Renovation 4th Edition
Page 18
T-straps and L-straps are face-nailed to members
joining in a right angle.
Framing angles are used extensively to reinforce
Caps and bases: 1. A CBSQ44 post base anchors a 4x4 to concrete; 2. BC6 post cap and base;
wood connections at 90° intersections. For seis-
3. AC6 post-to-beam connector, which can be attached after the members are in place;
mic strengthening and on shear walls, framing
4. BC460 half-base; 5. BC46 post cap and base
angles help prevent floor framing from slipping
off walls and supports during an earthquake.
hold-downs are massive steel brackets that
anchor framing to foundations and, when used
with long threaded rods, join framing on differ-
ent floors. When retrofitting to a foundation, use
epoxy to attach hold-down bolts to concrete, as
shown in the right photo on p. 252.
Clips vary by function. H-clips are an alternative
to solid blocking when installing roof sheathing.
They also act as 1⁄16-in. spacers so roof sheathing
can expand. Drywall clips allow you to eliminate
some blocking in corners, but it’s best to use
these clips sparingly; solid blocking is much
sticky nameS
CauLKiNG was the first on the market, so
that’s the default word for materials that fill
gaps and keep out weather.
SeaLaNtS generally refer to high-performance
compounds such as silicones and polyurethanes.
aDHeSiVeS stick things together; their fancy
name is quite a mouthful: elastomer-based
Made of 16-gauge steel, nail plates protect plumbing pipes and electrical wires from being
extrudable mastics. eLaStoMer indicates that
punctured by nails.
the product will stay flexible and rubbery, and
MaStiCS is a general term denoting any pasty or
gooey adhesive. that noted, adhesives also seal
and sealants adhere, although that’s not their
main mission.
74
chapter 4
stronger. Deck clips are nailed to deck joists, and
A number of factors should determine your
P R O T I P
then 2x4 decking is driven onto the sharpened
choice of adhesives: the materials being joined,
point of the clip. You can lay down decking with-
strength, durability, flexibility, shrinkage, job-site
choosing the right adhesive
out having to face-nail it; the clip also acts as a
conditions (especially temperature and humidi-
is tough. these compounds
spacer so that water can clear.
ty), workability, curing time, ease of cleanup,
are cutting-edge chemistry.
odor, and—increasingly important—an adhesive’s
Post bases and caps provide strong connections
Formulations of familiar brands
toxicity and green profile. Accordingly, there is
while eliminating the need to toenail posts,
change often—and often with-
now a wide selection of solvent-free, low-VOC
which tends to split them. Post bases are typical-
out warning. so here are four
adhesives that are nontoxic. To help you make
ly set in concrete, with posts then bolted or
commonsense tips: (1) use
your choice, many manufacturers now offer
nailed to the base. Bases also reduce post rot, for
manufacturers’ online product
interactive, online product selectors.
selectors to narrow your choice
their raised standoffs elevate the post and double
As a rule of thumb, both solvent-free and
of adhesives. (2) get friendly
as a moisture shield. Post caps resemble a pair of solvent-based adhesives have the same holding
with the resident adhesive expert
U-brackets set at right angles to each other: One
power once they’ve cured. However, it should be
at the lumberyard, who may have
U, upside down, straddles the top of the post,
noted that solvent-free adhesives, which cure by
gotten a lot of feedback from the
while the other, right side up, receives the beam
field. (3) test a tube before you
evaporation, can be affected by rain and job-site
on which the joist will sit.
buy a case. (4) “but it’s cheap” is
temperatures outside a range of 40°F to 100°F.
Miscellaneous metal connectors are often
always a fool’s bargain.
Also, solvent-free adhesives may set poorly
needed. Where you absolutely must notch stud
between two nonporous surfaces and won’t bond
edges to accommodate plumbing, a metal shoe
to some metals. On the other hand, solvent-based
plate reinforces the stud and protects the pipe
adhesives, which cure via a chemical reaction,
from errant nails. Speaking of protection, this
discussion would be incomplete without men-
tioning nail plates, which protect wires and pipes
from stray nails when finish walls go up.
