Page 29 - Green Builder's Resilient Housing Design Guide 2019

wall might be a good pressure washing.
The Roman Pantheon, the medieval SLAM TEST: ICF walls can take a beating
cathedrals of Europe, the Hoover Dam—
these enduring structures continue IRECT POUNDING OF HIGH WINDS on a building is not nearly as damaging as flying debris driven
to thrive because of their concrete by those winds. A recent simulation conducted by Texas Tech University’s Wind Engineering
construction. Long after new concrete Research Center compared the impact resistance of residential concrete wall construction to
hardens, it continues to cure, getting D conventional framed walls. A compressed air cannon was used to propel a 15 lb. 2x4 wood stud
progressively stronger as time goes on. “missile” traveling at speeds up to 100 mph against four wall types: wood frame, steel frame, concrete and
What makes ICF construction even insulated concrete form.
more durable is the method in which the The speed used was calculated as the equivalent of the weight and speed of debris generated during a 250
walls and floors are tied together with mph tornado—well above even the most extreme tornado or hurricane wind velocities. All of the concrete test
overlapping reinforced steel, resulting in walls were poured at 3000 PSI compressive strength, with aggregate size ¾”, 6” slump.
a monolithic structure that will stand the As you might expect, the debris passed completely through the light-wood and light steel framed walls. The
test of time. The bottom-line benefit for concrete walls fared significantly better, with damage only to any exterior finishes, and in some cases, slight
owners: far fewer maintenance headaches dents in the insulation foam. But, most importantly, no cracks in the concrete were observed.
and substantial savings over the life span The report summarizes its findings as, “The strength and durability of concrete walls offer unmatched
of a building. resistance to the devastation of major storms.”

ICF DIVIDENDS AFTER A FLOOD More Information: The following publication and video are available from the Portland Cement Association. To order call PCA
A little known fact about hurricanes and Publications at 1.800.868.6733. Ask about VC511 “Concrete Homes- Built In Safety”. Source: Portland Cement Association
natural disasters is that the worst damage
to buildings often takes place after the fact. CONCRETE WALL TEST RESULTS
That’s because as winds and flood
waters subside, the power grid may WALL TYPE: TEST WALL DESCRIPTION: SPEED OF DEBRIS: RESULTS:
take weeks or months to get working Concrete: ■ ■ 6” thick reinforced concrete wall, 109.0 mph No cracking, front face
again. During that time, the inside of the ■ ■ #4 vert. reinforcing bars, 12” o.c. scabbing or back face spalling
structure becomes an ideal environment ■ ■ No finishes of concrete observed.
for mold to form, with extremely high
■ ■ 6” thick reinforced concrete wall, 102.4 mph No cracking, front face
humidity, heat and plenty of bacteria and
■ ■ #4 vert. reinforcing bars, 24” o.c. scabbing or back face spalling
organic substances.
■ ■ No finishes of concrete observed.
With ICF walls, however, even a small
dehumidification system can reduce ICF: ■ ■ Block ICF foam forms 103.8 mph Debris penetrated vinyl siding
moisture levels enough to save the ■ ■ 6” thick flat concrete wall and foam form. No cracking,
building. ICF homes typically require ■ ■ #4 vert. reinforcing bars, 12” o.c. front face scabbing or back
32 percent less energy to cool than ■ ■ Vinyl siding face spalling of concrete wall
comparable wood-framed structures, (Tested a second time with similar results.) observed.
which in normal times means a high ■ ■ Block ICF foam forms, 99.0 mph Debris penetrated and
return on investment, and in disaster ■ ■ 6” thick flat concrete wall, cracked brick veneer. Foam
scenarios, can mean the difference ■ ■ #4 vert. reinforcing bars, 24” o.c. form dented. No cracking,
between a total loss, and a minor setback. ■ ■ 3” brick veneer with ties spaced 1’-0” front face scabbing or back
A small generator, or a solar array with ea.way. face spalling of concrete wall
a DC-powered mini split system can take observed.
advantage of an ICF building’s small ■ ■ Panel ICF foam forms, 96.7 mph Debris penetrated vinyl siding
energy footprint to reduce humidity and ■ ■ 4” thick flat concrete wall, and foam form. No cracking,
heat levels to a point unfriendly to mold ■ ■ #4 vert. reinforcing bars, 24” o.c. front face scabbing or back
growth. ■ ■ Vinyl siding face spalling of concrete wall
While others in the neighborhood are observed.
wrangling with insurance companies and ■ ■ Block ICF foam forms, 100.2 mph Debris penetrated synthetic
spending many sleepless nights, the ICF ■ ■ Variable thickness “waffle” concrete stucco finish, and foam SOURCE: WIND ENGINEERING RESEARCH CENTER, TEXAS TECH UNIVERSITY
owner can rest easy, knowing that his or her wall, 6” max. thickness, and 2” min. form. Impact of wall at 2"
house will soon feel like a home again. GB thickness. thick section. No cracking,
■ #4 vert. reinforcing bars in each 6” front face scabbing or back
■
Source: Original content courtesy of Amvic vertical core at 24” o.c. face spalling of concrete wall
educational materials, used with permission ■ ■ Synthetic stucco finish. observed.
®
and edited by Green Builder Staff (Tested a second time with similar results.)

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