7 Things to Consider When Specifying Expansion Joints

There are a number of things to consider when specifying expansions joints, but before we get into the specifics, let’s review the details on why building joints are so important.

Why do we Need Building Joints?

A building can move in any direction—expanding, contracting, or sliding along the X and Y axis as well as up and down along the Z axis. Joints are needed to relieve this movement where there are long expanses and where the structure would crash into another fixed or independently moving structure.

What Type of Movement is the Building Subject to and How Much?
The type of movement a building is subject to impacts the joint. A standard expansion joint system allows for a range of motion of ±25 percent of the nominal joint width. For example, a 102-mm (4-in.) nominal expansion joint system will support a gap dimension of 76 to 127 mm (3 to 5 in.). An expansion joint specified to seismic standards supports movement of ±50 percent or, in this example, a gap of 51 to 152 mm (2 to 6 in.).

It is recommended that you form a close relationship with the structural engineer to be able to share ideas and ensure you are both on the same wavelength. It is also very important to remember that nominal joint size is slotted in the building and it expands and contracts from this size. However, you are designing to minimum and maximum sizes, so your joint needs to cover the worst case.

Joint Performance Considerations

Joint systems basically close off the gaps in a building system and still allow it to move while permitting persons to move about freely inside without tripping or slipping, and also maintaining the ability to carry the floor loads that have to be moved or rolled over it. The following are seven things to consider when specifying expansion joints from both an internal and external aspect. You should choose joints that:

  1. Minimize slipping or tripping hazards over the joint.
  2. Support necessary floor loads.
  3. Maintain fire separation integrity.
  4. Maintain sound separation integrity
  5. Maintain thermal separation integrity.
  6. Maintain moisture barrier integrity.
  7. Provide acceptable continuation of the finish.

In-depth Information About Building Movement

There are various types of building movements caused by the different forces to which a building is exposed. These forces, which have a bearing on joint integrity, include:

  • Thermal expansion and contraction caused by seasonal temperature changes
  • Moisture (rain/snow/humidity)
  • Sway caused by wind
  • Differential movement (seismic events, etc.)

Be assured that all these types of movements occur in every building and you should consider if the magnitude of the movement poses a threat to the structure or integrity of the finishes used to cover the structure?

Thermal Expansion and Contraction

This is a simple linear equation: Large temperature swings and expansive materials like steel and longer lengths create conditions for expansion and contraction. Understanding the thermal sensitivity and coefficient of expansion of the structural material is key to determining movement needs. Glass and wood generally have a lower coefficient of thermal expansion than metals. Question: Will your building be exposed to the full climatic range of temperature swing due to loss of power or off-hours energy conservation? If so, then the full climatic temperature swing should be calculated.


Porous materials are prone to expansion (swell) and contraction (shrink) from moisture (rain, vapor, etc.). The swell and evaporation of water in building materials may impact the integrity of the structure over time. Freezing water inside structural components is of particular concern in colder climates as this causes significant strain on structural materials. Parking garages are examples of movement under sidewalks and drives.  They have considerable support structures beneath the surface. Moisture is mostly prevalent in gymnasium floors as architects will manage for moisture in all other applications. Wood fibers expand when wet—they get fatter, not longer. Wood expands in direct proportion to its moisture content. Different species of wood are more or less susceptible to expansion due to the varying structure of the grain. 500 inches of wood gym floor with an expansion coefficient of .0037 and a moisture change of 3% will expand 5.55 inches.


Wind on the face of a long expanse can cause the building to move perpendicular to the thermal expansion and contraction resulting in differential motion. Some joints are not capable of moving in two directions. (Use your hands flat to the ground to demonstration motion in two directions—side to side and towards and away from you.)

Remember it is important to take into account that all of these elements: heat, moisture and wind have an effect on the amount your building moves. Therefore, the kind of joints you specify will play a key role to helping minimize tripping hazards, provide support, maintain separation integrity for fire, sound, thermal and moisture barriers, and provide an acceptable continuation of the finish.  

Nystrom expansion joints are manufactured to solve a variety of expansion joint scenarios. Custom sizing, materials, and color finishes ensure that whatever you need for your project, we’ve got you covered. Our commercial building products are shipped direct from our central manufacturing facility or from one of our strategically located stocking locations, Nystrom delivers the expansion joints you need.

