New Code Would Allow Unvented
Attics
Builder Costs Rising as Boom Rolls
On
Could New Glue Squeeze Mortar Out of Block
Walls?
Pool Slide
Offcuts
More Locales Mandate Fire SprinklersAsphalt roofing manufacturers oppose the change,
fear trapped moisture and rot
Builders, designers, and manufacturers have long debated
whether and when to vent attics, and a recent change to the
International Residential Code aims to put that debate to rest.
The 2004 code supplement allows unvented roof assemblies if two
conditions are met: The interior surface of the ceiling has no
vapor retarder and the underside of the roof deck is insulated
with impermeable insulation with enough R-value to keep its
monthly average temperature at or above 45¼F. The new
provision will tentatively be included in the 2006 version of
the IRC.
Proponents of the change say it will save energy by bringing
ductwork inside the home's conditioned space, and reduce mold
and mildew problems in humid climates where attic vents can
bring humid air into the building envelope.
But the new code language is not without its opponents. Earlier
this year, the Asphalt Roofing Manufacturers Association
petitioned the International Code Council to repeal the change.
Dave Roodvoets of DLR Consultants, which represented ARMA in
the effort, says the issue isn't roofing, but moisture
problems. He worries that requiring "air-impermeable"
insulation could actually make a home more susceptible to rot
by trapping moisture inside, even though it is keeping exterior
moisture out. "Ventilation compensates for a lot of sins," he
says. And he claims that proponents don't have enough research
to justify the change. "Even the best researchers have only a
few years of data on unvented attics in humid climates."
Ten-year-old houses built in Florida with
spray-foam-insulated hot roofs, like the one shown in this
detail from Building Science Corp., have fared well.
Investigations have shown that unvented attics may actually
reduce condensation and mold problems when compared with vented
attics, because moist outdoor air can't get in.
In practice, the requirement for air- impermeable insulation
means spray foam, and some unvented attic proponents have
charged ARMA with opposing the change only because it reduces
the market for fiberglass insulation, which some roofing
manufacturers also make. Roodvoets dismisses the charge. "It
has nothing to do with the type of insulation," he says.
"Manufacturers have just seen too many instances where moisture
in the attic causes damage to the house."
Armin Rudd of Building Science Corp. in Westford, Mass., who
worked on the code-change proposal, says there's no evidence to
support the charge that homes with unvented attics trap
moisture. He says that researchers have found that buildings
with unvented attics in hot, humid regions are actually less
likely to have condensation and mold problems than buildings
with vented attics. And while he can point to only five years
of measured data, he says there have been no reported problems
with unvented attics that were built in Florida over the past
10 years. "Conditioned attics with spray foam have been in
place successfully for a decade," he says. "It's a proven
building technology."
ARMA's proposal was shot down at the ICC Code Development
Hearings in March. Roodvoets says the association hasn't
decided whether to continue the fight. "It has been suggested
that we come back with proposed modifications to current
wording," he says. But he isn't hopeful about repealing the new
language: "It seems to have strong support among code
officials." — Charles Wardell
Builder Costs Rising as
Boom Rolls On
A stutter step in housing starts caused brief worry last
winter, as November figures dropped unexpectedly. But starts
bounced back in December with the biggest one-month jump in
seven years, and private residential construction posted a 13
percent gain for January and February 2005 over 2004. The condo
market entered 2005 red-hot, with existing condo sales up 22
percent for 2004, continuing a remarkable nine-year streak of
record sales.
Entering spring of 2005, the building industry continued to be
an engine for job growth. Builders had added a net 68,000
workers to their own payrolls in 2004, while residential
subcontractors hired an additional 77,000. Growth in
construction employment outpaced the nation's base rate of job
growth by two to one in 2004. By March 2005, builder payrolls
were up 7 percent over the previous March, as total
construction employment topped 7 million.
The bad news? Tight supplies and rising prices for just about
everything builders buy. The Bureau of Labor Statistics'
Producer Price Index for construction materials was up 0.9
percent in February (9.9 percent since February 2004), led by
surging costs for several key materials. Cement and concrete
rose by 9 percent on the year, gypsum products by 21 percent,
and steel mill products by a whopping 46.5 percent. Scrap-iron
prices dropped slightly in late winter, but major increases in
iron-ore prices signalled continuing cost pressures in the
steel industry. And, after diving through the fall of 2004,
framing lumber prices zoomed back in late winter toward
previous peaks. Along with high prices came reports of
shortages: Among the materials listed in short supply for
February and March by the Institute for Supply Management's
survey of purchasing executives were roofing shingles, steel,
and concrete.
