Designing Your Addition

The process of designing your addition is actually the development of thought about a physical situation that you want to change. The design process opens your mind to new ways of understanding the space that you already have. The more familiar you are with your house and the possibilities for modifying it, the more opportunities it will present to you.

Before you begin to plan your new addition, be sure you know what you have to work with. In Section 2 you surveyed your house, assessing the physical condition of its foundation, structural framework, exterior surfaces, and mechanical systems. In that section you also used that information to draw a base plan of your house, a necessary step before you can begin to design your addition.

Planning your addition involves much more than a rough sketch on the back of an envelope. Many professionals say that proper planning represents more than a third of the work to be done in any building or adding-on project. But just because it difficult, don’t try to get by with inadequate planning. As a homeowner you have a tremendous advantage in planning—you have continuous access to your home and you know the kind of activities that go on there. You can test and revise ideas and change your plans accordingly. You can take your time. and you can have a lot of fun.

What Do You Want In Your Addition?

If you feel that step one of the planning process is deciding how to expand the kitchen into the back porch, or where to add the extra bedroom, you‘re getting ahead of yourself Back up. Your first task, which could take weeks or even months, is to examine your needs, desires, and motivations for wanting to add on to your house in the first place.

Ask yourself this question: What should our home look like in five years? The idea is to see in larger perspective what you and your family really want for your home. Then you can form long-range goals and design an addition that best meets those goals.

How do the members of your household go about discovering their wants and needs and setting goals? The best way is to make lists. Start a notebook. You’ll come back to it time and again. Your initial lists don’t have to be well written, logical, or even practical. It’s important to include everyone in your family, even future members.

Sit down together and list what you want for your home. You can use the list of questions in the box on this page to stimulate your thinking. Be sure to note your desires as well as your needs, since extravagant fantasies don’t cost anything at this stage. There’s plenty of time to be practical later. Simply write down what comes to mind. E.g.:

+ More storage, especially for sheets and towels

+ A greenhouse window in the kitchen

+ A fireplace

+ Somewhere for the kids to play

+ A family feeling of warmth and togetherness

+ A larger dining area

+ A quiet place to study

+ A bright and sunny feeling

+ Secret and private spaces

+ More room for guests

+ A television room where the TV can’t be heard from the kitchen. Also list the underlying reasons for each idea. Why do you want to make a change? Do you need more space, want a more modern look, or intend to make your house more energy efficient?

After everyone has had a chance to offer ideas, pool them together. You will have dozens of suggestions and dozens of reasons for them. After some refining, you will have a tool to use in the next step, which is to establish a list of concrete goals. These goals may change over the coming weeks and months, but for now continue to add to your list as new ideas occur to you. Try to identify the underlying reasons that over lap and build on each other.

These reasons and their suggestions will help generate some specific goals for your home addition. E.g.:

+ A kitchen where the family can come together

+ A walk-in closet so the new down stairs bathroom won’t feel messy and cluttered

+ A dining room for formal and elegant entertaining

+ An attractive facade and entry to make guests feel welcome

+ An upstairs master suite with an intimate, private feeling

+ A sunny breakfast nook to make it easier to get going in the morning

+ A basement recreation room where the children can play without getting underfoot

Reasons are important because they can help bring agreement over differences later on, they can help you see other ways to accomplish the same goals, and they can help you set priorities.

Room-By-Room Planning

The house inspection and base plan you completed in Section 2 provided new information for revising and refining your goals, made you more aware of your home s construction and all the features you want to preserve, and showed you any limitations that might prevent a particular type of addition.

Once you’ve established your long-range goals, the next step is design. Design is probably the single most important aspect of your addition, so important that it can easily determine the success or failure of your project. Many people associate the word design with style and deco ration. But in the context of planning an addition, it means much more. It means an overall plan that offers the best solution to problems presented by the situation at hand. Design decisions involve intangibles. Often there is no one right answer; any problem may have a number of good work able solutions.

In planning your addition, whether it’s a simple bump-out, a single room, or a whole wing, common sense often determines the most appropriate use of space. Your experience and house inspection notes will also guide you. Here are some overall guidelines to remember.

