With the slowdown in the housing industry, predictably the attendance at the Pacific Coast Builders Conference (PCBC) dropped from prior years by reportedly 25-30%. While the traffic decrease was noticeable in the booth, the quality and awareness of the prospects was up from prior years. People seemed to be more knowledgeable, interested and were asking good questions regarding specific projects.

The event was also very useful as a validation for clients we are already working with. Many came into the booth for meetings and to discuss projects currently in progress.  During these difficult times, our customers are encouraged that we are continuing to support them and help them build business.

The market for Insulated Concrete Forms (ICF) in commercial/multi-unit residential is still underdeveloped in most areas of the west coast.  PCBC appears to be helping raise awareness among more advanced builders which is allowing this market segment to gain traction.

Despite the decline in numbers, we expect see more real business develop out of the exposure at PCBC this year than in other years.  Overall, PCBC remains one of the strongest lead generation activities California, and maybe even the West in general.

Thanks to Bill Juhl of Amvic-Pacific for providing feedback for this entry.

In the past, Insulated Concrete Forms (ICF) were primarily used for residential construction and low-rise commercial projects. Today, as developers, architects and builders strive to build green, energy efficient and sustainable buildings at an affordable cost, ICF has become a viable and cost effective building solution for hi-rise applications as well.

It is no longer uncommon to see ICF structures in excess of 10 stories. While the industry celebrates this success, it opens up new challenges for the building and design communities. There are several unique considerations that require special attention which are discussed below.

Product Selection

When selecting an ICF for hi-rise construction, product features such as interlock, foam density, block size, form capacity, web design and web spacing should be evaluated. These elements can make a considerable difference in the efficiency and successful completion of a hi-rise project. It is also essential to consider the manufacturer’s training materials, technical assistance and engineering support when reviewing a product’s compatibility for a project. It is worth the small additional cost for a reliable brand since the objective is often to enable occupancy as quickly as possible.

Engineering

Engineering is an extremely important factor for hi-rise construction. Walls can be designed either as non-load bearing or load bearing using a variety of different concrete core thicknesses. A wall with a large number of openings typically requires structural column designs between the openings up the entire building. This can lead to the requirement of considerably more reinforcing steel and wider concrete core thicknesses. Connections to floor slabs, internal walls, stair wells and elevator shafts must all be reviewed carefully as there are numerous alternatives to these design elements.

Bracing

ICF walls are typically supported on the inside of the building footprint only. On lower buildings it is easy to add additional bracing to the exterior if required, as it can be easily installed and removed. The taller a building is, the more difficult it is to install exterior support due to safety concerns for workers, added labor hours and increased material costs. Areas that often require additional form support are at floor connections where the ICF has to be cut to accommodate the floor system. It is important to work closely with the ICF manufacturer to develop creative ways to solve these issues from the interior side of the wall.

Safety

Due to the increased heights in hi-rise construction, safety and liability are much greater concerns. Scaffolding systems must meet the proper engineering and safety requirements for hi-rise structures and should be equipped to provide both front and back safety rail applications. Fasteners used to secure to the ICF wall and floor slab must be engineered for the application. Additional use of safety lines etc. might also be necessary.

Pouring Concrete

Pouring ICF walls is more challenging for hi-rise applications than low-rise applications. As building height increases, wind and precipitation are usually intensified which can increase the difficulty of a concrete pour. Special attention must be paid to concrete mix design, slump, aggregate, admixtures, lift rates, consolidation and pump flow to prevent forms from bulging or failing. Attention to detail when installing the forms and following proper pouring techniques are necessary to ensure straight, plumb walls, limit liability and reduce the risk of job-site injury. In addition, an experienced crew, pump operator and a high quality ICF should be combined to ensure a successful, safe pour.

Tell us about your hi-rise ICF experiences, tips and tricks!

Internal mechanical vibration is the most consistent and effective method of consolidating concrete for Insulated Concrete Form (ICF) applications and therefore will be the focus of this entry.

Equipment

Low modulation (small movement) and high frequency (many times per minute) is the best method to vibrate within Insulated Concrete Forms (ICF). The most effective vibrator to achieve this result is an immersion type concrete vibrator with a 12’ (3.7m) flex shaft. The specific requirements differ slightly for different concrete core sizes. The following chart provides the recommended specifications for concrete vibrators used with ICF:

Technique

The most important part of consolidation is proper technique. To vibrate properly, plunge the vibrator head to the bottom of the 4’ (1.2m) lift of concrete as quickly as possible and retract it slowly (approximately 3” (76mm) per second). Remove the vibrator head and re-insert it at a distance 1.5 times the radius of action. This will create an overlap with the previously vibrated area ensuring proper consolidation. When working on subsequent lifts, repeat the above method, but also penetrate into the top 6” (152mm) of the previous lift. This will fuse the lifts together, eliminating any pour seams or cold joints.

Keys to Success

For effective concrete consolidation, follow these three guidelines to ensure success:

1. Use a concrete mix with a slump of at least 6” (152mm).
2. Brace corners and lintels very well and vibrate them thoroughly.
3. Hire an experienced trained operator.

Change Building Priorities

After all the death and destruction we have experienced in recent years from tornadoes, hurricanes and other extreme weather, it is clearly time to shift our thinking about the way we build. We have repeatedly wasted resources, time and most importantly lives, by re-building the same types of buildings that have previously blown away, fallen down and crumbled around us. Now we must re-evaluate our priorities and strive to meet the following goals when building structures:

1. Implement measures that will reduce risk of casualties.
2. Reduce downtime and disruption caused by damage.
3. Reduce damage repair costs.

ICF Building Solution

The strength of a tornado in the United States is estimated using the Enhanced Fujita Scale (EF Scale). The scale has six categories from zero (EF-0) to five (EF-5) representing increasing degrees of damage.

To simulate the wind speeds present in tornadoes, the Wind Engineering Research Center at Texas Tech University was the first to design an air cannon that could shoot 2x4s and other objects to duplicate flying debris conditions during high winds and tornadoes. Debris flying at over 100 mph passed right through a standard wood framed wall leaving inhabitants at risk, while an ICF wall with 2 1/2” of Expanded Polystyrene (EPS) foam on each side of the concrete, was not damaged.

An ICF wall can offer a wind resistance of 250+ MPH which is equal to an EF-5 tornado. The strength is based on the wall’s composition of steel reinforcement and concrete. In addition, ICF walls are resistant to the water-damage often associated with tornadoes, hurricanes and other storms.

ICF construction helps to meet the priorities stated above by providing a secure structure for occupants, reducing damage to a building’s structure and reducing repair costs after an extreme weather event.