Ultimate Guide to Adding On--Before Building Begins

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Whatever style and size of addition you envision for your house, advance planning is the key to a smooth construction process and satisfying results. Among other information, this chapter includes design considerations for common types of additions as well as a guide to complying with local building codes—and when to hire a contractor for part or all of the many jobs that go into an addition.

__Making an Addition Look Right

Taking Nature into Account

Planning for a Livable Addition

__Expanding Up—Unobtrusively

__How to Fit On a Large Addition

__Planning the Job to Run Smoothly

Detailed Drawings for an Addition--Tips for Choosing a Contractor

Scheduling Permits and Inspections

7__ A sketch for an addition

Making an Addition Look Right

Common sense suggests an ugly addition is a bad bargain: It may reduce the value of your property, and it is often difficult to live in. Conversely, a well-designed addition is likely to be a good investment as well as a source of everyday satisfaction.

If you possess architectural talents, you may want to create your own design, but most people hire a professional. Either way, the first step is to list the use and dimensions of any new space, taking into account considerations like those in the checklist below. Drawings of the plan will be needed to obtain a building permit ( -- 17). An architect will do the drawings as part of the job; if you are the designer, you can hire a draftsman or make the drawings yourself.

Fundamental Considerations:

Site conditions, zoning ordinances, community rules, and your space requirements all will help determine which of three basic design options to pursue: building out horizontally from the house, building up above it, or building a major addition. Illustrations show how each type of addition can be adapted to suit different house styles.

Ordinarily, the architecture of an addition should echo that of the original house. When the addition must depart from the house style, the difference should be clear and obviously intentional; an imitation that is inexact can look as though it is a mistake.

A Pleasing New Roof: The roof of a successful addition generally matches the slope, overhang, and covering of the existing roof. The main exception is an addition with a shed roof. In that case, a shallow slope often is used to contrast with the steep slope of the house roof.

Planning Windows and Siding: If windows on an addition look like those on the house, the addition will be less obtrusive. Horizontal spacing can vary, although it should not seem random. Vertical alignment, however, is crucial. If the tops of windows do not line up, the result is a distracting jagged line.

Siding generally is the simplest detail to match to the house. You may also prefer a contrast: Combi nations of shingles, clapboard, brick, or vertical planking are often used, although they can look fussy on a small house.

Preserving a Focus: As you weigh design options, consider how the addition will affect the focus of the house—the exterior point that draws and holds your eye, such as the front door or a large window. Ideally, each side has its own focus, but front and side views matter most. An addition may replace the original focus, but if it adds secondary focus—a large feature like a sliding-glass door, for example—it confuses the design. Partly for this reason, many additions are built at the rear, leaving facades unchanged.


An attractive addition that is well suited to one part of the country could lead to trouble in another locality. In regions with heavy snowfall, for example, roofs must be built steep enough to shed their wintry load. Just the opposite is true in an area that is vulnerable to hurricanes:

Steep gable roofs present a large target to high winds. Roof overhangs are also a danger there, since storms can pry off the roof by blowing under the edge. In parts of the country where earthquakes may occur, brick chimneys are among the elements to be avoided. Building codes take regional conditions into account, but it is a good idea to discuss such concerns with the local building department, which may have additional suggestions to ensure that nature and your addition are fully compatible.

Planning for a Livable Addition:

If possible, plan for rectangular rooms, approximately half again as long as they are wide; these are generally most comfortable.

For the best light and ventilation, locate windows on two walls.

Try to place doors near corners to provide more unbroken wall space for chairs and tables.

Consider how each room will relate to surrounding ones, anticipating possible problems with noise, access, and light: A noisy family room should not be next to a bedroom, for example.

A bay window.

The classic bay window is a simple addition suiting many styles. The stock unit, bought ready-made with a metal roofing kit, is generally designed to adorn a traditional two-story Colonial house (bottom); here, the window is mounted on the side of the house, leaving the appearance of the façade unchanged. The floor of the bay is supported by floor joists that are cantilevered from those in the original house. To create a two-story bay typical of Victorian Gothic, you can stack two stock units—complete with traditional curved windows, if desired. In this example, the addition is blended with the original house by giving the bays curved-shingle siding that matches the roof gable. For a modern ranch house, a bay can be assembled by building a shallow room extension from ordinary window units, 2-by-4 stud framing, and a concrete-block foundation wall.


A new room.