+ Consider key activity centers. Some rooms serve a single function, while others may have several uses. Imagine how your household members might use each new room you’re thinking of adding—for conversation, reading, game playing, television viewing, sleeping, and so forth. Also consider where guests tend to gather.

+ What is the physical space like? Will the room you’re planning be large enough for its intended purpose? Will it be too large? If it’s too large, it may present visual and auditory problems. What is the shape of the room? Are the proportions pleasing? In general it’s best to keep room shapes simple for effective use of space and low construction costs.

+ How does the new space work with the old? As you plan your addition, pay special attention to the way the new and the old spaces fit together. Will the addition have a separate entrance? If not, how will access to the new space affect traffic patterns? Will any of the existing space have to be remodeled?

+ Traffic patterns and circulation. Traffic flow and circulation are a major consideration in room layouts. Al though areas must be separated, they need to be properly related as well. Circulation provides the key to a good floor plan.

+ Don’t overlook details. Minor de tails can make a big difference in how a room works. As you work on your plan, consider these points: Do the doors swing the right way? Will they cause awkward disruptions? You may have planned enough light switches and electrical outlets, but will they be accessible once the room is furnished? Will closet space and storage be adequate? Are several furniture arrangements possible?

+ Do you have enough light and ventilation? Would a skylight or more windows help? Will the artificial lighting be adequate? Even if you have air-conditioning, each room should have natural ventilation as well.

+ Can you improve energy efficiency? Will your addition face south for heat gain in colder areas? Will trees shade the windows? Will ceiling height and expansive window areas affect heat loss?

Kitchens

If you plan to add on a new kitchen, or to expand your old one, first consider the overall purpose you want it to serve. Is it to be a work center only? Or do you need a multipurpose room for dining and family activities? Second, decide which type of eating arrangement you prefer. Do you want a breakfast nook, a serving counter, an alcove, or a separate dining room? Third, arrange the various activity centers to provide the most efficient kitchen plan.

Every kitchen has three main activity centers:

+ The food storage center includes the refrigerator/freezer, cabinets, and counter space.

+ The cooking center includes a range or cooktop, oven, counter space on either side, ventilating equipment, and cabinets and drawers for utensils.

+ The cleanup center includes the sink, counter space on either side, a garbage disposal, a dishwasher, and a trash compactor.

The efficient arrangement of these three centers is called a work triangle. The most common layouts are illustrated here:

Left: The L-shaped kitchen eliminates through traffic, and can create an eating area adjacent to the work triangle. Middle: The U-shaped kitchen is generally considered the most desirable. It offers continuous counter area and the shortest walking distance between appliances. The island kitchen, a modified U or L shape, is a good plan for two people who like to cook together. If the island is used as a cooking center, however venting can be a problem. Right: The corridor kitchen is the simplest and often the most economical arrangement. The corridor should be at least 4 feet wide to allow traffic to pass, but the kitchen location shouldn't encourage through traffic.

The one-wall kitchen is the least desirable layout, but may be necessary in some situations. If it's , the sink should be in the center of the work flow. The overall length of the kitchen wall should be no more than 13 feet.

The location of each activity center determines the efficiency of the kitchen. E.g., the range shouldn't be located next to the refrigerator. Nor should the range be located directly under a window. Breezes may interfere with gas burners, and curtains can catch fire. The local code may determine the location of the range for venting and safety, so check on this. The sink is best located under a window for natural light and a view. The dishwasher should be within 12 inches of the sink, placed so that its door does not block traffic.

As you plan, keep the following dimensions in mind:

+ For efficiency the overall size of the kitchen should be not more than 160 square feet.

+ Distances recommended by efficiency experts for the three sides of the work triangle are: 4 to 7 feet from the sink to the refrigerator, 4 to 6 feet from the sink to the range, and 4 to 9 feet from the range to the refrigerator. This means that no two basic appliances should be less than 4 feet apart.

+ The total perimeter of the work triangle should be 12 to 22 feet.

+ Allow 15 to 18 inches of counter space on the latch side of the refrigerator for loading and unloading.

+ Allow 30 to 36 inches of counter space on both sides of the sink.

+ Allow at least 24 inches of counter space on both sides of the range; 30 inches is preferable.

