ICF 101: THE ULTIMATE GUIDE TO
INSULATED
CONCRETE FORMS
TABLE OF CONTENTS
ICF 101:
THE ULTIMATE GUIDE TO INSULATED CONCRETE FORMS
Looking to learn more about Insulated Concrete Forms (ICFs) and how
they can benefit your construction project?
Whether you’re a homeowner, real estate agent, contractor, architect
or distributor, this e-book will help you understand Insulated Concrete
Form wall assemblies, their advantages, and how to get started with ICF
building design and construction.
»
Chapter 1: What are ICFs
»
Chapter 2: A Closer Look
»
Chapter 3: The Benefits of ICFs
»
Chapter 4: How to Build with ICFs
»
Chapter 5: ICF Success Stories
»
Chapter 6: How to Get Started on an ICF Project
»
Chapter 7: Additional Tools and Resources
Image Caption
Project Name
Image Location
Aspire Trade School
Huntersville, North Carolina
CHAPTER 1: WHAT ARE ICFS
UNDERSTANDING ICFS
Insulated Concrete Forms, or ICFs, are stay-in-place forms that are stacked, reinforced
and filled with concrete to form exterior and/or interior walls of a building. ICF
construction is an alternative to conventionally formed concrete walls, standard wood
or steel framing and concrete blocks (CMUs). ICFs are made from foam insulation and
remain in place as a permanent part of the wall assembly. Not only do ICF walls offer
robust structural integrity, they also provide impressive energy efficiency and interior
comfort. ICFs can be installed below-grade for basements and foundations, as well as
above-grade for multi-story buildings all the way to the roof.
ICF BUILDING TYPES
Insulated Concrete Forms are used to construct residential and commercial buildings of
all shapes and sizes, including:
» Single-family homes
» Schools
» Hotel & hospitality buildings
» Office buildings
» Retail & mixed-use spaces
» Swimming pools
» Medical Buildings
» Government & military structures
» Dormitories & apartment complexes
» Churches
During and after construction of the
Sookepoint Ocean Cottage Resort
Sooke, British Columbia
6 BUILDING COMPONENTS IN 1
ICF construction condenses six building elements into one. The forms
themselves provide the insulation, and once filled with concrete, they create
the structural wall assembly. An air barrier and vapor barrier are also built
into the system due to the permeance levels of the foam insulation. Lastly, ICF
blocks have embedded fastening strips for easily anchoring interior and exterior
finishes, like drywall and cladding.
1. Form System
2. Wall Structure
3. Insulation
4. Air Barrier
5. Vapor Barrier
6. Interior & Exterior Finish Anchorage
Habitat for Humanity
Multi-Family Project
Peterborough, Ontario
CHAPTER 1: WHAT ARE ICFS
orms 6-in-1
6. Interior/Exterior Finish Anchorage
In this section, we’ll dissect an ICF wall assembly to understand its different
components, including the insulation, webbing, fastening strips, concrete core,
alignment system, and reinforcement materials.
INSULATION
ICFs are made of two panels of expanded polystyrene (EPS) foam insulation. As these
lightweight blocks are stacked, they lock together for an air-tight enclosure with
continuous interior and exterior insulation.
EPS foam exhibits high compressive strength, rigidity, and exceptional thermal
insulation, making it an ideal choice to regulate indoor temperatures, reduce sound
transmission, and improve overall performance of the building envelope.
Insulated Concrete Forms are offered in different shapes, foam thicknesses and
concrete core sizes to accommodate the performance needs of the project. In addition
to the straight standard blocks, 45-degree and 90-degree corners are available, as
well as radius ICF blocks for curved walls.
Standard Nudura ICF blocks are 8 feet (2.44 m) long, 18 inches (457 mm) tall, with two
sides of 2-5/8 inch (67 mm) thick insulation and a core for concrete between 4 and
12 inches (100 mm- 300 mm), which create an R-value of R-24. Higher-performing
options with wider insulation and/or concrete cores are also available.
CHAPTER 2: A CLOSER LOOK
What is R-value and thermal mass?
WEBBING
Embedded webs or cross ties within the form hold the two layers of foam together,
preventing compression and supporting reinforcement during concrete placement. They
are generally made of polypropylene or polystyrene plastic, but some may be steel.
The foldable design of Nudura ICFs makes the blocks easier to move around the
jobsite and reduces transportation costs since you are maximizing freight space by not
shipping empty air.
FASTENING STRIPS
ICFs also have built-in fastening strips, typically at 6-inch (152 mm) or 8-inch (203
mm) increments , for attaching finish materials like interior drywall and exterior
cladding to the form.
While the design varies by the ICF manufacturer, Nudura’s fastening strips are located
every 8 inches (203 mm), indicated by a diamond pattern on the form, visible from the
outside and inside. They are 1-1/2 inches (38.1 mm) wide, continuous up the full height
of the form, and have a mechanism that interlocks the fastening strip to the one below
and above it. ICF fastening strips provide a comparable fastener pullout strength to
dimensional studs. Note that different types of exterior cladding will have different
installation instructions for attachment to an ICF wall.
Nudura Insulated Concrete Forms
are folded and stacked in a truck
for easy transport.
CHAPTER 2: A CLOSER LOOK
REINFORCING MATERIALS
Steel reinforcement, also known as rebar, is typically placed both vertically and
horizontally within the ICF blocks prior to pouring concrete. While optional, fiber
reinforcements within the concrete mixture itself can increase stability and in some
cases, reduce the need for rebar.
