A metal lath is fastened directly to the Reward formwork to hold the stone to the wall and withstand the dead weight.  The lath is fastened to plastic furring strips that are located every 6 inches on center.  The 1 ¼” wide furring strips are embedded into the EPS foam plastic panel and are recessed ½” from the foam face.  They are marked on the foam panel for location.

Reward recommends a sharp pointed, corrosion resistant course thread screw.  Typically a #6 to #10 screw approximately 1 ¼” to 1 ½ inches in length is common.  A screw with a lath washer is recommended to ensure that the lath is fully secured.  Nails or staples are not recommended.

Reward has tested different fasteners for both direct withdraw and also for lateral resistance from the plastic furring flanges (see fastener test results).  The direct withdrawal value is used to calculate the fastener spacing to withstand lateral loads from wind pressure and seismic loads.  The lateral resistance test result is used to calculate the fastener schedule to withstand gravity dead loads such as the self weight of the stone.  The ½” recess distance was included in the test.

The test results in the Reward test summary report are all shown as ultimate loads.  A safety factor must be applied to each of these ultimate values for designing the fastener schedule to withstand the project specific design criteria.  The Reward ICC ES evaluation report, ESR-1552, lists a select few of the tested fasteners.  The values in the ESR-1552 report are allowable loads and already include the safety factor.

Once the screw to be used for attaching the metal lath is determined, the fastener schedule must be determined utilizing the tested direct withdrawal and lateral tests.  Consult the design architect or structural engineer for applying these tested values to the project’s design criteria.

For example, if the design wind and seismic load is 25 psf and the allowable direct withdrawal of the screw is 50 pounds.  The fastener spacing should be no greater than 2.0 square feet.  Similarly, if the dead weight of the manufactured stone is 15 psf and the allowable lateral value of the screw is 45 pounds, than the maximum fastener spacing is every 3.0 square feet.

The steps beyond the lath attachment to the Reward ICF wall are the same according to the manufactured adhered concrete masonry veneer’s manufacturer’s requirements.  Follow the stone veneer manufacturer’s installation procedures.

Avoiding Drywall Joint Cracks

It is very important to fasten drywall properly and to control and monitor the interior humidity and temperature once the Reward ICF walls are stacked, the concrete is placed, and the building envelope is enclosed.

New construction has new materials and the materials typically have some amount of moisture. The Reward ICF wall also has fresh concrete that is going through the curing process. As the moisture from the concrete wall and new materials vaporize, it increases the humidity levels inside the building’s shell.

Controlling Humidity and Temperature

When the drywall is fastened to the interior walls it is critical to control and monitor the humidity level and keep the interior at a constant temperature. If the humidity is not controlled under certain conditions, the water vapor exiting the ICF concrete wall could eventually lead to drywall cracking along the drywall joints. The drywall joint is a weak link consisting of drywall joint compound and joint tape. Moisture can potentially cause the drywall to swell leading to joint cracking.

If the humidity and temperature is not controlled properly after the building is enclosed both before and after occupancy, the moisture can lead to drywall cracks.

It is recommended to control and monitor the humidity and temperature both during construction after the building is enclosed and after occupancy. Moisture will continue to evaporate for up to the first 12 months of occupancy. If the humidity is not controlled it could lead to condensation on windows and moisture creating problems with different materials.

Fastening the Drywall

Typically the drywall is hung horizontally with the longer side (i.e. 8’ or 12’) of the drywall running horizontal and the short side (4’) running vertical.  There are two types of joints – a butt joint and a tapered joint.  The drywall edges are tapered on the long sides (i.e. 8’ or 12’) and the drywall edges are square cut on the short sides (4’).  Therefore the taper joint runs horizontally and the butt joint runs vertically.

The drywall must be attached to the Reward ICF wall using a #6 or greater sharp point course thread drywall screw spaced as required by the applicable code but no greater than 30 inches apart both horizontally and vertically.

The horizontal tapered joint can be fastened up to every 6 inches on center and should not exceed 30 inches on center.  Reward recommends a maximum fastening spacing of 24 inches on center equal distance across each 48 inch long form.  This places two fasteners horizontally along each ICF form.

