The Material List for an 18X14 Foot Room Addition

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Building a room addition can be accomplished by the do-it-yourself builder.

The successful construction of a room addition begins in the planning stage. How the room addition is fitted to the home varies by the intended use, current home structure, size of the lot and local building codes. The configuration of the new room addition also affects the materials list and costs of the remodeling project.

Foundation and Sub-floor

The materials used for the foundation of the room varies according to geographical location of the home and the configuration for how the addition is fitted to the main structure. A second story addition does not require a foundation, but may require additional 2x4 or 4x4 supports in the first floor walls. A first-floor room addition will require a concrete slab poured as the foundation, use of cinder blocks or other solid support system. The sub-floor is constructed from 2x10 lumber, or from prefabricated floor joists that resemble I-beams. The floor joists are then covered in plywood.

Structural Materials

Wood or steel are options for building the walls, ceiling joists and rafters. Walls may also be constructed of cinder block or concrete forms. For a traditional stick-built home, that is one constructed from wood, a variety of lumber sizes will be required. Lumber cut as a 2x4 is used for the wall studs, cross-supports and mudsill. Ceiling joists, headers and rafters are constructed from 2x6 lumber choices. Plywood or wafer-board sheathing is applied to the exterior of the constructed walls and roof, for additional support and to create a solid structure.

Exterior Enclosure

The exterior sheathing may be wrapped in a vapor barrier sheet or tar paper for waterproofing and insulation benefits. Afterward, a siding material, which can be wood clapboard, metal, vinyl, a concrete-infused wall board or brick veneer, is added. The roof is finished with a material that either matches or contrasts the rest of the house. Options include asphalt shingles, ceramic tiles or galvanized metal that may also be coated with a protective and color finish.

Utility and Mechanical

The intended use of the room dictates the materials needed for utilities such as plumbing, electrical and telecommunications. A room addition that expands a kitchen may not need new plumbing added, while an addition to replace the old kitchen will require a plan that includes fresh water and gray water pipes. A new home office may not require a hand washing sink, but will need wiring to accommodate phone and Internet access, along with sufficient electrical outlets for equipment.

Interior Finish

The number and type of windows and doors are also dictated by the intended use of the room. Nationwide, building codes require that any room used as a bedroom have a minimum of one window. This is a safety factor in the event of a fire. A room addition to serve as a family room may have a large sliding glass door that services double duty as a window. Prior to covering interior walls with sheet rock, fiberglass information is added for insulation. This completes the construction, then the room is finished with paint, wallpaper and a decorative floor covering.


Cynthia Clark

Cynthia Clark began writing professionally in 2004. Her work experience includes all areas of small-business development, real-estate investments, home remodeling and Web development. Clark is skilled in a number of design disciplines from digital graphics to interior design. Her diverse background and commonsense problem-solving skills allow her to tackle a variety of topics as an online writer.