How Timber Restoration Inc. saved federal agency $650,000 by injecting tired wooden trusses with epoxy
Fort Meade is a 13,000 acre military base 15 miles northeast of Washington, D.C. Commissioned in 1917 to train draftees for the war to end all wars, the camp was named for General George Meade who, in 1863, led the Unions Army of the Potomac to victory at Gettysburg.
In addition to being the headquarters of the first US Army and the home of the 35th Artillery Brigade and the 11th Armored Cavalry, Meade also houses, according to the Army Times, batteries of missiles deployed to protect the nations capital. Also based there is the National Security Agency.
Renovate/rehab the warehouse
Early in 1990 one warehouse, circa 1954, required both renovation to accommodate administration operations and rehabilitation to replace and reinforce the weary wooden trusses and columns supporting the roof. The 300-ft.-long structure was, in the acronymic jargon of its occupant, the National Security Agency, identified as SAB #1 (meaning Support Activities Building). It was thought to require both the repair of cracked and dried-out timber members and the addition of laminated wood members as well as new steel supports.
Heading the project for the government were engineers with the Department of Defense. The general contractor was C.E.R., Inc., Baltimore, specialists in construction and repair of military facilities on the East Coast.
Estimate for roof hits ceiling
"The original repairs planned for the 45 heavy timber trusses," said Richard Matri, president of Timber Restoration, Inc., Saddle River, NJ, "and included installing new wooden members and adding both wooden and steel reinforcement to the original trusses. This would have required a large amount of new material and a tremendous quantity of shoring to stabilize the roof while sections of the trusses were taken apart to install new shear-plate connectors. The original repair estimate was over $1,200,000.
"That was when David Rosseau, secretary/treasurer of C.E.R., called me." Together with injection consultant, Richard Avent, Dean of Civil Engineering at L.S.U., they performed a walk-thru of the structures."
In the opinion of Richard Avent and myself the solution for SAB #1 was to repair the structurally damaged trusses with epoxy injection."
The Defense Departments engineers and general contractor listened because both T.R.I. and Richard Avent have impressive credentials: among T.R.I.s recent projects were the design and installation of the wooden domes for NYCs Ellis Island Immigration Museum; new supports for an AT&T computer building; and replacement of bottom chord members of the bowstring trusses for the terminal building at Westchester County Airport in New York. This project also included epoxy injection of certain truss members. Mr. Avent, a widely published author of numerous papers for ASCE, is a recognized pioneer in epoxy injection of timber trusses. Timber Restorations bid of $580,000 was warmly received relief.
Wood is different
"In addition to continual on-site help from our consultant, Richard Avent, start-up work was assisted by technical rep from Lily Corp., Aurora, Il. The T.R.I. trio refined the procedures and got SAB #1 off to a swift start. And for this phase our VP, Lance Verderame, spent hours on the up-and-down scissor lift to bird-dog operations," continued Richard Matri.
According Verderame, "For the injection of the truss joints, we inserted Lily ports in each joint, then sealed them with Sikadur 31, Hi-Mod Gel.
Because they were dealing with our specialty, wood, they knew that in addition to the obvious cracks they had to eye the minute fissures in the wood grain. Following the method outlined by Richard Avent in ASCEs Journal of Structural Engineering, Vol 112, 1986, about testing joints before injection, they coated them with a soap film, used 25-psi compressed air, and watched for bubbles. They marked and repaired all leaks. Tedious, sure. But great insurance!
"To contain the injected epoxy we coated the timber with Sikaguard 62, highbuild epoxy. It sealed all the pinholes and eliminated any leakage.
"Once the joints were prepd, we injected Sikadur 35, H-Mod LV, using one of our 4 Lily CD-3 mix/meter/shoot cabinets," concluded Lance.
As job super Harold Fioravanti reported, "In addition to the joints in each truss we also had to reinforce the joint heels. We did this by nailing splices in place then gelling around the splice with Sikas 31 paste epoxy. Finally we injected the thin Sikadur 35 between each splice and truss."
Best by test
As dictated by the engineer, shear blocks were routinely fractured by Richard Avent. And, when tested according to ASTM parameters, every sample comfortably exceeded design specs.
Timber Restorations hundreds of gallons of Sikagard 62, and the pair of Sikadurs 31 and 35 were trucked to Meade from the Beltville, MD, branch of Sika-authorized distributor Kenseal Construction Products, whose sale rep John Franco had triggered T.R.I.s joining Sika's exclusive S-aC cadre.
"We started our part of the rehab in February 91 and finished June 25. Among the satisfaction I personally got from the Fort Meade project," admitted Richard Matri, "was the letter co-signed by the chiefs of NSAs engineering management and facilities engineering departments that acknowledged appreciation of C.E.R.s and our special effort . . . and the outstanding professionalism that you both demonstrated during the rehab and repair of the SAB #1 Facility. That was another great one for both our portfolios."