A modest outward expansion—front, side, or back—is the most common type o addition. To keep it from looking like a bump on the house, the addition generally is given a roof that echoes the original. (Here and in some pictures following, the original lines o1 a house are indicated in gray.) On a split-le house, for example, an addition often duplicates the shape of the one-story portion. The two roofs have the same height and so meet naturally in valleys. The same approach works at the back or front of a ranch house (center). On a massive, boxy house, however, it is better to extend the original shape. For example, the walls and roof on one side of a Colonial house (bottom) can be extended to create a traditional salt-box shape, with a half story of storage space opposite the second floor of the house. A clash of styles between old and new windows is averted by the distance between them and by the large-scale simplicity of the new windows—a clear contrast to the old.


A wraparound addition.

This design is particularly suited to two special types of houses: a small house, which would be overwhelmed by the mass of an ordinary addition, and a house on a lot so small that local setback requirements prohibit a large addition in one direction. For the Colonial house at top, the addition roof is offset from the house roof but duplicates its width, pitch, and soffit detail so well that the addition looks like a part of the house. On the Cape Cod (lower drawing), the front edge of the house roof has been extended with short rafters, and hips have been made from prefabricated trusses, creating a hip-on-gable roof that matches the pitch of the original gable roof.

Extending an entire side.

A shed-roofed addition that extends one end of a house suits almost any style of architecture. It is a traditional feature of American farmhouses, and because of its simplicity, adapts to such complicated styles as the Victorian or the Elizabethan. A shed roof that is designed with a much shallower pitch than the original has a simple line that does not clash with the house roof or obstruct the second-story windows. For the Elizabethan house, 1-inch boards applied over stucco or plywood siding match the original half- timbered style. On the large, boxy Colonial, the full-side addition preserves the lines and massive look of the house.

Expanding Up—Unobtrusively

When the shape or terrain of a lot precludes building an addition outward, the solution may be to build up—either with a shed dormer (below) or with a living space above a garage . This can pose a tricky design challenge, however: second-floor additions have a tendency to over whelm the architecture of a house.

To avoid obvious bulkiness, many upward additions are placed behind the house. If a second-story addition is at the side, you may be able to extend the house roof over the addition. An abundance of windows can also make the new construction look less massive; horizontal panels of windows near the roof look best. To pre serve symmetry, match the existing window spacing and locate addition windows either directly above first- floor doors and windows or centered between them.

The floor plan of the addition is determined largely by the location of the doorway or stairway that provides access to it. You may have to build a stairway. Try to place the lower landing in little-used space that opens off a hallway—a linen closet, perhaps, or the corner of the garage next to the house door—and place the up per landing in a corner of the addition.


A shed dormer.

From the street, the dormer at the back of the Colonial house at upper left is hidden by the roof, the mo common arrangement. The dormer addition on the C Cod house above, by contrast, is located in front. Although this changes the facade, symmetry is presented by centering the second-story windows between the original door and windows. The ceiling of this dormer is only 7 feet high because of the relatively low ridge of a small Cape Cod roof but the large windows make it seem higher. Both additions cover less than two-thirds of the roof and stop short of the overhang, leaving a border of the original roofing to minimize their apparent size.


A room over the garage.

If a garage originally was covered with a sun deck, an addition can be erected directly on this platform and then can be covered by a sideways extension of the house’s original roof; in the example seen above, at top, the large windows play down the size of the addition. An addition on top of the garage of a one-story house (middle) needs a roof that matches the roof of the main house; here, an elaborate hip-on-gable roof over a big two-car garage makes the remodeled wing the largest, most prominent part of the house. An addition over a garage attached to a two-story house generally can be covered by extending a gable roof; in the example shown at bottom, a hip roof diminishes the visual bulk of the addition.

How to Fit On a Large Addition

A massive expansion of a house—perhaps by adding a second story (below) or by constructing a wing to one side —raises a number of practical issues along with the inevitable aesthetic considerations. For one thing, such an addition usually alters the traffic pattern inside the house. Care must taken so that people do not have to walk through the kitchen to get to a bathroom or through a bedroom on the way to a patio. Hallways may be needed, at least 36 inches wide so that furniture can be moved easily.

Traditionally, such an addition also required posts, girders, and bearing walls to support standard floor joists; nowadays, wood I-beams that can span a greater distance without a central support are often substituted ( -- 92). Floors and walls must provide channels for plumbing and ducts, and floors may need to be reinforced under heavy plumbing fixtures.

