What are the typical physical properties of LWIC?

Material Type	Cast Densilty (PSF)	Air Dry Density (PSF)	Weight per inch (PSF)	R Value per inch (BTU Units)	Compressive Strength (PSI)
Aggregate	44-60 PCF	22-28 PCF	1.9 PSF/IN	1.49	125+PSI
Aggregate	60-68 PCF	35-41 PCF	1.9 PSF/IN	0.90	300 PSI
Cellular	34-42 PCF	28-36 PCF	2.5 PSF/IN	1.20	200 PSI
Cellular	42-50 PCF	38-46 PCF	3.0 PSF/IN	1.00	250+PSI

How do you increase the R-value of LWIC?

The R-value of any LWIC is increased by adding expanded polystyrene insulation board during application of the LWIC. A LWIC system (LWIC plus EPS insulation) can easily achieve 50 R's for the installation.

What is the equilibrium moisture content of cellular concrete?

The equilibrium moisture content of cellular concrete is typically 14%-18% by weight.

When can LWIC be roofed?

Roofing may begin 2-4 days after placement. The base sheet fastener should attain a minimum 40-pound withdrawal value.

How resistant to weather is LWIC?

After a LWIC deck is roofed, it is highly resistant to weather conditions as has been demonstrated for over 60 years of continuous applications in all geographic areas of theUnited States and in other parts of the world.

If EPS is in place and a threat of rain exists, what is the best procedure to follow?

Place the slurry coat so that the bond holes are full of material. It is not necessary to slurry coat the board surfaces. A slurry coat on the board is acceptable for next day topping without any special treatment such as a bonding agent.

What types of roof membranes can be installed over LWIC?

Built-up Roofing, Modified Bitumen, and Single Ply Membranes of various approved compositions have been successfully installed over LWIC.

How far can cellular concrete be pumped?

Cellular concrete is a very easily pumped, highly fluid mixture. The bulk of cellular concrete is placed by pumping. Cellular concrete typically will move through the pump lines using less pressure than typical heavier grout mixes. Documentation of cellular concrete being pumped up to and exceeding 500 ft. vertically and 10,000 feet horizontally is commonly available. This is also dependent on the contractor's equipment capability.

Are control joints needed for thermal movement in a LWIC system?

No.

What is an acceptable finish for LWIC?

A surface finish free of ridges and protrusions is an acceptable finish for roofing application. Most LWIC is left to self-seek a level and not surface �finished� in the traditional sense. Much cellular concrete is covered by another material. A floor overlayment type smoother tool can be used simply to break the surface air cells and create a more uniform and polished look to the surface in the rare case when a more uniform surface appearance is desired.

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