Estimating Outside Walls

Outside Walls

If the Outside Walls fields are locked, the BidMagic construction estimating software program will calculate them, based on the perimeter of a rectangular project, using 2 * (Longest Length + Widest Width). If you unlock the fields, you can enter your own quantity for the total length of exterior walls on each story.

The 'suggested' perimeter calculated by the BidMagic estimating software is usually correct, even for non-rectangular projects. It will be off in the following cases:

• A 'C' shaped building.
• A building with non-right angle corners.
• In stories that have a longest length or widest width that are different from the ground floor's.

When computing the length of exterior walls, start by measuring the total length of all walls that are exposed to the outdoors and that are being worked on, for each story of the project.

• For new construction, enter the total length of all exterior walls.
• For an addition, enter the total length of exterior walls in the addition only. Do not include the contact wall where the addition and the old building meet.
• For a gut/rehab project, include the total length of all exterior walls that will be worked on in some form--whether they are getting new framing, new insulation, new wallboard or new trim.

When measuring the length of outside walls, measure right through doors and windows. Include the length of all exterior walls that show up on the plans, even if they are not full height.

Exclude porches, decks and sheds. Also exclude the garage, unless you are including it as part of the main building.