FAQs

  • Cellular Concrete FAQs
  • Insulating Concrete Roof Systems FAQs
  • Underlayment Systems FAQs
Cellular Concrete FAQs
  • What is cellular concrete?
    Lightweight cellular concrete (LCC) contains type (I) II‐V Portland cement, water, and a preformed foam. The foam looks like shaving cream and is varied in quantity to control the unit weight of the cellular concrete. These air voids are established in the material via the introduction of either a protein-based or synthetic-based foaming agent that reacts mechanically and chemically with the other components to entrap the air and can produce cast density material as low as 24 PCF (pounds per cubic foot). The cement particles coat the foam bubbles that are stable enough to withstand the hydration process leaving behind a uniform matrix of air voids which is why cellular concrete is lightweight.
  • Are foam concrete and cellular concrete the same thing?
    Yes! There are many different terms used to refer to lightweight cellular concrete. The term ‘flowable fill’ is a generic way to describe any self-hardening low viscosity fill such as lightweight cellular concrete. Other variations of LCC include permeable lightweight cellular concrete, low density cellular concrete, foamed concrete, cellular grout (often used to reference pipeline and tunnel work), flowable soil cement, plastic soil cement, controlled density fill, and controlled low strength material CLSM.
  • Why should I use cellular concrete on my project?
    Cellular concrete is lightweight, inexpensive, flowable, self-compacting, and readily available. Construction schedules get shorter, site footprints get smaller, and access is nearly impossible in some situations. It is imperative to provide a solution that is reliable and dynamic enough for each unique problem condition. Cellular concrete cures rapidly without need for additional compaction and requires a minimal setup area to place a substantial amount of material.
  • How much does cellular concrete cost?
    Cost is dependent on many factors which include but are not limited to: size of the project, location, density of material, site conditions, and many others. When comparing the cost of cellular concrete on a cyd to cyd basis, many externalities of the wholistic project design get ignored. A few of the beneficial impacts on the entire project are time, reduced construction traffic, minimal jobsite footprint, and lower related construction costs (compaction, recompaction, foundations, retaining walls, and distribution slabs).
  • How is cellular concrete made?
    Cellular concrete is produced on the jobsite. Cement and water are batched onsite, and preformed foam is blended in to produce the specified density. Then, the material is pumped into place in lifts of about 4 feet (this can vary depending on the project).
  • Is cellular concrete pervious?
    Similar to clay, cellular concrete has a high porosity (air content). However, as in clay, these pockets of air are not interconnected, so the permeability is rather low (1×10-4 to 1×10-7 cm/s). For pervious cellular concrete, see the Pervious LCC section for pervious cellular concrete.
  • Is cellular concrete the only material you have available for my project?
    No! We offer a wide arrange of Value Engineering solutions for projects. Contact us to discuss the use of other products, such as geofoam and pervious cellular concrete. 
  • Is cellular concrete excavatable? Cellular concrete is a low-density, low-strength material that can be easily excavated using mechanical equipment such as backhoes.
  • Can I place equipment on top of cellular concrete? Yes, it is recommended that a protection material (which could be backfill or something as simple as plywood) be placed directly on top of the cellular concrete to prevent any damage to the surface of the material.
  • Can cellular concrete be used as flowable fill around pipelines? Yes, however, buoyancy and heat of hydration must be taken into consideration. It is recommended that all pipelines be filled 100% with water during placement and for at least 24 hours after the material has been placed to allow the material to set and cool down.
  • How is cellular concrete placed and how far can the material be pumped? Cellular concrete is placed through a 2″–4” concrete hose; typically, we like to be within 800’ of the mobile batch plant; however, as long as we can move our foaming system close to the point of placement, we can pump distances over 800’. Please contact us to discuss your project.
  • How long do I have to wait to place my next lift of cellular concrete or to be able to walk on the material? Cellular concrete usually cures in about 12 hours. You will be able to place a lift the very next day and walk on the material to continue your project.
  • What will be the water demands for the mobile batch plant on my site? The water demand will vary depending on the size of the job; however, we recommend that at least 60 gallons of water per CY be considered as the minimum. The gallons per minute (GPM) will dictate the rate of placement out on the site, so 125 GPM is typically the requirement for a mid-level job (800 CY/day).
  • Where can I find more information about cellular concrete?
    Please see our technical information page, and contact us to discuss your potential project needs. Follow us on Twitter, Facebook and LinkedIn to find out even more fun facts!
  • Who can I speak with to learn more about cellular concrete?
    Our in-house expert, Jeff Wykoff, would be happy to set up an informational presentation for you and your team to understand your project needs and provide more insight into the many applications and advantages of using lightweight cellular concrete. Please send us a message through our contact us page or reach out to Jeff directly at jwykoff@cell-crete.com. Depending on your state licensing board rules, we can provide an hour of continuing education by your verified attendance in our webinars.
Insulating Concrete Roof Systems FAQs
  • What advantages are there in using an LWIC Roof Deck System?