About Nystrom

Since 1948, Nystrom has been the go-to manufacturer of specialty building products offering a wide range of floor, roof, wall, ceiling and stair access products that create safer, more accessible buildings. Nystrom is also proud to offer hassle-free services like access to technical experts, REVIT tools for BIM, HPDs for LEED v43-part specifications and AIA continuing education courses.

Nystrom partners with BSD SpecLinkMasterSpec and BIMsmith for specification tools and are proud members of AIA, CSI, LBC, Sustainable Minds, HPDC and USGBC. Many Nystrom products meet the following standards: ADA, ASTM, Florida-Approved, FM Approved, IBC, IFC, Intertek Warnock Hersey, Miami-Dade Approved, NFPA, NYCBC, OSHA & UL.

Nystrom Honored with 2020 Employer of the Year Award

Nystrom, Inc. Headquarters, Minneapolis, MN – LockLeed International Chief Executive Officer John Henka presents 2020 Employer of the Year award to Nystrom Senior Human Resources Director Susan Aaker and Nystrom Chief Operating Officer Matt Benson

Minneapolis, MN – Commercial building products manufacturer Nystrom, Inc. was presented with the 2020 Employer of the Year Award by LockLeed International for its efforts in hiring military talent.

Founded in 1948, today CEO Sue W. Thomas, leads 190 manufacturing and business support employees. The company is true to its five core values – profitable growth, lead by example, customer first, raise the bar and balance – which is supported by recruiting dependable, conscientious, distinguished employees.

Nystrom, Inc. Headquarters, Minneapolis, MN – 2020 Employer of the Year award for Nystrom

Since entering a partnership with LockLeed in 2020, Nystrom has hired six veterans and was recognized in January 2021. “It’s a privilege to work with a military organization like LockLeed, and we are honored to be presented this award” said Susan Aaker, Senior Human Resources Director. “The 3% of our workforce that are veterans bring invaluable life experience, skills and leadership to the company. They give the same commitment and dedication to the success and growth of our company as they did in service to our country. We look forward to increasing the number of military employees through our partnership with LockLeed in the years to come.”

View the LockLeed newsletter for more details.

About LockLeed International

At LockLeed our mission is to develop partnerships with world-class organizations and assist with the process of placing talented candidates into great positions. Our goal is to facilitate communication between companies and veterans; helping both sides understand the language of the other so that both sides win. At LockLeed we are building bridges between employers and veterans.

About Nystrom

Founded in 1948 as an independent representative for building product manufacturers, the Nystrom quickly shifted to its own manufacturing operations and grew its business through product diversification and acquisitions, including the 100+ year old Babcock-Davis brand. Today, led by CEO Sue Thomas, Nystrom has 180 manufacturing and business support employees with an extensive national partner network throughout North America. Yes, we have job titles here—but they don’t define us. So what gets us powered up each day? For starters, we are true to our five core values— profitable growth, lead by example, customer first, raise the bar and work/life balance. We think big – because we’re all about creating the ultimate hassle-free service for our customers. We make a difference in our communities. No matter who you are or what you do with us, you’ll find endless ways to be part of something greater than yourself.

We hire for the following positions:
Engineering • Welders • Assemblers • Machine Operators • Customer Support • Sales • Technical Support • Estimating • Drafting & Design • Finance • Information Systems • Human Resources • Marketing & Product Development • Purchasing, Logistics & Supply Chain • Facilities Management

Nystrom Highlights Architectural Projects Around the Globe

Nystrom products are specified by some of the world’s leading architecture and design firms on projects that range from athletic stadiums to performing art centers. We are proud to showcase a number of high-profile projects that utilized some of our products.


Nystrom was proud to supply a wide range of materials for the Riyadh Metro, a rapid transit system in Saudi Arabia consisting of six metro lines with 85 stations. Roof Hatches provided safe access to roofs, while Roof Top Smoke Vents were used that automatically open to release heat, smoke, and noxious fumes in the event of a fire emergency, as required by International Building Codes. Nystrom Access Doors were incorporated into the design providing access to mechanical, electrical and plumbing fixtures behind walls. The product’s flexible manufacturing takes the hassle out of custom sizing, materials and colors. Entrance grilles were used to improve Interior Environmental Quality by stopping dirt from entering the building, improving Interior chemical and pollutant source control.  All of our Nystrom products work individually performing their respective jobs, but also in tandem helping to meet overall codes and provide a safe, functional and aesthetic environment for citizens taking advantage of this metro system.  
Qatar’s Al Bayt Stadium will host the FIFA World Cup in 2022. This state-of-the-art structure received sustainability certificates of green design, construction management and energy efficiency. Al Bayt Stadium features Nystrom Fire Rated Access Doors, Fire Rated Floor Hatches and Roof Hatches. The I-series Insulated Access Doors provide access through openings in fire-rated walls and ceilings, while Nystrom Roof Hatches provide safe and convenient access to commercial building roof areas using interior ladders and stairs. Nystrom’s powder coat finish provides the ultimate in corrosion resistance and outstanding exterior durability.


