Insulating concrete form or insulated form of concrete (ICF) is a formwork system for reinforced concrete that is usually made with rigid thermal insulation that remains in place as a permanent interior and exterior substrate for walls, floors, and roof. The forms are modular, interlocked units that are dried (without mortar) and filled with concrete. The units locked together like Lego bricks and made shapes for the walls or structural floors of a building. ICF construction has become commonplace for the construction of high-performance commercial and high-performance housing due to tighter energy efficiency and building codes resistant to natural disasters adopted. ICFs can be used with a superficial foundation protected by frost (FPSF).
Video Insulating concrete form
Development
The ICF construction technique was first developed in Europe after World War II as a cheap and durable way to rebuild damaged structures. The first patent for isolated fixed-in-place formwork for concrete was registered in the early 1940s using recycled wood waste and cement as an insulating material. This patent is registered by August Schnell and Alex Bosshard in Switzerland. The first form of ICF polystyrene was developed in the late 1960s with the ending of the original patent and the advent of modern foam plastics. Canadian contractor Werner Gregori filed the first patent for foam-type concrete in 1966 with a "16-inch-tall, 48-inch-high block with tongue-and-groove interlocks, metal bonds, and waffle-grid cores."
The implementation of ICF construction has been on the rise since the 1970s, although initially hampered by a lack of awareness, code building, and confusion caused by many manufacturers selling a slightly different ICF design rather than focusing on industry standardization. ICF construction is now part of most building codes and is accepted in most jurisdictions in the developed world.
Maps Insulating concrete form
Construction
Isolation of concrete form is made from one of the following materials:
- Polystyrene foam (most often expanded or extruded)
- Polyurethane foam (including soy based foam)
- Cemented wood-cement fibers
- Cement-bound polystyrene beads
- Mobile concrete
- Thastyron, a mixture of cement, water, and expanded polystyrene.
Strengthening of steel rods (rebar) is usually placed in the form before the concrete is poured to provide a bending strength of concrete, similar to bridges and high-rise buildings made of reinforced concrete. As with other concrete formworks, the form is filled with concrete at a 1-foot to 12 foot elevation to manage concrete pressure and reduce the risk of bursts.
Once the concrete has healed, the shapes remain permanently in place to provide a variety of benefits, depending on the material used:
- Thermal insulation
- Hard
- Good Surface burning characteristics rating
- Space to run power lines and pipes. Form materials on both sides of the wall can easily accommodate electrical and plumbing installations.
- Support for drywall or other finishes on the interior and plastering, brick, or the other side of the exterior
- Enhanced indoor air quality
- Set the humidity level and reduce the growth of fungi (higrik buffer)
Categorization
Isolation of concrete forms is usually categorized in two ways. Organizations whose first concern relates to concrete classify them first by the form of concrete in the form. Organizations whose primary concern is concerned with the making of forms classifies them first by the characteristics of the form itself.
With concrete form
Flat Wall System
For Flat Wall System ICFs, concrete has a flat wall shape of solid-boned concrete, similar to the shape of a concrete wall constructed using a removable shape.
Grid System
Grid Screen System
For Screen Grid System ICFs, the concrete has a metal shape on the screen, with horizontal and vertical channels of reinforced concrete separated by solid material form areas.
Waffle Grid System
For Waffle Grid System ICFs, the concrete has a hybrid shape between Screen Grid and Concrete Flat Wall systems, with a thick reinforced concrete grid and has a thin concrete in the central area where the screen grid will have a solid ICF material.
Post and Lintel System
For Post and Lintel System ICFs, concrete has a horizontal member, called lintel, only at the top of the wall (Horizontal concrete at the bottom of the wall is often present in the form of a footer or lintel wall of the building below.) And a vertical member, called a post, in between the threshold and the surface where the wall is resting.
With shape characteristics
Block
For ICFs Blocks, the exterior shape of the ICF is similar to the Concrete masonry unit, although ICF blocks are often larger in size because they are made of materials of lower density. Very often, the ends of the ICF block are made to interlock, reduce or eliminate the need for the use of a binder between blocks.
