Rastra Inc. Building Solutions

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March 8, 2017
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RASTRA Inc. is the original  Insulating Concrete Form (ICF) that was developed in partnership with BASF in Austria in 1972. RASTRA Inc. CICF block as we know it today, is the result of continuous product enhancement over these last 40 plus years.  Since then over 9 million units have been utilized in various building projects.

RASTRA Inc.  and it’s Composite Insulated Concrete Form (CICF) block is recognized as the ultimate building solution foreconomical and environmentally-friendly construction. This stay-in-place (CICF) is made of a lightweight composite material produced with 85% recycled polystyrene (EPS) and 15% cement by volume.

RASTRA Inc. blocks achieve strength from a combination of features specifically designed to maximize both shear and compressive strength.
First, there is the RASTRA Inc. MIX- a lightweight mixture of small EPS beads and concrete combined to form a compound EPS concrete.  Although initially manufactured using virgin polystyrene, only recycled material is primarily used today. RASTRA Inc. MIX  is ideal for use as a wall material as it provides superior heat/cold insulation, is dimensionally stable, highly resistant against fire, frost, mold and other climate influence and accepts plaster, stucco or any other type of wall covering with ease.

By itself, RASTRA, Inc.  is not a structural building material.  Wall strength is achieved when steel reinforced concrete is added into the interior cavities. The interior cavities of RASTRA Inc. blocks are designed to maximize strength when filled with concrete and steel reinforcement, creating a rigid skeleton of 6” diameter, both vertical as well as horizontal; columns inside the panel.

The interior cavities or channels provide an extremely strong wall using the lowest possible amount of concrete ranging from 0.26 – 0.31 cubic feet per square foot of wall. By using different qualities of concrete and/or various amounts of reinforcement, in horizontal, vertical or even diagonal directions, the load capacity can be adapted to satisfy nearly any building requirement, including multi-story and seismic applications. RASTRA Inc. has been ICC certified for use above or below grade.   Vertical loads of up to 100 tons per lineal m (80 kips/lin.ft.) of wall have been successfully tested without failure.

With optimum reinforcement, load-bearing capacity in all directions is increased. Installation is simplified as the RASTRAInc. system consists of only two components.

The lightweight components that make up the RASTRA Inc. system are used to form exterior and/or interior walls for residential, commercial, multi-family and industrial buildings. Building with RASTRA Inc. blocks is fast, simple, and can even be constructed by unskilled laborers thus providing substantial costs benefits.

Additional benefits of RASTRA Inc. blocks are superior thermal performance thereby reducing energy costs and excellent sound insulation.  Also, RASTRA Inc. blocks are 700% stronger than wood frame construction, can withstand a category-5 hurricane or tornado force winds and has a UL extended 5 hour fire rating – substantially safer than any wood frame house..


Basements & Foundations

In cold climates, energy experts tell us up to 40% of a home’s heat loss is through the ground. RASTRA Inc; CICF blocks  create the perfect basement walls for locking out winter and keeping warm heated air inside. Currently, about 1/3 of all CICFs sold are used in residential basements.

There are countless numbers of commercial applications suitable for RASTRA Inc. products.  This fact is supported by thousands of commercial installations throughout the world.

Industrial – Preassembled panels installed with a tilt-up construction provides an economical build out.  Good applicability has been developed for industrial projects, where load-bearing and good insulation is important.

Cold Storage Facilities – Cold stores have been designed with walls consisting of face to face doubled RASTRA Inc. blocks to meet extreme insulation and highest load-bearing capacity at the same time.

Multi-Family & Hotels – Sound absorption and fire resistance make this an excellent application for any project designed with shared walls and need for fire walls.

Health Care & Retirement Living – The ability to improve indoor air quality is an important feature for healthcare facilities.

Agricultural Buildings – The ability to better control the interior environment provides an improved agricultural building more productive.


The Thermal Performance of RASTRA Inc. blocks virtually eliminate air leaks.