Expansion upward with a full second story, which involves removal of the old roof, is a job usually left to professionals. It is often possible simply to extend first-floor walls upward, matching the first-floor siding and window style, and to top them with a new roof that exactly matches the previous one. But the massive addition also permits radical changes in style: So little is left of the original house that the designer has a relatively free hand.

A separate, two-story wing alters proportions radically, but because it leaves the old roof intact, it generally is most attractive if it follows the style of the house. The resulting house looks like the original, but bigger.


Unusual second stories.

Rather than lift the roof to stretch e house, the planners of these two examples completely altered the original architecture with distinctive second stories. In the upper illustration, a conventional gable-roofed ranch house was doubled in size by building on top of it two overhanging gable-roofed wings—one for parents, one for children—that bracket a second-floor sun deck and are connected by a glassed-in breezeway. At bottom, a gambrel roof, assembled from a spider-web of roof trusses to form sloping interior walls and a high cathedral ceiling, transforms one wing of what had been a typically shaped tract house.

A two-story wing.

At top, a new section imitates the others of a half-timbered Elizabethan house that already had a variety of wings; the second story of the addition overhangs the first on cantilevered floor joists, a typical feature of this style. The roof, siding, and windows of the addition match those on the existing structure. On the Colonial at center, only the seam in the exterior wall gives away the new wing, which is simply a sideways extension of the original. The hipped roof blends the shape of the addition with that of the house. The addition to the Victorian at bottom extends a gable of the original roof, dividing the side of the house into three matched wings.

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Planning the Job to Run Smoothly

Deciding what to build is just the first step in planning an addition. You must submit a building-permit application, accompanied by a set of precise scale drawings of the addition. You may render them yourself or have an architect do the work from your own rough plans.

Taking Control Yourself: You may opt to act as your own general contractor, reserving some of the work for yourself and hiring others to do the rest. If you take on this role, be prepared to ensure that code requirements, some of which can be difficult to interpret, are met.

In addition to the building permit, you’ll have to acquire permits for plumbing, electrical, and heating work. Tools and materials must be purchased, scheduling between sub contractors coordinated, and inspections arranged.

When to Get Help: If you have limited time or expertise, hire out jobs that call for a high level of skill or specialized equipment. Large concrete slabs, plastering, deep excavations, and extensive grading fall into this category. Similarly, if working at heights greater than 10 feet is disconcerting, let someone else handle the siding and roofing jobs. Excavations deeper than 4 feet always require professional shoring.

Even if you feel up to a task, it may be uneconomical for you to take it on. Professionals often can do jobs such as installing wallboard and shingles for less than you would pay for materials alone be cause they buy in large wholesale lots. Save small or complicated jobs for yourself; leave large open surfaces that can be covered quickly to a subcontractor.

Enlisting a Contractor: Whether you are hiring a general contractor or a subcontractor, shop around for bids on both labor and materials. Read all contracts care fully and modify standard forms to specify your expectations for workmanship, materials, and approximate schedules. Include an agreement that the people you hire will provide lien waivers from their suppliers and from any subcontractors on the job, stating that each of them has been paid.






















The formal language of blueprints.

These symbols represent elements commonly included in an addition. All are readily recognized by those in the building trades, and many, such as those for washbasins or doors, are obvious at first glance. More abstract symbols, standing for such elements as switches or thermostats, are easy to decipher in the context of the floor plans, elevations—showing heights of windows, doors, and ceilings—and cross-sectional views.


Two plans.

The site plan—depicting proposed development of the property—and the cross-sectional view are two of many drawings submitted with an application for a building permit. The site plan, stamped with conditional approval and a seal of review, has a cross-hatched area showing the intended addition—at the back of the house over an old patio, which is to be replaced by a free- form design. The cross-sectional view includes building and materials specifications, with abbreviations for items such as gypsum wallboard (GWB), concrete masonry units (CMU), and a grading code for plywood roof sheathing (CDX). Other drawings may include elevations, foundation and floor framing, roof framing, and a floor plan.

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Working Safely around Lead and Asbestos Lead and asbestos, known health hazards, pervade houses constructed, re modeled, or redecorated before 1978. When disturbed, as they are likely to be during construction of an addition, they pose a threat unless handled as described here.

Lead is found primarily in paint. Home test kits for lead in paint are avail able at hardware stores, or call your local health department or environmental protection office for other testing options.

Asbestos was once a component of wallboard, joint compound, insulation, flooring and associated adhesives, as well as roofing felt, shingles, and even flashing. When removing small samples of such materials for testing, mist the area with a solution of 1 teaspoon of low-sudsing detergent per quart of water to suppress dust. Then take the samples to a local lab certified by the National Institute of Standards and Technology.

