How Much Soffit Do I Need?

In order for any building to be protected, the roof must overhang the edges of the walls, leaving a roughly triangular gap between the roof and the wall. This section of the roof is known as the eaves and so to prevent excessive air flowing into the gap, horizontal boards are fitted, known as soffit boards. Soffit boards usually run all the way round a building and are used to seal the gap to prevent the weather, or animals from entering the roof space.

There are 7 steps you can take to calculate the right amount of soffit board you will need for your building:

  1. Stand at one corner of the building where the roof needs soffit boards. Attach one end of your tape measure to the ground, using a tent pin. Make sure that the tape measure is in line with the end of the wall.
  2. Start walking to the opposite end of the wall, taking the tape measure with you and take a note of the length of the wall.
  3. Repeat steps 1 and 2 for each wall on your building that requires soffit board.
  4. Add together the lengths of all walls to know the total eaves length.
  5. Next, measure the width of the eaves gap, if it isn't possible to fill it with a standard width board attached to the wall. Work out the square feet/metres of soffit board you need by calculating the total length of all of the walls by the width of the eaves gap.
  6. It's best to add 10% to your calculated length to allow for any mistakes that you may make, including cutting errors and damage caused during installation.
  7. Finally, divide the total length of the eaves (including the extra 10%) by the length of the soffit strips you have chosen to use. If you are using a single strip around the entire building, you should round the number up to the next whole number.

We provide an entire range of soffit boards, including plain, vented and hollow which conform to a number of British Standards and come complete with industry leading guarantees. Our soffit boards offer a blemish free, maintenance free solution, which are impermeable to weather and will not deteriorate or rot.

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