+ Countertops are normally 24 inches deep and 32 to 36 inches high, depending on personal preference and comfort.

+ For specific appliance and cabinet sizes, measure your existing units carefully or take new dimensions from manufacturers’ catalogs and data sheets. Be sure to allow sufficient space for doors to swing open completely.

For more information and ideas about kitchen planning, see our guide How to Design and Remodel Kitchens.

Bathrooms

First, consider the overall function of the bath you want to add. Will it be a half-bath with a washbasin and toilet, or a full family bath? Do you want to include a dressing area or laundry equipment? What about extras such as a sauna or steam bath? Will the bath be used by all family members? Economy is an important consideration in deciding on location and layout. Use existing plumbing lines whenever possible. This means a back-to-back arrangement with another bath or kitchen, or an upstairs bath located over the first-floor plumbing connections.

The layout of the principal fixtures can be a U-shaped, L-shaped, or corridor arrangement. If you live in a cold climate, locate the water supply and drain-waste-vent lines in an interior wall to prevent freezing. Avoid a layout that allows a door to swing into any fixture. Don’t locate the tub under a window. Cold drafts can be uncomfortable, and the window is more difficult to open with the tub in the way. The best tub layout is en closed by three walls or an alcove.

Several dimensions are specified by the plumbing code; check your local code for additional spacing.

+ Generally a full bathroom requires a space at least 5 by 7 feet.

+ The thickness of the wet wall that conceals the drains and soil stack may need to be 2 by 6 inches rather than 2 by 4.

+ Allow a minimum of 24 inches from the front rim of a toilet to a facing wall.

+ Allow 18 inches from the center line of the toilet to an adjacent wall and 15 inches to an adjacent fixture.

+ The minimum size for a shower stall is 32 by 32 inches.

For specific fixture sizes, measure the existing fixtures carefully or take new dimensions from manufacturers’ catalogs and data sheets. For more information and ideas on planning a bathroom, see How to Design and Remodel Bathrooms.

L-shaped; Corridor; U-shaped

Dining areas

For obvious reasons, the dining area should be located near the kitchen. The dining area need not be a separate room. Although there are advantages to screening the dining area from the kitchen, an alcove that's part of the kitchen or living room saves space and allows for multiple traffic patterns.

In making your plan, consider these key dimensions:

+ To seat eight people comfortably, you’ll need an area approximately 12 by 15 feet.

+ Allow at least 24 inches of table space for each place setting; 30 inches is better.

+ Allow at least 36 inches from the edge of the table to a nearby wall to provide adequate space for seating and rising.

Dining area

Living rooms

The typical living room serves several functions with a single furniture arrangement. Design your new living room to accommodate all the activities that will be going on in the room.

Plan your room arrangement for maximum flexibility. You’ll need to have access to several activity areas at the same time. Avoid plans that require rearranging furniture every time you want to play a game or watch TV.

Living room

Traffic patterns are critical. The number of entry/exits to the living room should be kept to a minimum. To protect the living room, an en trance hall or foyer should provide direct access to other rooms of the house.

The following dimensions will affect your planning.

+ Although it’s difficult to give a minimum size, 12 by 18 feet is considered a small to modest size for a living room.

+ The maximum distance that allows a comfortable arc of conversation is between 6 and 8 feet.

Bedrooms

First, consider the different activity areas and functions of the bedroom(s) you plan to add. The needs for a master bedroom are obviously different than for a child’s room. For in stance, a master bedroom may include sitting and dressing areas, walk-in closets, and a private deck.

Unless you have a family room or a playroom, you may want to provide extra play space in a child’s bed room. Teenagers will need a place to study, including a desk, comfortable chair, and good lighting. You might build loft beds that create usable space underneath.

Because of drafts, beds shouldn't be located under a window. One wall of the bedroom should be free of doors and windows to allow for the bed. Plan sufficient space on either side of the bed to accommodate a bedside table, and to make it easy to make up the bed.

Here are some key dimensions:

+ The minimum bedroom size is usually 70 square feet, but check your local code on this.

+ Allow at least 22 inches from the edge of the bed to an adjacent wall or closet for room to make the bed.

