ically come in 2-in. by 100-ft.
girder. For this reason, short sections “scabbed
Existing studs
rolls or bundles of 50 precut
on” don’t work and are usually prohibited by
strips 36 in. or 45 in. long. Cut
local building codes.
strips with a utility knife, and
New studs
To insert the new joist, remove blocking or
attach them to the studs with
bridging between the affected joists, and bend
hammer tackers, using 3⁄8-in.
over or snip off flooring nails protruding from
staples. (Fortifiber® is one
the underside of the floor. Then eyeball the new
manufacturer.)
sister joist and note its crown: If its arc is exces-
sive, power plane it down so that you don’t bow
up the floor as you drive the joist into place.
Beveling the leading top edge of the joist will also
make sledging into place easier. Once the new
joist is in position, use bar clamps to draw it tight
to the old joist. Face-nail the two together, stag-
gering 16d nails every 12 in. If there’s no room to
New
swing a hammer, use a pneumatic palm nailer to
partition
drive the nails most of the way.
angled-end joist. Where joists will rest on a
Existing studs
foundation mudsill at one end and hang from a
girder at the other (rather than sitting atop it),
Finish
cut away the top corner of the end that will rest
surface
on the mudsill so it will fit between the mudsill
and subfloor. Cut the other end square to butt to
Where a new partition abuts an existing wall,
the girder. Place the angle-cut end of the joist on
cut back finish surfaces to the centers of the
edge over the mudsill, then lift the squared end
nearest stud on either side, and add studs
and slide it toward the girder until it butts
to nail the partition to.
against it. Angle-cut joists must be a few inches
shorter than the original joist you’re sistering to.
You may need a plumbed adjustable column
the high spot and gradually tapering out.
or a screw jack to raise the joist until it’s flush to
Because knots are hard, they’ll take more passes.
the underside of the subflooring. Once it is flush,
Use your straightedge to check your progress,
use a double-joist hanger to join the new joist
and use taut strings to check the whole wall
and its sister to the girder. Face-nail the two
again after building up or planing down the
joists, staggering 16d nails every 12 in. Remove
studs. Caution: Wear eye protection when using a jacks and replace blocking between joists. Should
power planer.
the double-joist hanger overlap a hanger already
Common sense and “feel” are a big part of this there, predrill the metal so that you can nail
process: If all the studs in the wall have a slight
through both hangers with case-hardened hanger A palm nailer is ideal in tight spaces
bow inward or outward, the wall won’t be flat,
nails. To learn more about jacking safely, see
where you don’t have room to swing
but drywall covering it may look flat. In that case, chapter 10.
a hammer.
leave the studs as they are.
Flitch plates. Steel flitch plates are sometimes
bOlSTering JOiSTS
used to reinforce undersize beams or joists.
Because they are typically 3⁄8 in. to 1⁄2 in. thick
Widespread sagging or excessive springiness in
and must be predrilled, they’re not well suited to
a floor is probably caused by joists that are too
casual installation by nonspecialists. There’s
small for the span or by post, pad, and founda-
more on flitch plates on p. 64–65.
tion failure, as covered in chapter 10. Isolated
joist failure is usually caused by insect or water
meTal STudS
damage, alterations to the joist, or a point load
from a heavy piece of furniture or bathtub.
Lightweight steel studs are still relatively rare in
If there’s infestation or rot, correct that
home construction, but they are appropriate for
condition first.
certain tasks. They’re dead straight—one big
Structural Carpentry
201
surface to—especially 15⁄8-in.-wide studs, which
won’t take up much room in space-starved base-
ment remodels.
Stud
zzzzzz nailing Off Sole Plates
Metal stud walls are also a snap to take out
because they’re assembled with self-tapping
Sole plate
sheet-metal screws. That’s why they’re used so
often on commercial or retail spaces. A green
delight, they can also be recycled completely.
leveling ceilings. Metal studs really shine when
you need to level a ceiling whose slope would be
especially noticeable against, say, cabinets with
crown molding. Because metal studs are so light,
they go up quickly, yet they are sturdy enough to
support a new drywall ceiling. This procedure is
called “furring down a ceiling,” and using metal
studs is much easier than ripping tapered wooden
SOLE PLATE OVER JOISTS
strips to create a leveled ceiling, which is hugely
time-consuming and often doesn’t look very good.
1. Start by tearing out the existing drywall or
plaster ceiling to expose the ceiling joists. (If ceil-
ing joists are undersize or rotted, fix those condi-
Sole plate
tions first.)
