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Build a Screened Porch

Construction How-To, Decks, Outdoor Living, Porches and Gazebos June 28, 2003 Sonia



 

 

 

 

 

 

 

 

 

Ahhhh, the romance of a screened porch—lemonade and cool comfort for those hot summer days and a hammock or chaise lounge for slumbering those warm nights away. And it’s all outside where you can still enjoy Mother Nature without the hassle of insects. A screened porch not only can add to the enjoyment of your home, but to the value as well. A screened porch can also be constructed in three phases. Many homeowners have started with a patio, added a roof and then ended up screening a porch. The porch shown is a prime example of building in phases over a period of time. Or the project can be done as a single phase from beginning to end. (For a low maintenance product for your porch, check out Latitudes Decking Products, click here.)

 

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Support

Whether adding an enclosure to a roofed area, or building from start, in many instances you will be required to provide a building plan for any home addition to local building authorities. You may also be required to obtain a building permit.

Regardless, the first step is to create a solid base for the construction of the porch. In some instances decks may be used. In this case the area of the deck with the porch must be floored over with a solid material to keep the insects from coming up through the cracks in the deck. Additional support must also be placed under the deck to support the additional weight of the porch, as well as any snow that may accumulate in northern climates. In many instances, however, the porch will be constructed on a concrete or other type of solid patio. The ideal scenario is to pour a concrete slab for the porch, which can then be further embellished with a slate or quarry tile floor. A screened porch will have to handle the elements, so make sure all materials used are for exterior use.

If using a poured concrete slab, or other solid surface, make sure there is proper drainage of water away from the house, as water will get into the porch during storms. Most builders consider 1/4-inch slope per foot the proper design for a concrete patio. For a 12-foot porch this would be 3 inches, and this is too much for a porch constructed on a slab. For the porch shown, a pitch of 1 inch for the 12-foot length was used. This doesn’t hamper construction quite as much as the sharper pitch, but still allows water drainage.


The slab must be laid out and formed. If you do not have the proper tools or experience with concrete work, you may wish to have a contractor do this portion. Pouring a slab of the size shown is do-able for many Extreme How-Toers, if time is taken in laying out the project so it is square and formed to the proper pitch. Concrete tools can be rented at many rental stores. Do not attempt, however, to mix the concrete for this project. You will need to purchase bulk concrete.

Make sure the slab is well reinforced and a footing is poured around the edge. The footing should be sized to match your geological location. Check with local concrete dealers as to the size and depth required. After forming but before pouring, place a layer of gravel down, followed by welded wire reinforcing. Pour the concrete, level it off with a drag and trowel it smooth. You can hand-trowel, but a power trowel speeds the work. If building a screened porch on a new slab, place anchor bolts around the perimeter in locations for the bottom plate of the porch. The plates can then be bolted to the slab to anchor the porch in place. The porch shown was constructed on an existing concrete slab and, in fact, with an awning over the slab. The structure was simply framed and screened. In this case the lower plates were anchored in place with a rented concrete gun that shoots anchors through the plates into the concrete.

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Framing

In the case shown one corner post was already in place but partially rotted. A garage formed another side of the porch area. During construction the roof was slightly jacked up and propped in place. The old post was removed, a 2-by-4-inch top plate was put in place and new corner posts were inserted beneath it. Then the door-side posts were installed as well as the opposite corner post. The roof was then lowered slowly in place, and the posts were anchored to the top plate with 3 1/2-inch exterior wood screws “toe-nailed” through the sides of the posts into the top plate.

If constructing a totally new screened porch without the roof already in place, construct the front wall with a bottom and top plate, the 4-by-4-inch posts, 2-by-4-inch “studs” and the blocking for the lower framing. Stand the wall upright, make sure it is plumb and then brace it in place. Construct the side walls, stand them up and anchor them to the outside wall. Or you can erect the posts, plumb them and add the framing and blocking made from 2-by-4s. Cut a 2-by-6-inch inside “plate” and fasten it inside the front wall, flush with the top edge of the plate. This adds strength to the front support, or you can use a double top front plate. Then cut an inside support plate for each side and anchor it as well.

If constructing a roof, as opposed to screening-in a roofed porch, fasten a sill plate to the house between the two side walls and flush with their top edges. The rafters can then be positioned down on top of this. Joist hangers can also be used to help anchor the house ends of the rafters in place. In many instances the roof pitch will match that of the house. Or in some cases, such as the one shown, the roof pitch is much shallower. Make sure the pitch is correct for your area and snow load. Again, check with local authorities. Two-by-6-inch rafters are recommended for the more shallow-pitched porch roofs. Extend the roof outward 1 foot past the walls. Use blocking on the side to anchor the hanging rafters. Fasten a fascia board to the front edges of the front rafters and to the sides.

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Use a bevel gauge to lay out rafter angles.

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Cutting the framing is quick easy with a cordless circular saw.

The top can be any number of materials, including translucent sheeting or solid roofing materials. Clear, translucent, as well as colored fiberglass panels are available for roofing. These offer weather protection and shade, with the amount of shade depending on the amount of light transference allowed by the material. A number of products are available, such as Filon Supalite, a clear, lightweight rooflight with a 3-inch pitch profile. Make sure when using these types of products to follow the manufacturer’s pitch recommendations. Filon Supalite GRP rooflights are very tough and impact resistant, withstanding high winds and heavy hailstorms. The material has exceptional durability, and does not shatter over time, nor expand or shrink. It is easy to handle, pliable and easy to cut with no special equipment. The porch shown features solid roofing materials. The underside was covered with white vinyl soffit material to match the white vinyl siding. In addition, a ceiling fan with a light was added. When installing ceiling fan/lights in screened porches, make sure you choose a ceiling unit that is approved for outdoor, wet or damp use.  (For Decking Material, Check out Latitudes Decking)

Screening

The next step is to add the screening. Screening is available in a wide range of materials including rustproof bronze, copper or aluminum, as well as anodized aluminum with a baked on finish, and even vinyl. Vinyl has become increasingly popular because it’s easy to work with and durable, although not as durable as some of the metal screens. The traditional method of installing screening on porches is to fasten the screen in place and cover the edges with batten boards. The porch shown was first painted, the screen applied, then the painted batten boards were nailed over the installed screen. The hardest chore is installing the screening without having sags or wrinkles. Cut the wire to fit the opening, overlapping by 1 inch. Fasten the top edge in place with staples. Pull the screening down and, starting in the middle of the bottom edge, work toward each side, making sure the screening is smooth and not wrinkled. Then begin in the middle of each side and work to the outside edges, again smoothing and stapling. Once the screening is fastened, nail the 3/4-by-1 1/2-inch batten boards over the screen edges.

 

Finishing

Purchased wooden or prepainted metal or wood screen doors may be installed in the door openings, hinging the screen doors to batten boards and overlapping the posts and upper framing. Screen door closures or springs and hooks can be used to hold the door or doors shut. On the porch shown splashboards were installed along the bottom to prevent rainwater and mud from splashing into the porch. The splash blocks were cut from wood siding and fastened to the bottom blocking and posts after the screening was installed.

 

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