+ Allow at least 40 inches in front of a dresser or bureau to provide access to all the drawers.

+ Allow at least 36 inches in front of a closet to provide access and room for dressing and grooming.

Bedroom

The Design Process

The preceding design suggestions, together with your house inspection and long- term goal list, give you the information you need to start the actual design of your addition. Design is both a process and an end product. The design process is a series of techniques used to create new ideas and to define the project.

The end product of this process is a finished design. Its first stage is a concept plan, which shows the general arrangement of space and how different elements of the design re late to one another. A working plan takes the concept plan to its conclusion, showing the exact sizes, shapes, and materials to be used. The working plan, usually in blueprint form, is used by the building department and contractors for permits, estimates, and actual construction.

This section will show you how to develop a concept plan for your addition. The techniques used in the design process are divided into three stages: research, create, and critique. During the design process you will go back and forth between these phases in a continuing cycle.

Research. This is the preliminary stage of all design. Research is simply a matter of gathering all the information you can find that pertains to your particular addition needs. There are many sources to which you can turn.

Magazines. “Shelter” publications, which deal with the home and its design, are full of innovative plans and new ways to use materials and products. The ads will keep you in formed about the newest and best of the products currently on the market.

Trade publications. If you have access to a large public library or the office of an architect or contractor, look over some of the magazines distributed only to the trade. Some manufacturers, such as hardware producers, advertise only to the trade, and you will not get to see their products anywhere else.

Manufacturers. In most ads, the manufacturer provides some method for obtaining further information. This information includes brochures, many of them in color; specification sheets that give actual dimensions and finishes for the various lines of products; pamphlets that instruct you on how to install certain elements; and lists of dealers in your area.

Professional and trade associations. Manufacturers and professionals belong to associations that of ten provide lists of local dealer sources and materials. They may also produce informative booklets. Most will not recommend individual manufacturers, suppliers, or design professionals, but they can be helpful in answering your general questions.

Showrooms and home shows. One of the best ways to get hands-on knowledge about specific products that intrigue you is to visit the show rooms of kitchen, bathroom, and bed room specialists; building suppliers; plumbing suppliers; lumberyards; home improvement centers; and home shows. Although some outlets sell only to contractors and other professionals, you can still inspect an array of products, with specifications, that you might not find elsewhere.

Your notebook. You will quickly ac cumulate a pile of materials that you should organize to maintain a sense of order during your planning. File folders, scrapbooks, and three-ring binders with pockets are all helpful for grouping brochures, magazine pages, and notes. Separate them under such headings as Layout, Kitchen, Office, Appliances, Lighting, and so on. As you sort your papers into categories, the whirl of ideas circling around in your mind will also begin to sort itself out.

Clip photos from brochures rather than keeping piles of dog-eared pamphlets. Make a note of any dimensions necessary for planning, and put pamphlets dealing with installation aside during the planning stage.

Create. In this second phase, all the research you’ve assembled, including the base plan of your house, is put to use. Some of this information has an obvious, direct application to your project. Much of your research, however, is only raw material that you as the designer will transform into something totally new. Your creativity will develop new ideas and new solutions. Some of these ideas will be good, some not so good, but in this part of the process that doesn’t mat ter. The essential task is to create as many different ideas, sketches, and plans as possible.

Critique. In this final stage, you evaluate the ideas and plans generated in phase two. This involves a conscious sorting and selecting process. You discard poor ideas and re fine those that show some promise. In phase two your thinking is imaginative, fanciful, and free-wheeling; in phase three it's conservative, rational, and pragmatic. In combination, these two stages of the design process provide a natural check and balance.

Is it time to hire a designer?

If you plan a major addition to your house, or if you’re not entirely certain of what you want, you should definitely consider hiring a professional designer—an architect, building designer, or draftsman. The many advantages of hiring a professional far outweigh the cost of the services. The designer’s experience can pay off in several ways: saving money on materials; simplifying construction procedures; preparing contract materials for the contractor; making sure the project meets local codes and zoning ordinances; preparing working drawings; and most importantly, creating an efficient and pleasing arrangement.

