Whether it’s in the form of boards, shin-gles, or shakes, wood siding is durable and, with annual maintenance, should last the lifetime of the house.

To prevent deterioration of wood board siding, repair simple surface problemsholes in the wood, split and
warped wood, and damaged paint -as soon as they appear (see below and on facing page). Severely damaged board siding can’t be effectively re-paired; in this case, you’ll need to replace the affected siding (follow the in-structions on pages 44-45).

When shingles or shakes are dam-aged, it’s usually best to replace them, since repairs to these materials are hard to conceal. Instructions for re-placement appear on page 45.

Be sure to determine the cause of any serious damage before replacing siding. If moisture is causing the prob-lem, find the source by checking for de-teriorating roofing (page 29), leaking gutters or downspouts, and poor drain-age (pages 36-37). Consult a profes-sional if you can’t locate the source of the leak. Once you pinpoint the prob-lem, be sure to make the necessary repairs; new siding installed over prob-lem areas will just deteriorate again after a short time.

If after removing damaged siding you see evidence of dry rot or insect infestation (page 41), call in a
professional.

Repairing Board Siding
Replacing Damaged Boards, Shingles & Shakes

Repairing Board Siding

Damage to wood board siding can often be repaired inconspicuously Repairs usually involve filling holes, fixing split or warped boards, and repainting. Siding that’s badly damaged should be replaced
(pages 44-45).

Repairing holes. Small holes in wood board siding can be filled with wood putty available at lumber and paint stores. The putty comes in a variety of shades for matching lightly stained wood.

To conceal a small hole, fill it with wood putty and allow the putty to dry completely If the hole is fairly large, ap-ply the putty in layers, letting each one dry completely before applying the next. When the final layer is dry sand the surface smooth. Then finish the putty to match the surrounding siding (unless you’ve used putty in a shade that matches the exterior).

Repairing split boards. A clean split or crack can be repaired by prying the board apart and coating both edges with waterproof glue, as shown at right. Then either nail or screw the board back into position or, for a less visible repair, drive a row of temporary nails just under the lower edge of the board and bend them up over the edge to hold the board in place. Remove the nails once the glue has set.

Repairing A Split Boards

Repairing warped boards. Warped or buckled boards usually show up where boards have been fitted too
tightly during installation. If a board has nowhere to expand when it swells with moisture, it warps or buckles.

To straighten a warped or buckled board, first try to pull it into line by driving long screws through it and into the wall studs. Use a portable electric drill to drill pilot holes and countersinks for the screws (page 15), then insert the screws and tighten them. Cover the screw holes with wood putty; then sand and finish as you would after repairing holes in siding.

If that doesn’t work, you’ll have to shorten the board to give it more room. Pull out the nails within the warped area or cut them with a hacksaw blade. Con-tinue removing nails to the nearest end of the board. Pull the end of the board outward; then file it with a rasp, sand with sandpaper, or use a block plane to
remove wood on the end little by little until the board fits. Renail the board.

Fixing paint problems. Paint prob-lems can result from a variety of causes: wrong paint, improper surface preparation before painting, careless painting, harsh sunlight over a long period of time, or improper wall venti-lation. Except in the last case, the prob-lem can be remedied with a proper paint job (see facing page).

Ventilation depends on your cli-mate and the presence or absence of a vapor barrier. Increasing the amount of ventilation may involve adding vents to the roof, gables, and soffits (page 39) or installing a fan (page 185). Check your local building code for the recom-mended ventilation for your home.

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Replacing Damaged Boards, Shingles & Shakes

Sometimes, a board is so badly dam-aged or decayed that your only choice is to replace it. Similarly a shingle or shake that’s damaged should be re-placed rather than repaired.

Replacing boards
The approach to replacing board siding depends on the milling of the boards (common types are shown be-
low) and how they’re nailed. Often, the trickiest part of the job is finding a re-placement that matches the original. No matter what type of siding you’re replacing, you’ll have to cut the damaged piece and remove the nails in order to pry it out. After repairing any damage to the building paper with roofing cement, you’ll need to carefully measure and cut the new piece so it will fit correctly For best results, cut out and replace a section that spans at least three studs. Use a carpenter’s square when marking cutting lines to keep them at right angles. Pull nails out of the old siding with a nail claw or nail puller, or cut off nail heads with a hacksaw blade.

