Second fix
Skirting / perimeter trim
- where
- net trim length (m)
- room length (m)
- room width (m)
- deductions (m)
- additional returns (m)
- order length (m)
- waste (%)
Explain this equation
Gives the length of skirting or other perimeter trim for a rectangular room, then an order length and a rough count of stock lengths.
L and W are the room length and width in metres. D is the total length deducted for doorways and other gaps. R is the total length added for returns, such as round a chimney breast. Lnet is the net trim, w the waste percentage and Lo the order length.
2(L + W) is the room perimeter. Deductions are subtracted and returns added to get the trim actually fixed. Waste is applied as (1 + w/100). The stock count is the order length divided by the stock length, rounded up.
A 5 × 4 m room has an 18 m perimeter. Less 0.9 m for a door and plus 0.2 m of returns, it is 17.3 m. With 10% waste that is 19.03 m, or five 4.2 m lengths.
Watch out: the stock count is a total allowance, not a cutting plan. Walls longer than one stock length need joints.
Calculate linear trim from a rectangular room after deductions and returns.
Enter your values to see the result.
Good to know
Deductions and returns are total lengths in metres. Stock count is an aggregate allowance, not a cut plan; check each wall run and joint locations.
Limits
Skirting stock allowances do not guarantee every run can be cut from those stock lengths.
Sources
- Geometry / arithmetic
This is a calculation aid, not a structural design or compliance certificate. Every default is an example, not a specification for your project.