Flat Roof 101: Parts of a Commercial Roof Explained
You’ve got a big roofing project coming up and you feel a sense of dread.
You know the roofing contractor is going to end up talking about this, that, and the other – all of which are important to the health of your roof and the total of your quote – but, industry terms can be hard to follow along with. You aren’t in the roofing business, so you probably don’t know all the parts of a commercial roof.
This usually isn’t a problem – but now you’re in a situation where you might have to talk about the substrate, the membrane, and leaking penetrations.
Don’t worry – learning the different roofing components doesn’t have to be hard. We’ll help you understand them well enough to face your roof repairs and even roof installations with confidence.
The Major Parts of a Roof
Most commercial roofs are flat roofs, which are obviously a different type of roof than a pitched one (pitched are most often used for residential roofs).
For commercial flat roofs, there are only a few major components. Let’s work our way from the top of your roof down.
Membrane / Roofing Material
You’re probably most familiar with this part because it’s the most visible. This is the outermost commercial flat roof surface.
There are several common roof coverings used in commercial applications:
Modified Bitumen Roofing
Modified bitumen is a hybrid material made of asphalt and either rubber or plastic that’s reinforced with fiberglass.
Metal Roofs
There are two kinds of metal roofing systems – standing seam and corrugated metal roofing with exposed fasteners. Both have long lifespans and high energy efficiency.
Built-Up Roofing (BUR)
BUR is made of multiple layers of asphalt, ply sheets, and reinforcing fabrics.
Single-Ply Membranes
These roofing materials are applied in a single layer. Thermoplastic polyolefin (TPO), polyvinyl chloride (PVC), and ethylene propylene diene monomer (EPDM) are all popular single-ply roofing materials.
Each roofing material has its strengths and weaknesses. They can also vary widely in cost, which means they’ll be one of the biggest reasons quotes may fluctuate in price. Metal roofs tend to be more expensive than TPO roofing. But, a metal roof’s energy efficiency could end up saving you money. Before you get a roof installation done, it’s a good idea to familiarize yourself with each type of roof’s details.
Roof Cover Board
A cover board is the next layer down. It’s a thin substrate that provides additional protection against water damage and increases the roof’s durability. Sometimes a cover board isn’t necessary, but it helps handle additional stress or extreme weather conditions, so it’s never a bad idea.
Substrate
The word substrate can be a little confusing. This is another component of a commercial flat roof – but what the substrate is can vary from roof to roof.
The substrate is the surface you apply the roofing material on top of. This means it could be a cover board, it could be an underlayment, or it could be the deck itself.
Roof Insulation
The next part of your low-slope roofing system is the insulation. Like roofing materials, different types of insulation vary widely in price resulting in major variations in roof installation quotes.
Don’t be tempted to skimp on insulation. A high-quality material helps boost your building’s energy efficiency and lower power costs.
Underlayment / Vapor Barrier
Under the insulation, you may have a vapor barrier or a waterproofing layer of underlayment installed. This layer provides an extra barrier of protection for the decking.
Roof Deck
The deck is the base of your roof structure. It carries a heavy load by holding the rest of your commercial roofing system. This is an important component of the roof and can cause major issues when it’s damaged (including a whole roof collapse).
Roof decks are made of the following materials:
Concrete
Concrete is popular in industrial buildings thanks to its increased strength and fire resistance, but it’s heavy. Additional structural support may be necessary.
Steel
These decks are highly durable and fire-resistant, making them a great choice for commercial use.
Tectum
These roof decks are made of a mix of wood fiber and cement. They’re great for soundproofing buildings, though not as fire-resistant or durable as concrete and steel. They’re a popular choice for auditoriums, event halls, churches, and gyms.
Wood
Wood isn’t the best at carrying heavy loads but they’re popular among smaller commercial buildings because they’re cost-effective. They are more prone to damage from moisture and pests.
Other Important Roofing System Terms
Drainage Systems
Your drainage is an important part of your roof and should be checked with every thorough roof inspection. Blocked drainage leads to issues like major water damage when not addressed.
Gutters
Gutters are pipes or troughs that run along the edge of the building to collect rainwater.
Downspouts
Downspouts are the vertical pipes that lead from the gutter to the ground to redirect water away from the building.
Scuppers
Scuppers are holes in the sidewall of your roof that allow water to drain off.
Drains
Drains are installed at the lowest point of your roof and usually have a strainer to keep debris from clogging your pipes.
Drip Edges
Drip edge flashing is installed along the roof edge to direct water into your gutter and protect the cover board from moisture.
Penetrations
When a roofer talks about this term, they mean anything that interrupts the roofing membrane: HVAC machines, drains, skylights, vents, etc.
All penetrations have to be sealed with flashing or else water can get into your system and shorten its lifespan.
Roof Coatings
Commercial roofing contractors can apply a roof coating to your membrane. Coatings increase your roof’s UV protection and add an extra layer of waterproofing. If your roof isn’t in too bad of shape, roof coatings can delay a roof replacement by several years.
Roofing Services Made Easy
Now when you sit down with your roofing company you’ll understand what they’re talking about when they say penetrations, membrane, or underlayment.
But, even if you didn’t know these parts, a good roofing company cuts through the lingo and industry terms to make sure you understand everything – from the work that needs done to what it will cost.
At TEMA, we believe the relationship between roofing contractors and customers is more than just a fly-by-night deal. It’s a long-term partnership involving clear communication and an investment in your business’s success.
When you talk to us about your roofing project, we don’t just make sure you understand the different parts of a commercial roof we’ll be working on but also the strengths, weaknesses, and costs so you can make the best decision for your business.