Too often the first cost-cutting move in an adding-on project is to dispense with the designer’s services. In many instances this is a serious mistake. The designer’s responsibility is to provide the best possible design for the amount of money you have to spend. Even if you prefer to handle the design yourself, you should have a professional designer review your concept plan. A few simple changes or suggestions at this point could save you hundreds of dollars and a lot of disappointment in the future.

Concept drawings

Concept drawings illustrate every aspect of your planning and design process, from the most formless of notions to the detailed drawings on which blueprints are based.

The bubble plan

bubble plan

Your first plans of your addition should be rough sketches, even doodles, that merely show spaces and zones in relation to each other. From your list of goals and needs, you will probably see certain groupings emerge. Represent these on paper with bubbles, linking them to each other where there should be a passageway or flow of space. Don’t worry about scale, shape, or detail. The purpose of the concept drawing is to figure out solutions to your particular needs for additional space. Use a concept drawing to get an idea of how you want one space to relate to another; the size of the rooms; the connections and circulation between the new spaces and the old; and special design considerations, such as sequences and the separation of public and private spaces. Concentrate on how you will use and move around within the spaces and what form the space will take. Remember that there are usually many good solutions to any design problem, not just one.

At this point you are seeing how various functions relate to each other in terms of the space they occupy in your home. For instance, areas for eating and areas for preparing food should be close to each other, if not connected. Do you also want them to be connected to an entertaining area? Do you want eating areas close to sleeping areas? How do the sleeping areas relate to entertaining areas? Where should working areas be?

Experiment with many different arrangements—tracing paper is cheap. As you arrange and draw your preliminary concept designs, keep in mind that you are creating space for activities—studying, eating, relaxing, socializing, sleeping. Think of the real or ideal connections between these spaces, such as easy access from the dining room to the kitchen, or from the laundry area to the bedroom or bathroom. Pay particular attention to circulation—the effective use of any room is reduced if it becomes simply a corridor from one place to another.

Draw sketch after sketch on tracing paper, saving only those that seem to have the best points. Most of all, be conscious of the basic form—the bubbles of space—and how well various designs create continuity and flow, and answer your needs. This is the time to experiment with a variety of forms for the spaces you want to add to your house. You can lay out rectangles, squares, circles, angles, and free forms in many sizes and configurations, each on a separate overlay, to see whether they appeal to you or not. During the concept phase, limit your attention to general uses and structural considerations. Later on, during the working-drawing phase, you can refine your plan and select actual materials and dimensions.

At some point you will need to merge these bubble diagrams with the floor plan of your existing house. One way is to draw the floor plan as a bubble diagram and see how it meshes with your experimental plans. You may see a way to alter a few spaces to accommodate all your needs and wants; or you may have to consider an extensive addition.

Refining the concept drawing

Your next step is to convert the bubble diagram into a more refined representation of spaces. Now the size, shape, location, and relationship of these spaces becomes more important. You must take into consideration the dimensions of existing rooms that will remain intact, the condition of the house, and environmental factors like views and sunlight.

Use graph paper to speed the measuring process. Then use tracing paper to refine ideas by duplicating only certain rooms or sections and trying out variations for adjacent areas.

Keep playing with various ideas, spaces, and sketches. E.g., you might turn a sketch upside down and ask yourself, “What if we did this?” Or you might remove all the labels from your plan and switch rooms around to see what happens. Just because a room is designated as a laundry room or a bedroom doesn’t mean it can’t serve another function as well. Some of your most creative ideas will emerge from this kind of playful attitude. The design process is a cycle that takes time; don’t expect to design everything in one sitting.

Gradually you’ll refine your ideas to the point where one or more concepts show possibilities. Now is the time to begin incorporating dimensions and standard lumber sizes. Many building materials come in 4- by 8-foot panels; lumber is sold in 2- foot increments. Plan to use these standard sizes in your design. It’s fine if your plans remain rough at this stage of the design, but eventually you should provide as much detail as you can.

Once you’ve settled on an interior floor plan, it’s time to think about how the addition will affect the exterior of your house. Start by making rough sketches of the existing exterior, then show with dotted lines or a second color how the addition will appear from all sides. Use the illustrations above as a guide. Pay particular attention to the appearance of the new roof line in conjunction with the old, and to the places where the addition meets the existing house. Section 3 outlines the most common exterior design problems to watch for, and their solutions.

