Vermiculite concrete roof deck systems allow architects, engineers and contractors versatility in design, high performance and reasonable cost. These systems will use a lightweight concrete consisting of portland cement, water and vermiculite concrete aggregate. It is recommended that all vermiculite roof deck systems be applied by an applicator approved by a member of the Vermiculite Association, Inc.

Lightweight
When compared with structural grade concrete, vermiculite concrete is 15% of the weight. This results in considerable savings from the footings thru the structural steel.

Fireproof
The fire proofing characteristics of vermiculite concrete are recognized nationwide by insurance companies, state rating bureaus and local building officials. Underwriters' Laboratories have assigned up to 4-Hour ratings to systems that employed vermiculite as one of the components.

Versatile
Vermiculite concrete can be applied over a variety of bases, allowing architects and engineers ample flexibility in their design criteria. The thickness of the concrete can be varied to permit necessary slope to drain.

Insulation
Vermiculite concrete has excellent insulating properties. Three inches of vermiculite concrete is equivalent to 1 1/2" of rigid board insulation layed over steel decks. One inch of vermiculite concrete is equal in insulating value to 20 inches of regular concrete.

Ease of Application
Vermiculite insulating concrete is easily placed by modern specially designed pumping equipment. Up to 25,000 square feet can readily be placed in one day.

Reroofing
Slope to drain systems employing vermiculite concrete and polystyrene ventboard provide an economical solution to existing flat roofs with damage due to ponding of water.

Substrates
Vermiculite concrete is suitable for installation over most structurally sound roofing systems with structural decks of concrete, metal, or wood. Care must be taken to properly vent decks poured over impervious materials.

This system provides a maintenance free, economical roof system. It consists of high tensile galvanized steel centering, welded or attached with self tapping screws to the supporting steel framing together with either a 1-6 or 1-8 mix of vermiculite concrete. The thickness of the concrete may be varied to provide necessary drainage slope. Minimum thickness of the concrete shall be two inches over to top plane of the steel centering.

Caution: Do not use calcium chloride or other additives containing salt in the concrete when used over galvanized sheets.

Vermiculite concrete lends itself to providing both drainage slope and high insulating values to various types of precast concrete units such as core type structural slabs, channel slabs and prestressed single and double tees. Vermiculite cast-in-place concrete provides a smooth surface for applying the built up roofing membrane. Should additional venting be required the use of roof vents similar to McKinley Roof Vents should be installed - one vent for each thousand square feet of roof area.

This system of superior insulating value consists of polystyrene board and vermiculite insulating concrete applied over structural bases of regular concrete, metal or wood. This system provides flexibility that will meet most design criteria. Insulating values can be varied by changing the thickness of the polystyrene board. Proper slope to drain can be obtained with the vermiculite concrete. Minimum thickness of the concrete shall be two inches.

SCOPE:
This specification covers vermiculite insulating concrete. Materials shall conform to the ASTM standards. Thickness shall be as indicated on the drawings. A minimum of two inches is recommended.

A. CEMENT shall be type I or type III Portland Cement in accordance with ASTM standards C-150.

B. VERMICULITE shall be in accordance with ASTM standard C-332 Group 1.

C. AIR ENTRAINING shall be liquid neutralized vinsol resin used at the rate of approximately 1 pint per four cubic feet of vermiculite.

D. WATER shall be clean and potable.

The proportion of cement to vermiculite shall be in the ratio of one part cement to __parts vermiculite. The wet density shall be __psf, oven dry density___ psf and compressive strength ___ psi in 28 days. (See Physical Properties Chart above for mix proportions) At Architect's direction, four 3" x 6" cylinders shall be taken from each days pour and submitted to independent testing lab for strength and density test.

1. EQUIPMENT shall be of special design to insure proper mixing in as short a duration as possible. Only that amount of water necessary to have mix pumpable and flowable in hose shall be used. In no case shall this exceed 3 1/2 gallons per cubic foot of vermiculite.

2. MATERIALS shall be placed in panels in a continuous operation. Material shall be screeded with a straight edge. No tamping, rodding, vibrating or steel troweling is necessary. When fill is used to slope for drainage, screeds shall be set to proper grade to insure slope.

No traffic shall be allowed on deck for 24 hours from completion of pour or until deck will support traffic without damage. In very dry weather the deck shall be sprinkled to prevent drying out. Otherwise the roof membrane shall be applied as soon as the deck has sufficient strength to support foot traffic and surface is dry enough to develop adhesion between deck and hot asphalt or pitch. Under normal conditions this will occur within three to five days.

ROOFING
Roofing shall be applied in accordance with roofing manufacturers specifications for light weight poured decks.