By observing the precautions listed below, you can safely deal with lead or asbestos-laden building materials. Or consider hiring a contractor who is Ii censed in hazardous-substance removal or abatement-especially for a large project indoors. A professional is advisable if you suffer from cardiac or respiratory problems or if you don't tolerate heat well; the work requires a tightly fitting respirator and protective clothing that is hot to wear. Tackle a roof only if you are experienced in working at heights, keeping in mind that a respirator impairs vision.

To remove materials containing asbestos, observe the following:

• Keep children, pregnant women, and pets away from the area.

• Always wear protective clothing (available from a safety-equipment supply house or paint store) and a dual-cartridge respirator.

• Indoors, seal off openings to the work area from the rest of the house with 6-mil polyethylene sheeting and duct tape. Cover rugs and furniture that can't be removed from the work area with more sheeting and tape. Turn off air conditioning and forced-air heating systems.

• Outdoors, cover the ground in the work area with 6-mil polyethylene sheeting. Never work in windy conditions.

• Never sand asbestos-laden materials or cut them with power machinery. In stead, mist them with water and detergent, and remove them carefully with a hand tool.

• On a roof, pry up shingles, starting at the top, misting as you go. Place all debris in a polyethylene bag; never throw roofing material containing asbestos to the ground.

• When you finish indoor work, mop the area twice, then run a vacuum cleaner equipped with a high efficiency particulate air (HEPA) filter.

• Take off pr clothing-including shoes-before leaving the work area. Wash the clothing separately. Shower and wash your hair immediately.

• Dispose of the materials as recommended by your local health department or environmental protection office.

To remove materials with lead, follow the procedures above. If you must sand, do so with a sander equipped with a HEPA filter vacuum.

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Tips for Choosing a Contractor:

Examine permits on file at the building department for jobs similar in scope to yours. Call owners of the houses for references and per mission to inspect the jobs.

Be wary of a contractor with customer complaints on file at the local Better Business Bureau or consumer protection agency.

Find out from the local building department or licensing bureau whether the contractor has a trade license, evidence of having passed a competency test. In some areas, a contractor must post a bond as insurance against bankruptcy or other default on work.

Ask the contractor for proof of workmen's compensation and liability insurance.

A clown payment of 10 percent should be adequate on large jobs; you may stipulate in the con tract for full payment to he postponed until the project passes final inspection.







Rough plumbing

Rough electrical




Final plumbing, electrical, mechanical, and building]

[When to call an inspector:

After preparing the trenches, but before pouring concrete;

After constructing the foundation walls and floor, but before backfilling;

After forms, gravel, vapor barriers, wire mesh, or steel are in place, but before pouring concrete;

Underground plumbing: after installing pipes, but before filling trenches or pouring concrete Aboveground plumbing: after installing pipes, stacks, and vents in framing, but before walls are finished and fixtures installed.

After running cable and grounding boxes, but before walls are finished or electrical devices installed;

After plumbing and electrical rough-in work is approved, but before insulation or wall finish materials are installed;

After ductwork and insulation are installed, but before walls are finished and equipment installed;

After installing all insulation material, but before installing wall or ceiling finish materials;

After walls are finished and all plumbing, electrical, and mechanical equipment and fixtures are installed and working, but before occupancy]

[Major checkpoints:

Excavation, soil conditions, reinforcement;

Walls, backfill material;

Forms, soil condition, reinforcement;

Stacks, vents, pipes;

Circuits, grounding;

Sizes, spacing, holes, notches;

Ductwork and insulation surrounding it;


Plumbing: fixtures and pipes watertight; electrical: outlets, switches, and other devices operational; mechanical: ductwork unobstructed; building: structure weathertight, doors and windows in operation, grading completed]

The right times for inspections.

In most areas an addition must pass several inspections before it can receive a certificate of occupancy. The inspections are listed above in the sequence in which they normally occur; while not all of them are required in every area, a building permit generally requires at least four distinct inspections. These are an inspection of the foundation work, one of the framing, one after the insulation is in, and a final inspection when all the work is complete. The separate permits for electrical, plumbing, or heating or air- conditioning work also commit you to inspections of the rough installation and of the finished work. The second column in the chart indicates the point in the construction sequence when you must call in an inspector; the third column lists the main features that will be checked for their conformity to building codes.

Monday, March 31, 2014 15:17 PST