The vertical butt joint should be placed either equal distance over the 1 ¼” wide plastic furring strip or at midpoint between two plastic furring strips.  Avoid having one sheet of drywall extending past a plastic furring strip more than the other sheet of drywall.  Preferably Reward recommends using two screws spaced equal distance per each 16” height course of Reward ICF forms.  In addition to fastening the drywall with screws, it is recommended to run either a bead of glue or spot glue using a compatible glue along each side of the butt joint within an inch or two of each drywall edge.

Control Joints

Gypsum wallboard is subject to some form of movement induced by changes in moisture and temperature just like any other building product.  Control joints are necessary in walls to relieve the stresses that occur from this movement.  Control joints are added to prevent cracking in gypsum wallboard due to movement.  Control joints should be incorporated in 30 foot intervals.  ASTM C 840 and GA-216 are two standards where the requirements for control joints are addressed.

There are times when the concrete placement height, lift height and consolidation issues are questioned and even viewed as one. In reality, these are all independent issues that must each be considered individually.

Occasionally a structural engineer, a specifier, or an inspector may want to dictate the maximum free fall height of concrete placement to prevent segregation. In these cases the limited heights that may be requested can increase costs without improving the in-place quality of the concrete.

Concrete Placement Heights

Concrete placement operations are planned to allow for the free fall of concrete. There are two heights that must be considered and treated differently. They are the overall free fall height of concrete and the lift height of concrete.

Concrete placement is recommended in 4 foot lifts. This does not mean that the concrete can not be placed greater than 4 foot in height or free fall greater than 4’. The concrete is typically placed in a continuous operation in two to three lifts by making passes around the perimeter or section of the wall. Concrete is commonly placed 10 to 12 feet in height during one concrete pour in 4 foot lifts. The 4 foot lift recommendation has nothing to do with consolidation. This recommendation is used as a guideline for concrete form pressure to avoid exceeding the formwork’s capacity. The height of which the concrete is placed does not create honeycombing or voids.

The American Concrete Institute (ACI) does not directly address the height of concrete placement. Neither ACI 301, “Specifications for Structural Concrete,” nor ACI 318 “Building Code Requirements for Structural Concrete,” limits the maximum distance concrete can free fall. Field studies have shown that free fall from great distances does not reduce concrete quality or compressive strength.

In the specification notes to the owner’s representative, ACI 336 states that recent research on free-fall concrete has confirmed that free fall does not cause segregation, at least for fall heights up to 60 feet.

The American Society of Concrete Contractors (ASCC) has written a Position Statement #17 addressing the free fall of concrete. At least four field studies have shown that free fall from great distances does not reduce concrete quality. The ASCC position statement goes on to state that although the field studies have been for caissons, the results should also apply to other structural elements such as walls, columns, and mat foundations.

ASCC references a 1994 FHWA study the provided test data leading the investigators to conclude that “the general expectation that concrete striking of the rebar cage will cause segregation or weakened concrete is invalid” and they found “no segregation or strength differences between low and high slump concrete mixtures.”

Bruce Suprenant wrote an article titled “Free Fall of Concrete” in the June 2001 issue of Concrete International that summarizes many of the findings discussed in this technical brief.

For those who intend to restrict free-fall heights, they must consider that it does decrease concrete production rates, which increases owners’ costs without increasing concrete quality.

In summary, Reward Wall Systems recommends placing concrete generally up to 10 to 12 feet in 4 foot lifts.

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Along with our quality products and intensive client support, Reward’s technical information and long term industry experience also help to set us apart from other wall system companies. There are few companies, as a whole, that have the amount of qualified experience on an unlimited range of ICF projects. Most other ICF companies are a name, some with an army of sales people, but they lack the knowledge and previous insulating concrete form SUCCESS to educate the industry for proper growth. This is just another reason why architects, engineers, builders and homeowners alike enjoy working with our ICF product lines and most importantly…our people.

An important aspect that insulating concrete form contractors must always be cognizant of is safety when working with concrete boom pump trucks. A successful ICF project can be ruined if a major catastrophe or injury would happen to occur. Safety should always be a top priority. The concrete pump operator and contractor must be aware of potential dangers and take proper precautions.

