Flat Patio Roofing: Installing Rolled Roofing Like A Pro

Installing a flat patio roof is a complex process that requires careful preparation, precise measurements, and meticulous application. It is a popular choice for DIY enthusiasts due to its relatively low cost and ease of installation. Before starting, it is important to gather the necessary tools and materials, including roofing cement, a utility knife, a hammer, roofing nails, and the roll roofing material of your choice. The installation process begins with measuring the roof's surface area to determine the number of rolls required, followed by marking the roof with chalk lines to guide the placement of the roofing material. The roofing cement is then applied, and the roll roofing is cut to fit each section of the roof. The first layer of roofing is installed, followed by the second layer, which overlaps the first to prevent water seepage. Plumbing vents are sealed, and the final piece is applied and sealed with roofing cement. Finally, a thorough inspection is conducted to seal any loose nails and trim excess roofing material.

Prepping the roof surface

Clean the Roof Surface:

Start by thoroughly cleaning the roof surface with a push broom or a 1/4 sheet sander to remove any dirt, debris, and loose nails. Keep an eye out for any protruding nails and use a hammer to drive them down. Ensure the roof surface is smooth and free of any obstacles.

Repair and Prepare the Roof Deck:

Inspect the roof deck for any loose or damaged wood. Repair or replace any faulty sections to ensure a solid base for your roll roofing. If your roof is currently shingled, you have the option to remove the shingles or install the roll roofing over them. However, removing the shingles is recommended for a smoother and flatter surface.

Understand Local Building Ordinances:

Before proceeding, familiarize yourself with the local building ordinances and regulations regarding roofing. Roll roofing is typically suitable for roofs with a 1:12 or 2:12 pitch. Check with your local authorities or a roofing professional to ensure your roof is a good candidate for roll roofing.

Measure and Calculate Roofing Materials:

Measure the length and width of each section of your roof. Multiply the length and width of each section to get its area. Add the areas of all sections to get the total surface area of your roof in square footage. Don't forget to account for overhang, trimming, and roof valleys by adding 5% to 10% to your total. This calculation will help you determine the number of rolls of roofing material you need to purchase.

Gather Necessary Tools and Supplies:

Before starting the installation, gather all the necessary tools and materials, including roofing cement, a utility knife, a chalk line, a hammer, roofing nails, and, of course, your chosen roll roofing material. Having everything ready beforehand will make the installation process more efficient.

Prepare the Roll Roofing Material:

Unroll the roofing material and lay it out flat on the ground. Roll roofing tends to curl, so placing bricks on its corners will help keep it flat and easier to handle when you're on the roof.

By following these steps, you'll be well-prepared for a successful roll roofing installation. Remember to take your time, work with a partner if possible, and always prioritize safety when working at heights.

Marking with a chalk line

Before you begin marking with a chalk line, it's crucial to prepare your roof surface. This includes measuring the length and width of your roof to determine the total surface area and the number of rolls you'll need. It's recommended to buy 5% to 10% more material than needed to account for overhang, trimming, and covering any valleys on your roof.

Now, let's get into the marking process:

• Measure 35 inches: Using a measuring tape or a yardstick, measure 35 inches up from the bottom edge of your roof. This measurement is crucial as it determines the placement of your first roll layer. Mark this spot clearly.
• Create a straight chalk line: Using your chalk line tool, snap a chalk line across the entire roof, connecting the spots you marked in the previous step. Ensure the line is straight and level to provide a uniform guide for laying your rolls.
• Check for alignment: Double-check that your chalk line is perfectly straight and aligned with the bottom edge of the roof. This step is important to ensure that your roofing rolls will be installed evenly and neatly.
• Mark for additional rows (optional): If you're planning to install multiple rows of roofing rolls, you can mark the positions for the subsequent rows. Measure and mark spots 32 inches above the first chalk line for the second row, and continue marking at the desired intervals for any additional rows.
• Mark around obstacles: If your roof has any obstacles, such as plumbing vents or valleys, make sure to mark their positions as well. These marks will guide you when you cut holes in the roofing material to accommodate these features.

By following these steps, you will have successfully marked your flat patio roof with a chalk line. The chalk lines will serve as a guide for installing your roofing rolls accurately and ensuring a straight and uniform finish. Remember to take your time and double-check all your measurements and markings before proceeding to the next steps of the installation process.

Applying roofing cement

When applying roofing cement, it is important to work in dry weather, as this will ensure the cement adheres properly. Professionals may be able to work in a wider range of weather conditions, but for a DIY approach, dry weather is best.

Before applying the cement, the area must be cleaned thoroughly. Remove any dust, dirt, or debris, as these will reduce adhesion and durability. A wire brush can be used to clean the area, and a hammer to knock off loose material and drive down any nails.