Common Board Sidings

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Tongue-and-groove siding. Be-cause the boards are locked together by the tongues and grooves, the dam-aged piece must be split lengthwise as well as cut at the ends, as shown below, before it can be removed.

It’s easiest to make the cuts with a circular saw; set the blade depth just shy of the thickness of the siding. Saw almost to each edge, holding the blade guard back and dipping the moving blade down into the wood to start each cut. Hold the saw firmlyit may kick back. Also, be careful not to cut into ad-jacent boards.

Overlapping styles of siding. Clap-board, bevel, Dolly Varden, shiplap, channel rustic, and other overlapping styles (bottom left) are face nailed tostuds or sheathing. Though the boards overlap, you can replace a damaged piece without removing other boards (you may need to pry up the board above the one you’re replacing to free the last pieces of damaged board). To replace all types of overlapping siding, follow the directions for replacing clap-board siding illustrated below.

To provide a solid nailing base for the replacement board, center the end cuts over studs, if possible. You can use a back saw to cut clapboard, bevel, and Dolly Varden siding; make the cuts in shiplap and channel rustic siding with a circular saw, as described under “Tongue-and-groove siding,” facing page. If nails are in the way of your saw cuts, pull them out.

Replacing Tongue-And-Groove Siding

Board-and-batten siding. To remove board-and-batten siding, pry up the battens on either side of the damaged board far enough to raise the nail heads, then pull out the nails. Repeat this process until you’re able to remove the damaged board.

Patch any cuts or tears in the building paper with roofing cement. Replace the damaged board and batten
with identically sized new ones. Seal all joints with caulking compound; then stain or paint.

Replacing shingles & shakes
When a shingle or shake splits, curls, warps, or breaks, you’ll have to take it
out and replace it. The replacement technique depends on whether the shingles or shakes are applied in single or double courses (rows).

In a single-course application, each course overlaps the one below by at least half a shingle or shake length. The nails are concealed under the shin-gles or shakes of the course above. Re-placement procedures are the same as for a shingle or shake roof (page 32). Double-coursing calls for two complete layers of shingles or shakes. Here, the nail heads are exposed. To replace a damaged shingle or shake, simply pull out the nails, remove the damaged piece, slide in a replace-ment, and nail.

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Replacing Clapboard Siding

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Moir? Method of Strain Analysis. The moir? technique depends on an
optical phenomenon of fringes caused by relative displacement of two
sets of arrays of lines. The arrays used to produce the fringes may be
a series of straight parallel lines, a series of radial lines emanating from
a point, a series of concentric circles, or a pattern of dots. The straight
parallel line grids are used most often for strain analysis work and
consist of equal width lines with opaque spacing of the same width
between them. These straight parallel lines are spaced in a grating
scheme of typically 50 to 1000 lines per inch for moir? work. In the
cross-grid system of two perpendicular line arrays, the grid placed
on the specimen is referred to as the model grid. The second grid is
referred to as the reference grid and is overlaid on top of the model grid.
Often a thin layer of oil or some other low-friction substance is placed
between the model grid and the reference grid to keep them in contact
while attempting to minimize the transmission of strains from the model
to the reference grid.

To obtain a moir? fringe pattern the grids are ?rst aligned on the unloaded
model so that no pattern is present. The model is loaded and light
is transmitted through the two grids. Strain displacement is observed in
the model grid while the reference grid remains unchanged. A moir?
fringe pattern is formed each time the model grating undergoes a deformation
in the primary direction equal to the pitch p of the reference grating.
For a unit gage length, ?L = np, where ?L is the change in length per unit
length, p is the pitch of the reference grating and n is the number of fringes
in the unit gage length. In order to calculate  ?_x,  ?_y, and  ?_xy, two sets of
gratings must be applied in perpendicular directions. Then displacements u
and v (displacements in the x and y directions, respectively) can be established
and the Cartesian strain components can be calculated from slopes of
the displacement surfaces: ?_xx = ?u/?x, ?_yy= ?v/?y, and ?_xy = ?v/?x + ?u/?y.
The displacement gradients in the z direction, ?w/?x and ?w/?y,
have been neglected here because they are not considered in moir? analysis
of in-plane deformation ?elds.