    Competing systems typically use mechanical fasteners through the insulation boards to the deck below. These thermal breaches can reduce the system’s R-value by as much as 30%. These thermal bridges are eliminated in LWIC Roof Deck Systems—mechanical fastening is to the top LWIC layer only and does not affect the EPS insulation board in the system. Few roof decks have regular drainage patterns or built-in slopes for positive drainage. Positive drainage is achieved by combining a stair-stepped EPS board with custom sloping of the LWIC, creating a more efficient and cost-effective system over conventional tapered insulation board systems.
  • How is Cell-Crete’s use of this system possibly different from others in the industry?
    Cell-Crete has been installing LWIC Roof Decks for over 45 years. Being an approved applicator means that they have the experience, equipment and endorsement of the manufacturer when installing an LWIC Roof Deck. Cell-Crete is also leading the nation in installations over wood deck. They have installed more over wood deck than anywhere else around the country.
  • Why use lightweight insulating concrete?
    Low Density Insulating Concrete Roof Decks provide a solid, monolithic system that provides a fire and wind uplift rated system at a very competitive cost. These roof decks are permanent, as only the membrane needs to be replaced in the event of reroofing. If leaks do occur in the membrane, the roof deck can be dried out and have a new membrane installed, unlike other systems that may require a replacement if leaks occur. The monolithic system also provides a heat sink that protects the membrane from thermal shock, which can help extend the life of the roofing membrane.
  • What is the equilibrium moisture content of LWIC?
    The equilibrium moisture content (EMC) of cellular concrete ranges from 12% to 20%. However, there is no definite time frame as to the period of time it takes to reach this equilibrium. This can be compared to wood that falls within the same range. It may feel dry, and it has a similar EMC.
  • What roofing membrane systems are compatible with LWIC?
    LWIC roof deck systems are compatible with built-up roofing systems as well as Single-Ply roofing systems, either mechanically fastened or fully adhered systems.
  • What substrates are compatible with LWIC?
    LWIC may be cast over galvanized metal deck, structural concrete, wood decks, and existing roof systems.
  • What advantages do lightweight insulating concrete systems provide?
    LWIC Roof Decks are permanent, insulative, dimensionally stable, non-combustible, economical and easily reroofed when the membrane needs to be replaced. LWIC Roof Decks also have excellent fire and wind uplift ratings, and are efficient overall.
  • Is vented metal deck required with insulating concrete systems?
    It is acceptable to utilize non-vented, galvanized steel decking in lieu of vented, galvanized steel decking as a substrate for the insulating concrete roof deck system. Since insulating concrete has only one-fourth the mix water of the expanded aggregate concretes, there is adequate moisture relief at the side and end laps of the steel decking.
  • What is the R-value for LWIC?
    LWIC has an R-value of 1.0 to 1.34 per inch, and the encapsulated EPS insulation board has an approximate R-value of 4.0 per inch (exact values vary per manufacturer).
  • What are the minimum slope requirements?
    LWIC has a minimum slope requirement of 1/8” per inch.
  • What does the LWIC system weigh?
    LWIC Roof Deck Systems typically weigh approximately 8 to 9 psf (R rating of R-30).
Underlayment Systems FAQs
  • What kind of water access and pressure do you need?
    We require faucet or well access within 200′ of the pour with 35–40 lbs. of pressure. Specific location/requirements will be discussed prior to the pour.
  • We have a stairwell. What do we need to do in this area?
    A bulkhead (piece of wood) needs to be installed at the top of the stairway. This provides a place for the pour to stop, and eliminates crumbing at the stair’s edge. The bulkhead will need to be the same depth as the pour depth. This allows an even floor/step surface. The bulkhead will become a permanent fixture or it may be replaced with finished lumber. Example: If you are pouring 1 1/2″ of gypsum underlayment on the floor above the stairwell, you will also need to provide a piece of wood that is 1 1/2″ tall and runs the width of the stairs and/or landing.
  • What is the best way to secure our radiant floor heat tubing?
    Tubing needs to be as flat as possible to ensure that it is covered with the proper depth of product and does not incur damage once the pour is complete. The tubing or cable will be secured by stapling or gluing (depending on the type of subfloor) every 24 to 30 inches.
  • How long will it take for my floor to dry and how can I tell when it is?
    Under normal drying conditions, our product dries 1/8″ per day. Normal drying conditions require good ventilation and dry air. Air movement is the key factor in drying time. Humidity and cold weather tend to increase drying time; direct sunlight tends to decrease drying time.
    To see if the floor is dry and ready for floor goods, you may perform the following steps:

    • Cut a piece of 2′ x 2′ plastic film.
    • Tape all four sides to the floor.
    • Leave the plastic in place for 48–72 hours.
    • Once you remove the plastic, if the covered floor is darker than the uncovered area, the floor is still wet.
    • Repeat this process until the covered and uncovered areas are the same color. Additional moisture-testing techniques can be found in Maxxon’s Procedures for Attaching Finished Floor Goods to Maxxon Underlayments. Download further information on best drying techniques here.
  • How do I install floor goods over your products?
    All of the Maxxon underlayments we install provide an excellent base for your finished floor goods. Our customers have successfully installed glue down vinyl and composition tile; ceramic, quarry and marble tile; glue down, “floating” or nail down wood flooring; and carpet.
  • How do I know which sound mat is right for me?
    There are many factors that go into determining which sound control mat you should choose:

    • Floor/ceiling assembly
    • UL design number
    • Acoustical requirement
    • Budget