Panel
The ICFs panels have a flat rectangular shape from their flat wall sections often the height of the walls and have a width that is limited by the manipulability of the material at a larger size and by the general purpose of panel size to build walls.
Board
ICF boards have ICF Block size in one dimension and ICF Panel in other dimensions.
Characteristics
Energy efficiency
- Minimal, if any, air leakage, which increases comfort and reduces heat loss compared to walls without a solid air barrier
- High thermal resistance (R-value) is usually above 3 KÃ, mÃ,²/W (in American customary units: R-17); this results in energy savings compared to uninsulated stones (see comparison)
- Continuous isolation without thermal bridges or "insulation gaps", as is common in framed construction
- Thermal mass, when used well and combined with a passive solar design, can play an important role in further reductions in energy use, especially in climates where it is common to have temperatures outside the swing above the inside temperature at noon day and below at night.
Strength
- Insulating concrete forms make structural concrete walls, either monolithic or pegs and beams, which are up to ten times stronger than wood-framed structures.
- Structural integrity for better resistance to natural forces, compared to framed walls.
- ICF system components - both poured concrete and the material used to make ICF - do not rot when wet.
- Isolation of concrete forms a structural system, if used in high seismic risk zones, has an acceptable ductility.
Sound absorption
ICF wall has a much lower acoustic transmission rate. The standard thickness ICF wall has shown a sound transmission coefficient (STC) between 46 and 72 compared to 36 for fiberglass and drywall insulation standards. The level of attenuation of sound achieved is the function of wall thickness, mass, component material and air rigidity.
Fire protection
ICF walls can have a fire resistance rating of four to six hours and negligible surface combustion properties. It should be noted that the International Building Code: 2603.5.2 requires the insulation of plastic foams (eg Polystyrene foam, Polyurethane foam) to be separated from the interior of the building by thermal barrier (eg drywall), regardless of the fire barrier provided by central concrete. Forms made from cement - wood fiber (for example), polystyrene beads (for example), or air (ie cellular concrete - for example) have an inherently fire rating.
Indoor air quality
Because they are generally built without a plastic vapor barrier layer, ICF walls can regulate moisture levels, reduce the potential for molding and facilitate a more comfortable interior while maintaining high thermal performance. However, the foam can emit gas, something that is not well studied.
Environmental sensitivity
ICF walls can be made with a variety of recyclable materials that can minimize the environmental impact of buildings. The large volume of concrete used on ICF walls has been criticized, as concrete production is a major contributor to greenhouse gas emissions.
Vermin
Since the entire interior space of the ICF wall continues to be occupied (no such loopholes can occur between blown or fiberglass insulation and wooden frame walls) they cause more difficulty for casual transits by insects and pests. In addition, while the shape of plastic foam can sometimes be passed through tunnels, interior concrete walls, and Portland cement from cement bond forms create a much more challenging barrier for insects and pests than wooden walls.
Consider building design
When designing a building to be built with ICF walls, consideration should be given to supporting the weight of the wall that does not rest directly on other walls or foundations of the building. Consideration should also be given to the understanding that the load part of the ICF wall is concrete, which, without special preparation, does not extend in any direction to the edges of the shape. For lattice and post & amp; lintel system, the placement of the vertical member of the concrete must be arranged in such a way (for example, starting at opposite or resting angles (eg doors) and working to meet on unbroken walls) to transfer the load correctly from lintel (or beam bonds) to the surface supporting the wall.
Development process
ICF construction is less demanding, because of its modularity. Less skilled labor can be used to lay down the ICF form, although careful consideration should be taken when pouring concrete to ensure fully consolidate and heal evenly without cracking. Unlike traditional wooden beam construction, no additional structural support other than temporary scaffolding is required for openings, doors, windows, or utilities, although modifying the structure after concrete cures requires special concrete cutting tools.
Floor and foundation
ICF wall is conventionally placed on a monolithic plate with an embedded rebar rod that connects the wall to the foundation.
The ICF decking is becoming an increasingly popular addition to the general ICF wall construction. ICF decking weighs up to 40% smaller than standard concrete floors and provides superior insulation. The ICF decking can also be designed together with ICF walls to form a continuous monolithic structure united by rebar. The roof of the ICF deck is less common, as it is difficult to pour concrete on a sloping surface.