Freight constraints will help keep supplies of all raw
materials tight in 2005. Experts say congestion in West Coast
ports, which reached crisis proportions in 2004, is likely to
pose chronic problems for a decade or longer. Lumber suppliers
in the U.S. and Canadian West are also complaining of nagging
rail-car shortages. Record oil prices add to shippers' woes:
With gas and diesel costing more at the pump, truckers have
begun adding a fuel surcharge to their per-mile rates. —
Ted Cushman
Could New Glue Squeeze Mortar
Out of Block Walls?
ITW TACC recently introduced Mason Bond, a single-component
moisture-cured polyurethane glue designed to take the place of
mortar in concrete masonry unit (CMU) walls. According to the
company's business manager, Tim Walsh, the idea came from a
Detroit contractor looking for a faster way to lay block. ITW
TACC first tested an off-the-shelf polyurethane adhesive and
found that it would glue CMUs together, but it created a mess
because it was thin and ran out of the joints. This led the
company to develop a thicker version, which goes on in a
1/4-inch bead and can be applied with a standard caulking gun
on small jobs, or pumped from 5-gallon pails or 55-gallon drums
on larger projects. Walsh claims the bond achieves 100 percent
strength in 24 hours.
New
materials must undergo independent testing to verify that they
meet code. In March 2004, several test walls were built with
Mason Bond and subjected to flexural testing at the National
Concrete Masonry Association Research and Development
Laboratory. The 8-inch block walls measured approximately 4
feet wide by 8 feet tall and had ungrouted cores. An inflatable
air bag applied uniform pressure to each test assembly; the
testers gradually increased the pressure until the wall
ruptured and failed. By code, the modulus of rupture for an
ungrouted wall of this type must be at least 63 psi; the
average modulus of rupture for the Mason Bond walls was 349
psi. In some cases, the block broke before the joint did.
Weighing the cost. More
important than the product's extra strength is its potential to
save labor by eliminating the need for mortar. So far, the
manufacturer has built only test walls, so no one knows how
much time Mason Bond would actually save. But, according to
Walsh, masons who have tested the glue say it cut their labor
hours in half.
Mike DeBlasio, a masonry contractor in Littleton, Mass., says
labor typically accounts for 75 percent of the cost of a CMU
wall, and a big chunk of that time goes into mixing and hauling
as well as applying the mortar. It also takes time to clean up
and dispose of mortar that falls on the ground or is left over
at the end of the day. Eliminating these tasks could
significantly reduce the labor to lay block.
Mason Bond is a polyurethane adhesive
designed to replace mortar in concrete masonry walls. Flexural
testing at an independent lab shows the glued joint has more
than five times the bond strength required by code and is in
some cases stronger than the block itself
(bottom).
As for material cost, DeBlasio reckons that $10 worth of sand
and masonry cement yields 3 to 4 cubic feet of mortar, which is
enough to lay as many as 75 8-inch blocks, depending on the job
and the mason. That comes to about 14 cents per block. ITW
TACC's Walsh says that the Mason Bond needed to lay one block
should cost about 15 to 20 cents. If the new product saves any
time at all, though, the additional material cost would be a
minor consideration.
At present, Mason Bond is being promoted for simple
applications like fastening cap pieces and outside corners on
dry-stack retaining walls. The company hopes to see it used for
basements and other building walls in the future, but for now
there are serious challenges. Because Mason Bond goes on thin,
it can't be used to level the wall; this means the first course
must be set and perfectly leveled on a bed of mortar. Also,
because most CMUs are slightly irregular, stacking them with
thin glue joints could result in a wall that isn't straight on
top. One solution would be to assemble most of the wall with
Mason Bond and use a second bed of mortar to level the final
course.
