Three-season Porch - Part 4 of 4

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Three-season porches add living space to your home. Typically, they are wired with lights and electrical service, but they are not hooked into your heating and cooling system.


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A three-season porch blends indoor comfort with an outdoor atmosphere. It is a transition space between your home and yard. Windows with self-storing screens line each wall to provide plenty of fresh air and an enjoyable view of your landscape, while keeping insects and inclement weather at bay.
Building a three-season porch is an ambitious project, but like any large-scale project, it can be divided into simple, manageable steps, making the construction process less daunting. Because each building situation is different, you’ll need to create your own plans and plan drawings to reflect the specific details and dimensions of your home and yard. For example, the distance from the ground to your home’s entrance will vary, affecting the height of the deck frame posts and the steps and landing. Make sure all plans comply with your local building codes and zoning laws. You will need to submit complete plan drawings, including an elevation drawing and a floor plan, along with an estimated cost of materials in order to be issued a building permit.

What You'll Need


Circular saw
Caulk gun
Power auger or clamshell digger
Reciprocating saw
Hand tamper
Power miter saw
Hammer drill


2 x 2s
2 x 4s
Lag screws
Joist hangers
Post anchors
Angle brackets
Hurricane ties
Common nails
Joist-hanger nails
Box nails
Siding nails
Roofing nails
Finish nails
Deck screws
Masonry screws
2 x 4 trusses (8-in-12 pitch)
Silicone caulk
Construction adhesive
Roofing cement
15# building paper
Compactible gravel
12"-dia. concrete footing forms
Asphalt shingles
Windows with self-storing screens
Combination storm door and threshold
12 x 12" aluminum louvered vent


Step 1

Three-season Porch

Install the gable vent. At the gable wall, mark the location for the vent, then drill 3⁄8" holes at each corner. Draw reference lines between the holes and cut at the lines using a jigsaw. Position the vent cover over the opening, making sure it is level, then fasten it to the sheathing with 4d galvanized box nails.

Step 2

Three-season Porch

Install the siding. Cut 1"-wide strips from the top edge of the siding pieces to use as starter strips and install along the top edge of the base trim using siding nails. Cut the first course of siding to fit between the corner trim boards with a slight gap (1⁄8" or so). Attach with 6d siding nails driven at stud locations, about 11⁄4" down from the top edge. Install the next course so the bottom covers the siding nails on the course below. Finish the installation, maintaining a consistent reveal. Ripcut the final pieces to size, if necessary, and caulk all gaps and seams.

Step 3

Three-season Porch

Add steps. Install steps to gain access to the porch. There are many types of steps you can build. Because the porch is attached to your house, any attached steps must be supported by footings that extend past the frostline. The concrete pad seen here is supported by such footings. The undercarriage for the steps, made from pressure-treated lumber, is essentially a mini-deck supported by a ledger on one end and a framed wall on the other end. The landing area must be at least 4 ft. wide and 3 ft. deep.

Step 4

Three-season Porch

The steps themselves are made with wood stringers that support wood risers and treads. In most areas, if you have more than two steps you are required to include a grippable handrail.

Step 5

Interior Finishing Ideas

Because a three-season porch is treated as an outdoor space, finish the interior using materials suited for indoor/outdoor applications. They will hold up best over time and against exposure to the elements. Wood paneling or tongue-and-groove wainscoting (photo A) are the most practical choices for finishing the porch walls. Both are easy to install and are much more durable than wallboard. Ceilings can also be finished with paneling or with a suspended ceiling system.

Step 6

Interior Finishing Ideas

Use finish-grade lumber or decorative moldings to trim out corners and windows (photo B). Note: Before you finish the walls and ceiling, install all electrical receptacle and fixture boxes and run the cables from the main service panel. The porch should be wired on its own ground-fault protected (GFCI) circuit.



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