Additions: Evaluating a Home’s Potential

When you begin to think about how best to meet your needs for more space, some of the most important aspects to consider are intangibles.

Look at your home as a potential buyer might. Be honest in your assessment of its merits and faults. and keep in mind that even a seemingly costly addition might still be cheaper than moving to another house.

Style. Do you like this house—its architecture and feel? It possible to change the look of a house radically during the adding-on process, but a major change in style, although attractive, can make a house stand out disturbingly among its stylistically similar neighbors.

Neighborhood. Is the neighborhood one of the best in the area, or suffering a bit from neglect? It isn't considered economically wise to over-improve your house in relation to the neighborhood. Continuity in size, material, craftsmanship, and cost along the block is desirable. A five-bedroom, three-bathroom house with a solarium and a gazebo located in a neighborhood of mostly two-bedroom one-bath tract homes would not be worth as much as if it were located in a neighborhood of similar houses. This is the single most important factor when considering if you would be able to recover the cost of your planned addition upon resale.

Schools. Even if your children are grown, the quality of the local schools will affect the resale value of your home should you want to sell it someday.

Services. What kinds of services are available nearby? Where is the nearest shopping center? Is the house convenient to public transportation and to free way access?

The owners of this historic house wanted to replace a too-narrow back porch with an attractive space large enough for family gatherings.

Assessing a House and Its Lot

Before you spend too much time dreaming about that new addition, you’ll need to take an unbiased look at your home’s potential for enlargement. You’ll want to assess both the configuration of the lot it sits on and its structural soundness, as well as intangibles such as your attachment to the house and to the neighborhood.

Assessing a home you already own is similar to evaluating a house you’re considering purchasing, but your familiarity with the house is a definite help. You’re probably well aware of its condition, its pluses and minuses. Even so, taking the time to conduct a thorough evaluation can pay off. You may discover structural or other problems that have slipped by periodic maintenance checks, and the written notes you make during the inspection will help you pinpoint areas where assessment by a professional—a building inspector, structural engineer, architect, or contractor—might be warranted before you begin planning your addition.

If you’re shopping for a new home, this kind of evaluation can help you to eliminate those houses that aren't suitable for adding on. Once you’ve narrowed your choices down to one or two, you can call in a contractor, a designer, or an architect to verify the information you’ve gathered.

If you’re evaluating a house you already own with an eye to adding on, it’s important to determine what structural and code limitations you may have. If you’re asking yourself questions like, “I wonder if the foundation would take the weight of a second story,” or “Is that slope too steep to add on to the back of the house,” you’ll probably want to call in a professional. Still, before you make that phone call, it’s wise to know the condition of your house, and to have a good idea of what you want to add and where.

In thinking about your addition, keep in mind that adding to a house can put extra stress on its structure and systems. It makes little sense to attach an addition to a house with structural flaws. To evaluate the effects of adding on, you need to know the exact condition, capacity, and expected life of your home’s structural and mechanical components.

If you’re shopping for a house with add-on potential, do some homework first. Contact the local building department for information about set backs and other zoning restrictions that might limit the kind of changes you could make. Once you’ve narrowed your choices to two or three potential candidates, subject each to a rigorous inspection.

Allow two to three hours for a thorough home evaluation. If you’re inspecting your own home, you may want to couple this evaluation with a base plan drawing of the house and lot, as described on later.

Tools you’ll need:

Before you begin your inspection, arm yourself with the following house-assessment aids.

+ Binoculars for looking at the roof or

+ A ladder and rope if you’d prefer to climb up to check the roof

+ A flashlight for checking in basement and attic corners

+ A probe, such as a screwdriver, awl, penknife, or ice pick, for checking the condition of wood

+ Kneepads, to make crawling under the house easier

+ A marble, small ball, or level to check floors for level

+ A clipboard or a notebook and pencils

+ A metal measuring tape and graph paper, if you want to diagram your house during this inspection

Zoning, codes, and permits

Before you get too deeply into planning your addition, you’ll need to gather information about the various kinds of legal limitations that could have an impact on your plans—zoning, codes, and permits. (Of course, if your plans are being drawn up by an architect or designer, he or she will be responsible for taking this in formation into account. Or you might hire a building consultant to do a feasibility study of what is possible, taking into account not only legal considerations but the site and structure of your house as well.)

