How Thick is a Commercial Roof

How Thick is a Commercial Roof? Your Simple Guide for Edgerton, WI Businesses

Have you ever looked up at your commercial building’s roof and wondered, “How thick is that thing, anyway?” It might seem like a simple question, but the answer is really important for keeping your building safe, dry, and energy-efficient, especially with our Wisconsin weather here in Janesville and nearby places like Edgerton or Milton.

At Rooster Roofing, we’re your friendly neighborhood roofing experts right here in Janesville, WI. We help businesses like yours every day, from downtown Janesville (zip code 53545) to spots near Rotary Gardens or out towards Beloit and Evansville. We know roofs, and we’re here to break down what goes into the thickness of a commercial roof in a way that’s easy to understand.

So, let’s dive in and talk about how thick your commercial roof really is!

What’s Under the Surface? The Layers of a Commercial Roof

Think of your commercial roof like a really thick sandwich! It’s not just one single piece. Instead, it’s made up of several layers working together to protect your building.

These layers typically include:

1. The Structural Deck: This is the base layer, usually made of things like wood (plywood or OSB are common), metal, or concrete. It’s what holds everything up!
2. Insulation: This is super important for keeping your building warm in the winter and cool in the summer, saving you money on energy bills.
3. Vapor Barrier (sometimes): This layer helps stop moisture from inside the building from getting into the roof layers.
4. The Waterproof Layer (or Membrane): This is a big one! It’s the main shield against rain and snow. Different types of roofs have different materials here.
5. A Cover Board (often): This is like an extra shield placed over the insulation before the waterproof layer. It adds strength, protects the insulation, and gives a good surface for the top layer.
6. A Protective Top Layer (sometimes): This could be gravel, a coating, or even plants if you have a cool green roof.

Each of these layers adds to the overall thickness of the roof system.

How Thick Are the Different Parts?

The thickness of each layer can vary a lot based on the material used and what the building needs.

1. The Roof Deck (Sheathing)

The sheathing is the base layer on top of the beams or trusses. Its thickness is really important for the roof’s strength and how well it holds up against wind and snow loads – definitely something to think about with our Janesville winters!

• For wood sheathing (like plywood or OSB), the minimum allowed thickness is pretty thin, about 3/8 inch.
• But for good strength, especially so it doesn’t bow or bend between the supports, a thickness of 5/8 inch is often recommended. Building codes might even say it needs to be at least 19/32 inch thick.
• Different wood materials have different typical thicknesses; for example, OSB sheathing is sometimes used in a 7/16 inch thickness. Plywood can range from 3/8″ to 3/4″.
• If the deck is metal or concrete, the required metal thickness for roofing sheathing can be as little as 0.019 inches.

Choosing the right sheathing thickness depends on what kind of material you’re putting on top and how far apart the supports (like rafters or trusses) are.

2. The Insulation

This layer is a big reason why commercial roofs can get quite thick. Good insulation is key for energy efficiency and comfort inside your Janesville building. The thicker the insulation, the better its R-value (that’s how well it resists heat flow). Our cold climate in Wisconsin means businesses here often need a good amount of insulation to meet energy code rules and keep heating costs down.

• A popular type of insulation for commercial flat roofs is called polyisocyanurate, or polyiso.
• These boards come in different thicknesses, typically from 1 inch up to 4.5 inches.
• Sometimes, even thicker boards, like 4-inch ones, are used in certain spots, especially in tapered systems designed to help water drain.
• Installing insulation in multiple layers is a common and recommended practice. For example, using two layers of 2.6-inch thick polyiso can give you an R-value of R-30, which meets minimum code requirements in many areas, including where there’s lots of construction.
• Using multiple layers with staggered joints helps reduce heat loss through the gaps and improves the roof’s overall performance.

3. The Waterproof Layer (Membrane)

This is the skin of the roof! The thickness here depends a lot on the type of roofing material you choose.