Photoelasticity. The method of photoelasticity is based on the physical
behavior of transparent, noncrys- talline, optically isotropic materials that
exhibit optically anisotropic characteristics, referred to as temporary
double refraction, while they are stressed. To observe and analyze these
fringe patterns a device called a polariscope is used. Two kinds of polariscope
are common, the plane polariscope and the circular polariscope.

The plane polariscope (Figure 1.5.42) consists of a light source, two polarizing
elements, and the model. The axes of the two polarizing elements are oriented
at a 90? angle from each other. If the specimen is not stressed, no light passes
through the analyzer and a dark ?eld is observed. If the model is stressed,
two sets of fringes, isoclinics and isochromatics, will be obtained. Black
isoclinic fringe patterns are the loci of points where the principal-stress directions
coincide with the axis of the polarizer . These fringe patterns are used to
determine the principal stress directions at all points of a photoelastic model.
When the principal stress difference is zero (n = 0) or suf?cient to produce
an integral number of wavelengths of retardation (n = 1, 2, 3, …), the intensity
of light emerging from the analyzer is zero. This condition for extinction gives
a second fringe pattern, called isochromatics, where the fringes are
the loci of points exhibiting the same order of extinction (n = 0, 1, 2, 3, ).

where N is the isochromatic fringe order. The order of  extinction  n
depends on the principal stress difference (?₁ ?₂), the thickness h of the
model, and the material fringe value f?. When monochromatic light is used,
the isochromatic fringes appear as dark bands. When white light is used,
the isochromatic fringes appear as a series of colored bands. Black fringes
appear in this case only where the principal stress difference is zero.

FIGURE 1.5.42 Schematic of a stressed photoelastic model in a plane
polariscope.

A circular polariscope is a plane polariscope with two additional polarizing
plates, called quarter- wave plates, added between the model and the original
polarizing plates (Figure 1.5.43). The two quarter- wave plates are made of a
permanently doubly refracting material. The circular polariscope is used to
eliminate the isoclinic fringes while maintaining the isochromatic fringes.
To accomplish this, mono- chromatic light must be used since the quarter-wave
plates are designed for a speci?c wavelength of light. For the dark-?eld
arrangement shown, no light is passed through the polariscope when the model
is unstressed. A light-?eld arrangement is achieved by rotating the analyzer 90?.
The advantage of using both light- and dark-?eld analysis is that twice as much
data is obtained for the whole-?eld determination of ?₁ ?₂. If a dark-?eld
arrangement is used, n and N still coincide, as in Equation 1.5.65. If a light-
?eld arrangement is used, they are not coincident. In this case Equation
1.5.65 becomes

FIGURE 1.5.43 Schematic of a stressed photoelastic model in
a circular polariscope.

By determining both the isoclinic fringes and the isochromatic fringes,
the principal-stress directions and the principal-stress difference can be
obtained. In order to obtain the individual principal stresses, a stress
separation technique would need to be employed.

The advantages of the photoelastic method are that it allows a full-?eld
stress analysis and it makes it possible to determine both the magnitude
and direction of the principal stresses. The disadvantages are that it
requires a plastic model of the actual component and it takes a considerable
effort to separate the principal stresses.

