Planning Home Additions

A helpful guide to planning your home addition, broken down into five manageable steps


Need help planning house additions? Follow this handy guide to design an addition to suit your home and your lifestyle.

Maybe a new family member has arrived. Maybe you're tired of cramming your family into a tiny kitchen, or maybe you are finally building the master suite you've dreamed about for years. Whatever your reason for wanting to add on to your home, you know you need more space. But how do you go about building the much-desired addition?

We've broken down the planning process into five basic steps to guide you, from compiling ideas and determining a budget to choosing professionals. It's not so overwhelming when you take it one step at a time, so take a deep breath and dive in.

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Although the early stages of a remodeling project often include ideas sketched on a napkin, the best starting point for house additions is a wish list—a compilation of elements that will shape or influence the design. Making a list helps you prioritize, helps you edit your wants and needs, and helps you communicate with prospective designers or contractors.

Identify key objectives
Start your list by asking yourself what you want the project to achieve or what problems you want it to solve. If you're planning an addition, you obviously need more living space. Maybe you also need to improve your home's traffic-flow pattern or boost storage capacity. Or do you need more convenient indoor-outdoor access or more entertaining space?

Get inspired
To bring your wants and needs into clearer focus, allow yourself plenty of "dream time." Fill a scrapbook with photos and plans clipped from your favorite home-design magazines. Check the buying guide sections for information on products and materials. Pick up books or watch TV shows that feature remodeling or redecorating projects. Glean ideas and inspiration by touring new and remodeled homes in your town.

Choose some savvy splurges
Decide which special features—fireplaces, a kitchen island, or an elaborately outfitted media wall—are most important to you. Even if a feature seems costly, don't rule it out right away. You may be able to splurge on a couple of items and economize elsewhere.

Not all must-have items are costly
Laundry chutes, for example, are relatively cheap to build but require careful planning at an early stage. Getaway spaces—cozy nooks and crannies that offer spots to curl up and savor quiet moments—often make use of otherwise unused space, such as landings, dormers, and jogs in hallways.

You've had your chance to dream. Now it's time to head back to reality and take a look at the real-life factors that play a role in your project. Recognizing limits or constraints ahead of time heads off wasted efforts and disappointments later.

Calculate your clout
First, figure out approximately how much financial leverage you have to cover the cost of the project or to swing a home improvement loan. Take stock of your major assets, such as the equity built up in your home, your accumulated savings, and any of your investments (stocks, bonds, and other securities) that are easily liquidated.

Also consider your credit rating, your monthly payments, and any do-it-yourself skills you plan to apply to the project. An excellent credit rating and a low number of large monthly payments give lenders extra confidence about your ability to repay a second mortgage or home improvement loan. If you plan to cut costs substantially by doing some work yourself, be sure to cite it as part of your assets. Not only will your labor reduce your debt load, but it also conveys your commitment to the project.

Check out the site
Take a close look at the building site, or where you plan to construct the addition, plus the areas around it. Consider the location of trees or outbuildings you want to preserve; views you want to capture (or screen out); and exposures to sun, shade, or prevailing breezes. While you're at it, be sure to check for obstacles you need to remove, relocate, or work around, such as power lines, utility poles, and underground fuel or septic tanks.

Run it by city hall
Be sure to also look into the legal restrictions and building codes regarding what can be built on the property. Often, setback restrictions govern how close a structure can be built to property lines. Other legal constraints include height restrictions, building area ratios (allowable ratio of buildings to land), design covenants, and historic-district preservation ordinances. If your project doesn't conform in some way, you may be able to apply for a variance (special permission to disregard a particular ordinance).

Crunch the numbers
After reviewing your financial clout and the construction site, take a stab at crunching the numbers to decide whether you're in the ballpark regarding budget. Homeowners commonly underestimate remodeling costs.

Survey a few local designers or contractors to find out the average cost per square foot for remodeling projects in your area. When you ask for the information, refer to a price point or category that describes your project, such as "budget," "midprice," or "high-end." Low-end home additions without mechanical work typically cost $100—$130 per square foot. Extensive home additions in high-price areas cost much more. Once you obtain an estimate, add 10—20 percent to cover unforeseen delays and remodeling costs.

Once you form an idea of what you can afford, it's time to think more seriously about the structure of your addition. Here's a brief rundown of your options.

Choose manufactured or stick-built construction
A few decades ago, all home additions were built totally on-site, one piece at a time. The stick-built method offers flexibility and is still predominant, but manufactured (or modular) additions have gradually gained popularity. Fabricated on an assembly line at a factory using standardized designs, manufactured components can be varied somewhat for each project. Some manufacturers now offer a mix and match of modules, such as dormers, bays, and half gables, so an addition merges comfortably with the shape and style of an existing structure. Modular construction dramatically reduces on-site labor. Much interior finish work can be done at the factory, eliminating weather delays and allowing purchases of materials in bulk quantities.

