Corrugated Roofing Overlap: How Much Do You Need?

When installing corrugated roofing sheets, it is common to overlap 2m sheets end-to-end or side-to-side. However, this can create the potential for draughts or leaks in extreme weather and takes longer to install. The amount of overlap depends on the pitch of the roof. For example, a pitch of 15 degrees or over requires an overlap of 180mm, while a pitch between 5 and 10 degrees requires an overlap of 320mm. You also need to allow approximately 40mm for the Rock N Lock flashing on each side of the roof.

Overlapping 2m sheets end-to-end

When overlapping 2m sheets, the amount of overlap required will depend on the pitch of your roof. For a pitch of 15 degrees or more, an overlap of 180 mm is recommended. If the pitch is between 10 and 15 degrees, increase the overlap to 220 mm. For pitches between 5 and 10 degrees, an overlap of 320 mm is advised. It is also important to allow approximately 40 mm on each side of the corrugated roof for Rock N Lock flashing.

Additionally, it is recommended to install the roofing sheets with the prevailing wind direction in mind. By observing the weather and wind patterns in the area prior to installation, you can reduce the chance of wind uplift over time and increase the lifespan of the roof.

When it comes to the number of corrugation peaks to overlap, it depends on the roof pitch. For a pitch greater than 10 degrees, overlap one corrugation peak. If the pitch is less than 10 degrees, overlap two corrugation peaks. However, it is possible to overlap more than two corrugation peaks if you prefer to avoid trimming the sheets at the edge.

Overlapping corrugated roofing sheets lengthways

When installing corrugated roofing sheets, it is recommended to follow the prevailing wind direction in your location. This reduces the chance of wind uplift over time and increases the lifespan of the roof. If you are unsure of the wind direction, observe the weather and wind patterns in the area for a few weeks before installation.

The amount of overlap required for corrugated roofing sheets depends on the pitch of your roof. For a pitch of 15 degrees or more, an overlap of 180 mm is needed. If the pitch is between 10 and 15 degrees, increase the overlap to 220 mm. For a pitch between 5 and 10 degrees, an overlap of 320 mm is required. Additionally, allow approximately 40 mm on each side of the corrugated roof for Rock N Lock flashing. If the corrugation ends further out, adjust the overhang accordingly to maintain the required 40 mm deduction.

It is common to overlap 2-metre corrugated roofing sheets, especially when the roof length requires multiple sheets. However, using a single sheet of the correct length is faster and easier to install, reducing the potential for draughts or leaks.

Rock N Lock flashing

When installing corrugated roofing sheets, it is common to overlap 2m sheets end-to-end or side-to-side. However, this can create the potential for draughts or leaks in extreme weather. If you can, it is better to get the correct length in one piece as this is faster and easier to install.

For longer roofs, you will need to overlap the corrugated roofing sheets lengthways as well as widthways. The amount of overlap depends on the pitch of your roof:

• Pitch of 15 degrees or over: overlap 180 mm
• Pitch between 10-15 degrees: overlap 220 mm
• Pitch between 5-10 degrees: overlap 320 mm

Before installing your corrugated roofing sheets, remember to allow space for your Rock N Lock Flashings. You need to allow approximately 40mm for the Rock N Lock flashing on each side of your corrugated roof. If your roof width means that the corrugation ends further out, simply overhang your Rock n Lock a little and make the deduction less than 40mm to suit.

Overlapping corrugation peaks widthways

It is important to note that the direction of overlap should be aligned with the prevailing wind direction at your location. This reduces the chance of wind uplift over time and increases the life span of the roof. If you are unsure about the prevailing wind direction, it is recommended to observe the weather and wind patterns in the area for a few weeks before installation.

The length of the roofing sheets also plays a role in the overlapping process. While it is common to overlap 2m sheets, it is faster and easier to install sheets that are the correct length in one piece. Longer roofs may require lengthwise overlaps in addition to width overlaps.

When overlapping corrugation peaks, it is crucial to allow space for Rock N Lock Flashings. Approximately 40mm of space is recommended on each side of the corrugated roof. If the corrugation ends further out, you can adjust the deduction to less than 40mm to suit your roof width.

Overlapping more than two corrugations

Overlapping corrugated roofing sheets is a common practice, especially for 2m sheets. While it is possible to overlap more than two corrugations, it is important to consider the pitch of your roof when determining the amount of overlap required.

For roofs with a pitch of 15 degrees or more, an overlap of 180 mm is recommended. If your roof has a pitch between 10 and 15 degrees, you should aim for an overlap of 220 mm. For roofs with a pitch between 5 and 10 degrees, an overlap of 320 mm is suggested.

It is also important to allow for Rock N Lock flashing on each side of your corrugated roof. This requires approximately 40mm of space, although this can be adjusted if the corrugation ends further out.

Overlapping corrugated roofing sheets can be done lengthways or widthways, depending on the length of your roof. While it is a common practice, overlapping sheets can increase the potential for draughts or leaks in extreme weather conditions. Therefore, it is always faster and easier to install corrugated roofing sheets in one piece, if possible.

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