2. Using a laser level, establish a level line
around the room, 1⁄4 in. below the lowest point of
the ceiling joists.
3. At this height, drive nails into the corners
of the room. Stretch string perpendicular to
the ceiling joists at both ends of the room and
roughly every 3 ft. or 4 ft. in between.
Blocking
4. With the aid of a helper, lift the steel studs
over the leveled strings, and lower each stud until
Joist
its bottom edge is 1⁄16 in. above the strings. (The
1⁄16-in. gap is necessary to avoid moving the align-
SOLE PLATE OVER BLOCKING
ment strings.)
5. Once each steel stud is correctly positioned,
use 1-in. screws to attach it to a joist face; space
When a partition runs parallel to the joists, try
screws every 16 in. along the length of the stud.
to position it over a joist so you’l have something
Place screws back at least 1⁄2 in. from the lower
to nail the sole plate to. If you can’t reposition
edge of the joist. Use aviation snips or a metal-
the wall, add blocking between the joists.
cutting blade in a reciprocating saw to cut light-
weight steed studs.
TreaTing inSeCT inFeSTaTiOnS
advantage over much of the wood framing that’s
available today. If you work with them, eye
and
If you see signs of an infestation, hire a pest-
hearing protection are a must—as are rubberized control professional to assess and remedy it.
cloth gloves to protect your hands.
Pesticides are often toxic, and anyone unfamiliar
Metal studs are sometimes specified in resi-
with insect habits may not destroy all their nest-
dential situations where fire is a concern, say, in
ing sites or may apply pesticides inappropriately
common walls between living spaces and a
or unnecessarily. Moreover, local codes may
garage. They are also good for framing kitchen
require a professional.
lighting soffits or for forming chases, essentially
It’s often difficult to tell whether an infesta-
long, shallow boxes in which to run mechanicals
tion is active. For example, if a subterranean ter-
such as pipes, ducts, or wiring. As shown on the
mite infestation is inactive, a prophylactic treat-
facing page, lightweight steel studs are also ideal
ment may suffice. But if the infestation is active,
for furring out a foundation wall to attach a finish the remedy may require eliminating the condi-
202 Chapter 8
zzzzzz leveling a Ceiling with Steel Studs
Joist
Steel studs
Steel stud
Taut string
Low point
of joists
Nail
Nail
1/4 in.
1/16 in.
Taut string 1/4 in. lower
than lowest joist
Lowest joist
This wall sheathing shows evidence of fungi and insect
damage. After failed window flashing allowed water
Level laser line
Laser
behind a stucco exterior, wood-destroying fungi grew
around the room
quickly. Then subterranean termites tunneled, consuming
the moist, fungus-damaged wood. Cross-grain checking
just above center is a typical sign of fungus damage. A
beetle larva showed up, too.
Steel studs let you establish a level plane of nailers for eventual drywall.
tions that led to the infestation (such as excessive
As detailed in the text, measure up from a level laser line, drive a nail at
moisture and earth–wood contact) and an
each room corner, and stretch a string perpendicular to the joists at each
aggressive chemical treatment. Treatment usually
end of the room.
consists of applying a chemical barrier on the
ground that repels the termites or a “treated
zone” whose chemical doesn’t repel them initially wings of different sizes. Although they do tunnel
but later kills or severely disrupts them.
in wet or rotting wood, they do not eat it as food
Termites, the most famous of insect pests,
and are therefore less destructive than termites.
include drywood, subterranean, and Formosan
To locate their nests, look for borings rather like
types. Because subterranean termites need access coarse sawdust. Professionals will often drill into
to moisture in the soil, they build distinctive dirt
nests and spray them with an insecticide safe
tubes up along the surface of foundations. When
enough for inside use; dusting with boric acid is
they eat into the wood, they usually proceed with another common treatment.
the grain. Termites swarm in spring or fall.
