Have you ever heard of sarking board? If not, we’ve got you covered!

Sarking boards come with many insulating benefits and have qualities that can strengthen a building’s roof structure making them perfect for areas with extreme weather.

Find out more in the information below and learn more about what you need to consider when purchasing new boards for your property.

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What are sarking boards?

Sarking boards are softwood boards. They’re designed to fit onto roof rafters for extra strength to the building structure. They’re not required but are used in areas with high rainfall or environments commonly affected by torrential rain and high winds.

Scotland is especially familiar with this type of board as the country often succumbs to this varying weather. Scottish building regulations also state this must be used in many cases because of the extreme weather.

An alternative meaning of sarking is referring to a pliable membrane. This could be the following:

  • Felt
  • Polystyrene
  • Reflective foil

As a result, these materials can insulate, reflect heat and provide additional weather resistance. Working as a protective second layer for the roof, preventing rain from penetrating the roof cavity.

The material can also help reduce drafts, limiting dust from entering the building through areas with spaces around them like downlights and vents. Thus, improving thermal performance.

A professional fitting sarking board on a pitched roof.

Why use sarking board?

As mentioned, sarking boards help improve the quality of strength of a building’s structure when fitted onto roof rafters. However, the sarking board can also be used as an acoustic and thermal insulator.

Certain boards can also be used as sheathing boards to provide additional structural support to the roof and on external wall applications such as external wall insulation.

Additionally, if you own a new build, then this might be your choice. Unlike a refurbishment to the attic space that typically includes installing insulation between and underneath rafters, complete re-roofing processes must include installing sarking boards for areas where roof tiles or slates need removing and then replacing over the top.

A tradesperson fitting external insulation on a pitched roof.

Where do sarking boards fit?

How you install the sarking board is as follows:

  • Insulation at the bottom between and under or between and over the rafters (Required to reach the obligatory U-value.
  • Sarking boards with a 2-3mm gap placement between each board.
  • A breathable membrane to eliminate the need for roof ventilation
  • Roof tiles* or slates

*Note: If you choose tiles, you must install counter battens and tiling battens over the breather membrane. This will allow water to drain and ensure the tiles can attach.

Under NHBC, there are additional requirements to consider. Including the type of sarking material you choose.

A DIYer working on a pitched roof installation.

Types of sarking board

Here is a breakdown of materials that are accepted for use as sarking.

Sarking material |British Standard
Tongue and groove boarding BS 1297
Square-edged boarding BS 1297
Plywood (exterior grade) BS EN 636 service class 3
Chipboard (type P5) BS EN 312
OSB (type OSB3)BS EN 300

Whichever material you choose, ensure:

  • You install sarking in accordance with the manufacturer’s recommendations.
  • Keep the type and fixing of the roof covering in mind during the installation.
  • Use the sarking in accordance with relevant assessments.

How much does sarking board cost?

At Insulation Superstore we have many different sarking boards to choose from, each varying at different costs to suit your requirements. Here are some of the products we have available.

BoardPrice (From inc VAT)
Steico Universal Woodfibre Sarking/Sheathing Board
Steico Universal Woodfibre Sarking/Sheathing board
Isolair Woodfibre Permeable Sarking Board
Isolair Woodfibre Permeable Sarking BoardPOA

Sarking board sizes

Typical sarking board sizes have a width is 150mm. However, other sarking board sizes are available depending on your requirements. Varying thicknesses are also available depending on your requirements. Here are just some of the available boards we have here at Insulation Superstore.

Sarking board lengthSarking board widthSarking board thickness
1780mm 560mm 120mm
2230mm 600mm 22mm
2230mm 600mm 35mm
2480mm 750mm 35mm

Want to know more about different types of insulation boards? We have guidance on that and more in our wide range of help and advice. Don’t wait to check it out!

And on that note…

Choosing the right sarking boards for your project

Steico Universal Woodfibre Sarking/Sheathing Board

When selecting sarking boards for your construction project, start by assessing the climate conditions of your area to determine the necessary thermal and moisture resistance properties required for the sarking.

Then, consider the material composition of the sarking boards, opting for durable options that can withstand environmental stressors such as wind, rain, and temperature fluctuations. Ensure compatibility with other building materials and construction methods to guarantee seamless integration.

Lastly, evaluate cost-effectiveness and sustainability aspects, aiming for sarking boards that offer long-term value while minimising environmental impact.

The best part? Now you know what is sarking board and what you’re options are, you’re in the best possible place to choose the right sarking boards for your next project.

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