LEARN
The FRDA is committed to educating the construction and roofing industries, including both design and code professionals.
FREQUENTLY ASKED QUESTIONS
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 $1,500.00 membership dues. View and print a copy of the FRDA Membership Application.
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
NO! Surface cracking, while unappealing to the eye, in no way compromises the integrity of a lightweight insulating concrete roof deck.
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).
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 and their State Product Approval.
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.
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.
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. The Florida Construction Industry Licensing Board, in June 2004, affirmed the non-structural nature of LWIC and made a determination that as a result, LWIC applicators are not required to hold a general, building or roofing contractor’s license. See the letter from the Assistant Attorney General for the Construction Industry Licensing Board
Florida Building Code Section 1917
The FRDA participates in the modification of the Florida Building Code in order to clarify Section 1917 – Lightweight Insulating Concrete Fill. Please check back for updates and approval status of these modifications.
1917.1 Lightweight Insulating concrete.
Material produced with or without aggregate additions to Portland cement, water and air to form a hardened material possessing insulating qualities, which, when oven dried shall have a unit weight no greater than 50 pcf (801 kg/m3).
1917.1.1 Aggregate lightweight insulating concrete.
Insulating concrete formulated predominantly with perlite or vermiculite aggregate having a minimum compressive strength of 125 psi (861.8 kPa) when tested in compliance with ASTM C 495.
1917.1.2 Cellular lightweight insulating concrete.
Insulating concrete formulated by mixing a hydrated cementitious matrix around noninterconnecting air cells created by the addition of preformed foam formed from hydrolyzed proteins or synthetic surfactants. The cured cellular lightweight insulating concrete shall have minimum compressive strength of 160 psi (1103 kPa) when tested in compliance with ASTM C 495 and C 796.
1917.1.3 Cellular/aggregate (Hybrid) lightweight insulating concrete.
Insulated concrete formulated by combining preformed foam with low density aggregates to impart properties of both aggregate and cellular lightweight insulating concrete. It shall have a minimum compressive strength of 200 psi (1379 kPa) when tested in compliance with ASTM C 495 and C 796.
1917.2.1
Application of all lightweight insulating concrete roof decks shall be by applicators approved by the lightweight insulating concrete deck manufacturer. Product approval shall be required for all lightweight insulating concrete systems.
1917.2.2
The permit holder shall notify the building official 48 hours prior to the pouring of lightweight insulating concrete.
1917.2.3
The permit holder shall make available to the building official a job log with the following minimum items.
- Cast density recordings/hour.
- Product evaluation for application.
- Date and job locations identified.
- Results of any field test conducted.
1917.2.4
Once the roof deck system can support foot traffic, the building official shall have clear access and clear path at his option for inspection of lightweight insulating concrete.
1917.3 Testing
The building official may require tests of the lightweight insulating concrete to confirm the fastener withdrawal resistance, compressive strength or drainage ability.
1917.3.1
Existing roof assemblies to receive lightweight insulating concrete other than galvanized G-90 steel deck or structural concrete deck shall be tested for uplift for adhesion to the substrate to confirm compliance with design pressure.
1917.4 Materials and limitations of use
Lightweight insulating concrete, in conjunction with galvanized formed steel sheets, shall not be used as a roof deck in areas where highly corrosive chemicals are used or stored.
1917.4.1
Lightweight insulating concrete shall be poured over bottom slotted galvanized (G-90) steel decking as follows; cellular, 0.5-percent open; hybrid, 0.75-percent open, aggregate, 1.5-percent open. No lightweight insulating concrete shall be poured over a painted or nongalvanized steel deck.
- Lightweight insulating concrete over structural concrete slabs, twin tees, precast units or other nonventing substrates shall be vented to allow the escape of excess moisture.
1917.4.2
Minimum thickness of lightweight insulating concrete shall be 2 inches (51 mm) over the top plane of the substrate unless otherwise specified in the product approval. Lightweight insulating concrete shall be of sufficient thickness to receive the specified base ply fastener length.
1917.4.3
Galvanized coatings of formed steel sheets shall be in accordance with ASTM A 525 with a minimum coating designation of G-90. Base steel shall conform to ASTM A 446, Grade A, B, C, D or greater and ASTM A 611 C, D or E.
1917.4.4
Chemical admixtures shall be in compliance with ASTM C 494. Calcium chloride or any admixture containing chloride salts shall not be used in insulating concrete. Fiber reinforcement may be used to control cracking. Mineral admixtures shall conform to ASTM C 618.
1917.4.5
Vermiculite or perlite shall be in compliance with ASTM C 332, Group I. Foam concentrates shall be in compliance with ASTM C 796 and ASTM C 869.
1917.4.6
Mixing, placing and finishing shall be in compliance with the deck system product approval. Slurry coating, two-density casting and double casting shall be acceptable in accordance with the specific manufacturer’s recommendations.
1917.4.7
If the lightweight insulating concrete deck is to receive product approval for a direct-adhered roofing system, the deck surface shall be prepared to the requirements set forth in the roof system product approval.
1917.4.8
All base ply fasteners for use in lightweight insulating concrete roof decks shall have a product approval for use with the specific lightweight insulating concrete roof system in compliance with manufacturer’s recommendations and the design pressure of Section 1609 (Section 1620 for the High-Velocity Hurricane Zone).
1917.4.9
The lightweight insulating concrete fastener withdrawal shall have a minimum resistance for new pours of:
- 60 pounds (267 N) in 28 days when the fastener is installed and allowed to age in the concrete.
- 40 pounds (178 N) at time of roofing.
1917.4.10
Insulation board with lightweight insulating concrete shall conform to Type I expanded polystyrene insulation as defined in ASTM C 578.
- Packaged insulation board delivered to the job site shall comply with the provisions of Section 2603.2.
- Installation of insulating board in conjunction with lightweight insulating concrete shall comply with uplift requirements set forth in Section 1609 (Section 1620 for the High-Velocity Hurricane Zone). Insulation panels shall be placed in a minimum 1/8-inch (3.2 mm) slurry of insulating concrete while the material is still in a plastic state. The insulating concrete shall be cast over the insulation boards according to the insulating concrete manufacturer’s product approval. Insulation panels shall be provided with holes and/or slots for keying and venting.
1917.4.11
Reinforcing mesh shall be provided as required to meet fire-rating and/or special structural design requirements. Refer to a specific product approval for the specific requirements applicable to the product being installed.
CONTINUING EDUCATION
EDUCATING THE INDUSTRY
We would be glad to present a one-hour educational presentation to your group that details the uses, properties and benefits of Lightweight Insulating Concrete in a roof deck system.