical to a roof’s performance? Metal fasteners have a long history of securing roof membranes, cover board, and insulation to deck substrates, and they are still appropriate for many applications. More recently, technology for roofing adhesives and application methods provide additional fastening options that can improve longevity, durability, versatility, sustainability, and aesthetics.

Making the Right Choice in Roofing Adhesives

What’s the best choice of roofing adhesive for your low-slope building’s flat roof? Like all types of construction work, there are many considerations. Adhesive selection requires knowledge of the type of building, deck substrate, application needs, temperature and weather conditions, environmental factors, energy requirements, aesthetics, and budget.   

To get you started, here’s a primer on roofing adhesive options available in today’s commercial roofing market.

Four Common Types of Roofing Adhesives

Adhesives can be classified based on their chemical composition and how they are applied. 

Here are four common types of roofing adhesives:

1. Asphalt-Based

Asphalt-based adhesives are typically used to bond roofing membranes to the roof deck and other substrates – for example: cover boards, parapets, insulation. These roofing adhesives can be applied as a hot-melt adhesive or cold-applied adhesive.

2. Solvent-Based

Solvent-based adhesives are made from synthetic materials and are typically used for bonding roofing membranes or flashing (most commonly used for peel-and-stick roofing membranes). They are applied using a solvent, which evaporates during the curing process.

3. Water-based 

These adhesives, made from water-soluble polymers, are typically used for bonding roofing membranes or insulation and are applied as a liquid and dry to form a strong bond.

4. Polyurethane-Based 

Polyurethane (Poly) adhesives are increasingly popular in the construction industry based on their complete sealing, strong bond many types of substrates, flexibility, and durability. 

Poly-Based Adhesives come in single-component and two-component formulations:

Single-Component Polyurethane-Based Roofing Adhesives

Single-component poly-based adhesives adhere to many substrates, are resistant to temperature fluctuations, environmental exposure, UV radiation, building movement, expansion and contraction. They are known for standing up to high velocity wind and reducing uplift.  

One-component foam is convenient but has application, expansion, and performance limitations.

Two-component polyurethane-based insulation adhesives

Two-component poly adhesives expand more than single-component adhesives and are appropriate for larger surfaces. They provide a complete “bond”, cure more quickly, withstand temperature variations, are moisture-resistant, and are long-lasting. 

Two-component foam, while requiring mixing, is often chosen in large-scale projects as it provides more versatility and control over the expanding process.

Consider the Type of Roof System

Consider your building’s roof system when deciding on the best type of roofing adhesive.

Modified Bitumen Adhesives

These adhesives, formulated to bond modified bitumen roofing to various substrates, includes asphalt-based adhesives, solvent-based adhesives, and adhesive tapes. The two primary types—APP (plasticized) and SBS (rubberized)—both provide strong adhesion, flexibility, and resistance to environmental factors. These adhesives are hot-applied or cold-applied.

Built-Up Roof (BUR) Adhesives 

BUR adhesives match specific types of bitumen and are hot-applied or cold-applied, depending on the project’s requirements. Providing strong adhesion, they are flexible and resistant to environmental factors, UV radiation, temperature extremes, and weathering.    

Single-Ply Membrane Adhesives

Formulated for each type of single-ply membrane, these adhesives bind the membrane to insulation and overlays, such as cement board. They are available as contact, low-rise foam, and high-rise foam adhesives.

Application Methods for Insulation Adhesives

Adhesives that attach insulation boards to the roof deck are available as liquid applied adhesives, low rise foam adhesives, spray adhesives, and adhesive tapes. They help provide a thermal break and enhance the energy efficiency of buildings, with the choice of option depending on compatibility with the insulation material, the substrate, and the specific conditions of the application. Another advantage with adhesives is that you don’t have the thermal bridging that is common with mechanical fasteners.

Roofing adhesives being applied to a commercial roof.

Let an Experienced Contractor Help You Choose the Right Roofing Adhesive  

Roofing adhesives are more complex than you might imagine. They aid in durability, longevity, and safety, so choose wisely. Partner with a trusted contractor that examines all relevant factors, carefully follows manufacturing guidelines, and uses industry best practices.

Since 1956, Elite Roofing has served the Greater Toronto Area with a reputation for high quality workmanship and integrity. Contact us today.