Rethinking Expansion Joints in the Face of Quakes and Hurricanes
Expansion joints can be said to be among the most critical aspects of design in relation to building performance under geological and weather extremes.
In the wake of the recent earthquake, hurricane Irene, and tropical storm Lee, those of us on the East Coast are being given repeated reminders of a universal truth–storms and shakes need to the baseline for our structural design.
A new line of breakthrough expansion joint products means you can get extreme protection built into a single product installation with solutions for walls, floors, solid and split slabs. Now is a logical time to reflect on design practice as it relates to expansion joint sizing and product selection in relation to earthquakes and storm-force-wind driven rain.
Sizing in Relation to Product Capability
Proper sizing of joint gaps in relation to stiffness, height, geology, and thermal exposure extremes are among the considerations in sizing the distances needed between structures and/or structural elements within buildings.
But just sizing the gap for anticipated movements is only half of the equation.
Among the most frequent communication disconnects in the design process is the structural engineers responsibility for sizing the gap and the architects responsibility in selecting a product to seal it. These must be reconciled against the movement capability of the product to seal the gap. Usually this means the joint-gap needs to be wider than calculated without consideration of an expansion joint system installed in to the joint opening to seal it.
What Are You Sealing In or Out? What you desire to seal against will in part determine a products’ movement capability. A looped membrane or simple rail-and-rubber strip seal may seal out typical falling rain and would likely handle even seismic movement.
But, what about wind-driven rain, or worse, hurricane or tornado driven rain?
What about air-pressure differentials between the inside and outside of the building?
What about thermal insulation in respect to heating and cooling containment?
What about sound attenuation?
What about fire and smoke?
Looped membranes and strip seals will not provide any protection against any of these.
The Ideal Product
So the ideal product would be one that provides protection against all of these performance demands. Sounds too good to be possible, doesn’t it?
Yet after more than 30 years in the business of focusing our company strictly on the sealing of expansion joints, EMSEAL has evolved its product line and broken some remarkable paradigms to bring to market the Emshield family of products. Not only do these products perform in all of the conditions mentioned above, they have been independently tested to prove it.
Independent Tests Confirm Performance Claims
UL 2079 proves the products’ ability to handle thermal, sway and seismic cycling frequency. It also proves the products fire resistance in configurations to provide up to 3 hours of fire protection.
ASTM E283, E330, and E331 prove the products’ performance in excess of ABAA guidelines and at positive and negative pressures to match hurricane force winds and wind driven rain.
ASTM C518-04 confirm the products’ insulation R-Values.
ASTM E-90 reveals STC and OITC sound attenuation performance as high as 62 and 52 respectively–in standard depth configuration.
FTIR and DSC analysis proves the absence of wax in our products and is a cornerstone of our claims that EMSEAL will not bleed at temperatures up to 185-degF while simultaneously compressed to the minimum of our stated movement ranges.
Oh, and all of these tests were run on the products at the full extent of their claimed movement ranges. This means the products were in arguably their most vulnerable configuration. Which means that the tests are conservativebut relevant to real life conditions that could exist at the extent of your design and our claims.
Specify Quality Base your specifications and submittals on EMSEAL and demand in the spec that all others to provide the same independent testing to meet the performance standards that suit field conditions. Some products look the same, some are claimed to be the same, but unless the lab results prove it—they are not the same.
Walls, Floors, Decks, and Split Slabs
The Emshield line is comprehensive and features joint solutions, with built-in fire ratings for walls, floors, solid-slab decks, and even split-slab decks.
Local, Regional, National Help
EMSEAL’s technical service, problem solving, and specification development assistance is available locally, regionally, nationally, and internationally.