Invention tests durability of roofs Device determines if fire retardants have damaged plywood

August 01, 1991|By Liz Atwood | Liz Atwood,Evening Sun Staff

A local architect has invented a tool to help the owners of town homes decide whether to keep the roofs over their heads.

Thousands of town-house roofs are failing because fire-retardant chemicals used to treat the plywood sheathing caused it to deteriorate.

As a result, home owners and builders face the prospect of replacing unsound roofs. The cost of a new roof for a typical town house is about $2,000 to $2,500, although it can be much more.

Stanley Sersen, head of Architectural Support Group Inc. of Columbia, has invented a proof-load testing device, which is designed to show the strength of the plywood. A patent is pending and he hopes to market the instrument to home inspectors throughout the country.

Experts estimate that up to 35,000 roofs in the Baltimore area, and up to 250,000 nationwide, will have to be replaced in the next few years because of weak plywood.

Fire-retardant-treated plywood has been outlawed for roofs in Harford County, and a number of other localities have modified building codes that expand the alternatives available to builders.

A national task force currently is reviewing a plan to create a fund to pay for roof replacements. Home builders, plywood manufacturers and warranty companies, as well as home owners, would contribute to the fund. A decision is expected by the end of September.

If the plan succeeds, years of costly lawsuits could be avoided.

Sersen believes his device can help home owners determine whether they need to replace their roofs immediately or wait.

Sersen invented the device early last year, several months after learning that the fire-retardant chemicals placed on the plywood were found to be eating away at the wood.

Standing on top of the roof, workers can use the portable device to test the strength of the plywood. The mechanical instrument exerts up to 400 pounds of pressure on the plywood sheets. Normal plywood will sustain the weight, but wood weakened by the chemicals often will crack.

Sersen says he and his employees have tested about 1,000 roofwith the device. Inspecting fire-retardant-treated plywood roofs has become a major part of his architecture consulting business.

Sersen charges between $250 and $300 for an individual roof, but considerably less for multiple inspections in a town house development.

He now is looking to license his procedure to other building inspectors across the country. The device itself would sell for about $3,500.

Sersen would appear to have a potentially wide market for his invention.

The fire-retardant chemicals were used on the roofs of virtually every town house built east of the Mississippi throughout the 1980s.

Sersen uses the device on two standardized places on each town house roof and also picks two other points on the roof where the plywood sheets appear the weakest. The inspection includes a visual check of the plywood from both inside the attic and atop the roof.

Sersen says it is difficult to tell with only a visual inspection whether wood needs to be replaced. Only 7 percent of the roofs that have failed are visibly weak, he says. Conversely, some plywood may look bad, but is structurally sound.

"It takes away the question that home owners have about 'whether my roof is going to fail this winter,' " Sersen says.

The owners of new town homes may not have to face the same roof problems.

Baltimore-area home builders are employing a new generation of chemically treated plywood, or are opting for entirely different methods in hopes of avoiding the problems of the older roofs.

"People are saying to themselves, why take the risk?" says George Sheehan, president of the Home Builders Association of Maryland.

In Harford County, builders have no choice. That county outlawed fire-retardant-treated plywood on new homes last year, and instead gives builders other options for containing the spread of fire.

One of those methods has been widely adopted in other counties and received an award from the National Association of Counties. The method, designed by Harford's chief of building services, Madison Mitchell, allows builders to place five-eighths-inch fire-retardant gypsum board on the ceiling of the upper story and standard plywood above the trusses of the roof. The object is to slow a fire's spread to the roof.

Mitchell says he devised the method after considering the types of fire-retardant materials available. "It was done through common sense," he says.

Other counties, such as Anne Arundel, allow treated plywood but require letters attesting to its strength and a warranty from the manufacturer.

Even counties that still allow use of treated plywood without warranty letters have expanded the list of acceptable options that builders can use to meet fire codes.

Anne Arundel, Carroll and Howard counties have adopted the Harford alternative.

One of the most common variations is the attachment of sheets of fire-retardant gypsum board under the roof sheathing. This method has been accepted in Howard and Baltimore counties and in the city.

Another older method, the use of parapet walls, is an acceptable fire-control design, but one rarely used, for aesthetic reasons.

After 1992, builders of new town homes will not have to worry about which options to choose. The Maryland legislature has passed a law requiring sprinklers to be installed in new town houses.

Although more expensive, sprinklers are considered to be one of the most reliable forms of fire control.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.