The U.S. Department of Energy issued the following statement regarding air leakage.  “The most common insulation, fiberglass, does not stop air leakage” (Technology Fact Sheet 10099-767, U.S. Department of Energy).  Research shows that air leakage through exterior walls is the primary factor in moisture accumulation and heat loss.   Wind pressures can greatly increase the air infiltration even further, resulting in increased energy use.  Information presented in ASHRE indicates that for a two-story wood frame house with 8’ ceilings, 20 mph winds can easily double air infiltration.

It’s a little known fact that fiberglass insulation loses as much as 40% of its insulating capacity when outside temperatures fall below 20˚F.  When this happens, an R-19 fiberglass insulated wall performs as if it were only R-9.  LEED confirms through a Canadian cold weather study that concluded fiberglass loses half its R-value below 0˚F.

Fiberglass also performs poorly in the presence of humidity within a wall cavity higher than just 30%.  In winter this leads to condensation of moisture carried in by warm air through leaks through the wall.  This raises humidity levels inside the building.

Once fiberglass insulation becomes damp its performance decreases dramatically.  In fact, it only takes a 1.5% increase in moisture content in fiberglass to reduce its R-value by up to 50%.  When moisture is trapped in a conventionally-built wall cavity insulated with fiberglass and sealed with a vapor barrier, insulation becomes damp and loses its ability to insulate.  This also promotes mold growth and leads to structural damage.

Any type of insulation, including fiberglass or organic material loses its capacity to protect if it becomes wet and compresses from leaks or condensation from water pipes.
Rooms over the garage are often colder in the winter and warmer in the summer than the rest of the house. Floors made of RASTRA Inc. blocks, end corners and flat panels provide an increased level of insulation in these “bonus” rooms.

Today’s standard method of assigning R-values to wood frame and fiberglass walls does not account for thermal breaks in the insulating envelope caused by studs, headers, corner details, electrical outlets and plumbing that create air leaks.  This inflates the actual R-value beyond the wall’s true capability.  To arrive at a true R-value of an entire wall, other factors such as thermal mass, air tightness, and moisture tolerance must be accounted for as each contributes to the final result.
The typical wood frame wall has so many leaks, it’s like having a window open all the time, accounting for 25% to 45% of the total heat loss of the building. RASTRA Inc. virtually eliminates air leaks, creating more energy-efficient buildings.

RASTRA Inc. blocks provide an Effective R-value of up to R-48 with no heat loss caused by thermal breaks in the wall structure:

Besides air leaks, there is another factor that contributes to the insulation efficiency of the building exterior called a “Convective Loop”.  A convective loop occurs when air rises along a warm surface and falls along a colder surface, causing a circular movement of air.  This movement of air is often found inside wall cavities containing fiberglass insulation because the insulation does not fill the entire wall cavity, providing air room to move.  This movement of air transfers heat to the building frame and requires more energy to replace its loss.  Because a RASTRA Inc. build is a solid mass of insulating material, there is no cavity or void to allow air to circulate.  This eliminates the transfer of heat and reduces energy costs.

The insulation value of RASTRA Inc. blocks is 15 to 20 times higher than solid concrete.  The combination of RASTRA Inc. high R-value, ability to restrict air migration, and elimination of convective loops makes RASTRA Inc. a superior insulation solution.


Energy Savings

Until recently, buildings were built with limited emphasis placed on energy conservation largely because we enjoyed low energy prices.   These are very different times, and with unprecedented increases in energy costs, improving insulating efficiency is a financial decision that pays dividends for the life of the property.
RASTRA Inc. superior thermal performance and air tightness greatly reduces heat transfer and lowers energy consumption by 40 to over 50%.  By increasing the property’s true R-value with RASTRA Inc., HVAC equipment operates less often, also reducing energy costs.  Because less moisture filled air penetrates the exterior walls, the air conditioner doesn’t have to work as hard to remove the humidity from the air.  RASTRA Inc. even reduces heat loss from hot water pipes.

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