Adhesives, Caulks,
and Sealants
Common adhesives, caulks, and sealants look
the same, but their formulations are complex
and carefully formulated for specific materials
and expected conditions. They all generally come
in 10-oz. cartridges that fit into an applicator
(caulking gun). You simply cut the cartridge
nozzle to the desired diameter and squeeze the
long pistol-grip trigger to lay down beads of
the stuff.
construction adHesives
Construction adhesives bond to a variety of mate-
rials, including standard lumber, treated lumber,
Four popular adhesives, followed by their chemical names. From left: Gorilla Glue (polyurethane),
plywood and OSB panels, drywall, wall paneling, Gorilla Super Glue (cyanoacrylate), Weldwood® plastic resin (urea formaldehyde), and Titebond II rigid insulation, concrete and masonry, tile,
wood glue (polyvinyl acetate).
metal, and glass.
Construction adhesives are a boon to builders.
Instead of nailing sheathing every 6 in. around
Epoxy resins are typically mixed from
two components, whether as a paste
panel edges and every 10 in. in the field, builders
mixture used to fill sizable areas or as
using adhesives need nail only every 12 in. Being
a dual-cylinder injector where the
flexible, adhesives fill surface irregularities and
ingredients meet at the point.
double as sealants. Structurally, panels bonded
with adhesive are stiffer and capable of bearing
greater loads than panels that are only nailed.
Floor sheathing and stair treads bonded with
construction adhesives are far less likely to flex,
pop nails, or squeak. Drywall ceiling panels
bonded with adhesives do a better job of deaden-
ing sound and cutting air infiltration.
building materials
75
can bond to most surfaces and are little influ-
seaLants and cauLks
enced by temperature or the presence of water.
As noted in “Sticky Names” on p. 74, sealants and
caulks do pretty much the same thing: fill gaps,
can cause serious health problems.
keep moisture at bay, and reduce air infiltration.
Sealants tend to last longer, perform better, and
a potpourri oF adHesives
cost more. Here’s a look at the strengths and
Here’s a primer on common adhesives.
weaknesses of three major types of caulk.
Although caulks aren’t quite as diverse as con-
Polyurethanes are a great all-purpose water-
struction adhesives, they do have varying formu-
proof adhesive, capable of bonding wood, stone,
lations and properties. For specifics, go online or
metal, ceramics, and so on. Strong, versatile, and visit your lumberyard.
easy to use, polyurethanes such as Gorilla Glue®
and PL Turbo™ are favorites with builders and
Silicones are arguably the most durable and
woodworkers. Because a chemical reaction cures most water-resistant of any caulk. They are espe-
these glues, they are not affected by moist or oily
cially suitable for window glazing and slick bath-
surfaces; they can even join pieces that have
room and kitchen surfaces.
been finished. Before polyurethane glues dry,
Advantages: Silicones are incredibly
they can be removed by a solvent such as acetone tenacious on nonporous materials such as
or mineral spirits.
glass, glazed ceramic tiles, and metal. There’s
little shrinkage, and they can be applied at
Polyvinyl acetates (PVA) are a broad category of –40°F. Silicone sealants specified for metal
glues that range from water-based brands such as flue pipe function at 500°F. And silicones have
Elmer’s® white glue to Titebond® II and III, yel-
the best long-term flexibility, UV resistance,
low glues whose emulsions combine water and
and weatherability. Also, molds won’t grow
polymers. PVA glues are further divided into
on them.
three types: Type I is waterproof, Type II is water-
resistant, and Type III is not water-resistant.
Disadvantages: Silicones are messy to
Beyond that, all PVA-glued joints need to be
work with; wear rubber gloves to protect your
clamped until they cure, and, once dry, they all
skin. Once silicones have cured, it’s almost
have about the same holding strength.
impossible to remove them. Plus, they are
P R O T I P
bond breakers—that is, because nothing will
Cyanoacrylates (CA) are one-part or two-part
stick to an area they’ve tainted, think twice
use the same gun to apply
glues that set in 10 seconds to 10 minutes and
about trying them on wood, concrete, or other
caulking and construction adhe-
include the popular brands Krazy Glue® and
sive, but use a different tech-
porous surfaces they don’t adhere well to.
Super Glue®. Because they set strong and quick,
nique. because caulks and seal-
Avoid inhaling acetoxy silicones, and don’t use
CAs are prized by carpenters working one-handed,
ants fill gaps, push the gun away
them on metal because they’ll corrode it. Pure
say, to hold a miter joint in place until the glue
from you as you apply them,
silicones can’t be painted, although siliconized
sets. More expensive and much faster setting
pushing caulk into gaps. but to
acrylics can.
than polyurethane or PVA glues, CAs are not well
get an evenly sized bead of con-
suited to joining large surfaces.