Wall
The ICF wall is built one line at a time, usually starting from an angle and towards the center of the wall. The end of the block is then cut to fit to remove the most likely material. As the wall rises, the beams stagger to avoid a long vertical layer that can weaken the polystyrene formwork. A structural framework known as bucks is placed around the opening to provide additional strength at the opening and serves as an attachment point for windows and doors.
Interior and exterior finishing and exterior are affixed directly to ICF surfaces or tie edges, depending on the type of ICF. The stone and brick facade requires an extended ledge or rack angle on the main floor level, but otherwise no modifications are required. The surface of the ICF interior polystyrene wall must be covered with a drywall panel or other wallcoverings. During the first months immediately after construction, a small problem with interior moisture may look like concrete curing, which can damage the drywall. Dehumidification can be done with a small housing reduction or using a building's air conditioning system.
Depending on the contractor's experience and the quality of their work, properly inserted exterior foam insulation can be an easy access to ground water and insects. To help prevent this problem, some manufacturers make insecticidal foam blocks and promote the installation of drainage gutters and other methods for waterproofing. Disposal tiles are installed to remove water.
Pipes and electricity
Pipes and power lines can be placed in shape and poured into place, although settling problems can cause the pipes to break, creating costly repairs. For this reason, pipes and conduits and power lines are usually embedded directly into the foam before the wall covering is applied. Hot blades or electric saws are commonly used to create openings in the foam to install pipes and cables. power cable inserted into ICF using Cable Punch. while ICFs made from other materials are usually cut or dispensed with simple carpentry tools. Versions of simple carpentry tools suitable for forms of cement-type bonds are made for similar use with an autoclaved aerated concrete.
Cost
The initial cost of using ICFs rather than conventional construction techniques is sensitive to material and labor prices, but building using ICF can add 3 to 5 percent to the total purchase price on top of buildings using wooden frames. In most cases the ICF construction will cost about 40% lower than conventional construction (basement) due to labor savings from incorporating several steps into one step. Above the class, ICF construction is usually more expensive, but when adding large openings, ICF construction becomes very cost effective. Large openings in conventional construction require large headers and supporting poles, while ICF construction reduces costs, since only the reinforcing steel is required directly around the opening.
ICF construction can allow up to 60% smaller heating and cooling units to serve the same floor area, which can cut the final home cost by about $ 0.75 per square foot. So, the estimated net surcharges can reach $ 0.25 to $ 3.25. ICF homes can also qualify for a tax credit, which further lowers costs.
ICF building is cheaper over time, because it requires less energy to heat and cool space of the same size compared to other common construction methods. In addition, insurance costs can be much lower, because ICF houses are much more susceptible to damage caused by earthquakes, floods, hurricanes, fires, and other natural disasters. Maintenance and maintenance costs are also reduced, because ICF buildings do not contain wood, which can decay over time or be attacked by insects and rodents.
Advantages and Disadvantages
In areas prone to earthquakes and storms, ICF construction provides excellent strength, durability, sound insulation, and air tightness. ICF construction is ideal in temperate climates and mixed with significant daily temperature variations, in buildings designed to benefit from thermal mass strategies.
The R-Value isolation alone (R-value) of the ICF ranges from R-12 to R-26, which can be a good R value for walls. When the K-Value and U-Value are included, the actual R-Value performance of the wooden frame construction, 2x6 at 24 "oc with R19 batts, is R-13.7 while ICF has a performance level up to R-52. Energy savings are within 50% up to 70%. & lt; ref & gt; ["The ICF Effect"] Access ICFA at http://www.forms.org/images/cmsIT/fckeditorfile/ICFA Tech -% 20ICF% 20Effect (1).pdf & lt; ref & gt; [American Society for Testing and Materials (ASTM) Determination: C976] & gt; ref & gt; "Energy Concrete Home Comparison vs. Wooden Frame House"], RP119 Vanderwerf & lt; ref & gt; EnergyWise @ http://www.energywisestructures.com/
References
External links
- Insulating Concrete Form Association (North America)
Source of the article : Wikipedia
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