Insulated Concrete Forms Icf
Debris driven by high winds presents the greatest hazard to homeowners and their homes during
tornadoes and hurricanes. Laboratory testing at the Wind Engineering Research Center, Texas Tech University,
compared the impact resistance of residential concrete wall construction to conventionally framed walls. The
frame walls failed to stop the penetration of airborne hazards. The concrete walls successfully demonstrated
the strength and mass to resist the impact of wind driven debris.
What was tested?
How did the frame walls perform?
Various wall specimens were subjected to the impact of a 2 x 4 wood stud traveling at up to 100
miles per hour. This is equivalent to the weight and speed of debris generated during a tornado with 250
miles per hour winds. This testing covers the maximum wind speed generated in 99 per cent of the tornadoes
occurring in the United States. Wind speeds are less than 150 miles per hour in 90 per cent of tornadoes. Ten
wall specimens were constructed, each representative of the type of construction now used to build frame
homes and concrete homes in the U.S. Tables 1 & 2 describe each wall assembly tested.
The Wind Engineering Research Center’s compressed air cannon was used to propel a 2 x 4 wood stud
debris "missile" at the test walls. The stud was propelled along its axis with the leading end hitting the
specimen. Electronic timing devices measured the speed of the debris as it traveled from the cannon to the
test walls located 16’-6" away.
The frame walls lacked the weight and mass to resist the impact of the wind driven debris. In each
case, the debris traveled completely through the wall assembly with little or no damage to the
"missile."
Table 1: Frame Wall Test Results:
|
Wall Type:
|
Test Wall Description:
|
Speed of
Debris:
|
Results:
|
|
Wood
Frame:
|
2 x 4 wood studs at 16" o.c.,
3-1/2 in. batt insulation, 5/8 in. gypsum board interior finish, vinyl siding over 3/4 in.
plywood sheathing exterior finish
|
109.0 mph
|
The debris "missile" perforated completely through the wall assembly.
Little damage to the missile.
|
|
`
|
2 x 4 wood studs at 16 in. o.c.,
3-1/2 in. batt insulation, 5/8 in. gypsum board interior finish,
3 in. brick veneer with 1 in. air space, over 3/4 in. plywood sheathing exterior finish
|
69.4 mph
|
The debris "missile" perforated completely through the brick veneer,
and interior finish. Minor damage to the missile.
|
|
Steel
Frame:
|
Steel studs at 16 in. o.c., 3-1/2 in. batt insulation, 5/8 in. gypsum
board interior finish, vinyl
siding over 3/4 in. plywood sheathing exterior finish
|
103.5 mph
|
The debris "missile" perforated completely through the wall assembly.
Little damage to the missile.
|
|
|
Steel studs at 16 in. o.c., 3-1/2 in. batt insulation, 5/8 in. gypsum
board interior finish, synthetic stucco over 1/2 in. gypsum board sheathing exterior
finish
|
50.9 mph
|
The debris "missile" perforated completely through the wall assembly.
No damage to the missile.
|
Concrete Homes Built-in Safety
How did the concrete walls perform?
The concrete stopped the debris from traveling through the wall. Exterior finishes were damaged by
the impact, but the concrete walls were unscathed. Even the narrowest, 2" thick section of "waffle grid" ICF
wall was undamaged by the direct impact of the debris at over 100 mph.
Table 2: Concrete Wall Test Results:
|
Wall Type:
|
Test Wall Description:
|
Speed of
Debris:
|
Results:
|
|
Concrete:
|
6 in. thick reinforced concrete wall,
#4 vertical reinforcement bars, 12 in. o.c. No finishes.
|
102.4 mph
|
No cracking, front face scab- bing or back face spalling of concrete
observed.
|
|
|
6 in. thick reinforced concrete wall,
#4 vertical reinforcement bars, 24 in. o.c. No finishes.
|
102.4 mph
|
No cracking, front face scab- bing or back face spalling of concrete
observed.
|
|
ICF:
|
Block ICF foam forms, 6 in. thick flat concrete wall, #4 vertical
reinforcement bars, 12 in. o.c. Vinyl siding.
(Tested a second time with similar results.)
|
103.8 mph
|
Debris penetrated vinyl sid- ing and foam form. No cracking, front
face scabbing or back face spalling of con- crete wall observed.
|
|
|
Block ICF foam forms, 6 in. thick flat concrete wall, #4 vertical
reinforcement bars, 24 in. o.c. 3 in. brick veneer with ties spaced 1 ft-0 in. o.c. ea.
way.
|
99.0 mph
|
Debris penetrated and cracked brick veneer. Foam form dented. No
cracking, front face scab- bing or back face spalling
of concrete wall observed.
|
|
|
Panel ICF foam forms, 4 in. thick flat concrete wall, #4 vertical
reinforcement bars, 24 in. o.c. Vinyl siding.
|
96.7 mph
|
Debris penetrated vinyl siding and foam form. No cracking, front face
scab- bing or back face spalling of concrete wall observed.
|
|
|
Block ICF foam forms, variable thick- ness "waffle" concrete wall, 6
in. maxi- mum thickness, and 2 in. minimum thickness. #4 vertical reinforcement bars in each
6 in. vertical core at 24 in. o.c. Synthetic stucco finish.
(Tested a second time with similar results.)
|
100.2 mph
|
Debris penetrated synthetic stucco finish, and foam form. Impact of
wall at 2" thick section. No cracking, front face scabbing or back face spalling of concrete
wall observed.
|
Note: All concrete tested: 3000 psi comprehensive strength, maximum aggregate size
3/4 in, 6 in. slump.
What about damage from hurricanes?
What’s the bottom line?
Hurricane wind velocities will be less than the equivalent maximum speeds modeled in the tests.
Missile testing designed to mitigate property damage losses from hurricanes use a criterion of a 9-pound
missile traveling about 34 miles per hour.
The strength and durability of concrete walls offer unmatched resistance to the devastation of major
storms. Concrete homes are less likely to suffer major damage from debris than conventionally framed houses.
This greater measure of built-in safety makes cement-based ICF construction systems the quality choice for
your new home.
maximum aggregate size 3/4 in, 6 in. slump.
| 