ALIGNMENT SYSTEMS
To keep ICF walls plumb and secure while the concrete is being placed and
throughout the curing process, a metal alignment system is temporarily fixed to the
inside or outside of the hollow ICF walls. This alignment system is then removed
after the concrete has fully cured and can be reused on other projects.
CONCRETE
The cavity between the EPS panels of Insulated Concrete Forms is filled with
concrete, creating solid monolithic walls that offer excellent thermal mass,
insulation, soundproofing and structural stability.
CHAPTER 2: A CLOSER LOOK
Learn about fiber-reinforced concrete
Cured concrete within an ICF block.
Metal alignment system
on an ICF wall.
Vertical and horizontal rebar in an
ICF assembly.
Why build with ICFs instead of wood, steel framing or cinder blocks? This chapter covers the benefits of Insulated Concrete Forms and how they impact
both the building process and the quality of the finished structure.
CHAPTER 3: THE BENEFITS OF ICFS
CONSTRUCTION EFFICIENCY AND TIME SAVINGS
ICF technology condenses wall construction into one ready-to-install
form. By streamlining the building envelope process, subsequent trades
like drywallers, roofers, electricians and plumbers can proceed sooner,
speeding the project timeline. Tenants can occupy the structure sooner,
meaning a quicker return on investment for the owner.
The reversible and lightweight nature of Nudura Insulated Concrete
Forms, compared to heavier building materials, also saves time and
energy during unloading and installation. ICF forms can be installed in
virtually any weather condition, which decreases downtime for the crew
and enables year-round construction.
Kroenke Hangar Home
Palmer, Alaska
DESIGN VERSATILITY AND AESTHETICS
Insulated Concrete Form construction offers maximum design flexibility
with standard straight blocks, corners, curves, end caps, and many other
options. ICFs can also be custom cut to the shape or radius specified. They
come in a variety of foam thicknesses and concrete core widths that can be
combined to meet any performance requirements.
ICF walls can accommodate virtually any exterior finish, including masonry,
siding, stucco, EIFS and exterior panels, to create a beautiful façade.
Whether your style is art deco, craftsman or modern farmhouse, you can
create any aesthetic imaginable with ICFs.
CHAPTER 3: THE BENEFITS OF ICFS
WIND RESISTANT
ICF wall systems with steel-reinforced concrete contribute towards a continuous load path that hold
the building together during severe wind, moving the force from the roof down to the ground.
Nudura ICF wall assemblies are wind-resistant up to 250 mph (402 kph), equivalent to an F4 tornado
and Category 5 hurricane. For context, Hurricane Katrina and Hurricane Michael were both Category 5
storms with winds up to 174 mph (280 kph) and 162 mph (261 kph) respectively.
IMPACT RESISTANT
ICF walls stop airborne and wind-blown debris from penetrating the building exterior. A Nudura ICF
wall system was tested against the impact of debris at tornado wind speeds. A 15 lb (6.8 kg) wooden
2x4 beam was propelled at the wall at 100 mph (160 kph). The ICF wall remained intact with only
minimal damage to the exterior EPS foam.
FIRE-RATED
ICFs provide passive fire protection, limiting the spread of flames during a fire. Nudura ICF walls have
a fire-rating of 4+ hours, compared to wood-frame walls, which have a 45-minute rating, equating to
the time it takes for flames to impact structural integrity and tenants to evacuate.
This waterfront ICF home in
Mexico Beach, Florida was one of
few residential properties to
survive the Category 5 Hurricane
Michael in 2018.
ENHANCED STRUCTURAL STABILITY
ICF buildings are disaster-resilient, meaning they can withstand the most severe
weather conditions while maintaining their structural integrity. ICFs have proven
effective in surviving natural disasters, including tornadoes, hurricanes and wildfires.
Because of their durability, ICF walls are often used in the construction of safe rooms
and storm shelters. They can withstand high winds and flying debris far better than
wood-frame structures.
LONGEVITY
ICF buildings are very durable and require less maintenance than traditional building materials.
Therefore, structures built with Insulated Concrete Forms will have a longer lifespan, reducing the need
for more materials, labor and equipment to repair or replace them.
ENERGY EFFICIENCY
The combination of thermal mass and continuous insulation in an ICF system improves building
performance by minimizing air leaks, thermal bridging and heat transfer through the wall. The air-
tight building envelope reduces the structure’s energy consumption, its carbon footprint, as well as the
necessary size of its HVAC equipment. ICF buildings maintain the heated or conditioned air longer than
other construction methods, avoiding interior temperature fluctuations and enabling the structure’s
mechanical systems to heat, cool and ventilate the structure more efficiently.
Third-party testing shows that building with Nudura ICFs can lower operational energy demands by up
to 60%. For large buildings like schools, shopping malls and hospitals, the subsequent cost savings on
heating and cooling bills are substantial.
CHAPTER 3: THE BENEFITS OF ICFS
Divi Little Bay Beach Resort
St. Maarten
ICFS AND SUSTAINABILITY
Insulated Concrete Forms contribute to sustainable building design in numerous ways.
“By increasing the length or service life of buildings,
we can have an impact on the overall amount of
carbon that’s being produced by the building sector.”
-Andre Desjarlais
Oak Ridge National Laboratory
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