To learn about the legal restrictions enforced in your area, call or visit your local building department. The purpose of your visit is fact-finding. You want to learn all you can about how zoning regulations and building codes will affect your plans. These laws can vary from county to county. Don’t assume anything until you’ve checked it out.

Zoning regulations and ordinances

Zoning regulations usually affect exterior construction only, such as additions, not interior remodeling of existing living space. Zoning is intended to protect the quality of a neighbor hood. In some areas, particularly those with buildings of historical interest, only certain architectural styles are allowed. Ordinances can also prevent the unsuitable use of property within a specific zone. If your neighborhood is zoned for single- family houses, for example, you’re protected from any business that wants to build a factory or a fast-food restaurant right next door to you.

Zoning regulations also define the required setbacks for buildings. (A setback is the specified distance a building must be from a property line.) These distances can vary from front to back and side to side. E.g., the setback from the street property line may be 25 to 30 feet; on the side or adjoining property line the setback may be only 5 to 10 feet. You should know your property lines exactly. A fence isn't an assurance of the legal property line.

Zoning laws vary widely even within the same city, and there may be other special zoning requirements in your area. E.g., your zone may have a limitation that restricts how high your buildings can be. This is especially important on a steeply sloping city site.

Zoning regulations can block your plans in a number of ways. E.g., if you plan a second-story addition, the restrictions may require the addition to be set back farther from the street than the first floor is. Depending on the size of your lot, this may mean that the only place you are allowed to add on is to the rear of the house. Or the zoning code may require off street enclosed parking for your car. If so, that affects any plans to convert your garage to living space.

If you find that your plans conflict with the zoning regulations, you can apply for a variance, or exception to the law. Variances are intended to provide a bit of flexibility to the safety and quality standards of urban development. The permit appeals department can tell you how to apply for a variance hearing if it’s necessary.

Once you (or your architect) present your case, the decision is up to the local planning board.

In addition to zoning regulations, your property may have other restrictions you should know about. E.g., an easement gives someone else, such as the utility company or local municipality, the legal right to cross your property. A deed restriction may be written into your deed and limit the use of your property in some way. If you own a condominium or belong to a homeowners’ association, a set of conditions, and restrictions may determine what you can do to your property. Be sure to anticipate any of these potential problems by examining your deed and checking with the building department.

Building codes

Local governments also decide what building codes apply in your area. The purpose of the codes is to ensure that you and others follow minimum standards for construction. Different codes may be in effect in different regions. These include the Uniform Building Code, the National Electric Code, and the Uniform Plumbing Code, plus any slate and local codes. The building department can tell you how to obtain a copy of the appropriate code. If you’re planning to do much of the work yourself, buy a copy and study it. Usually you won’t need the complete code; a condensed version or guidebook can summarize the important facts you’ll need to know. Or the building department may have a publication that lists the major code provisions affecting home additions.

Some cities have new energy codes that require an entire house to conform to code if new rooms are added. In such a case, you might be required to install new windows throughout the house even if you are only adding a kitchen or a bedroom; or you might have to upgrade your heating system. Your city building code office can give you information on any such requirements.

Building permits

Most additions require one or more permits before work can begin. Permits are generally needed for any alteration that changes the structure, size, safety, or use of living space.

They are usually not required for projects considered to be normal maintenance such as painting, wallpapering, reroofing (unless you remove the sheathing), or window and door replacement.

But don’t attempt to interpret the regulations yourself. One of the reasons for your preliminary visit to the building department is to find out the type of permits necessary for your project. Ask if inspections are necessary and , if so, at what stage of construction. Once the work begins, an inspector will visit the site to be sure that you’re in compliance with the code.

Generally the code applies only to new work that’s to be done. Inspections aren't retroactive. If your house is old, you will probably not be expected to bring the entire structure up to code when you add on—unless, of course, the building inspector finds something that's a definite safety hazard. Then you’ll be expected to correct the situation within a reasonable amount of time. Also, improvement over a certain percentage of property value requires upgrading the whole structure to code.

