Porch building: what to know

What the job involves, what changes the price, and what to ask a pro.

What porch building is

Porch building constructs a covered or open porch with a foundation or piers, a framed floor, posts, a roof, railings and steps, styled to match the house. A porch adds shelter at the entry, and a good build ties the roof flashing, drainage and the floor framing into the existing house so water does not get in.

Signs you need it

  • The front or side entry has no covered space, and rain or snow lands on the door and the steps
  • An old porch was removed or failed, and the house needs a new entry that matches its style
  • The entry steps are steep or unsafe, and a porch with a landing would make the approach easier
  • A new front door or an entry change needs a protected area in front of it
  • A flat area next to the house needs a covered space for sitting, grilling or a bench
  • A home addition or a renovation calls for a porch that ties into the roofline and matches the trim

What the pro does

  • Check the house foundation, the grade and the existing roof to plan the porch height, slope and tie-in points
  • Set footings or piers at the marked locations, with post bases or anchors that keep the posts clear of the ground
  • Build the floor framing with joists and beams, sloped slightly so the water runs away from the house
  • Set the posts and build the roof frame, then install the roofing with proper flashing where the porch meets the house wall
  • Install the decking or porch boards, the railings and the steps, and the trim that matches the house
  • Finish with a paint or stain and check the drainage at the steps, the posts and the flashing before the job closes

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Porch size, height and style, since a tall or wide porch needs larger posts, beams and a bigger roof
  • Foundation type, such as piers, a slab or a full footing, which depends on the soil and the grade
  • Roof type and tie-in complexity, including whether the new roof must join an existing hip, gable or valley
  • Flashing and drainage details where the porch meets the house, which add materials and time
  • Railing and step design, such as wood balusters, metal railings or a wide landing with multiple steps
  • Permit and inspection stages, and any structural review needed for a large or tall porch

What a written quote should spell out

  • Porch dimensions, height, roof style and the foundation type named
  • Footing or pier count, size and depth, and the post and beam sizes
  • Roof framing, roofing material and the flashing at the house wall
  • Floor boards, railing style, step count and the trim details
  • Drainage at the steps, the posts and the floor, and the slope of the floor
  • Permit responsibility, inspection stages and the warranty on the work

Questions to ask before you hire

  • How will you tie the porch roof into the house, and what flashing do you use?
  • What foundation do you set, and how deep do the footings go for this soil?
  • How do you slope the floor so water drains away from the house?
  • Will the porch match the trim, the roof pitch and the style of my house?
  • Who pulls the permit, and how many inspections will the porch need?
  • What happens to the steps and the posts if the ground moves or freezes?

Red flags

  • Attaches the porch roof to the house without a flashing plan where it meets the wall
  • Sets posts directly on the soil or wood blocks with no base or pier
  • Builds the floor flat or sloped toward the house, which holds water against the framing
  • Says the porch does not need a permit without checking the local rules
  • Matches a roof pitch or trim style poorly, then says it is what the customer chose

What you can do yourself

A homeowner can paint or stain a porch, replace a few trim boards, or build a small ground-level platform with a pro's review of the plan. Call a pro for any porch with a roof, any porch attached to the house, any porch that is raised high or has steps, since those carry structural and water risks. Porch roofs and high framing involve falls and falling materials, so use fall protection and keep people away from the work area below.

Licenses and permits

Porch building is commonly done by licensed contractors, and a porch with a roof, a raised floor or an attachment to the house often needs a permit in many areas. Check with your state or local licensing agency and your local building department before work starts, especially for the footings and the tie-in to the roof.

Porch building questions

Why does my porch roof leak where it meets the house?

The usual cause is flashing that is missing or set wrong at the house wall, which lets water run behind the roof. A pro should check the flashing and the tie-in whenever a porch roof is built or repaired.

Can I add a porch later to an existing house?

Often yes, but the foundation, the roof tie-in and the drainage must be planned around the existing house. Ask the pro to check the framing and the grade before the design is final.

Do porch floors need a slope?

Usually, a slight slope sends water off an open porch floor and away from the house, which protects the framing and the door. Ask the pro how they set the slope so you can see it before the boards go on.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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