A four-season porch, also called a sunroom, projects from the house and has windows on three walls. All those windows provide a source of passive solar heat. You can design a four-season porch from scratch as an addition to your house or by converting an existing open porch. As an above-grade heated room, the square footage of your porch can be included in the total square footage of your house.
Determine the dimensions you want for the the room and whether you want a cathedral or another higher ceiling. You may choose a small room with seating for two to four people, making it a conversation area or a place to read. Or you may choose to make the space large to accommodate your family and to watch TV.
Choose the location for the four-season porch, which is typically built off a kitchen, living room or bedroom.
Decide whether the porch will be entered through a 30- or 36-inch-wide swing or sliding door, a wide door-less walk-through or if there will be no wall separating the sunroom from the room it adjoins.
Pick a window design that includes screens. Windows can be casement, gliding, single or double hung, awning, crank or palladium. When choosing a window, pick a design that is in keeping with the other windows of your house. If the other windows in your house lack grids, then your sunroom should also be gridless.
Evaluate the benefits of using a different exterior siding than the rest of your house. Brick, real or artificial stone, stucco or vinyl siding are some options. Walls must be insulated with sufficient electrical outlets as building code dictates for your area. Internal walls might be painted, papered or covered with bead board.
Plan for ceiling fans, skylights and window coverings to block out the sun on hot days. Decide whether you want the ceiling to be all glass or if you want a typical shingled roof. For the ceiling do you want a standard ceiling or wood, and do you want the beams to show? If you experience cold winters, a fireplace could be part of the plan. Overall heating and air conditioning for the room can be an add-on to your existing system or baseboard electric heat could be used for cold days while opened windows could be the solution for hot days. You may want to include a door to the outside.
Determine the type of flooring you want; tile or wood are the most popular. In either case, decide on the direction you want the tile or wood to be laid. Your choice also needs to coordinate with the adjoining room.
Draw the plan. Imagine standing at the doorway of the new addition to determine where windows should be and their width and height. Draw the lines for the walls and place the windows and external door (if desired).