You also want to find out what you need to apply for each permit. How many sets of working drawings? Can you draw the plans yourself or must they be done by a professional? If you’re planning an addition that changes the exterior dimensions of your house, do you need a plot plan that shows the addition in relation to the property lines? If you’re planning a second-story addition, do you need a structural evaluation from an engineer to be sure the foundation is adequate to carry the load? At what stage of construction will inspection schedules be necessary? What is the permit fee? How much time is necessary from the date of application to approval? Don’t assume you can get a permit on the spot as soon as you present your plans.

Remember, this is only a preliminary visit. You’re seeking information that may affect your plans. It’s too early to apply for a permit. That comes later, once the working plans are finished.

The lay of the land

Start your inspection from the street in front of the house. Look at the placement of the house on its lot. Where might an addition go? Estimate the percentage of the lot occupied by the house and any other buildings. Zoning requirements often specify that no more than a certain percentage of the lot may be covered by structures.

Note the way the house is oriented on the lot. Adding to the south-facing side can increase the solar efficiency of a house, while opening up windows on a north exposure can de crease heating efficiency. Note the position of large trees, mature shrubbery, driveways, and any additional structures that could limit add-on potential. Also record the positions of neighboring homes and their effect on light reaching the house. Consider adjacent sources of noise: Is the street heavily traveled? Where are the neighbors’ outdoor entertainment areas (decks, patios, hot tubs)?

Now examine the lot itself. A level lot generally offers the most cost- effective setting for an add-on. Retaining walls may be required to sup port structures on sloping lots. If the house is perched on a hillside, count on an expensive stepped foundation for an addition of any size.

The exterior

Begin your inspection by surveying the house from a distance. Does it sit squarely on its foundation? Look for uneven settlement, particularly at the corners. If the house has a pitched roof, does the ridge sag? Does the porch list? Do any of the walls bulge or bow? Look at the window and door frames. Are the lintels and sills horizontal and the corners of the frames square, and do windows and doors fill their frames? Look for discolorations on exterior siding, which may indicate water damage. Jot down notes about potential problems for closer inspection.

Roof. First, note the style and covering of the roof. It’s generally advisable to match the roof of an addition to the style and material of the original. Next, check the condition of the roof. You’ll probably be looking at asphalt (also called composition) shingles, the most common roofing material in this country. Are the shingles broken, cracked, or curled? Are any missing? Is discoloration or other deterioration visible? Dark patches on asphalt shingles indicate that the surface material has worn away. Again, look for any sagging at the ridge or on the roof faces. Try to find out the age of the roof so that you can estimate its remaining life. (Asphalt shingles, for example, can be expected to last 15 to 25 years.)

Look at the metal skirting (flashing) around the chimney and vent pipes. Do they form a complete seal? Are there any indications of leaking here or where the roof faces join? Move closer to the house and look up at the eaves for obvious signs of rot or de cay. Do the gutters sag? Note the position of any questionable roof areas for closer inspection from inside the attic.

Also check the condition of the chimney. Is it plumb, or does it lean away from the house? The joint between the chimney and the house should be tightly sealed. Check the mortar of masonry chimneys, and look for discolored bricks that might indicate leaks. The top of the chimney should extend 3 feet above a flat roof and 2 feet above the nearest high point on a pitched roof.

Foundation. Now walk around the perimeter of the house. Inspect the foundation, paying particular attention to any areas that appeared from a distance to be settling. Check for cracks—particularly vertical ones larger than 1/4 inch—in poured concrete or masonry foundations, and examine the mortar between bricks. The foundation should be exposed for 6 to 8 inches above ground.

Peeling paint on a concrete foundation may indicate moisture build up in the basement. Soil should be graded away from the foundation to channel runoff water away from the house. Look for signs of runoff pooling against the foundation. Check to see that downspouts have splash plates to channel water away.