• Single-ply membranes like TPO, PVC, and EPDM are very common on commercial flat roofs today.
• These are measured in mils (1 mil is 0.001 inches).
• Typical thickness for these membranes ranges from 45 mils (0.045 inches) to 90 mils (0.090 inches). A thicker membrane often means it will last longer because there’s more material to wear away over time.
• Modified Bitumen (Mod-Bit) roofs often have multiple layers, which makes them durable, but also adds to their thickness and cost.
• Built-Up Roofs (BUR), sometimes called “hot tar” roofs, are built by layering rolls of material with hot asphalt in between. These can have 4, 5, or even 6 layers, making them quite thick and very durable.
• Metal roofs have a different way of measuring thickness – using something called gauge. This can be a bit confusing because the lower the gauge number, the thicker the metal. Common gauges for steel metal roofing on commercial buildings are 24, 26, and 29 gauge. For aluminum, thickness might be measured in inches like .032, .040, or .050 inches. Metal roofs are known for their strength and longevity.
• While more common on homes, asphalt shingles are sometimes used on commercial buildings with steep slopes. They don’t add as much to the total thickness compared to other commercial materials, usually adding about 1/4 to 1/2 inch. Upgraded or designer shingles are often used for better durability.

4. Cover Boards and Other Layers

As mentioned, a cover board provides a strong base and protection for the layers below. They can also add a little extra insulation value. For example, a 0.5-inch thick polyiso cover board adds about R-2.5 to the overall R-value. Vapor barriers or other underlayment layers also add a little bit to the total thickness.

Putting It All Together: What’s the Total Thickness?

When you add up all these layers – the deck, insulation, waterproof material, cover board, and others – the total thickness of a commercial roof can vary a lot!

• A typical commercial roof assembly might be anywhere from 1.5 inches to 7 inches thick.
• However, especially for flat roofs that need a lot of insulation to meet energy codes (like here in Janesville, WI!), the total thickness is often more in the range of 12 to 20 inches.
• And if a building has a “green roof” with soil and plants, that adds even more thickness, sometimes between 18 and 36 inches.

So, as you can see, there’s no single answer to “How thick is a commercial roof?” It really depends on several things!

Factors That Influence How Thick Your Roof Needs to Be

Choosing the right thickness isn’t just a guess. A lot of different things play a role:

• Climate: This is a big one for us in Janesville! Our cold winters and hot summers mean good insulation is crucial, and that adds thickness. Areas with heavy snow loads or strong winds also need more durable, potentially thicker materials and stronger decks.
• Type of Building & Roof: Flat roofs typically need more insulation layers and waterproof protection than sloped roofs, which affects thickness. How the building is used also matters. Does it have heavy equipment on the roof, like HVAC units? Will there be a lot of people walking on it for maintenance or repairs? This affects the needed durability and potentially the thickness of the top layers.
• Materials Used: As we saw, different materials have different inherent thicknesses and require different underlying layers.
• Building Codes: Local building codes in Janesville, Rock County, and Wisconsin have minimum requirements for roof thickness, especially for things like structural strength and energy efficiency. We always make sure our roofs meet or exceed these local rules!
• Structural Requirements: The beams and structure holding up the roof have to be strong enough for the weight of the roofing materials. Thicker roofs, especially those with lots of insulation or heavier materials like tile, weigh more.
• Energy Efficiency Goals: If you want to lower your energy bills and make your building more efficient, you’ll likely need more insulation, which increases the roof’s total thickness.

Thinking about these factors helps figure out the perfect roof thickness for your specific building in Janesville or the surrounding areas like Brodhead, Delavan, or Lake Geneva.

Why Thickness Matters (It’s More Than Just a Number!)

The thickness of your commercial roof isn’t just a technical detail; it has real benefits for your business:

• Better Insulation & Lower Energy Costs: A thicker roof with more insulation means less heat escapes in the winter and less heat gets in during the summer. For Janesville businesses, this means lower heating and cooling bills – saving you money every month!
• Increased Durability and Protection: A properly thick roof system with strong layers and potentially a cover board is more resistant to damage from harsh weather (like snow, ice, hail, and wind we get in Wisconsin!), foot traffic for maintenance, and even things like rooftop equipment or solar panels.
• Stronger Structure: The right sheathing thickness prevents sagging and ensures the roof deck can support the weight of the materials and anything else on the roof.
• Reduced Problems: Multiple layers of insulation and a good overall thickness can help prevent issues like air leaks, moisture getting into the roof (which can cause big problems like rot or condensation), and even help the top membrane last longer by preventing buckling or splitting.

Is Thicker Always Better?

You might think, “Okay, so thicker is better, right? Let’s just get the thickest roof possible!” But it’s not quite that simple. Like many things, “it depends”.

While adding more insulation is generally a good idea for energy efficiency, just adding thickness to other layers isn’t always necessary or the most cost-effective option.