Setting Outriggers

The contractor must evaluate the site conditions and communicate them to the pump truck dispatcher and operator. They need to know the size of pump needed, back-filled areas, underground obstructions, soil conditions, muddy or soft areas, and site restrictions. The outriggers should be firmly placed before unfolding the boom. Cribbing is used to spread the load out to the soil from the outriggers. The general rule is to use as much cribbing as is practical; too much is better than too little. After placing the cribbing on even soil, place the weight of the truck on each outrigger one at a time. If the pad starts to sink, retract the foot and add more cribbing. Continue setting each outrigger using the same process.

Do not place the outriggers on a hill or too close to an excavation or cliff. The one-to-one rule must be followed by keeping the outrigger back one foot from the edge for every one foot of vertical drop. If necessary, move the truck to a different location to avoid any of these areas.

When unfolding the boom, continue to keep an eye on the outriggers for any shifting or sinking into the soil. Keep people out from underneath the boom whenever possible.

Operating the Boom and Pumping Concrete

The pump operator should show the contractor the locations of the emergency stop switches. It is important to wear personal protective gear such as goggles or safety glasses, hard hat, ear protection and rubber gloves. Never stand between the ready mix truck and the pump. Stand off to the side where the driver can see you. Always be aware of overhead electrical power lines. If the pump or boom becomes energized with high voltage, anyone or anything that touches it will be at risk of electrocution. Be sure someone is always monitoring the location of the boom and that it stays at least 17 feet away from electrical wire.

Do not let the concrete level in the hopper become so low that you can see the top of the valve mechanism. If this occurs, immediately stop the pump as air can be compressed into the cylinders. This creates a dangerous situation; as the air is expelled from the hopper or pump line it could act as a cannon shooting out concrete. Slowly restart the pump with caution.

The person at the end of the hose should hold the hose loosely with both hands, keeping it out away from him. He should also be sure not to hug the hose. Spend as little amount of time as possible standing under the boom. Two important issues to avoid at the end of the hose include never kinking the hose and never hanging heavy devices from the hose. If the hose becomes kinked it will cause the pump to have maximum concrete pressure. A heavy device at the end of a hose can cause extreme hazard to the individual holding the hose. If the hose were ever to whip, it could easily knock him down. A heavy device at the end of a hose can cause extreme hazard to the individual holding it. If the hose were ever to whip, it could easily knock the person down.

Read our series on Concrete Placement in ICFs to get a good understanding of the type of concrete to use and the proper placement in insulating concrete forms. Remember if the concrete is not what was specified: SEND IT BACK

Precast Hollow Core Concrete Floor

Precast hollow core planks are manufactured at a factory and delivered to the job site. Overhead cranes are used to lift the planks into position. The planks are usually 3 or 4 feet wide with grooves on the sides. After the planks are craned into place side by side, the grooves are grouted together and a concrete topping is placed over the entire top of the hollow core floor.

The hollow core floor is connected to the insulating concrete wall by 90-degree bent rebar placed between the planks in the grouted groove area. The vertical rebar or vertical rebar dowels must extend past the first and second concrete pour a minimum of 40 bar diameters. The minimum bearing area, concrete wall and rebar connection must be designed by an engineer of record.

It is very important to pre-plan by figuring out the elevation of the floor with respect to the hollow core depth and the iForm height to optimize the construction efficiency and minimize form support. The iForm is usually stacked so that the top of the plank elevation will be at the top of an iForm course. This will minimize form support on the exterior of the wall.

The planks can be installed to either bear directly on the wall or to bear on the Ledge ICF. The Ledge Form from Reward, reinforced with the xLerator, has a uniform bearing capacity of 1,700 plf. The planks can not be placed on the Reward wall until the concrete in the insulated concrete form has reached adequate strength.

And for the daily followers out there there will not be a post until June 3rd due to blog master Troy leaving for a couple weeks to get married and to honeymoon in Hawaii.

Tall wall applications work well with ICF construction if scaffolding and bracing systems are incorporated together. There can be different types of scaffolding systems that will work. First you need to determine the height of wall that is to be constructed as there are two types of tall wall that will figure into your bracing mechanisms. There is the 12’ to 24’ and the 24’ and beyond.