There is also the problem of eliminating the standard 3/8-inch
mortar joint, which is part of the typical 8-inch CMU module
(blocks are 75/8 inches tall). From an aesthetic point of view,
people expect to see those wider grout joints, so unless the
block is concealed, the mortarless joint could be a hard sell
to some clients. —
David
FranePool Slide
During a season of record-breaking rainfall, landslides have
become a common sight in Southern California. This concrete
swimming pool slid down a Bel-Air hillside in February when the
soil around it gave way. It's not surprising, actually, that
the pool remained intact. The steel-reinforced shell of a
concrete pool is not all that different from the hull of a
ferro-cement boat. Developed in the 1840s, ferro-cement
construction has been used in buildings, airplane hangers, and
water tanks. The method was also used to construct the hulls of
full-size ships during both world wars. —
David FraneOFFCUTS
Senior Canadian officials met with a U.S. trade
representative in Toronto last February to discuss ways to
reach a negotiated settlement in the two countries'
long-running dispute over softwood lumber pricing, reports the
Toronto Globe and Mail. One idea floated, says the paper, was a
lumber export tax imposed by the Canadian side to make up for
what the U.S. claims are unfairly low prices for timber charged
by Canada's provinces to Canadian logging firms. But observers
said negotiations are unlikely to bear fruit until after a
North American Free Trade Agreement panel rules on an
"extraordinary challenge" filed by the U.S. following repeated
adverse decisions in earlier NAFTA proceedings.
Big Buddy and Tough Buddy portable propane heaters were
voluntarily recalled by the U.S. Consumer Product
Safety Commission and Mr. Heater Inc. on March 31. Sold from
September 2004 to December 2004, units with model number MH18B
(found on the back of the product) may have a leaky valve,
creating a potential fire hazard. To get a replacement heater,
contact Mr. Heater at www.regcen.com or 800/385-2605.
Builders in Dallas are offering everything from
appliance upgrades to free maid service to lure buyers
into signing on the dotted line, reports the Dallas Morning
News. Although demand for new homes remains strong in the
Dallas-Fort Worth area, new builders entering the market have
raised the inventory of unsold new homes in the vicinity to
nearly 8,000, up from just 4,200 in the year 2000, says the
paper.
A recent report by the New Jersey State Commission of
Investigation cites "an astonishing statewide panorama
of waste, fraud, and abuse" in new-home construction, including
"shoddy and negligent workmanship" and "widespread inspection
irregularities." The commission found that in many cases
inspections were not performed or pressure from builders to
move a project to the next phase resulted in incomplete
inspections, and that inspection office personnel "accepted
gifts and other inducements from representatives of builders
and/or developers ... tainting the public's perception of their
ability to perform a vital function as dispassionate sentinels
over the process." See the complete report at
www.state.nj.us/sci.
More Locales Mandate
Fire Sprinklers
According to Peg Paul of the Home Fire Sprinkler Coalition
in Frankfort, Ill., there has been a recent surge in the number
of jurisdictions mandating sprinkler systems for new homes,
including a dozen districts in the Chicago area, as well as
smaller towns in states from Arizona to Maryland. But for
builders who have to install the systems and explain the
additional costs to home buyers, safety isn't the only issue to
consider.
"It creates another sub you have to deal with,
which adds time to your project," says Patrick Costello of
Forty West Builders in Ellicott City, Md. He had to install
sprinklers in a new development when the town passed an
ordinance in January 2004 requiring them in new single-family
homes. "The subs have to become familiar with the codes and
problems that can arise. And there's the need to help buyers
get comfortable with the idea of installing these
systems."
Costello points out that the cost of the systems was higher
than the initial estimate. "The numbers quoted by the sprinkler
associations to install these systems are about 1 percent to 2
percent of the cost of the project," says Costello. "But our
costs were higher than that. For each system, we ended up
paying about one dollar for each square foot of the structure.
So, for a 3,000-square-foot house with a 1,500-square-foot
basement, you're going to end up paying about $4,500 for a
system. There are also issues with wells and septic tanks that
can complicate the process and increase costs."
Concern over costs isn't confined to builders. Last year, Mesa,
Ariz., voters defeated a referendum on mandatory sprinkler
systems by a two-to-one margin. Meanwhile, the nearby town of
Goodyear passed a mandatory sprinkler installation law that
will go into effect in July. Builders had fought unsuccessfully
to make sprinklers an option they would have to offer buyers
rather than a requirement, and one town councilman cited
concerns that the sprinklers would require larger water meters,
which could lead to bigger impact fees and higher home
costs.
"I understand the concerns," says Gary Keith of the Home Fire
Sprinkler Coalition, "and I know that the process of installing
sprinklers may not be smooth in communities that have just
implemented these requirements. But we have towns that have had
this requirement in place for 10 or 15 years, and their
problems are minimal. The data from those communities shows
that these systems can save lives. So I would ask builders to
look at this as an opportunity to add an important safety
feature and to see home sprinkler systems as something that
would be desirable to many buyers." —
Charles Wardell