Powder-post beetle holes look like tiny BB-gun
Discourage the return of subterranean termites
holes; their borings resemble coarse flour. Because
by lowering soil levels around foundations, foot-
these insects favor the sapwood, evidence of bor-
ings, and the like.
ings may be only superficial until you prod with
Drywood termites hollow out chambers sepa-
a pocketknife. Still, holes are not a sure sign of
rated by thin tunnels and often travel cross-grain; an active infestation. One approach is to remove
they eject fecal pellets through holes, with the
the damaged wood, sweep up borings, paint the
pellets forming pyramid-shaped piles. Fumigation area, and monitor it for a year. If holes reappear,
is effective for drywood termites, but it’s ineffec-
it’s an active infestation: A professional will need
tive for treating subterranean termites because
to fumigate the wood or apply a pesticide.
their colonies are located in the ground and
fumigation gas does not penetrate the soil.
dealing wiTH rOT
Formosan termites, whose colonies may
If wood is spongy, contains wispy fibers that look
exceed 1 million individuals, are wreaking havoc
like cotton, or disintegrates without reference to
along the Gulf Coast of the United States; they
the grain, it is infested by a rot fungus. The white
live in the ground or in buildings and build huge, strands are spores.
hard nests.
Carpenter ants are red or black, 1⁄4 in. to 1⁄2 in.
long. Sometimes confused with termites, these
ants have narrow waists and, when winged,
Structural Carpentry
203
If the rot is limited to a few spots, suspect
leakage and look for other clues above. Water
may be entering from inadequate roof flashing,
zzzzzz Sistering Joists
blocked gutters, or—quite common in older
SISTER JOIST SITS ATOP SILL AND HANGS OFF GIRDER
houses—windows or doors that lack flashing
altogether, in which case there will probably be
Subfloor
fungus damage to walls and ceilings inside. Also,
look for structural damage beneath tubs, sinks,
New joist
Slide joist
and water heaters; if you find any, make sure the
cut 2 in. short;
to girder.
angle-cut this end.
damage hasn’t progressed into subflooring and
floor framing.
Rotted wood, unsightly as it is, poses no
2
threat to healthy wood nearby, as long as you
1
control the moisture that encouraged the fungus
in the first place. Cut out deteriorated sections,
3
but don’t bother to remove discolored wood that
Attach hanger
is solid; leave it in place, especially if flooring is
when joist is
Girder
2x6 mudsill
flush.
water, insects, rot,
Double
joist hanger
and mold
whether structural damage is caused by insects or
To a sister a new joist when one end will rest on a mudsill and the other will hang
rot fungi, excess water is usually at the heart of the
from a girde, angle-cut the mudsill end and slide it into place. Then raise the other
end until it’s flush with the girder before attaching with a hanger.
problem. before treating the specific agent causing
the deterioration, reduce excess water by maintaining
gutters, improving drainage, grading the soil away
from the building, eliminating wood–soil contact, and
improving ventilation.
SISTER JOIST SITS ATOP SILL AND GIRDER
spores, so they’re virtually everywhere. but they can’t
establish colonies on wood with a moisture content
Beveled edge
Subfloor
(mC) less than 28%, and they go dormant if the mC
drops below 20% or the air temperature drops below
40°F. Household molds, also caused by fungi, thrive
in a similar moisture and temperature range. So if
New joist
moisture-meter readings in your basement or crawl-
space are too high, reducing excess moisture may
solve both wood rot and mold problems.
How you reduce moisture, however, is something
experts can’t agree on (see 256–259 and chapter 14
Girder
or mudsill
for more on mitigating moisture and mold). many
building codes recommend covering dirt floors in
crawlspaces or basements with sheet plastic and
installing screened vents to circulate air and disperse
moisture: 1 sq. ft. of vent per 100 sq. ft. of floor space
Old joist
is the standard formula. whereas another group of
builders argues that it makes more sense—especially
in the humid South—to close vents, insulate crawl-
To “sister” a new joist to one that sits atop a mudsill
on one end and a girder on the other, bevel the leading
space or basement walls, seal air leaks, and install a
top edge so it will “sledgehammer “ into place.
dehumidifier. That, they argue, will stop mold from
colonizing and migrating to living spaces. best bet:
See which approach builders in your region favor.
204 Chapter 8
nailed to it. You can reinforce existing joists by
sistering on new ones, but before doing so, allow
Stair liNgo
the old joists to dry thoroughly.
The two-part epoxy repair discussed on p. 163,
As shown below, stringers and carriages support steps. Stringers serve as the diagonal
though interesting, is primarily a cosmetic fix.
support frames on each side. And carriages carry by means of a sawtooth pattern cut
Most epoxy fills are inappropriate for structural
into them. Stringers and carriages are often fastened together. Another option is a
elements. Some companies, such as ConServ
housed stringer, in which a stringer has routed grooves that receive and support tread
Epoxy, make products specifically for structural
and riser ends.
repairs.
Stair Repairs
Stairs are complicated to build, and problems
can be tricky to diagnose. For example, it may
Renovation 4th Edition Page 47