Thermoelastic Stress Analysis. Modern thermoelastic stress analysis
(TSA) employs advanced differential thermography (or AC thermography)
methods based on dynamic thermoelasticity and focal-plane-array
infrared equipment capable of rapidly measuring small temperature changes
(down to 0.001?C) caused by destructive or nondestructive alternating
stresses. Stress resolutions comparable to those of strain gages can be
achieved in a large variety of materials. The digitally stored data can be
processed in near- real time to determine the gradient stress ?elds and
related important quantities (such as combined-mode stress intensity factors)
in complex components and structures, with no upper limit in temperature.
The ef?cient, user-friendly methods can be applied in the laboratory and
in the ?eld, in vehicles, and structures such as bicycles, automobiles, aircraft,
surgical implants, welded bridges, and microelectronics. Optimum design,
rapid prototyping,  failure analysis, life prediction, and rationally accelerated
testing can be facilitated with the new TSA methods
(Color Plates 8 and 11 to 14).

Brittle Coatings. If a coating is applied to a specimen that is thin in comparison
with the thickness of the specimen, then the strains developed at the surface
of the specimen are transmitted without signi?cant change to the coating.
This is the basis of the brittle coating method of stress analysis. The two kinds
of coatings available are resin-based and ceramic-based coatings.
The ceramic-based coatings are seldom used due to the high application
temperatures (950 to 1100?F) required. The coatings are sprayed on the
component until a layer approximately 0.003 to 0.010 in. thick has accumulated.
It is also necessary to spray calibration bars with the coating at the same time
in order to obtain the threshold strain at which the coating will crack.
These calibration bars are tested in a cantilever apparatus and the threshold
strain is calculated using the ?exure formula and Hookes law. Once the
threshold strain is known and the actual specimen has been tested, the
principal stress perpendicular to the crack can be determined by using
Hookes law. The procedure is to load the component, apply the coating,
and then quickly release the loading in steps to observe any cracks.

The main advantages of this method are that both the magnitude and
direction of the principal strains can be quickly obtained and that the coating
is applied directly to the component. This also allows a quick analysis of
where the maximum stress regions are located so that a better method can
be used to obtain more accurate results. The main disadvantage is that
the coatings are very sensitive to ambient temperature and might not have
suf?ciently uniform thickness.

Mechanical Testing

Standards. Many engineering societies have adopted mechanical testing
standards; the most widely accepted are the standards published by the
American Society for Testing and Materials. Standards for many engineering
materials and mechanical tests (tension, compression,  fatigue, plane strain
fracture toughness, etc.) are available in the Annual Book of ASTM Standards.

Open-Loop Testing Machines. In an open-loop mechanical testing system
there is no feedback to the control mechanism that would allow for continuous
adjustment of the controlled parameter. Instead, the chosen parameter is
controlled by the preset factory adjustments of the control mechanism.
It is not possible for such a machine to continually adjust its operation to
achieve a chosen (constant or not constant) displacement rate or loading rate.

A human operator can be added to the control loop in some systems in an
attempt to maintain some parameter, such as a loading rate, at a constant level.
This is a poor means of obtaining improved equipment response and
is prone to error.

Closed-Loop Testing Machines. In a closed-loop, most commonly
electrohydraulic, testing system, a servo controller is used to continuously
control the chosen parameter. When there is a small difference between the
desired value that has been programmed in and the actual value that is being
measured, the servo controller adjusts the ?ow of hydraulic ?uid to the actuator
to reduce the difference (the error). This correction occurs at a rate much
faster than any human operator could achieve. A standard system makes
10,000 adjustments per second automatically.

A typical closed-loop system (Color Plates 9, 11, 15) allows the operator
to control load, strain, or displacement as a function of time and can be
adjusted to control other parameters as well. This makes it possible to
perform many different kinds of tests, such as tension, compression,
torsion, creep, stress relaxation, fatigue, and fracture.

Impact  Testing.  The most common impact testing machines utilize either
a pendulum hammer or a dropped weight. In the pendulum system a hammer
is released from a known height and strikes a small notched specimen, causing
it to fracture. The hammer proceeds to some ?nal height. The difference between
the initial and ?nal heights of the hammer is directly proportional to the energy
absorbed by the specimen. For the Charpy test the specimen is mounted
horizontally with the ends supported so that the pendulum will strike the
specimen in midspan, opposite the notch. In the Izod test the specimen
bottom is mounted in a vertical cantilever support so that the pendulum will
strike the specimen at a speci?c distance above the notch, near the unsupported
top end. A large variety of the drop-weight tests are also available to investigate
the behaviors of materials and packages during impact.

