How to Convert a Porch Into a Sunroom
A sunroom can extend your living area and add value to your home. A sunroom allows you create a well-lit room where your family can enjoy the beauty of the outdoors while remaining comfortable and away from insects.
Before converting a porch or screened in porch into a sunroom there are several things you need to consider:
1. Contact your local building department to determine what type of permit you require. Depending on your plans, you will usually need a construction permit and electrical permit if you are adding lights and outlets. Plumbing is usually not found in this type of renovation, but you may want to extend an air conditioning duct into the space which may also require a permit.
2. A thorough investigation must be done to determine if the foundation is adequate for a living area. Raised porches are typically built similar to a deck and the wood posts must be sound and free from rot or insect damage.
3. The roof and gutters must be in good condition. Since you will be adding windows, it is important that the rainwater is diverted away from window flashing and overhangs.
4. The floors on porches may slope away from the house to allow any water to drain away from the structure of the home. Depending on the pitch of the floor, you may opt to keep this slope to add character, or you will have to raise the floor joists on the outer edge to make the floor level. If you have a concrete slab as the floor, you can install exterior grade wood flooring, such as mahogany, directly on top of the slab or use carpet or tile.
5. Depending on the exterior finish of the home you may want to remove it, cover it with paneling or drywall, or leave it exposed. Vinyl siding should be removed; wood siding can be left in place if it is in good condition, and stone or brick can be left exposed.
Windows and Doors
The main costs incurred when converting a porch into a sunroom will be with the windows. Depending on how wide the openings are or whether you go with panels that reach to the floor as with sliding doors, you can expect to pay between $500 and $2,000 per opening. You can choose to construct windows out of window stops and acrylic sheets, but they will not be operable and not as energy efficient. This will also lead to more of a 3-season room. You can also consider aluminum frames where you can switch between screens and storm window panels.
You will also want to add a door to provide an entrance and egress from the room to the outside. It should be a good quality door and should go with the theme of the rest of the construction. It could be a French door, slider, or insulated fiberglass or metal door with a large glass panel in the top half of the unit. It is possible to have a sunroom without a door if the porch is on the side of the house and not a main entrance. But just because you add a door, doesn’t mean you have to use it. It is easier to install one when you are converting the porch then having to go back and do it later. A slider may cost around $750, a French door can be between $700 and $1,500, and a metal door may be about $400 to $600.
Depending on the original construction of the porch, you will most likely have to install small knee walls for the window units to sit on and framing above the windows to fill in the space between the ceiling and window. You may want to construct a solid wall on the sides for privacy. Expect to pay about $60 for material for a solid wall 8’ x 8’. (7 studs, 1 top plate, 1 sill plate, 2 sheets of ½” 4’ x 8’ plywood)
Mechanical, Electrical and Plumbing
As stated in the introduction, you probably won’t have any plumbing in the sunroom. If you want to install a small bar sink, expect to pay between $400 to $800 for a sink, faucet, piping and drains, and cabinet.
You may install electrical receptacles along the wall between the house and the sunroom since it will most likely already have receptacles nearby. An electrician will charge about $50 per outlet, but you can do the work yourself for about $20 per outlet.
Light fixtures are another consideration. Your porch may already have a light on the wall or a ceiling fixture. The best option is to remove the wall light and use this as a junction box to extend a line into the ceiling for installing a few lights or ceiling fans with light kits. If you choose to install ceiling fans, use units that are rated for damp locations or exterior use. They cost between $90 to $120 per unit. Standard light fixtures can be relatively inexpensive, about $15 upwards to $75 or $80 for more elaborate lights. Since you will most likely be spending more time in the room when it’s sunny, you shouldn’t overdo it with ceiling light fixtures. If you need extra light, use a floor lamp.
If you originally had a light on either side of the doorway, you may want to install wall sconces in their place. Remember that the original light switch is inside the house so you may want to install a new light switch inside the sunroom for convenience.
Mechanical refers to heating, ventilation, and air conditioning, HVAC, and you may not want to add any heating or cooling in the sunroom. It can be difficult to extend a forced air register and return into the sunroom since you have to go through the exterior wall and most of your existing registers will stop at below the finished floor inside your home. It is possible to install a takeoff from the original branch line, install a balancing damper, and run it inside the exterior wall and then install a wall register in the sunroom. This may not provide adequate cooling in the summer, and in the winter you should have solar heat gain in the room to make it comfortable. A better option may be to purchase a portable air conditioning unit and use it on hot days when you’re in the room. (See Buying Tips For Portable Air Conditioners). This will save energy in the long run and won’t strain your existing system. For heating, consider a portable ceramic heater, radiant heat panel, or cove heater. A portable AC unit cost around $350 for a 10,000 BTU unit, a ceramic heater may be $30 for a 4,000W heater and a cove heater may cost around $80. You may also want to install the cove heater above the doorway with a wall thermostat. (See Electric Space Heater Selection and Operation).