The anatomy of a house: Chimney; Splash block; Floor joist; Ridge board; Roof sheathing; roofing felt; Rim joist; Stud wall; Foundation wall; Shingles

Foundation and basement

Look for the fuzzy white columns of termite tubes snaking up the foundation. Termites and dry rot can destroy wood from inside, with little visible evidence. Examine any wood adjacent to the foundation, such as siding or porch supports. If you question its soundness, probe it with your screw driver. If the wood feels like cork, it’s seriously rotted

Foundation depth is determined by local temperatures, soils, and the height of the house. If you’re considering adding a story, the original foundation may require beefing up, an expensive proposition.

Siding. Note the type (wood, stucco, aluminum, vinyl, masonry) and the condition of the siding. If the siding is in poor condition, re-siding the whole house will increase your options for changing its look—but it will also add to the expense of the addition.

Carefully check wood siding for rot (especially the bottom courses along the foundation), and for bubbled or flaking paint, which may indicate in sufficient ventilation of the home’s interior. Note bulges or cracks in stucco; deteriorating mortar between bricks or stones as well as breakdown of the bricks; and dents, chips, or cracks in aluminum or vinyl siding.

Gutters and downspouts. Look up to spot holes in gutters. Watch for sagging. Note any discoloration of siding where gutters and downspouts meet, and any missing or broken downspouts. Check these areas closely during your interior inspection. If you are up on a ladder to inspect the roof, check the gutters for evidence of overflow. Do they have screens or baskets to catch leaves and other debris?

Windows and doors. Note the type of windows and doors; you’ll probably want matching ones for the addition.

Check the caulking between window and door frames and the siding, probe wood frames for rot, and check that windows and doors are snug but not sticking in their frames.

Problem house:

• Uneven settlement of foundation, especially at corners
• Cracks in foundation
• Sagging roof ridge
• Sagging or listing porch
• Bulging or bowing walls
• Out-of-horizontal door and window frames.
• Discolorations on siding. Shingles loose, broken, cracked, curled, missing, discolored
• Sagging gutters
• Chimney leaning, not plumb
• Chimney brick discolored.
• Mortar crumbling.
• Soil graded toward instead of away from foundation
• Termite tubes
• Rotted siding
• Bubbled or flaking paint

The interior

Start your inside examination at the bottom and work your way up.

Basement. An unfinished basement provides the best clues to the overall condition of a house because foundation and framing are exposed, but even a finished basement can tell you a lot.

Does the basement smell musty or feel damp? Look for signs of moisture—discoloration along the lower wall surfaces; a powdery white or multicolored efflorescence on ex posed concrete; damp wood sills or discoloration of framing members. Check the location of any foundation cracks you identified on your external examination. Does water appear to have entered through them? If you are looking for a house to buy, ask questions of the owners if you see tools or stored furniture raised off the floor.

Probe all questionable wood for rot or insect infestation. Carefully inspect the wood sills (these rest on the foundation and support the wall framing). Any water leaking down through the outside walls will end up here. Check the floor joists where they rest on foundation walls or the sill, framing supported in concrete pockets, and wood posts resting on a concrete floor or concrete piers.

Now look up at the basement ceiling. Dark stains on floor joists may indicate dry rot. Do the floor joists sag? Are water marks visible on the subfloor above the joists? These might indicate leaks in the kitchen or first-floor bath.

The basement is the best place to identify structural (bearing) walls in the house above. Most homes have at least one interior bearing wall in addition to the exterior bearing walls. It generally runs the length of the house and perpendicular to the floor joists, often where they overlap. Any interior wall with a girder, post, or foundation beneath it's probably a bearing wall. Removing all or part of a bearing wall to permit an addition will mean extensive structural work to replace the support.

The basement can also be the best place to examine the condition of the existing plumbing, wiring, and heating systems.

Plumbing. If your addition might include a sink, toilet, bathtub, or water-using appliance, you’ll want to check the adequacy of the plumbing. The line entering the house (the sup ply line) should be at least 1 inch in diameter, and it shouldn't be lead (gray in color). Copper pipes are desirable. Most building codes allow plastic pipe for drain-waste-vent systems (the line leaving the house) in single-family homes, but there are usually some restrictions.