Testing your plans

Review the key dimensions in the section on design basics to be sure you’ve allowed minimum spacing. You should also trace the traffic pat terns on a separate overlay to see if the circulation is efficient.

Determine if your concept plan for your addition really meshes with your needs and goals. If it doesn’t, refine the plan until all your requirements are satisfied. Don’t compromise your goals just because you haven’t found a solution yet. Keep sketching and refining until you do.

After you have created one or more concept plans that seem right, there are several techniques you can use to test them. Each of these ideas can help you visualize your plans more easily and possibly point out flaws and problems.

A walk-through. In your mind’s eye simply imagine yourself walking through your plan from one end to the other. Pay particular attention to the circulation patterns between the existing house and the addition. Re verse directions and walk through the space again. Concentrate on imagining yourself in each part of the addition. Imagine each member of the family doing the same. Ask other members of your household to look over your plan and imagine themselves walking through it.

Interior elevations. If you are having trouble visualizing certain aspects of your design, doing a scale drawing of each room’s walls is useful for seeing how things fit, and for selecting finish materials.

Scale models. Take the template concept into three dimensions. Use cardboard or balsa wood from a hobby shop to construct a model of your addition. Don’t worry about de tails or exact sizes—it’s the overall space that’s important. Scale models range from the simple to the sophisticated. A hobby shop or your local library will have books of detailed instructions for their construction.

Slides. Take several slides of the exterior of your house and project them onto drawing paper. Use the projected house to trace your old house and sketch in the form of the addition. (You can also use snapshots blown up to 4 by 5 or 8 by 10 inches.) This will help you visualize the size of the addition in proportion to the existing house.

Stakes and string. Set up stakes in the ground at the outlines of the proposed addition and stretch strings between them to show the outlines of the rooms.

The working drawings

Your concept plans show the general arrangement of spaces in your existing house and in your proposed addition, and how all of the different elements of the design relate to one another. The dimensions may be only approximate. Before you can proceed with your project, you need to develop a set of working drawings. A working drawing is an accurate, scaled rendition of your final concept drawing. Working drawings are so called because the information on them alone should be sufficient to allow a contractor to build your addition.

A working drawing indicates graphically what kind, what size, and how many of each item you will need to complete the project. It also shows how to put the materials together. You may be able to draw these plans yourself, or you may want to hire a professional to do it for you.

First find out if the local code re quires working plans to be professionally drawn and if any structural elements require engineering analysis. If so, you will have to contact an engineer, designer, or draftsman to provide these services. If your local building department does permit you to draw your own plans, be sure to determine how detailed they must be.

Even if you hire a professional designer to draw up your working plans, you should provide him or her with the most complete drawings you can, including room dimensions and specifications for materials. Step-by- step instructions for drawing working plans are beyond the scope of this guide. To learn the proper symbols and procedures you can use a drafting text such as Drafting: Tips and Tricks of the Trade by Bob Syvanen.

Four Additions to the Basic House Plan

L-shaped addition

A small wing added to this basic house contains a new master bed room and large bath with a hot tub/spa. Remodeling of the original second bedroom and bath was necessary to allow access to the new wing. Bubble plans for each addition illustrated here show traffic circulation patterns throughout the original house and the addition.

U-shaped addition

With the addition of two wings, the basic house gains three new living areas: a spacious guest bedroom with bath; a private study with a loft accessible by a spiral staircase; and a secluded patio that can be reached from both new wings as well as from the second bedroom in the original house. As in the L-shaped addition, remodeling of the original second bedroom and bath was necessary.

Small second-story addition

Partial second story

This small second story, placed over the garage and storage area, is com pact but efficient, adding a second bath, a guest bedroom, and either a fourth bedroom or a study. Stairs fill the original storage area.

Large second-story addition (Plumbing aligned vertically)

Large second story

This second-story addition is set back 10 feet 1 inch from the chimney. A cozy window seat area leads into a new master bedroom, complete with hot tub/spa, and into a spacious studio or home office. In fact, the studio is so large that it could be divided into a guest bedroom and a small study. Plumbing is vertically aligned from the addition to the existing bathroom.

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