How to Build Additions to Existing Homes

Consult with a property appraiser to find out how much equity you have in your home if it is needed to finance the addition. Ask the appraiser to assess the worth of your home with the planned addition. Meet with a designer and project manager to determine the scope of the addition. Revisit with the appraiser, then talk to a banker about the estimated budget.

Select a qualified contractor, perhaps by meeting with officers of homeowners associations in your area. Obtain references, and call the Better Business Bureau to ask about complaints. Enlist an architect if the home addition has vaulted ceilings, major roof-line changes or the home was designed by an architect initially, experts at the National Association of Home Builders say.

Envision your ideal space and build a wish list that includes what you must have and amenities you'd like to have. Ask the contractor about cost-saving options, for example, left-over flooring from another project or a bathroom garden tub from a close-out store.

Begin by digging and pouring concrete footings; build the foundation for the crawlspace or basement first. Have block layers install the entire foundation and allow the mortar to dry. Start the framing process by ordering lumber boards, exterior plywood or particle board sheathing, exterior-grade plywood and roofing materials. Hire a roofing company to plan any removal of your existing roof and to tie the roof of the addition to the home's framework. Have the builder install windows and exterior siding to enclose the addition.

Build interior framing for dividing rooms and creating doorways. Have ductwork and vents installed for tapping into your existing heat and air systems. Install drywall for ceilings under the attic, then insulation in exterior walls and attic areas. Hire a qualified electrician to install wiring, outlets and light fixtures. Engage an electrician who can offer specific input about wiring upgrades if your home is older.