Check the condition of all exposed pipes for evidence of rust, corrosion, or leaks. If the pipes are galvanized iron (also gray in color), layers of sediment and corrosion inside may be restricting water flow. Also consider the size of the water heater. A family of four requires at least a 40-gallon tank.

Look for insulation on the hot water pipes. Older systems may be wrapped with asbestos, which can be a health hazard if disturbed. Asbestos insulation looks like pressed paper or cardboard, and is usually gray in color. Disposal can be costly, as most landfills and dumps will not accept this material.

Check the water pressure through out the house by turning on an up stairs faucet and shower and then opening the kitchen tap. Does the water trickle to a halt? Also try flushing the toilet and running the shower at the same time.

Wiring. The house should be sup plied with at least 100-ampere, 240-volt (three-wire) service to handle modern appliance loads. Check for three-wire service where wires from the utility pole attach to the house. You can tell by checking the service panel near the electric meter whether the house has modern circuit breakers or fuses, and how many circuits it has. An add-on will likely require a new circuit to serve it; expansion blanks may be available on some service panels.

Also look for evidence of frayed or bare wiring in the basement, and in the attic.

Heating. Finally, consider the type and age of the heating system. It may prove inadequate to serve a large addition, and a separate heating unit may be most cost effective.

Check the distribution pipes of older gravity-type warm air furnaces for the presence of asbestos insulation. Breaks in the pipes can permit asbestos particles to travel throughout the house.

Living spaces. This is the fun part of the inspection. Start by siting down the floors. If they appear to slope, use your marble, ball, or level to check. Look for cracks at the corners of door and window frames, in exterior corners, and across ceilings. Write down the location of major cracks and check for structural causes. Open and close doors and windows; binding can indicate uneven settlement of the foundation or sagging in the structure of the house.

Acoustical ceilings in homes built before 1979 may contain asbestos. Any deterioration or disturbance will free hazardous asbestos particles into the air.

Note how much light enters each of the rooms, and consider how an add- on might affect that light. Bump-out additions and skylights can let more light into otherwise dark rooms. With out proper planning, however, adding on to the only side of the house that receives good light could darken existing rooms.

Attic Inspect an unfinished attic for leaks, and check rafters and wall studs for water stains or rot. Use your flashlight to look through the rafters at the discoloration or water damage on wall sheathing. Check the chimney for aging mortar and cracks or breaks in its skin.

Service panels

Three-wire service head

Home Evaluation Checklist

Exterior evaluation

Orientation of house : N S E W

Evidence of settling

Distance to lot boundaries: Front _______ Sides _______ _______ : Back ____________________

Lot: Flat? Sloped (gentle/steep; direction)?

Landscape : Trees/plantings to preserve?

Retaining walls : Drainage (weep holes) adequate? : Leaning toward slope (good) rather than away from slope (bad)?

Other structures (location, light)

Sources of noise

Best/worst views

Electric service Three-wire? _______ Entrance location ____________________________ Ground in place (wire from service panel to brass clamp in soil)?

Roof : Material _______________________________________________________

Age Condition—sags/low spots in ridge/faces?

Covering missing/worn/warped/cracked/lifting?

Flashings (chimney/vent pipe/roof valley/skylight/dormer) intact? _______

Gutters missing/sagging/cracked/rusted/peeling?

Vents (at eaves/gables/ridge)?

Chimney : Leaning/bowed?

Condition—masonry (deteriorating bricks/stone/mortar?)

Chimney-house joint tight? Liner and cap?

Height above roof _______________________________

Siding Material Age Condition—discoloration? Missing/cracked/peeling/warped/dented/rusted/rotten/deteriorating (especially adjacent to foundation)?

_______________________________

Joints tight?

Shrubs/vines against siding?

Foundation : Material __________________

Amount visible _______________ Soil graded away from? __________

Downspouts intact/drain to splash plates?

Condition—large cracks (location)?

Discolored/wet? __________________ Paint peeling/blistered?

Mortar crumbling? Insects or insect damage (termite tubes/rot in adjacent wood) evident? __________

Settling/leaning/buckling (location)?

