Panelizing Houses - Continued
It's important to remember, though, that this machine's
capabilities can't be fully realized without good software to
run it. As my shop foreman says, "Without the software, it's no
better than a $25,000 tape measure."
Subcomponent nailer. The second station on the line is the
subcomponent nailer, which allows one operator to assemble
headers, corners, partition lead-ins, and other framing details
before the panel reaches the framing table. Our homes generally
have standard window and door sizes to make it easier to
assemble and inventory subcomponents (Figure 4).
Figure 4.At the subcomponent nailer, the operator
consults the shop drawing for the panel design and then nails
together jack studs and headers for window and door openings,
and tees for intersecting walls and corners (top). Common
header sizes, jack studs, and tees are kept in inventory to
speed production (bottom).
Framing table. Next in line is the framing table; this is where
the preassembled subcomponents and studs are automatically
placed and clamped within the top and bottom plates. A man on
each side of the table rolls a carriage holding double
pneumatic nail guns; he fastens the plates to the studs and
subcomponents as he goes (Figure 5).
Figure 5.At the framing table, the subcomponents
are the first pieces fastened to the plates, along with any
cripple studs (A). Steel fingers (painted yellow) ensure
accurate 16-inch o.c. spacing and can pivot to lay flat when
they interfere with the placement of a double stud, tee, or
header (B). Once the remaining studs are placed, the whole
panel is held together with pneumatic rams while it's nailed
off with special weight-assisted two-gang framing nailers (C).
Before the panel moves on, any twisted studs are pried into
place with a tweaker (D) before being nailed with a pneumatic
nailer; blind cavities are filled with insulation
When this operation is completed, the wall panel is rolled to
the squaring table and sheathing bridge.
Squaring table. Here, the panel is instantly squared to within
1/32 inch and the sheathing is applied and stapled
automatically. Once the sheathing is tacked in place, we cut
out the windows and door openings with a two-man router (Figure
6). In our shop, the sheathing bridge is manually positioned
over the studs and a pneumatic nailer travels back and forth
across the bridge, automatically fastening the sheathing
Figure 6.Window and door openings are cut with a 3
1/4-hp router mounted on a steel sled. Suspended from a cable,
it retracts out of the way when not in use and can cut out a
door or window in about a minute.
Figure 7.Before the panel is sheathed, it's pushed
into shape on the squaring table, which is checked daily for
accuracy. Pneumatic rams and a pawl on one end squeeze the
panel while the sheathing is fastened (top). In more automated
shops, the sheathing nailer, which weighs 100 pounds, might be
robotically positioned, but on this line the task is done
manually by two people (middle) with the help of a laser
Then the panel is lifted off the table by electric hoist, and
stacked and banded for shipment (Figure 8).
Figure 8.The completed panels are picked from the
line with an electric hoist and stacked in the order in which
they'll come off the truck at the job site. The author limits
panel length to about 12 feet so that they can be stood up by
How Much It All Costs
The assembly-line equipment accounts for the biggest capital
investment, but there are many other smaller purchases that add
up, too. For example, all the equipment in the line is
air-driven, so a high-volume air compressor is essential.
We also precut floor joists and rafters using a 7 1/2-hp
power-feed radial-arm saw, and there are several cutting
stations requiring top-quality miter saws. Plus we have
forklifts, trucks, rolling tables, benches, and other small
So, what's the bottom line? Aside from the price of the
facility itself — which, of course, varies by location
— costs for the equipment, software, and installation
needed for a new semiautomatic operation run in the range of
This is a significant expense, but it provides an efficiency
that can't be touched with on-site building. Moreover, it's far
less than the million or more dollars that can be spent on a
fully automated plant. With sufficient volume, this cost
amortized over several years makes sense, given the increased
Our company can produce a full set of plans — complete
with shop drawings — and turn out a custom
2,500-square-foot house with panelized and sheathed walls and
precut floors and rafters in about 60 man-hours. A skilled
framing crew can have a simple design erected and dried-in
within one week; designs that are more complex may take another
More Than Just a Shell
While framing is an important element of off-site building, our
company has introduced another level of off-site efficiency
with our prebuilt architectural details. We routinely build
front entrances, cornices, pilasters, and Greek Revival corners
in our shop so that they can be quickly installed in the
Again, producing these pieces requires sophisticated drafting
capabilities. All of our architectural details are drawn in
minute detail, and we are able to quickly access the
appropriate designs in our large library stored in
We also prebuild many of the less complex exterior trim pieces
because we can do it faster and better in our shop than in the
field. We rabbet the fascia, prerip all soffit pieces, apply
crown mold to fascia, and prebuild returns and corner boards
Figure 9.It's the exterior trim that makes the
author's colonial reproduction homes distinctive and popular
(top). Soffit and fascia, water tables, corner boards, and
custom windows are all produced in the author's shop, along
with much of the interior millwork. Since the homes generally
have the same exterior details, much of the exterior trim can
be mass produced and kept in inventory (bottom).
We buy most of our material from one supplier. Since full units
of framing lumber are the norm and save time and handling at
the lumberyard, we get lower prices. We use so much molding our
supplier has made special arrangements with the molding
producer for factory priming of profiles not commonly available
with a primed finish.
We have to buy 5,000 or 10,000 feet at a time, but since our
facility has plenty of storage, this isn't a problem.
Myths and Misconceptions
One of the myths about off-site building is that customization
is impossible. While it's true that our company has a standard
catalog of colonial reproduction homes, most of our builders
and homeowners either customize these plans or start from
scratch with our design department.
Once the design is finalized, we price the panelized shell
package with all windows, doors, trim, roofing, and siding, and
we also price a separate interior package that includes stairs,
doors, flooring, trim, and cabinetry. Exterior home packages
generally range in price from about $45,000 to $150,000.
Another common myth is that off-site construction is of lower
quality than site-built. I don't think that's true.
Our plans are scrutinized by the designer and production team,
so any quirks or problems are addressed well ahead of time; and
the homes are constructed in a controlled environment with
greater oversight than most site-built houses receive.
Considering the advances that have been made in the house
panelization industry, any builders looking to increase volume
and overall efficiency should consider setting up at least a
small off-site building program so they can remain productive
when the weather is bad.
Even though our new facility could probably turn out hundreds
of homes a year, we've chosen to stay small because my staff
and I want to be home builders — not assembly-line
Mike Connor is a home builder in