Cove Heater Mounting
If your porch is on a slab, you can’t really install any insulation. If it is wood and above grade, you should install insulation under the deck between the joists. Install a vapor barrier after you insulate and then sheath the bottom of the joists to keep mice and other animals from using the insulation as nesting material. Use ¼” or 3/8” exterior grade sheathing.
The three most important parts of the finish work will be the drywall, flooring, and moldings. Painting is important too, but the costs and time is relatively small compared to the other three.
Flooring can be the original decking as long as it is in good condition. You may want to repair or replace sections of the flooring. Deck board can split and become loose overtime and they may be more worn near the entrance. Consider repainting or sealing the wood after the room is enclosed. Although it’s better to work with the room open, your heavy work will be completed with the windows, framing, and drywall completed. Just open some of your new windows to provide adequate ventilation when working.
Slate Floor installed in Sunroom
You can install new wood flooring on top of the existing wood or concrete floor. Wood decking should be screwed in tightly with 2 1/2 inch deck screws. For concrete floors, you can install sleepers, strips of wood laid flat on the concrete slab. Contact your building department to determine what type of wood is best for your area. Pressure treated may be used, or some composite wood that is not affected by any moisture. The wood flooring or underlayment can be screwed into the sleepers and then tiled or carpets over. Install a vapor barrier between the concrete slab and sleepers. You also have to determine the finish floor height inside the home and the on the porch. Sometimes the threshold of the door will be the determining factor.
You may also want to install carpet or tile directly on the concrete. Make sure the surface is free of paint and any loose areas are patched with floor leveler. Carpet and tile can be glued directly onto the slab. If you are using ceramic tile or stone such as slate, you may also want to install radiant electric heat. A new product called Zmesh can be installed onto wood or concrete subfloors. See it at http://zmesh.com/floorheating.html
Moldings can be very involved, especially around the windows. Casing and sills can be installed around all the windows, casing around the doors, and baseboard can be installed around the perimeter of the room.
Sunroom Molding and Baseboard
Drywall will be needed around all of the new windows installed and patching around any access holes cut for wire runs. Install insulation inside all the wall cavities and in any gaps around window and door frames. Don’t drywall over any electrical boxes that have live wires inside, this is a code violation. Instead consider installing a decorative panel or picture over the box after a box cover has been screwed into place. You may opt to install bead board or paneling over the framing instead of drywall.
The exterior of the sunroom may match your existing exterior, but do not necessarily need to. If you have a brick or stone home, it may be costly and difficult to install brick around the new sunroom. In most cases wood or vinyl siding is used as the exterior finish. Flat wood panels can be installed between the window and door units to provide a cleaner look. You can also use extruded PVC boards for a lower maintenance option.
Sunroom with Vinyl Siding
Always install the windows and doors according to the manufacturers’ specifications especially in regards to the flashing detail. Make sure that you have adequate cap flashing and caulking in place to prevent any leaks.
Many porches have a window somewhere along the length of the home. If you don’t like the appearance of a window looking into your new sunroom, you may want to remove it and install a French door. This way you don’t lose any light and you can an additional entrance to the room. Make sure that you install locks on the interior doors you add, or install a keyed entrance lockset on the exterior door or doors in the new sunroom for security.
Another option would be to fill in the window, which I don’t recommend for aesthetics. A better alternative would be to install interior window shutters on the existing room to have the option for closing off the view of the sun room or open then to provide natural light.
A small consideration for sunrooms on the front of the house would be to move the doorbell to the new entrance of the sunroom. Some low voltage doorbell wire is all that you need.
You may want to change the door leaf leading to the sunroom with a full-glazed door. Simply remove the existing door and install the new door panel on the old hinges. Measure the door opening and order a new leaf at your local lumber yard or home center. You may need to plane the edge or trim the bottom to fit the existing opening.
Tools and Materials
Deck Screws (Stainless steel)
Compressor and Nail Gun (optional)
Drywall, drywall tape, drywall screws and spackle
Electrical switches, outlets, light fixtures
Flooring – Wood, ceramic tile, carpet
While converting a porch into a sunroom can be challenging, it can be done over time to limit the disruption and spread out the costs. It will not only provide additional living space, it will also add to the value of your home.