Windows Frame material (wood/metal/coated wood)? Style

Condition—cracked/broken glass? Frame material/finish intact? Caulking sound? Weatherstripped? __________ Frames square?

Doors: Material

Condition—tight/square in frames? Weatherstripped?

Paint/finish intact? ______

Thresholds rotted/swollen/uneven?

Trim (windows/doors/decorative): Material (wood/metal/other)?

Missing/rotted/needs caulking or painting?

Special features (cornices/columns/shutters)?

Porches, decks, and patios Attachment to house sound? Supports (wood/concrete) sound? _____ Do wood supports rest on ground?

Stairs and railings sound?

Garage: Door sound/operates smoothly? Header over door opening sagging/bowed? Slab cracked/heaving?

Roof sound? Spacing (inches) between wall studs ______

Interior evaluation

Basement or crawl space : Foundation walls—large, open cracks visible? _______

Bowed/leaning? Damp/wet/watermarked/discolored/efflorescence?

Wood—in contact with soil? _______ In contact with cement? Signs of rot/insect damage?

Ceiling—sagging/split/decaying floor joists?

Signs of leakage from kitchen/bath above?

Floor—evidence of moisture/flooding?

Cracks in slab (location)?

Concrete piers in place (directly under beams/girders)?

Ventilation (especially if crawl space) adequate?

Signs of condensation/leaking around windows or on walls?

Plumbing system:

Location of main drain ____

Location of water supply entry

Location of main plumbing run to existing kitchen/bath

Main shutoff valve working? Pipes—rusted/corroded/crusted/heavily patched/sagging? Hot water pipes insulated? Capacity of water heater _________ Sufficient?

Waste disposal to city sewer or septic tank? _________

Heating system: Type, Age, Location ______

Rated output (BTUs/hour) Provides adequate, evenly distributed heat? ____ Emits odors/fumes? Heating ducts insulated?

Electrical system: Location of service and branch panels

Rating of main service panel (60/100/150/200 amps) Fuses or circuit breakers? Frequent overloads (blown fuses/ tripped circuit breakers) or flickering/dimming of lights?

Wiring frayed/corroded?

Living spaces Signs of settling—cracks in exterior corners? ___________ At corners of window/door frames? ______Across ceiling?

Bulging or bowing walls? ________Doors/windows open and close freely?

Signs of moisture/leaks—on ceiling below baths? _____On wall- coverings? Around windows/doors? Floors—sloping?

Springy/spongy? : Creaky?

Staircases—framing sagging? Out of square?

Decaying/damaged stairs/rails? Creaking treads _________

Fireplace—masonry cracked/loose/deteriorating? Mortar missing/crumbling? Flue lined? _____ Coated with soot? _____ Bathrooms and kitchen Ventilation adequate?

Signs of leaks / water damage -- deteriorating/cracked/missing/stained wall-coverings?

Buckled/decaying floor covering?

Water pressure adequate/weak?

Drainage adequate/sluggish?

Attic : Structural—sagging/cracked/rotted rafters? _________

Decaying roof decking/wall sheathing?

Signs of leakage—on roof decking? On rafters?

Around chimney/vent pipes? On wall sheathing/studs?

Light visible through roof? ______________

Ventilation—gable/eave/roof vents absent/blocked?

Evidence of moisture/condensation (damp insulation)?

Vent pipes exhaust in attic? _________

Depth of insulation in floor _________

The Base Plan

Before you begin to plan and design your addition, you need to have as much ex act information about your existing house as possible. The evaluation checklist on above will show you what you‘ve got; but creating an addition requires translating your three-dimensional house into two dimensions: the base plan. This plan will be a valuable aid; not only will it help you get familiar with the de tails of your present lay out and make the relationships of the spaces clear, it will help you to visualize your addition.

If you already have a base plan or blueprint of your house (obtained from your builder, a former owner, or the city building department), you can use that instead of drawing your own. However, you will still have to make sure that it's drawn accurately, and incorporate into the plan any changes that have already been made. You’ll also probably want to copy the plan onto graph paper, because the smaller scale and more manageable size will make it easier to plan your addition.