The new NASA Measurement Systems Lab brings together multiple research and engineering groups to improve the time required for projects to move from idea to completion. Meeting the new timelines requires intense collaboration and heavy foot traffic on the building stairwells. The architect specified Nystrom Two-Part Ribbed Bar Stair Treads with EcoTread for the concrete stairs to prevent slips and falls. Nystrom’s Two-Part Ribbed Abrasive Stair Nosing is designed to save stair treads during the construction phase. The product’s sub-channel and plywood inserts are installed while the building is under construction. When the building is near completion, the temporary plywood tread is replaced with the final install of the abrasive anti-slip safety material. The stair treads are made of a unique recycled material that offers benefits beyond safety. In addition to its anti-slip properties, Nystrom Stair Treads features continuous color and an optional vision line. The treads are Title 24 compliant and come in nine color options.
The University of California, San Francisco Medical Center is a research and teaching hospital in San Francisco, California, and is the medical center of the University of California, San Francisco. Nystrom Access Doors and Floor Doors were utilized in this project to provide easy access to mechanical, electrical and plumbing fixtures behind walls and to provide access below ground between building floors. Our flexible manufacturing takes the hassle out of custom sizing, materials, and colors.
TARGET FIELD Minneapolis, MN
Located in downtown Minneapolis, Minnesota, Target Field is the home ballpark of the Minnesota Twins, the state’s Major League Baseball (MLB) franchise. Nystrom Expansion Joints were used in the construction of this facility to solve a variety of expansion joint challenges. Sizes, materials and color finishes were customized to meet the design aesthetic of the popular sports venue.
Named the Nokia Theater when it was constructed (now called the Microsoft Theater), this famous performance venue is located in downtown Los Angeles, California, at the L.A. Live entertainment complex. The theater auditorium seats 7,100 and holds one of the largest indoor stages in the United States. Nystrom’s Acoustical Smoke Vents were used to block the intrusion of exterior environmental noise. This Nystrom product is specifically designed for performing arts centers and theaters, every detail of which is crafted with skill and precision.


NGONG PING 360 Lantau Island, Hong Kong
The Ngong Ping 306 is a bi-cable gondola lift on Lantau Island, Hong Kong. Owned by MTR Corporation, the operator of Hong Kong’s rail system, it is a major tourist attraction that is connected to a retail and entertainment center adjacent to the cable car’s upper station. Nystrom worked with the builder to supply Roof Hatches for the project providing safe and convenient access to and from roof areas while also mitigating long-term wear due to our ultimate corrosion resistance and outstanding exterior durability.
LAMMA POWER STATION Po Lo Tsui, Lamma Island, Hong Kong
The Lamma Island Power Station is a coal- and gas-fired power station originally built for Hongkong Electric in 1982. Today, it is the second largest coal-fired power station in Hong Kong. Nystrom provided Roof Hatches to the power station during its most recent expansion. The hatches offer safe and convenient access to roof areas across the facility using interior ladders and stairs, and always meet building codes, fire and life safety requirements. Outside, Nystrom’s powder coat finish provides the ultimate corrosion resistance and outstanding exterior durability.

As you can see, Nystrom’s products are a perfect fit for any premier construction project where quality and performance demand the best. For more information on how our products can help you achieve your architectural and design goals, visit nystrom.com

About Nystrom

Since 1948, Nystrom has been the go-to manufacturer of specialty building products offering a wide range of floor, roof, wall, ceiling and stair access products that create safer, more accessible buildings. Nystrom is also proud to offer hassle-free services like access to technical experts, REVIT tools for BIM, HPDs for LEED v4, 3-part specifications and AIA continuing education courses.

