The Right Roof Overhang For Seamless Plastic Gutters

Gutters are essential for protecting your building's structure. They prevent water from pooling around your home's soil and foundations, averting costly structural issues and safeguarding your health. When considering the overhang on your roof, it's crucial to ensure that the gutters are attached correctly to the fascia board of your building, not the roof deck itself. The amount of overhang depends on various factors, including the roof's pitch, steepness, and local climate. For example, roofs with clay tiles or asphalt shingles can overhang further than metal roofs due to the friction that slows down water flow. The width of your gutter also plays a role in determining the required overhang. While there is no one-size-fits-all answer, the National Construction Code (NCC) provides guidelines for gutter widths, and the general recommendation is to have a slight overhang to protect the gutter from leaves and debris.

How much roof overhang for plastic gutters?

Gutter width and roof pitch

Gutters are essential for protecting your building's structure. The size and pitch of your roof play a role in determining the amount of water flow during a rainstorm. A large, steep metal roof, for instance, will not require as much overhang as a flatter roof with a smaller area. The pitch of the roof is a critical factor in gutter design, as the gutter must be able to handle the water flow rate, especially from a steep roof.

The width and depth of a gutter are calculated using the length of the gutter, the rainfall intensity, and the design area. The length of the gutter is used to determine the ratio of depth to width. This ratio is then used to find the required width and depth of the gutter. The width is determined by multiplying the ratio by the rainfall intensity and the design area. The width is then multiplied by the ratio to find the depth. For pitched roofs, the plan roof area is multiplied by a factor to determine the design area, which is then used to calculate the required gutter size.

The amount of roof overhang also depends on the type of roof. Roofs made of clay tiles or asphalt shingles can overhang further above the gutters compared to metal roofs due to the friction these materials provide, which slows down the flow of water during storms. The National Construction Code (NCC) specifies that gutter widths should be between 115mm and 150mm. However, the width you choose will impact the minimum overhang required for your roof. For metal roofs, the ends of the sheets should overlap into the gutter trough by around 50mm.

Additionally, the pitch of the roof can impact the pitch of the gutter. The standard pitch for a gutter is about 1/4 inch per 10 feet. Increasing the pitch can increase the gutter's water-handling capacity, but it may also affect the gutter's appearance. It is worth noting that the pitch of the gutters is typically determined by the gutter company during installation, taking into account various factors such as the size and shape of the roof, the amount of rainfall, and the presence of trees or open fields surrounding the building.

Overhang and roof material

The overhang of a roof and the material it is made of are important factors to consider when installing gutters. The overhang, or protrusion, of a roof is essential for protecting your building's structure. If there is insufficient overhang, water will drip down the side of the building, causing damage to the walls and foundations. On the other hand, too much overhang can cause water to miss the gutter, eroding the soil at the base of the building. The ideal amount of overhang depends on the roof material and the type of gutter being installed.

For metal roofs, the ends of the sheets should typically overlap into the gutter by around 50mm. Metal roofs allow water to drain much faster than other materials, so a smaller overhang is necessary to ensure that water does not overshoot the gutter. In high wind areas, drip edges are recommended for metal roofs to prevent the wind from getting under the overhang and potentially causing damage. Additionally, metal roofs often require a downspout screen to protect the gutter from leaves, sticks, and debris.

Roofs constructed with clay tiles or asphalt shingles create more friction, slowing down the flow of water. This allows for a greater overhang without the risk of water missing the gutter. For asphalt shingles, a typical overhang is around 1 inch, while for clay tiles, a slightly larger overhang is acceptable due to the increased friction.

The type of gutter being installed also plays a role in determining the ideal overhang. For example, a valley gutter on a pitched roof must be at least 400mm wide, with 150mm of metal roof overhang on each side. Gutter widths can vary from 4 to 8 inches, with the most common options being 5 or 6-inch aluminium gutters. The building's architecture and local climate also influence the required size of the gutter, with gutters in areas of high rainfall needing adequate catchments to divert water away from the building.