If you have no base plan, you’ll need to draw up your own from scratch. Doing it yourself has the benefit of making you thoroughly familiar with every corner of your existing house, and with the possibilities for adding on to it.

Your base plan will be a scale drawing showing the floor plan of your house, including all rooms; walls, windows, and doors; stairs; closets, storage areas, and cabinets; appliances such as stove and refrigerator; plumbing fixtures such as sinks, bathtubs, showers, and toilets; water heater, air conditioner, and other electrical devices; and electrical out lets and plumbing lines. Imagine that you have taken the roof off your house and are looking straight down into it. Make a separate plan for each floor of your house.

The tools you’ll need to draw up your base plan are simple: a 20- or 50-foot steel tape measure, a pad of graph paper, and a soft-lead pencil. At this stage, you will draw your plan freehand, using the graph paper to keep the proportions accurate and writing the dimensions on the plan as you go along. A convenient scale for most plans is 1/4 inch to the foot. Be sure to note on the plan the scale you are using.

Begin drawing your plan with any room you choose. In orienting the first wall line on the paper, be sure to leave enough room to draw in the entire house. Draw the plan with north at the top or on the left side of the paper; this standard practice will help others reading your plan to orient themselves to the site.

In each room of your house, start with overall dimensions and work down to details. Begin by measuring the length and width of the room. Measure the distance of doors and windows from a corner or the end of a wall and from each other. Measure the width of their moldings or trims. Draw a line for each wall, leaving the proper amount of space for each door or window. Draw a second line outside the first. These parallel lines indicate a normal 4-inch wall. Fill in the space between the two lines with solid penciling.

Next draw in the doors. If a door swings, show it in the open position, drawing a quarter-circle from the hinges. Make a semicircle if the door swings both ways. For sliding doors, draw in the fixed one, and then indicate whether the sliding one is inside or outside the fixed one, and show it about halfway open. For folding doors, show a series of little w’s to the depth of each panel. Show pocket doors half open, sitting within the stud wall pockets. Draw in the windows, showing the way they swing. Use the half-open position for sliding windows.

Measure the width and depth of cabinets, closets, and other built-in storage areas, indicating the swing of their doors. Measure and draw in floor grilles. Measure the hot water heater, furnace, air conditioner, and any other electrical devices and draw them in on your plan. If there is a door leading to their space, measure and draw in the length and direction of its swing. Note the location of all outlets, light switches, and light fixtures. Indicate where water and gas lines enter the house.

Remember that the purpose of this first, rough drawing is to gather in formation. Details like door swings and light switches don’t need to be drawn perfectly at this stage.

Once you’ve recorded every significant detail on your base plan, get a clean sheet of graph paper and transfer the plan, making this version more precise. Use the architect’s rule to scale off dimensions; use triangles to draw angles; and use a template or compass to draw circles. Use a com pass spread to the width of the door to indicate its swing.

This plan will become the basis on which you will design your addition, so you’ll need several copies of it.

Should I obtain professional advice?

Consulting with a professional before you begin to plan your addition can ease your mind about the feasibility of adding on, and it may reduce the amount of research you’ll need to do during the planning process. It’s up to you to decide whether a professional evaluation is in order at this point.

If you are confident about the structural integrity of your home and there’s clearly room on the lot to expand, a professional evaluation may not make sense now. On the other hand, if you uncovered foundation or structural problems during your inspection, or if the only direction for expansion is down a steep hillside or on top of the existing house, consulting a professional at this point will give you a clearer idea of what will be involved in adding to the house. If you’re purchasing a house to enlarge, it makes sense to get a professional opinion before you buy.

Building inspection firms can verify your findings regarding structural condition. They may also be able to advise you about foundation modifications that might be required to support an additional story. If the lot is steep, or if you plan to add a substantial load to a home’s foundation, consider an initial consultation with a structural engineer or a soils engineer. Architects and contractors also perform inspections. In Section 5 you’ll find more information about what various professionals do, and about working with them in the planning and design process.

Rough base plan

Finished base plan

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