Polyurethanes are versatile multipurpose caulks
struction adhesive, pull the gun
toward you, in a “lazy s” motion.
but are not as tenacious as silicones.
epoxy resins are famous for their strength.
Where two panels meet over a
Advantages: Because they attach equally
Typically mixed from two components, epoxies
framing member, apply a tight
well to wood, masonry, and metal, they’re
can bond to materials on which almost nothing
zigzag of adhesive so both edges
good for caulking joints where dissimilar
else will—that is, when the surface areas to be
will seat well.
materials meet. Polyurethanes won’t corrode
bonded are small or when dampness is extreme.
metal. They’re easy to work, although polys get
Epoxy products are especially important in foun-
pretty stiff as temperatures approach freezing.
dation repairs and seismic strengthening (for
Shrinkage is negligible. They’re great for
more information, see chapter 10). Unlike most
skylight flashing and metal roofs. And they can
other adhesives, epoxies also maintain structural be painted. Also, they’re easier to work than
strength across a gap.
silicones, even though they’re solvent based.
Styrene-butadiene is a good all-purpose exterior
Disadvantages: Polyurethanes have poor
and interior glue for joining materials of low
UV resistance, but additives or painting can
porosity, such as tile and masonry.
improve that dramatically. Although they are a
hot-melt glues are applied using an electric
good all-purpose caulk, they don’t have the
glue gun and are excellent for tacking surfaces
durability or shelf life of silicones.
quickly—they’re the glue of choice for building
templates out of thin plywood strips (see
chapter 13).
76
chapter 4
30-lb. Live Load 10-lb. dead Load L/360
Floor joists*
S p a n ( f e e t a n d i n c h e s )
2x6
2x8
2x10
2x12
Species
S p a c i n g o n C e n t e r
or group
Grade
12 in. 16 in. 19.2 in. 24 in. 12 in. 16 in. 19.2 in. 24 in. 12 in. 16 in. 19.2 in. 24 in. 12 in. 16 in. 19.2 in. 24 in.
Douglas sel. struc.
12–6
11–4
10–8
9–11
16–6
15–0
14–1
13–1
21–0
19–1
18–0
16–8
25–7
23–3
21–10
20–3
fir–
no. 1 & btr. 12–3
11–2
10–6
9–9
16–2
14–8
13–10 12–10
20–8
18–9
17–8
16–5
25–1 22–10
21–4
19–1
larch
no. 1
12–0
10–11
10–4
9–7
15–10 14–5
13–7
12–4
20–3
18–5
16–9
15–0
24–8
21–4
19
–6
17–5
no. 2
11–10
10–9
10–1
9–3
15–7
14–2
13–0
11–8
19–10
17–5
15–11
14–3
23–4
20–3
18–6
16–6
no. 3
9–11
8–7
7–10
7–0
12–7
10–11
10–0
8–11
15–5
13–4
12–2
10–11 17–10 15–5
14–1
12–7
Douglas sel. struc.
11–3
10–3
9–8
8–11
14–11
13–6
12–9
11–10
19–0
17–3
16–3
15–1
23–1
21–0
19–9
18–4
fir
no. 1
11–0
10–0
9–5
8–9
14–6
13–2
12–5
11–6
18–6
16–10 15–10
14–5
22–6
20–6
18–9
16–9
(South) no. 2
10–9
9–9
9–2
8–6
14–2
12–10
12–1
11–3
18–0
16–5
15–5
13–10 21–11
19–8
17–11
16–1
no. 3
9–8
8–5
7–8
6–10
12–4
10–8
9–9
8–8
15–0
13–0
11–10
10–7
17–5
15–1
13–9
12–4
Hem-fir sel. struc.
11–10
10–9
10–1
9–4
15–7
14–2
13–4
12–4
19–10
18–0
17–0
15–9
24–2
21–11
20–8
19–2
no. 1 & btr. 11–7
10–6
9–10
9–2
15–3
13–10
13–0
12–1
19–5
17–8
16–7
15–5
23–7
21–6
20–2
18–3
no. 1
11–7
10–6
9–10
9–2
15–3
13–10
13–0