Nystrom partners with BSD SpecLink, MasterSpec and BIMsmith for specification tools and are proud members of AIA, CSI, IIBEC, LBC, Sustainable Minds, HPD and USGBC. Many Nystrom products meet the following standards: ADA, ASTM, Florida-Approved, FM Approved, IBC, IFC, Intertek Warnock Hersey, Miami-Dade Approved, NFPA, NYCBC, OSHA & UL.

19 States That Should Be Specifying Florida-Approved Roof Hatches

Hurricanes Are A Key Consideration

June marked the start of hurricane season that typically includes 12 tropical storms and 6 hurricanes. While Florida is most prone, these damaging and costly storms routinely affect 18 other states, which are listed below. Is your state included? Your building roof is susceptible to hurricane damage.

The information below is a list of costliest Atlantic hurricanes. The most expensive tropical cyclone on record in the Atlantic is held jointly by hurricanes Katrina and Harvey, both of which resulted in approximately $125 billion in property damage during the year they occurred. A majority of the costliest Atlantic hurricanes in recorded history have peaked as major hurricanes. However, weaker tropical storms can still cause widespread damage. Tropical storms Alberto in 1994, Allison in 2001, Lee in 2011 and Imelda in 2019 caused more than a billion dollars in damage. Wind damage encompasses a large portion of storm damage as well, evidenced by Andrew, Irma and Michael.

Hurricane Andrew Leads to Code Changes

Due to the destructive, wide-sweeping damage of Hurricane Andrew, Floridians took a hard look at why their buildings failed. In 1996, the Florida Building Codes Study Commission was created. During their 16-month study, the commission found a complex and confusing patchwork of codes and regulations that had been developed, amended, administered and enforced differently by more than 400 local jurisdictions and state agencies with building code responsibilities. In the case of Hurricane Andrew, the problem was not weakness in the codes themselves that contributed to the extensive storm damage. Rather, it was the inability to enforce and comply with the confusing system of multiple codes and administrative processes. It had become clear that Florida needed a single, statewide building code system.

Building Products Impact

Due to these improvements to the building codes, manufacturers that sell into Florida must obtain approval through the Florida Product Approval process or the Miami-Dade County Notice of Acceptance. To be certified, manufacturers must pass these High Velocity Hurricane Zones test protocols:

TAS 201-94 – Impact Test. During this test several 8-foot-long 2 by 4’s are shot from an air cannon to simulate large missile impact on strategic points on the product.

TAS 202-94 – (Static) Air Pressure & Water Penetration Test. This test is designed to test structural overload with both positive and negative pressure. The testing of the design is performed at +/- 50%, +/- 100% and finally +/- 150% of static air. Additionally, a stream of water is blasted at the product at 15% of the testing load. To pass, the product must withstand these static forces, with no failure, for 30 seconds.

TAS 203-94 – Cyclic Wind Pressure Loading Test. This is a pulsating series assessment designed to test wind pressure loading. During this test there are 671 – 1 to 3 second cycles at 50%, + 50% and 120% of the testing load.

Experts recommend specifying hurricane-tested roof hatches that are both Florida Product Approved and Miami-Dade Notice of Acceptance (NOA) products – not only in Florida, but in all hurricane-affected regions throughout the US. 

About Nystrom

Since 1948 Nystrom has been the go-to manufacturer of specialty building products offering a wide range of floor, roof, wall, ceiling and stair access products that create safer, more accessible buildings. Nystrom is also proud to offer hassle-free services like access to technical experts, REVIT tools for BIM, HPDs for LEED v4, 3-part specifications and AIA continuing education courses.

Bringing GFR Access Doors Closer to the Customer

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New H20 Load Rated Large Equipment Hatches

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How SunLit™ Roof Hatches and Smoke Vents Influence Indoor Air Quality

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Fire-Rated Floor Doors and Access Doors

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Specifying Fire Extinguisher Cabinets

6c8e95a9feefa98ae7cf295fb763In the event of a fire, a missing, empty or tampered fire extinguisher can lead to catastrophic loss. It is this reason that the installation of fire extinguisher cabinets is necessary. Fire extinguisher cabinets are designed to keep fire extinguishers, hoses and blankets secure while still providing accessibility in the event of a fire emergency. Although there are many options for fire extinguisher cabinets, we will cover the top three commercial uses.

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