Concrete forms have taken a new shape-and purpose. Insulating concrete forms (ICFs) are rigid plastic foam forms that hold concrete in place during curing and remain in place afterwards to serve as thermal insulation for concrete walls. The foam sections are lightweight and result in energy-efficient, durable construction.
ICFs consist of insulating foam, commonly expanded polystyrene (EPS) or extruded polystyrene (XPS). The three basic form types are hollow foam blocks, foam planks held together with plastic ties, and 4 x 8 panels with integral foam or plastic ties. ICFs can be used to form various structural configurations, such as a standard wall, post and beam, or grid. They provide backing for interior and exterior finishes.
Insulation values of ICF walls vary depending on the material and its thickness. Typical insulation values range from R-17 to R-26, compared to between R-13 and R-19 for most wood-framed walls. The strength of ICF structures relative to lumber depends on configuration, thickness, and reinforcement. However, ICF walls are designed as reinforced concrete, having high wind and seismic resistance.
There are many ICF wall types. Products are differentiated based on the type of form and the shape of the concrete sections. Products are further differentiated by how forms attach to each other, how finishes are attached to the wall, insulating values, foam types and other features.
Basic Material Used:
Insulated concrete forms (ICFs) are hollow, lightweight forms manufactured
using two 21/2 inch (63.5m), 1.5lbs/cu.ft density expanded polystyrene (EPS) panels
which are connected by uniquely designed, high impact polypropylene webs. During
construction, the forms are stacked then filled with concrete making stable, durable
and sustainable walls.
The following are basic components of ICF system,
Basic Components of ICF System
§ Formwork (Stay-In-Place)
¢ Plastic
¢ Expanded Polystyrene
¢ Extruded Polystyrene
§ Concrete (Cast-In-Place)
§ Steel reinforcement
Structural Design of ICFs Covered by Prescriptive Method
Where the IRC and Prescriptive Method are not yet accepted, when certain ICF types are not covered by the Prescriptive Method, or when buildings do not meet the applicability limits of the Prescriptive Method, engineered designs (usually with sealed sets of plans) may be necessary in order to obtain building permits. For systems and applications that are not covered by the requirements in the Prescriptive Method, the NAHB Research Centre, under sponsorship of the Portland Cement Association (PCA), completed the publication entitled Structural Design of Insulating Concrete Form Walls in Residential Construction. This publication, available from PCA, is a guideline for the design of single- and multi-unit residential structures using ICF wall systems. It includes step-by-step design procedures for ICF, a comprehensive design example, and many design aids, such as graphs, charts, and tables, to assist design professionals.
Most ICF manufacturers have taken steps of their own to have their proprietary systems approved by various model code organizations. Evaluation Reports produced by code bodies are available from those manufacturers. Most ICF manufacturers will also provide design services if necessary.
Types of ICF Systems
ICF are basically forms for poured concrete walls that stay in place as a permanent part of the wall assembly. The forms, made of foam insulation, are either pre-formed interlocking blocks or separate panels connected with plastic ties. The left-in-place forms not only provide a continuous insulation and sound barrier, but also a backing for drywall on the inside, and stucco, lap siding, or brick on the outside.
Although all ICFs are identical in principle, the various brands differ widely in the details of their shapes, cavities and component parts. Block systems have the smallest individual units, ranging from 8" x 1'4" (height X length) to 1'4" x 4'. A typical ICF block is 10" in overall width, with a 6" cavity for the concrete. The units are factory-moulded with special interlocking edges that allow them to fit together many like plastic children blocks.
Panel systems have the largest units, ranging from roughly 1' x 8' to 4' x 12'. Their foam edges are flat, and interconnection requires attachment of a separate connector or "tie." Panels are assembled into units before setting in place - either on-site or by the local distributor prior to delivery.
Plank systems are similar to panel systems, but generally use smaller faces of foam, ranging in height from 8" to 12"and in width from 4' to 8'. The major difference between planks and panels is assembly. The foam planks are outfitted with ties as part of the setting sequence, rather than being pre-assembled into units.
Within these broad categories of ICFs, individual brands vary in their cavity design. "Flat wall" systems yield a continuous thickness of concrete, like a conventional poured wall. "Waffle grid wall" systems have a waffle pattern where the concrete is thicker at some points than others. "Screen grid" systems have equally spaced horizontal and vertical columns of concrete which are completely encapsulated in foam. Whatever the differences among ICF brands, all major ICF systems are engineer-designed, code-accepted, and field-proven.