The 12’ to 24’ can be built with the standard bracing systems that are on the market. The standard bracing systems offer extensions for their systems. The extensions would include the extended strong back that splices to the lower strong back. Also there is tall wall turnbuckle longer in length for the upper adjustment of the upper pour. The first pour of the wall will just require the standard 10’ to 12’ bracing system. The extension kit for the bracing system will be added for the second pour. The issue with this type of scheme is the transition from walking platform to second walking platform. There is that area where you can’t reach the height of wall on first walkway and it is too low for the second walkway. This area, without moving the first walkway up, can be stacked using a man lift. The man lift could also be used for the setup of the second walkway bracket and turnbuckle. The first turnbuckle will stay in place while the second section of wall is being stacked and poured. This system will work for walls in these height ranges.

The method I like best is using masonry frame type or tower type scaffolding that in most instances is readily available. This type of scaffolding can be used from the ground up to the top of wall. This method of scaffolding & bracing will accommodate walls from ground floor to at least 54’ in height… which is the tallest wall in the industry so far, courtesy of Reward Wall Systems and our Largest ICF structure to date, in the U.S.

The mason’s frame is easier to add to the wall as it is coming up. The working platform can be added to as each section as each are being constructed. This type of scaffolding is something that most construction companies are familiar with. Also large construction companies usually already own their own. Or the scaffolding can be rented local. This type of scaffolding can be adapted to also brace the wall as it is being constructed. The system is OSA compliant if constructed properly. Also, material can be stocked in place as the walls are being constructed much like CMU type construction.  By using our standoff bracket and strong back the walls can be braced and adjusted off of the scaffolding. The system will work best using side bracket for the walkway.

Reward recommends using pipe & clamp that will attach to the frame for the standoff attachment. The pipe & clamp will allow the standoff bracket to be attached where it is needed instead of where the frame is located.

One of the benefits to using this type of bracing/ scaffolding is that you can have multiple people working on the walls at once. This method of tall wall ICF construction will give you the ease of access to different areas of the wall at once. For instance to inspect the forms for any missing reinforcement or special embed applications. Also if there are areas that might need bracing added while pouring or if problem might arise while pouring you can get to the area. We also like the fact that it allows you to adjust the walls with better precision. The main focus is that the walls turn out straight, plum, level and flat. Using this method you can accomplish just that.

There are, of course, other methods of bracing tall wall that might have been used. But from Darryl’s experience, this method has proven itself to work and work very well.

The New Standard of Sustainability. Tell the World.

Energy efficiency is determined by several factors such as the walls, windows and doors, roof or ceiling, mechanical systems; and internal loads such as lighting, appliance use, and number of people.

The first place to start when improving energy efficiency is the building envelope. The building envelope consists of the foundation, the walls, the doors and windows, and the roof. It’s difficult to have an efficiently conditioned building without controlling the enclosure. The overall performance of a well designed and energy efficient mechanical system is reduced, if the envelope is not efficient, thus costing you money.

WHY are insulating concrete form walls inherently energy efficient?

What is great about ICF walls is that they perform well in respect to the “Chosen Three” of energy efficiency- conduction, convection, and radiation. How so you may be asking?

Your Home Loses and Gains Heat in 3 ways:

-Conduction- def. The transfer of heat through two objects due to a temperature difference.
ICF walls have a consistent R-value that reduces thermal transfer through the wall assembly.

-Convection- def. the transfer of heat through circulation of heated part.
ICF’s are virtually airtight which reduces the “circulation” of heated air from one side to the other, which give a structure a consistent indoor climate

-Radiation- def energy that is transmitted through one side of an object and absorbed by the other side.
The thermal mass in ICF walls reduces the radiation of temperatures from one side of wall to the other.

There is not another wall system that can control all three of these elements of energy efficiency in one system. By the way did you notice R-value truly effects only one of the “Chosen Three”?

But why does everyone advertise and INFLATE the R-values of their product when that’s not truly what it is? We do not know. Our guess is that other ICF manufacturers or other wall systems or products in general use the highest number they can find, or create, to try to mislead customers into thinking their product may be superior.  What they don’t tell you is that R-values are tested in a lab, so R-values may be different in different climate zones etc.  Also, some folks use “Effective” R-value number instead of “Actual” R-value.  Watch this couple minute video of Richard Rue, from NASA spinoff company EnergyWise Structures, truly explain the importance of the Chosen Three and the misleading R-values.