Modern roofing materials, especially single-ply membranes, are very advanced. Manufacturers have made them lighter and easier to install while still being very durable. Getting the absolute thickest membrane available might cost more and be stiffer to work with during installation.

The goal isn’t just the thickest roof; it’s the right thickness for your specific building, material type, climate, usage, and budget.

How Rooster Roofing Helps Janesville Businesses Get the Right Roof

Choosing the correct roof system and thickness for your commercial building can feel complicated, especially with all the different materials, code rules, and factors to consider. That’s where Rooster Roofing, your local experts in Janesville, WI, comes in!

We specialize in commercial roofing and understand the unique needs of buildings in our Wisconsin climate. Whether your business is a retail store in the 53546 zip code, an industrial building in Edgerton, or an office near the Rock River in downtown Janesville, we can help.

We’ll look at your specific building, talk about your energy efficiency goals, your budget, and how the roof will be used to figure out the perfect roof system and thickness for you. We take into account the local building codes and weather patterns to make sure your roof is durable and protects your investment for years to come.

Rooster Roofing serves all of Janesville, WI, and the surrounding communities, including:

• Brodhead
• Delavan
• Edgerton
• Beloit, WI
• Evansville, WI
• Milton
• Monroe
• Madison
• Lake Geneva

We’re here to be your trusted roofer!

Our Services for Your Janesville, WI Business

Besides helping you understand roof thickness, Rooster Roofing offers a full range of services to keep your commercial or residential building covered:

Commercial Roofing

We are experts in all types of commercial roofing systems, from single-ply (like TPO and EPDM) and Modified Bitumen to Built-Up Roofs and metal roofs. We handle installation, repairs, and maintenance for businesses throughout Janesville and beyond.

Residential Roofing

While we focus on commercial thickness here, don’t forget we are also skilled in residential roofing! We work with common residential materials like asphalt shingles and metal panels, providing quality work for homes in Janesville and our service areas.

Roof Repair

Got a leak or damaged spot? No matter the material or type of roof, our team can handle roof repair quickly and effectively to prevent bigger problems.

Roofing Installation

Whether it’s a brand new building or you need a full roof replacement, we provide professional roofing installation services, ensuring every layer is installed correctly, including the right thickness of insulation and membrane.

Roof Maintenance

Regular roof maintenance is key to making your roof last as long as possible. We can inspect your roof, check the condition of the materials, look for wear and tear (like how TPO wears 1-2 mils per year), and perform preventative tasks. This is especially important for identifying potential issues before they become costly repairs.

Roof Replacement

When your old roof is worn out or damaged beyond repair, we provide expert roof replacement services. We’ll help you choose the best new roof system for your building, considering all the factors we discussed, including optimal thickness for durability and energy efficiency.

Gutter Installation

Gutters might not be part of the roof’s main thickness, but they are vital for directing water away from your building and foundation. We offer professional gutter installation to protect your property.

Siding Installation

Like gutters, siding works with your roof to protect your building. It adds an extra layer of insulation and protection against the weather. We provide quality siding installation services to complete your building’s exterior shield.

Finding the Right Thickness for Your Janesville Building

Understanding roof thickness is important, but applying that knowledge to your specific commercial building in Janesville or the surrounding areas is where the real value is. You need a roofer who understands the local needs and the best practices for different materials.

Instead of just guessing, the best way to figure out the perfect roof system and thickness for your Janesville business is to talk to a professional. A skilled roofer can inspect your current roof (if it’s a replacement project), evaluate your building’s structure, consider your budget and goals, and recommend the right combination of layers and materials to give you a durable, energy-efficient roof that will last for years.

Conclusion

A commercial roof is a complex system made of many layers, each contributing to its overall thickness. While typical commercial roofs are between 1.5 and 7 inches thick, they can be much thicker (12-20 inches or more) depending on the amount of insulation and material type used.

Factors like our Janesville climate, your building’s type and use, the materials you choose, and local building codes all influence how thick your roof needs to be for the best durability, performance, and energy efficiency. Getting the thickness right is key to protecting your investment and keeping your business comfortable.

Don’t let the question of roof thickness stress you out! Rooster Roofing is here to help Janesville, WI, and the nearby communities like Monroe and Madison. We’re your trusted local roofing experts ready to guide you through choosing and installing the perfect roof system for your commercial building.

Ready to learn more or get a professional assessment? Contact Rooster Roofing today! We’re proud to serve Janesville and all of Southern Wisconsin.