How to Estimate Building a house?

Simple House Building / November 13, 2019

Sketch the Framing Eric Brownstone/E+/Getty Images

Start by doing a sketch of the building to be framed including the roof. It is important to identify the location of doors and windows and any other vent opening. Having the right dimensions or working with standard measurements will provide additional savings at a later stage, as waste material will be minimized.

Layout framing. Photo J Rodriguez

Write down each measurement in inches and use a marker to keep track of what framing areas have already been added. This take-off process will be ideal to determine the logical sequence you will be using when framing the building. Make separate lists for every plank of different widths and every stud, strip or timber you will need.

How Many Studs Would You Need? Studs. Photo J Rodriguez

For each wall, you will need to add three times the length of the wall; two of them to be used as top plates and the third one will be the bottom plate. To determine how many studs you will need, divide the length of the wall by 16, as studs are placed every16 inches. Remember to add four studs for each corner. Bottom sill plates are made from pressure treated lumber. Be specific when ordering pressure treated lumber.

Studs Quick Calculation Stud spacing. Photo J Rodriguez

As a quick estimate calculation, the studs needed for your work can be obtained by doing the following math:

  • Linear feet of wall construction x 0.75 for 16" O.C.
  • You will need three studs for each 90-degree corner
  • Add four studs for every 45-degree corner.
  • For wall intersections, add two studs.
  • Add two stud for openings that are five feet wide or less.
  • One stud is needed for openings over five feet wide.

Remember to add 15% for waste when doing the estimate.

How Many Headers Do I Need When Framing? Headers. Photo J Rodriguez

Now let’s determine how many headers will be needed when framing. When the door being used is wider than six feet, you need to add three pieces for each side of the door. When the door opening is less than six feet, only two pieces of wood are needed. Write down two pieces of 2" x 12" that will be used for the headers of each door. These headers will be equal to the size of the opening plus seven inches when the door is less than six feet. One ½" x 12" plywood piece is also needed to match the width of each header.

Roof trusses. Photo J Rodriguez

Let’s start framing the roof. Determine the slopes side of the building. Divide that measurement by 16 and then add two. This number will be the total amount of wood trusses required for the roof. These two trusses will be at the start and the end of the wall. To calculate the fascia, measure the length of each slope side, add double the overhang measurement on each end of the roof.

Don't forget those little details. Photo J Rodriguez

The final framing estimating step will be to determine how much sheathing we need. Start by measuring the height of each wall. Multiply that number times the length of the wall and then divide by 32. For every wall opening, multiply the height times the width and divide it by 12, and add all opening together. Subtract the openings’ from the total area of the wall. Round up to the nearest whole and repeat for each wall. Once you have all walls measured, add all those numbers to determine the total number of sheets needed. Example: a 20' long wall that is eight feet high with one typical window (4'x5') would figure like this, 20' x 8'= 160 sq.ft. ; 4' x 5'=20 sq.ft. Take that 160 and subtract 20, divide by 32, 160-20/32=4.37, and that would be the number of sheets needed, in our case five. This project will require five sheets of four by eight OSB sheathing to cover the total area of a wall 20' x8'.

Framing Estimate Total Cost

Remember, that all framing material needs to be verified and must meet local building codes. Also, make sure to get at least three vendor quotes for comparison and take into consideration that the location of the project will also affect the pricing for the material. As a good guesstimate, you can use a number between $15 to $30 per square foot on an average project. It has been determined that framing can be somewhere between 65% to 70% of the total cost of building a structure.