- How long has Lightweight Insulating Concrete (LWIC) been used in the construction industry?
LWIC has had successful applications throughout the country for over 60 years.
- Is LWIC structural in nature?
NO! Lightweight insulating concrete is a low density concrete. Its purpose is to provide insulation to the building while providing a solid base for the roof membrane application. However, it has been found to play a significant role in the diaphragm action of a bar joist and metal roof deck system.
- Can the use of LWIC extend the life of my roof membrane?
YES! The thermal mass of LWIC means that it is slow to heat up, as well as cool down. This results in less wear and tear on the membrane as the expansion and contraction is significantly reduced during the heating and cooling cycles of day and night. In addition, the monolithic system that LWIC roof decks provide mean no joints are present (as between rigid insulation boards) that can impart undue stress onto the membrane.
- How does the use of LWIC affect the re-roofing process?
LWIC is re-roofable. In most cases, only the roof membrane would need to be removed and replaced. This provides a significant cost savings as the labor to remove the insulation, plus disposal fees are taken out of the equation.
- Can I use non-slotted metal roof deck substrate for my LWIC installation?
YES. Not all lightweight insulating concrete systems require a slotted metal roof deck. BOAF (Building Officials Association of Florida) interpretation of the FBC is that lightweight insulating concrete can be installed over a non-slotted steel deck, provided proper venting is achieved as required by the manufacturer’s product approval. In all cases the metal roof deck must be galvanized. As with all roof insulation systems, the specifier should refer to the product manufacturers
(click here) and their State Product Approval.
- But do the bottom slots of the steel deck enhance the wind-uplift resistance of the system?
NO. There is no correlation between slotted steel deck and wind-uplift resistance.
- How long after rain event should I wait prior to Roof Membrane Installation?
There is no set time requirement between a rain event and the installation of the roof membrane. Your Roof Membrane Manufacturer and/or LWIC Applicator can give you a good time estimate on a case by case basis depending upon the amount of rainfall encountered. At the very least, all standing water should be removed from the surface and any seems, edges and/or the surface should be free of the shadow-like effect of absorbed moisture (the LWIC should possess the normal light grey color of dry concrete).
- Does surface cracking cause problems with a LWIC roof deck?
NO! Surface cracking, while unappealing to the eye, in no way compromises the integrity of a lightweight insulating concrete roof deck.
- Can LWIC be used in Enhanced Hurricane Protected Assemblies (EHPAs)?
YES! In the past 5 years, extensive testing has been done to qualify LWIC systems for use in Enhanced HurricaneProtected Areas. Currently, there are many of these systems that are approved for use in EHPAs by the Florida Board of Education. Contact your local applicator or manufacturer to determine which product is right for your project by
(clicking here).
- What kind of products are installed by FRDA members?
Following is a list of products installed by FRDA members:
· Aggregate Insulating Concrete Systems
· Cellular Insulating Concrete Systems
· Poured Gypsum Decks
· Metal Roof Decks and Accessories
· Roof Membrane Fasteners
- How do I become and FRDA Member?
Simply follow the link below, fill out the Membership Application and return it to the FRDA office in Tallahassee. At the next FRDA Membership Meeting, your application will be put before the General Membership for a vote. If accepted, you will become an FRDA member upon the receipt of your $1,000.00 membership dues. To view and print a copy of the FRDA Membership Application,
(click here).