Enter the total square footage of the wall and select the size of the shiplap to determine the total number of shiplap needed.

Shiplap Formula

The following formula is used to calculate the total number of shiplap needed to fill a wall. 

SL = TA / SLA
  • Where SL is the number of shiplaps
  • TA is the total area of the wall (ft^2)
  • SLA is the total area of the shiplap (ft^2)

For the equation above, a person should always round up by at least 1 to have extra coverage if needed.

To calculate the number of shiplaps needed, divide the total area of the wall by the total shiplap area.

Shiplap Definition

What is a shiplap?

A shiplap is a ground of boards that are used for covering walls and roughs that are most often used for cladding.

Example Problem

How to calculate the number of shiplaps?

First, determine the total area that needed to be covered. In this example, we are looking at a wall that has a total area of 200 square feet of space.

Next, determine the area of one shiplap. The ship laps this person wants to use are a total of 7″ X 16″. To calculate the area of this shiplap, we multiply the length and width and then divide by 144 to get the result in square feet.

SLA = L*W/144

SLA = 7*16/144 = .777 ft^2

Finally, calculate the total number of shiplaps needed for this projected using the formula above:

#SL = 200 / .777

#SL = 257.58

You should then round up to at least 258 boards.