Create one addition or several
A chief advantage of putting new space under one roof and on one foundation is cost. Several small additions cost much more to build than one large one. Also, multiple additions usually require more design input because each unit must be merged individually with the existing structure. However, a single addition doesn't always provide the best option. In some cases, problems need fixing at opposite ends of the home. Sometimes a property lacks the space for a sizable multiroom addition but can handle two carefully positioned single-room structures.

Build up or out
For the majority of house additions, building out provides a sensible strategy, but sometimes it's best to build up instead. On extremely tight sites, such as in closely built older neighborhoods, no buildable area remains for horizontal expansion. Some homeowners choose to build up in order to preserve outdoor living space or to gain privacy for bedrooms in a new second story. You might get the space you need by raising certain portions of the roof.

Good projects are the result of teamwork, and teamwork relies on trust and communication. A project team can be looked at like a short-term marriage.

Hire the professionals
The number and type of people you need on your team depends on the scale and scope of your project. Even if you plan a rather small addition, you probably need a designer or draftsperson to prepare one or more working drawings to apply for a building permit; freehand sketches or rough diagrams normally don't suffice.

For more extensive projects, an architect can help you come up with the overall design. He or she can design an efficient layout and merge the addition's design with your existing house. Then you need to hire a general contractor to supervise construction.

Another route is to hire a design-build firm. It provides a complete package of services, including design consultation, construction drawings, and project management.

Costs for services vary widely. For design consultation, an architect or designer could charge an hourly rate ($50 and up); others charge a day rate or a percentage of the total project cost (usually less than 7 percent). Straight drafting services are usually billed at an hourly rate of $15-$25. A general contractor normally charges at least 20 percent over the other costs of the project.

Pick the right people
One sure way to track down good candidates is by word of mouth. Talk to neighbors and friends to find out if they experienced good results from a certain designer or contractor. Another good reliability clue is longevity; area professionals who have been in business for several years likely will be reputable and reasonably congenial; dishonest contractors don't usually stay afloat or around long. Take time to interview and get estimates from several candidates before selecting your professionals. Ask to see samples of their work, and check with the Better Business Bureau to see if clients have filed complaints about the company.

Spell out the project in black and white
All reputable designers and builders work according to terms set forth in a contract, a legal document that safeguards against misunderstandings and costly calamities. Most construction contracts contain three instruments: a text document written in fairly plain English, a set of blueprints (working drawings), and a list of materials. When you sign the text document, you agree to abide by all three instruments.

Contracts vary somewhat, but most include provisions for the following: a work schedule, including inspection dates and a completion date; a payment schedule (usually weekly or monthly installments, plus a final payment); statements designating liabilities and insurance coverage in the event of injuries, theft, or damage at the work site; and clauses that say the builder cannot be held responsible for delays that are caused by weather and other forces beyond his or her control.

If you plan to do some work yourself, spell it out in the text document. If you will obtain any materials and products on your own, indicate the items in the materials list.

Bring the design into focus
A good designer organizes your ideas in a floor plan that fits your lifestyle and steers you past the pitfalls of poor planning, such as dueling door swings, stingy storage, and skimpy windows.

Visualize the space
Your family lives in a three-dimensional space, not two-dimensional plans and elevations, so as your designer sketches a floor plan, try to imagine how the space will function in three dimensions.

Ask yourself or your designer a series of questions as you study the drawings. What will you see when you step into the space—a dramatic window wall, a cozy hearth area, or a bowling-alley vista leading your eye directly to the powder-room toilet? Put yourself in various spots on the plan and think about what you'll see in the real space.

As you "walk" through the home design plan, think about your family's daily routine. Is there ample seating in the gathering area? Will traffic circulate freely around the sitting space, or will people cut across the room?

Add to-scale furniture layouts
If you have furnishings in mind for the new space, make to-scale cutouts of the pieces and place them on the floor plan to see how they fit. If walls need to be shifted, do it now, not after the footings have been poured. To allow room for large breakfronts or media cabinets, ask for elevations of the walls and mark off the heights and lengths of the pieces to see if they seem proportional to the space. Check to see if your furniture arrangement requires electrical outlets in special locations. Think about placement of phone jacks and cable hookups, which are commonly forgot when planning house additions.

Request 3-D sketches
If you find an area hard to visualize and think it might pose a problem, ask the designer to create a three-dimensional sketch. A 3-D drawing shows how the space will appear when built. Even the most talented pro can't predict the appearance of every cubic inch and occasionally discovers minor goofs during rough framing, drywalling, or finish work.

Crunch the numbers again
Once you're satisfied with the design, it's time to take another look at the numbers—this time, a really hard look, because you'll be dealing with real numbers and you'll be expected to make a go or no-go decision fairly quickly. If the numbers seem manageable, you're all set to put your plan into action.

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