When applying the cement, it should be applied generously. A trowel or putty knife can be used to force the cement into small holes, fully filling them, or to spread it evenly over a flat surface. For sealing down shingles or flashing, use a quarter to half an inch-thick layer of roofing cement.

If you are using a wet formula, you may need to start with an eight-inch-thick layer and then add additional layers several hours later. For larger holes or fissures, you may need to install rolled roofing or other fabrics first before sealing with cement.

When applying roofing cement to a flat patio roof, you will also need to follow the steps outlined previously, such as measuring the roof, marking with chalk, and cutting the roofing material.

• Prepare the roof by cleaning it thoroughly and repairing any loose or damaged areas.
• Measure the length and width of the roof to determine how much roofing material you will need.
• Unroll the roofing material on the ground to relax it and make it easier to work with.
• Mark a chalk line 35 inches up from the bottom edge of the roof to create a straight line parallel to the drip edge.
• Cut the roofing material with a utility knife into sections that fit the roof.
• Apply a band of roofing cement along the top edge of the first row of roofing material.
• Position the first piece of roofing material along the chalk line, ensuring it lines up with the outer edge of the drip edge.
• Drive roofing nails along the bottom and sides of the first piece, placing them 1 inch from the edges and 6 to 10 inches apart.
• Repeat the process with the second row of roofing material, overlapping the first row by 4 inches and securing it with nails.
• Continue this process until the roof is complete, sealing the final top edge with roofing cement.
• Double-check your work and seal all nails with cement to prevent them from coming loose.
• Trim any excess roofing material along the roof's edges and seal the edges with another layer of cement.
• Allow the cement to dry according to the manufacturer's instructions.
• Clean the roof with a push broom to remove any dirt, debris, loose nails, and mud.
• Spray the roof with a hose to wash away any remaining dirt or residue.

By following these steps, you can effectively apply roofing cement to a flat patio roof, ensuring a secure and long-lasting installation.

Cutting the roll roofing

Before you begin cutting, it is essential to ensure that the roll roofing material is properly unrolled and laid out flat. Place a piece of 1/2-inch plywood on the ground and unroll the roofing over it. This step is important because it helps to prevent damage to the tar binding, which could result in leaks after installation. If the temperature is below 45-50°F (7-10°C), bring the roll roofing into a warmer area to prevent cracking.

Once the roll roofing is unrolled, use a tape measure to determine the desired length of each section. Mark a small notch on one edge of the roofing at the desired length using a hook-blade utility knife. This notch will serve as a guide for your cut.

With the roofing material still unrolled, align the blade of your utility knife with the notch you created. Then, roll the piece of roofing towards the knife and firmly pull the knife across the width of the material, using the handle of the knife as a guide to ensure a straight cut. Apply pressure as you cut through the roofing.

After cutting the first section, carefully roll it up to protect it from damage. Repeat the previous steps for each subsequent length of roofing material that needs to be cut. Cutting the roll roofing into manageable sizes, typically 12 to 18 feet, will make it easier to handle and manoeuvre during the installation process.

When cutting the roll roofing, always wear appropriate safety gear, such as gloves and eye protection. Work in a well-ventilated area to avoid inhaling fumes from the asphalt coating.

Installing the first layer

• Prepare the Roof Surface: Start by thoroughly cleaning the roof surface with a push broom to remove any dirt, debris, and loose nails. Hammer down any protruding nails to ensure a smooth and even base. This step is crucial to ensure the roofing material adheres properly.
• Mark the First Row: Measure 35 inches up from the bottom edge of the roof on both the far left and far right sides. Use a measuring tape or a yardstick for accuracy. Mark each spot with a chalk line, creating a straight line parallel to the drip edge. This line will guide the placement of the first layer of roll roofing.
• Apply Roofing Cement: Using a trowel, spread roofing cement along the edges of the roof section below the chalk line. Ensure the cement is applied evenly and is about 1/8 to 1/4 inch thick. This creates a watertight seal and helps the roofing material adhere securely.
• Cut the Roll Roofing: Using a utility knife, carefully cut the roll roofing to fit the width of the roof section. Double-check your measurements to avoid wasting material. Each section should be at least 35 inches wide to align with the chalk line.
• Install the First Layer: Line up the edge of the cut roofing material with the chalk line and the outer edge of the drip edge. Slowly and carefully lay the first layer, pushing it into the wet cement as you go to secure it in place and smooth out any wrinkles. Be cautious, as the cement can be slippery.
• Secure with Roofing Nails: With the first layer in place, use a hammer to drive galvanized roofing nails along the bottom edge and sides of the roofing material. Space the nails approximately 6 to 10 inches apart and about 1 inch away from the edges. Ensure the nail heads are level with the roofing material.

By following these steps, you will successfully install the first layer of rolled roofing, creating a solid foundation for the rest of the roofing project. Remember to work cautiously, especially when on the roof, and always prioritise safety.

Frequently asked questions