The Gold Lot was the place to be during World of Concrete for placing, finishing, and treating concrete slabs. At the Slab Construction Showcase, six different companies featured tools and techniques for placing the perfect slab from bottom to top. Here’s a recap.

Slab Construction Showcase

How to Efficiently Install an Effective Vapor Barrier

“When you place a concrete slab on grade, it’s exposed to soil that almost always has a moisture source,” said Dan Marks, technical lead for Stego. “The concrete may dry initially, but underlying moisture can eventually make its way up through the slab in the form of vapor.” Stego experts showed attendees how to install underslab vapor barriers to avoid moisture problems and keep slabs dry over their lifetime.

They demonstrated a typical layout including Stego Wrap Vapor Barrier and accessories, including several types of Stego Tape, Crete Claw, and Stego Mastic for sealing around pipes. The new Beast Screed, a vapor barrier-safe, fixed-elevation screed system, allows contractors to maintain floor levelness without having to re-establish grade during the screeding operation. “Vapor protection for slabs on grade is very important,” said Marks, “but it doesn’t have to be difficult or inefficient.”

Stego representatives helped contractors understand critical aspects of vapor barrier use, including the importance of following ASTM E1643 requirements for installing below-slab vapor retarders. They answered common questions about vapor barriers, including whether or not they cause curling and shrinkage. “It’s a hotly debated topic,” said Marks, who recommends several references, such as the Guide for Concrete Floor and Slabs Construction from ACI Committee 302, for tips and strategies for placing concrete to avoid warping, curling, and shrinkage.

Learn more about proper installation of underslab vapor barriers.


Next page: Using a Screed Support System to Strike-Off Slabs