How to estimate the price for building a porch

Updated February 21, 2017

Building a porch on a house can expand living and entertainment space. Estimating the cost of a porch must include all materials and labour. You can reduce that overall cost somewhat by doing some of the work yourself.

Measure the site for the porch with the tape measure and write down the exact measurements. Sketch the design in detail. Write down the amount of concrete needed for the porch foundation or concrete needed for porch footings that will support a wooden foundation. Concrete estimators for various projects can be found online.

Estimate how much lumber is needed to build the porch framework. Count 5 x 30 cm (2 x 12 inch) boards for support framework. Flooring and roofing will require these boards every 45 cm (18 inches). These larger support boards will need to be installed to support plywood sheathing on the roof or porch decking. Use 5 x 15 cm (2 x 6 inch) boards for floor decking on the porch. Estimate the cost for salt-treated timber for all components of the porch.

Add up cost of plywood sheathing in 1.2 x 2.4 m (4 x 8 foot) sheets for the roof area. Use exterior-grade plywood. Add up the cost of tar paper, asphalt shingles and stainless steel flathead roofing nails. Ask a hardware store sales person how many nails would be needed for the size of porch you are building. Enquire as to whether you can return any unused materials.

Figure in premade posts or scrollwork railings. Ask a sales person to help you estimate these costs. Buy these materials in hardwoods vs. soft woods for a longer lifespan. Hardwoods, such as oak or cedar, are excellent for this purpose.

Estimate the cost of paint or stain for the porch. Add the cost of freestanding steps or the cost of constructing steps. Figure in plywood and wood trim materials that will box in the end of porch rafters for the soffit areas and underside of the roof area. Use exterior-grade plywood. Check out the price of hiring an electrician to run wiring for porch lights and the cost of wiring. Add in the cost of one or more light fixtures, if necessary.


Talk to other homeowners who have built porches, if possible. Ask them to review your list to target any supplies you have forgotten to include. Go online to view all parts and pieces that make up the construction of a porch.


Design a porch that looks well with the overall design of your house and will not devalue it.

Things You'll Need

  • Tape measure
  • Sketch of finished porch
  • Sketch pad and pencil
  • Measurements of porch
  • Cost quote for concrete foundation or footings
  • List of materials
  • Calculator
  • Estimated number of hours for building
  • Comparative quotes from three builders
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About the Author

Judi Light Hopson is a national columnist for McClatchy Newspapers. She is founder of Hopson Global Education and Training and co-author of the college textbook, Burnout to Balance: EMS Stress. She holds a degree in psychology from East Tennessee State University, and has been a professional writer for 25 years.