Hardness Testing. The major hardness tests are the Brinell, Rockwell,
Vickers, and Shore scleroscope tests.

The Brinell hardness test uses a hardened steel ball indenter that is pushed
into the material under a speci?ed force. The diameter of the indentation left
in the surface of the material is measured and a Brinell hardness number
is calculated from this diameter. The Rockwell hardness test differs from
the Brinell test in that it uses a 120? diamond cone with a spherical tip for
hard metals and a 1/16-in. steel ball for soft metals. The Rockwell tester
gives a direct readout of the hardness number. The Rockwell scale consists
of a number of different letter designators (B, C, etc.) based on the depth
of penetration into the test material.

The Vickers hardness test uses a small pyramidal diamond indenter and
a speci?ed load. The diagonal length of the indentation is measured and used
to obtain the Vickers hardness number. The Shore scleroscope uses a weight
that is dropped on the specimen to determine the hardness. This
hardness number is determined from the rebound height of the weight.

stucco walls typically consist of three layers of stucco applied over wood spacers and wire mesh. The final coat is either pigmented or painted and can be textured in a variety of ways.

Cracks and holes in stucco can result from several causes, including poor-quality or poorly applied stucco
and settling. To protect your house from moisture damage, repair damaged stucco right away.

The keys to a successful repair job are slow curing of the patched stucco and careful matching of the color and texture of the patch to the existing wall. To match color, you can either add pig-ment to the final coat of stucco or paint the patch later on. Texturing is done with floats, trowels, or brushes. Following are directions for repairing cracks, small holes, and large holes.

Cracks. You can cover hairline and small cracks with a coat of latex paint or fill them with latex caulking compound and then paint with latex paint.

To fix larger cracks, use a cold chisel and ball peen hammer to under-cut the edges of the crack in the form of an inverted V (use the same technique as for interior plastered walls, pages 90-91). Then brush away loose stucco and dust with a stiff brush and dampen the crack with a fine spray of water. With a mason’s trowel or putty knife, fill the crack with stucco patching compound (available at home improve-ment centers), packing it in tightly; tex-ture to match the surrounding stucco (see text at right). Cure the stucco by dampening it once or twice a day for about 4 days.

Small holes. To repair a hole up to about 6 inches wide, first remove loose stucco with a cold chisel and ball peen hammer, undercutting the edges as for a crack, and blow out any dust. If the wire mesh is damaged, staple In a new piece. Dampen the patching site with a fine spray of water and pack the hole with stucco patching compound, using a mason’s trowel or putty knife. To cure the stucco, keep it damp for about 4 days.

Large holes. Holes larger than about 6 inches wide should be repaired using the same methods as for applying new stucco. You’ll need three coats of stuccoa “scratch” coat, a “brown” coat, and a final coat that you color and texture to match the original.

The first and second coats are made from one part Portland cement, three parts coarse sand, and 1/10 part hydrated lime, with enough water to make a fairly stiff paste. For the final coat, you use one part Portland cement, three parts coarse sand, and 1/4 part hydrated lime (use white Portland cement and sand if you’re adding pig-ment to the stucco).

To apply the stucco (see illustra-tions below), first prepare the surface by removing all the loose stucco, un-
dercutting the edges, and adding new wire mesh if necessary Be sure to press the first coat well into the mesh for a good bond. When this coat is firm, scratch it with a nail to provide grip for the second coat. Keep the first coat damp and let it cure for 2 days. Dampen the area with a fine spray of water before applying the second coat and keep the second coat damp for 2 days.

The final coat, the one you color, if desired, and texture, should be flush with the surrounding wall. While it’s wet, texture it to match (you’ll have to experiment a bit). For a smooth texture, draw a metal float across the surface. For other textures, daub a sponge or brush on the surface, or splatter it with more stucco and smooth down the high spots. To cure the stucco, keep it damp for about 4 days. If you plan to paint it to match the surrounding area, wait a month after curing.

Patching A Large Hole In Stucco

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