Twinbrook Quarter elevator pits and lagging walls get gold seal treatment

Twinbrook Quarter elevator pits and lagging walls get gold seal treatment

The Challenges

The Twinbrook Quarter project had to overcome waterproofing challenges for both its below-grade spaces and above-ground structures. The below-grade plan required a system that could be applied both horizontally beneath elevator pits and vertically along the soldier pile and timber lagged walls which provide excavation support. In addition, more than 100 tie-backs added to the project complexity, since each needed to be covered and precisely detailed to prevent leaks.

The Solution

Gordon Contractors was chosen to waterproof beneath 5 ½ -foot-thick mat slabs in the elevator pits, an area totaling around 11,000 square feet. Additionally, they needed to waterproof approximately 63,000 square feet surrounding the soldier pile and timber lagged support walls.

Design professionals recommended a suite of Henry® Company products based on past use for similar waterproofing applications. For this project, they specified Blueskin® PreSeal® 435, Blueskin PreSeal® 320, Henry Drain Board, Henry Tieback Covers, and Hydro-flex® Waterstop.

BlueSkin PreSeal is designed with a rugged cross-laminated, high-density polyethylene film that offers superior puncture and tear resistance. Installed prior to rebar and concrete placement, it features wide rolls resulting in fewer seams. On the jobsite, the system’s lightweight rolls are easy to transport, cut and position, making installation fast and easy.

Henry Drain Board is designed for vertical and horizontal installations at shallower depths where moderate compressive strength is required. Henry Hydro-Flex® Waterstop is an easy to use, preformed, self-adhesive hydrophilic waterstop that provides a watertight seal in cold joints on concrete structures.

The Gordon team first poured a mud mat to create a clean, stable base for the Blueskin PreSeal 435 installation. Once cured, they laid PreSeal 435 on the mat, extending the membrane edges up along the interior of the formwork. Thanks to PreSeal’s durable qualities, contractors were then able to construct a 5 ½ foot tall rebar cage directly onto the membrane. Once the mat slab cured sufficiently, they applied BlueSkin PreSeal 200 to the areas requiring additional waterproofing.

The team also attached Henry Drain Board 220 to the timber lagging. First, they installed a perimeter drain at the base level and connected drain weep connectors to a drainpipe that penetrated the wall into building interior. This pipe was designed to connect to the sub-slab drainage system.

Next, they installed BlueSkin 320 over the drain board. To complete the job, they cut the membrane and drain board away from all tiebacks and installed tie back covers and then sealed them using Blueskin PreSeal 120V Tape.

The Process

With more than 30 years’ experience and a Henry Authorized Contractor certification, Gordon Contractors successfully completed the job earning it a Gold Seal Warranty. The Gold Seal Warranty, which covers leaks caused by product or installation defects, is exclusively available to Henry Gold Seal Authorized Contractors.

Project Details

Building/project name:

Twinbrook Quarter elevator pits and lagging walls get gold seal treatment



Building location:

Rockville, MD

General contractor:

Gordon Contractors

Product Details:

Blueskin PreSeal® 435