Three Major types of ICF Systems are,
Screen grid OR Post-and- Beam (1st Generation) Waffle grid (2nd Generation) Flat (3rd Generation)
Key Features of each system,
1. Screen grid OR Post-and- Beam (1st Generation)
Ø Post and Beam Arrangement
Ø Most Versatile Because of its Stability and Strength
Ø While structurally Stronger Actually Lighter in Overall weight than other ICFs, this Factor make Batter in Seismic Prone Zone.
2. Waffle grid (2nd Generation)
Ø Closely Spaced vertical and Horizontal members with a concrete web between Members.
Ø Structurally Strong
3. Flat ICF System (2nd Generation)
Ø Flat wall ICF are System In Which the concrete within the form is uniform thickness throughout.
Ø It Requires Substantial Amount of Bracing.
Ø Ease to Pour Concrete
Ø Ease for the Lintel design Also
Manufacturer of ICF Systems
AMVIC REDDIFORM ARXX
Tools for Block Installation
§ Hand saw, folding pruning saw or conventional rip saw
§ Portable power saw
§ Keyhole saw
§ Table saw (optional)
§ Tape measure
§ Cordless driver drill and appropriate bits
§ Hammer drill
§ Reinforcing steel tie tools
§ Hammer
§ Framing square
§ 2 ft Spirit Level
§ 6 ft Spirit Level
§ Laser level, water level, or transit
§ Plumb bob
§ Mason's line (Enough to circle entire structure)
§ Chalk line
§ Foam gun
§ Reinforcing steel bender and cutter
§ Scaffold planks
§ Wall alignment & bracing system
§ Steel Stakes to anchor alignment braces (n/a if bracing off a slab)
Tools for Concrete Pour
§ Concrete Vibrator, 1 inch to 11/4 inch (25 to 32mm) head
– 10 to14 ft (3 to 4.2m) flexible shaft
§ Rubber gloves
§ Hard hats
§ Concrete finishing tools
§ Flat shovels for spill cleanup
Tools for Utility Installation
§ Hot Knife (for electric box cutout)
§ Electric chain saw (for cutting Romex wiring and plumbing channels)
§ Foam gun & Foam
Materials list
§ Reinforcing steel as required and accessories, e.g. ties, stirrups.
§ Screws to attach alignment bracing to ICF blocks (15/8 inch, 21/2 inch, #10 coarse thread)
§ Concrete Screws 11/2 to 13/4 inch to attach foot of alignment braces to concrete slab (TAPCON brand or equivalent)
§ Material for rough openings (i.e. 2x10, 2x6, etc.) lumber or plywood for fabricating wood bucks or vinyl bucks
§ Tie wire in rolls and in pre-made reinforcing steel tie loops
§ Anchor bolts, nuts, and washers or Simpson Strong-tie® ICFLC ledger connectors
§ Sleeves for mechanical and/or electrical fixtures
§ OSB or plywood for bridging cut joints, or removed webs, block outs for anchor bolts, etc.
§ Foam 2 Foam® EPS controlled-expansion foam/adhesive
§ Waterproofing / Damp Proofing system
ICF Advantages ……
Concrete Homes save Energy
Building a concrete home with insulating concrete forms (ICFs) saves energy and money. The greater insulation, tighter construction, and temperature-smoothing mass of the walls conserve heating and cooling energy much better than conventional wood-frame walls. This reduces monthly fuel bills. It also allows use of smaller heating and cooling equipment, saving money in construction.
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Houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses. A typical 2000 square foot home in the center of the U.S. will save approximately $200 in heating costs each year and $65 in air conditioning each year.
The bigger the house the bigger the savings. In colder areas of the U.S. and Canada, heating savings will be more and cooling savings less. In hotter areas, heating savings will be less and cooling savings more
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Comfort and Quiet with Concrete Homes
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Concrete walls built with insulating concrete forms effectively buffer a home's interior from the outdoors. The thick ICF sandwich of a massive material (concrete) with a light one (foam) sharply cuts fluctuations in temperature, air infiltration, and noise. They keep the inside of a house more comfortable and quiet than ordinary wood frame walls.
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Greater Strength
– Storm resistant - rated for a 250MPH wind load
– Blast Tested [Force Protection Equipment Demonstration (FPED V) April 26–28, 2005]
Better Fire Protection
– UL listed at 3 hours with ½" drywall; 4 hours with 5/8" type x gypsum
Quieter
– Sound Transmission Class rating of 50 or greater
Reduced Maintenance
– Conventional construction is prone to maintenance problems such as drywall pops and basement leaks
Resistant to pests
– ICFs provide no food source and contain nothing to attract termites and other pests
Resistant to mold
– the concrete, foam and steel in an ICF wall are not a food source for mold growth, unlike wood and other organic materials; the airtight nature of the ICF structure also provides for better moisture control, further reducing the chance for mold to occur
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