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Key Takeaways

  • LWIC can cut roofing cost by as much as 30%. Charlie Krauss, KPost’s Roof Deck Manager and Senior Estimator, puts the savings against other rigid roofing materials at up to 30%, which is why the company evaluates a lightweight insulating concrete option on every job.
  • Water use dropped from over 100 gallons to about 23. The original systems from the 1930s needed more than 100 gallons in the initial mix. Today’s cellular concrete traps air bubbles to lighten the material, uses roughly 23 gallons, and cures in two to three days.
  • It compresses the schedule by about three weeks. KPost CEO Keith Post reports installing LWIC systems on new projects in roughly seven days, which pulls about three weeks out of the overall job timeline.
  • Re-roofing needs no tear-off. A new layer goes over the existing roof, so nothing goes to a landfill. Billy Ward, KPost’s LWIC supervisor, notes the system can add slope or change slope direction on a re-roof and carries a 20-year guarantee.
  • It handles uplift and unusual roof geometry. LWIC sustains high uplift forces that often exceed rigid board systems, stays in place for the life of the building, and works well on complicated roofs with irregular slopes, skylights, or HVAC equipment in the way. It also meets LEED and R-value requirements.

We know that “going green” is good for the environment and for future generations. But it also is good for economic development. How?

Take lightweight insulating concrete, for example. It provides an environmentally friendly choice for any new and re-roofing project. It also is less expensive, permanent and durable. It is the type of construction that is best for future generations – leaving a light footprint while still being safe.

Green Is In

Currently there are more than 4.3 million people living and working in LEED certified buildings (according to a report by the U.S. Green Building Council).

The U.S. has the most LEED credential holders, contributing to building better, more environmentally sound commercial buildings and homes. Currently there are 13,000 USGBC member organizations, ranging from Fortune 100 corporates to small neighborhood businesses and representing 13 million employees and $1.8 trillion in combined revenue. This is no small effort!

While LEED and green building is becoming more popular, many believe that the cost of building to LEED certifications is more expensive. While this may be the case with some materials, it is not so with commercial roofing.

LWIC to the Rescue

“One of the major benefits of lightweight insulating concrete is cost savings. Head to head with other rigid roofing materials, we can cut the roofing cost as much as 30% by introducing LWIC,” said Charlie Krauss, KPost Company Roof Deck Manager & Senior Estimator. “Because it saves money and is very durable, we approach every job with an LWIC option.”

The benefits to lightweight insulating concrete are numerous. In addition to saving money, choosing LWIC over more rigid roof materials will provide:

  • Longevity – the product remains in place for the life of the building.
  • Durability – LWIC sustains very high uplifts often greatly exceeding other commercial roofing systems, particularly rigid board system.
  • Sustainability – the LWIC system stays in place, so there is no removing of original roofing and dumping in landfills.
  • Eligibility – LWIC will meet any requirements, including LEED and R values.
  • Versatility – ideal for complicated roofing and re-reroofing projects, particularly if unusual slopes are needed, or the roof has obstacles such as sky lights or HVAC systems.

In addition, lightweight insulating concrete systems have improved since their introduction in the 1930’s. Now the systems use cellular concrete that creates air bubbles, thereby making the concrete lighter. Plus, the newer systems use significantly less water, making them even friendlier to the environment. Originally, the systems required over 100 gallons of water in the initial mix. Now, LWIC systems need about 23 gallons of water, and cure in two to three days. This is a significant improvement in hydration rate PLUS the new LWIC systems can be installed much faster, positively impacting the project schedule.

“Lightweight insulating concrete is a quality product that provides strong value for our customers. Not only is it ideal for re-roofing projects, but for new projects we can install LWIC systems in approximately 7 days, picking up 3 weeks’ time and improving the overall job schedule,” said Keith Post, KPost Company CEO.

Re-roofing is another project type for which lightweight insulating concrete is well-suited. Many re-roofing projects have varying slopes. With LWIC, accommodating these different slopes becomes quite easy.

According to Billy Ward, KPost Company Supervisor for Lightweight Insulating Concrete projects, “LWIC is the best solution for re-roofing projects because you can add slope, can change slope direction if needed, and provide a better solution with a 20 year guarantee. With LWIC, we don’t have to tear off old roofing materials. Simply add a new layer and you are good to go.”

With the continued focus on environmentally friendly construction, it’s good to know that in the commercial roofing space, lightweight insulating concrete provides a green option that is cost effective, easy to use and improves project scheduling. That is truly a win-win!

FAQs

It is a poured cellular concrete deck system that combines structural fill, insulation, and slope in one application, installed over the existing deck or over an existing roof. Air bubbles are entrained into the mix to reduce weight while retaining insulating value. Because it is poured rather than fastened, it eliminates the fasteners, adhesives, and rigid board insulation a conventional assembly requires.

Large low-slope commercial buildings where drainage, re-roofing without tear-off, or minimizing penetrations matters most. That includes data centers, schools, hospitals, warehouses, and stadiums. KPost’s LWIC work includes data center projects for CyrusOne, T5, the SMU Data Center, 3000 Skyline, and Bank of America.

LWIC is placed over structural concrete, over steel deck, and on re-roof work over an existing built-up roof that is still sound. On steel deck it goes over a galvanized deck with slots or vent holes that let the mix release moisture as it cures. The deck type drives both the mix design and the venting details, so it gets settled during design rather than worked out in the field.

Far less than structural concrete, which is the entire point of the material. Lightweight insulating concrete runs a fraction of the density of normal weight concrete depending on the mix specified. The added dead load still has to be checked against the existing structure on a re-roof, because the system is poured in place at whatever thickness the slope being built requires, and that thickness varies across the roof.

It holds water by design during cure and releases it slowly afterward, which is exactly why venting is built into the assembly rather than offered as an option. Vented base sheets and deck venting give that moisture a path upward instead of letting it collect beneath the membrane. Moisture complaints on LWIC roofs almost always trace back to venting details that were left out or to a membrane that went on before the deck was ready. See our lightweight insulating concrete services for how these assemblies are designed and vented.

Lightweight insulating concrete is difficult to picture from a description, so here are the key installation steps on an actual deck:

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