The Basics of Roof Installation

roof installation

Roofing Columbus GA protects against the elements, provides insulation, and contributes to the overall appearance of a home. Many roofs leak at eaves and ridges or where a roof meets structures such as chimneys, skylights, or plumbing vents.

Install an inside foam closure strip to seal the corrugated underside of each metal panel. Use a square reference line to ensure that each panel is installed evenly. Screw the metal panels into place, spacing them and following fastening instructions.


While many homeowners focus on the shingles that adorn their roof, there is much more to a roof than what you can see. One of the most important components of any roof is the underlayment, which is a waterproof or water-resistant material directly placed on the roof deck before any other roofing materials are installed. This layer protects your home and the roof from moisture damage, leaks, and mold.

You can buy standard felt or rubberized asphalt underlayment, which is self-adhesive and provides an extra layer of protection against the elements. It’s also available in rolls that are easy to work with. Whether you’re working on a flat or sloped roof, the underlayment is a critical step in the roof installation process.

It’s recommended that you hire professional roofers to install the underlayment. Attempting to do so yourself can be dangerous. Falling from a roof can cause serious injury or even death. If you’re working on a steep or high roof, make sure to use a fall protection kit (harness and rope) purchased from a home center. You’ll also need to clear out a safe workspace for the contractors, and move any items near the edge of the roof away from it. Otherwise, stray nails could tear holes in the underlayment or the shingles.

Once the underlayment is down, install a metal drip edge along the bottom edges of your roof. This is optional and not required, but it adds a finished look to the roof and helps direct water into gutters. Nail the drip edge to the fascia boards at an angle that’s slightly less than 45 degrees, and nail it every couple of feet.

The next step is to waterproof the valleys. These are the areas of your roof that meet or create a v-shape, and they’re especially susceptible to leaks. Depending on your roof’s design, you can either have open or closed valleys, which should be waterproofed using an appropriate flashing material. To ensure your home is watertight, IKO recommends that you complete the valley flashing before installing shingles.


Once the underlayment and flashing are in place, the roofing contractor begins installing the shingles. The first row, called a starter course or strip, is cut from three-tab shingles and is applied with the self-sealing adhesive strips facing up along the roof’s eave. Starter courses yield a straight edge from which all field shingle rows can begin and provide extra weather protection at the roof’s eaves where ice dams often form, high winds raise shingles and allow water to seep underneath and rot the underlayment and sheathing, and moss grows.

Next, the contractor applies a pre-formed width of corrosion-resistant metal valley flashing, followed by a row of shingles, each with an overhang of 1/4 to 3/8 in. This helps to prevent rainwater from pooling behind shingles, which can lift and blow them away in high winds and force leaks at the roof’s valleys, at shingle joints or at any shingle cutouts.

Leaks are most likely to occur wherever a shingle layer is penetrated or interrupted, such as at a valley or where a roof plane butts against a wall. For long-lasting roof performance, IKO recommends open valleys rather than closed, which are completed during shingle installation by running a pre-formed width of copper or aluminum flashing through each valley and over the top of the shingles.

Plumbing stacks and vents should also be flashed before the shingles are applied. These are often the source of leaks when shingles wear out or break. Finally, a sheath of an ice and water membrane, which has a rubberized asphalt coating to seal around the shanks of the overlying shingle fasteners, is typically installed around the entire perimeter of the roof to protect it from moisture intrusion.

Before the shingles are installed, the roofing crew should clear any children’s toys or patio furniture from the area around your home that might be damaged by falling shingle debris. It’s best to keep a 15-foot clearance all the way around the house so that roofing professionals can easily walk everywhere on your roof. If you can’t move any items, place them inside a shed or cover them with tarps.


The flashing is a vital part of your roof that seals and protects areas where other structures meet the roofing. It prevents water seepage, a major cause of leaks and moisture damage, from infiltrating the building envelope. This is particularly important for areas where a feature like a chimney, vent pipe, or skylight is installed. These areas create small crevices that could lead to leaks if not properly protected. Flashing is a thin piece of impervious material, typically metal, that’s installed at these intersections.

A top-notch roofer will make sure to follow best practices and use high quality flashing when installing a new roof or replacing an existing one. It is usually made of a durable, weather-resistant material such as aluminum, copper, or steel. This protects it from corrosion caused by acid rain and harsh weather. Flashing can also be made of plastic or rubberized asphalt if these materials are a better fit for the project.

There are different types of flashing, often named for where they’re used or their shape: step flashing (installed at the bottom of a sloped roof to stop water entering) counter flashing (installed over step flashing to add protection and strength) valley flashing (used to seal a gap between two intersecting sections of the roof to keep water from pooling) pipe flashing (installed around ventilation pipes) and sill flashing (installed under windows and doors to prevent water ingress).

In addition to protecting against moisture penetration, flashing can help inhibit mold growth by keeping damp air out. It can also be used to seal cracks in walls and walls abutting the roof to reduce the risk of leaks and water damage.

Flashing should be installed carefully and with great attention to detail. If the flashing is not correctly installed, it can leak and cause serious structural damage to your home. For example, if you have long runs of flashing, it is important that they include expansion joints to allow them to move and expand with the house as it expands and contracts throughout the seasons.

The final stage is to add the shingles, which a professional roofer will do with careful precision to ensure that it’s done correctly. It is a time-consuming process that requires meticulous skill. This is the most visible element of your roof and can be a good indicator of how well your new roof is being installed.


The goal of roof drainage is to remove water from the roof surface as fast as possible to minimize the risk of roof leaks. It also prevents standing water (or ponding) that can damage most roofing materials over the long term. This drainage system is essential to the life of your roof, especially if you live in a rainy area or on a flat rooftop.

The drainage system consists of a series of drains, gutters, and scuppers that route the water away from the roof. The drains are often hidden by the parapet wall and soffit to maintain a clean look. The scuppers are placed along the edges of the walls to catch the water that runs off the edge of the roof and redirect it into the drain. The drains and scuppers are all connected to pipes that route the water away from the building.

If you have an existing flat roof, a professional can assess the condition of the drainage system to make recommendations about its improvement. In addition, a core sample can help determine the layers and composition of the roof to identify issues that could affect drainage.

There are several different types of roof drains, including inner and outer. Inner drains are commonly found on commercial buildings, but can also be used on residential flat roofs. This system consists of a grid of drains in the interior of the building, typically near the center. An inner drain system is more expensive than a gutter system, and it requires regular maintenance to keep the system free from clogs.

A professional can install a roof overflow drain in the center of the roof to handle heavy rainfalls. Overflow drains are typically connected to the building’s plumbing systems or a separate drainage system and route the excess water to prevent it from backing up on the roof.

Clogged roof drains are the most common cause of building interior flooding in freezing climates. Debris entering the roof drain causes a clog that eventually freezes and bursts, flooding the building interior with water. This can be prevented by vigilance regarding the cleanliness of the roof and by keeping debris away from the drains.