In summary, the amount of roof overhang for plastic gutters depends on various factors, including the roof material, the type of gutter, the pitch of the roof, and the local climate. It is important to consider these factors to ensure that the gutters function effectively and protect the building from water damage.

Drip edges

A drip edge is a vital part of a gutter system, integral to preventing water damage. It is a strip of metal, plastic, vinyl, or aluminium installed along the edge of the roof to direct water away from the fascia and into the gutters. The drip edge is typically installed before the roofing material is applied, providing a finished edge for the roof. It is also called an eave strip, roof edge, roof apron, or D-metal.

When choosing the materials for your drip edge and gutters, it is essential to consider factors such as durability, cost, and appearance. Metal drip edges and gutters are popular because they are durable, long-lasting, and resistant to rust and corrosion. However, vinyl and rubber drip edges are more cost-effective. It is also important to consider the local climate, as some materials, like plastic or rubber, can become brittle in cold climates.

To install a drip edge, place it so that the end with the flange or flare points down and away from the roof. Use roofing nails to secure the drip edge, nailing about every 12 inches, and ensuring the shingles cover the nails. When you place the next drip edge piece, it should overlap the first by an inch.

Gutter apron

Gutters are essential for protecting a building's structure, and the amount of roof overhang depends on the material of the roof. Metal roofs, for example, require less overhang than those made of clay tiles or asphalt shingles. This is because metal roofs cause water to run off more quickly, and too much overhang will cause water to miss the gutter and erode the soil at the base of the building.

Roofs made from materials other than metal possess enough friction to slow down the flow of water during a storm. As a result, these roofs can have more overhang without causing water to miss the gutter. However, it is important to note that too much overhang can cause leaves, sticks, and other debris to fall into the gutter and cause blockages.

The National Construction Code (NCC) provides guidelines for gutter widths, which must be between 115mm and 150mm. The width of the gutter will also determine the amount of overhang required. In areas with high rainfall, gutters must have adequate catchments to ensure water is diverted from the building. Steeply pitched metal roofs will also require less overhang than flatter roofs with smaller areas.

Gutter installation

Gutters are essential for protecting your building's structure. They prevent soil erosion, basement leaks, and siding damage, and they divert rainwater away from your house's foundation. Gutter installation can be a DIY project, but it's important to be careful and precise to avoid common mistakes. Here is a step-by-step guide to help you install gutters properly:

Planning and Preparation:

Before starting, ensure you have the right tools and materials. Measure everything and plan ahead to avoid issues during installation. Measure all the edges of your roof where gutters will be installed, including where downspouts will be placed. For measurements over 40 feet, you will need to place two downspouts, with one placed every 30-40 feet to ensure proper water flow.

Fascia Preparation:

Inspect the fascia and soffit for any rotted wood and replace it if necessary. Prime and paint all the wood before hanging the gutters. Create a chalk line across the fascia to guide your downslope measurements.

Support Brackets Installation:

Attach the support brackets to the fascia by drilling starter or pilot holes and screwing in the long hex head screws.

Lay the gutters into the support brackets and screw them into the fascia to secure them. Seal the gutters with caulk or gutter sealant, and install gutter flashing to keep water out of the seam between the gutter and fascia.

Downspouts and Elbows Installation:

Install the downspouts and elbows into the pre-cut holes. Screw the upper portion of the downspout to the downspout outlet, and use mounting straps to fasten it to the house. Seal all the seams of the downspouts.

Final Touches:

Install gutter guards to protect your gutters from leaves and debris. You can also install a diverter in the downspout if you have a rain barrel.

Regarding your specific roof overhang, the optimal amount depends on the type of roof you have. Metal roofs, for example, should have a smaller overhang compared to roofs constructed with clay tiles or asphalt shingles due to the difference in water flow speed. The National Construction Code (NCC) recommends gutter widths of 115mm to 150mm, which will influence the required overhang. Consult a professional if you are unsure about the appropriate overhang for your roof type.

Frequently asked questions