So, to try our best to break it down for you, and give honest values and representation of the R-value of ICFs, our Reward iForm has a steady state actual R-value of R-22 (Conduction!).  This is the clear wall R-value, the whole wall assembly and all its materials from inside to the outside face of the wall (foam < concrete > foam). This is not like a framed (wood or metal) wall where insulation is placed into the cavities of the wall and they call it an R-18, when in reality its clear wall R-value is more like R-13 or lower.  The wood or metal is not accounted for in the wall’s R-value, as a wood or metal stud by itself is an R-2 to R-6.

Secondly, the continuous EPS insulation and monolithic concrete wall provides an air tight envelope (Convection!).  This is probably the biggest factor contributing to the excellent energy performance of an ICF building.  Wood or steel framed structures need extra material and effort to even try to achieve this level of convection.

Finally, the thermal mass of the concrete in the ICF wall will moderate peak temperatures daily (Radiation!).  The thermal mass performance is a function of the climate or region of where the building is located.  A climate that has wider temperature fluctuations daily will get better benefits due to the thermal mass. Plus this will help to contribute to LEED v3: Indoor Environmental Quality points as well!

Once again R-value does not take into account Convection and Radiation.

So the ACTUAL R-values of Reward Insulating Concrete Forms is R-22, as are most ICFs.  What is “Effective” R value? The effective R-value is the comparative R-value that a framed wall would need to be insulated in order to have the same energy performance as the same building built with ICF walls.  It is not the R-value of the ICF wall.  The effective R-value considers the actual R-value, the air infiltration rate and the thermal mass.

So you can see why some people will say “Effective R-value” of 32 all the way up to 60 for ICF walls. All of the other factors you cannot test in a lab, as it will vary on climate and other variables. It is a COMPARATIVE measurement, with everything else being equal in the comparisons. As an example we say an effective R-Value of 32+.  That means in order for you to achieve that level on a non-ICF wall, you will need to insulate the framed wall to a level 32+ value.

Other areas of the envelope that will enhance the energy efficiency of the building would be to add energy efficient windows, to provide high quality design and construction of the openings, and to provide a well insulated roof and an energy efficient roof to wall connection.

Hopefully that gives you a better insight into R-values, green building and an overview of the building envelope.

The New Standard of Sustainability. Tell the World.

I will be posting information from our corporate offices from our President, CEO, VP, Technical Specialists, Regional Sales Managers, and Marketing to showcase a little bit of everything we are doing, talk about some trends in the Insulating Concrete Form (ICF) industry and pass along some information and things we learn everyday while visiting our customers and greening North America  5.33 sq feet at a time.

My goal for this blog is to try to connect with people on another platform and maybe start a discussion, teach something new, or even be taught something new in the process. Our tone is casual, and my jokes are horrible, however we have to keep the flavor light or this endeavor won’t be as FUN as anticipated. This is not a discussion forum, with freedom to post abusive language or spam, as all comments will be moderated. And for the legal jargon: Reward Wall Systems Inc reserves the right to control and edit all postings. Furthermore all content written by Reward is all rights reserved 2009. By posting pictures, words, or content, you are verifying that you have permission to do so.

Also if you need in depth questions immediately answered, the best way to reach us is through our customer service department, not through aBlog. 1-800-468-6344

On to the topics.

There will be 6 major topics we will try to schedule routinely in order to cover as wide of a range as possible. Don’t see something that you think we should focus on more? Tell me please, just add a smiley face at the end of your sentence.  :-)

From the Field

Common Trouble Shooting

Let’s get Technical!

Project Showcase

Unique Trends and Applications

Other

So we hope you find aBlog by Reward useful and informative and just a smidge bit entertaining. Feel free to comment, post follow-ups or even additional resources on a topic. There may be aBlog related contests and EXCLUSIVE information given out first to the community via aBlog throughout the year so be sure to come back often. We’ll talk to you soon.

Thanks and tell the world