SECUROCK Roof Boards— A Weapon Against Fire

Fire is a major concern for every building owner and designer of commercial properties.  Whether it is from inside the building or externally, a fire can cause life safety issues as well as major damage.  Fortunately, roof boards can help contribute to fire safety and lessen this issue for all concerned.  Below are some of the testing agencies that concern themselves with fire ratings, how the SECUROCK Roof Board portfolio can assist in fire safety, and a recent account of how SECUROCK Roof Boards made the difference.

Let’s first look at the two primary certification agencies: UL & FM.  UL (Underwriters Laboratories) is a global independent safety science company offering expertise across five key strategic businesses: Product Safety, Environment, Life & Health, University and Verification Services.  UL has both exterior and interior classifications.  FM (Factory Mutual) is primarily concerned with loss prevention issues. In terms of fire, FM tests are used to judge the contribution of roof assembly components to the spread of fire within a building. Both of these testing agencies are very critical to understanding how building products can contribute to fire safety.

For external fires, UL uses test standard UL 790 (equivalent to ASTM E-108) and FM uses FM 4450 or 4470.  UL 790 has three components: a spread of flame test to see how easy it is for fire to spread, intermittent flame to simulate wind conditions and a burning brand test to simulate burning objects falling on the roof.  From these tests, three classes (A, B, C) are determined with Class A being the best.  For FM 4450 (insulated steel deck) and FM 4470, the roof system is subject to a series of tests that subject it to internal fire, external fire, wind uplift, foot traffic, impact resistance, and susceptibility to heat and damage.

With internal fires, look to UL 1256 and UL 263 as well as FM 4450 or FM 4470.  UL 1256 and UL 263 evaluate resistance to fire that start within a building.  UL 1256 is for fire testing of roof deck constructions and uses two parts to evaluate “White House” and “Steiner Tunnel”.  For UL 263, a P series is given to systems that are able to contain fire and/or retain structural integrity during a given exposure time frame.  And because fire is a concern for parapet walls as well, both ⅝” SECUROCK Roof Boards meet the Type X classification per ASTM C1396, which is a 1-hr load rating on a wood stud wall assembly attached vertically with joints staggered 16 inches on each side and tested in accordance to ASTM E 119. With FM 4450 and FM 4470, a Calorimeter test will measure the fuel added to an internal fire from the roof assembly.  In order to achieve a Class 1 rating, you must pass this test.  A roofing system that qualifies for a FM Class 1 will qualify for the lowest insurance rates from FMG affiliated insurance companies.

We hope that helps with the basics of how products and systems are rated. Here’s how USG’s SECUROCK Roof Board products rate.  As always, fire classification is a complex subject, so don’t hesitate to contact any of our sales representatives, UL, or FM for further clarification.

Click here to download the PDF: Fire rating chart

Click here to open chart in Excel: Roofing Blog Chart

 

Finally, we’d like to share a recent incident that happened on a job that was using SECUROCK Gypsum-Fiber.  All of the pictures shown are from a recent job in Chicago that was under construction when a fire was ignited inside the building from a welder’s torch. This was not an external fire, but an internal fire. Wood blocking at the base of the curb caught fire from the welder’s torches. The fire traveled up the curb and across the roof.  The insulation burned down to the SECUROCK Gypsum-Fiber and was extinguished by the material at that time.  Had it not been for SECUROCK Gypsum-Fiber, more (or perhaps all) of the roof and building would’ve been lost.  Fortunately only a small area of roof board, insulation and membrane had to be replaced.  Regardless, sometimes it’s not only post construction fires that everyone needs to worry about, fires can happen during the construction period as well.

Please let us know if you have any thoughts or questions.

Gapping Recommendations for SECUROCK High Performance Roof Boards

Throughout our experience with roofing, many of us have seen movement on roof decks as materials interact with the environment during and after installation. The two main environmental factors are changes in temperature and moisture content. It is common practice to install control joints in the building industry. We see this in sidewalks, walls, floors and so on, allowing for the expansion and contraction naturally occurring in materials. Left unrestrained these materials do not crack or buckle. When panels are butted tightly over large areas and are allowed less than necessary accommodations for expansion; buckling, ridging or crushing is the end result. It is typical to recommend allowances for movement as all building materials are subject to dimensional changes in temperature and moisture.

When looking at physical properties of products there is usually data with the following verbiage like “Linear Variation with change in moisture, “Coefficient of Thermal Expansion,” or “Linear Variation with change in Temperature.” This is basically saying that all of these building materials (including SECUROCK High Performance Roof Boards) are affected by changes in temperature and moisture content. If a product doesn’t explicitly say what its data is, it is a good idea to find out so you can understand how moisture and temperature will effect installation.

It is clear that the environment affects building materials. In order to plan for movement, when installing SECUROCK High Performance Roof Boards, both thermal and hygrometric consequence should be taken into consideration. We would like to help out the community with a quick discussion of how to use these values. As always, design of proper expansion relief is the responsibility of the design professional; please also refer to organizations like NRCA for their guidelines with respect to treating gapping.

The following is an illustration of how to use expansion coefficients for hygral and thermal effects.

Securock High Performance Roof Boards have the following expansion coefficients for hygral and thermal effects:

	Securock Gypsum-Fiber Roof Board	Securock Glass Mat Roof Board
Thermal	8E-06 in/in ºF	8.5 E-06 in/in ºF
Hygral	8E-06 in/in %RH	6.3E-06 in/in %RH

 

 

 

The following tables show gapping allowance for runs with 4’x4’ and 4’x8’ panels for given additive temperature and humidity changes expected; values have been extracted and placed in the table for example. The numbers have been calculated to stay within NRCA guidelines where ¼” is the maximum allowable gap before insulation should be filled (see NRCA for further reference). In this table, ΔT can be defined as initial installation temperature and maximum expected rooftop temperature during install or directly following. The overall rise would be used. Similarly, the overall expected rise in % RH would also be used.

Gap needed per board using 4’x8’ Securock Gypsum-Fiber Roof Boards:

	ΔRH = 0%	ΔRH = 10%	ΔRH = 20%
ΔT = 25°F	.02”	.03”	.04”
ΔT = 50°F	.05”	.06”	.08”
ΔT = 75°F	.08”	.13”	.13”

 

Gap needed per board using 4’x4’ Securock Gypsum-Fiber Roof Boards:

	ΔRH = 0%	ΔRH = 10%	ΔRH = 20%
ΔT = 25°F	.01”	.02”	.02”
ΔT = 50°F	.03”	.03”	.04”
ΔT = 75°F	.04”	.07”	.07”

 

For example:

Given the table above, panels are kept in the shade at ground level and are noted to be 75ºF, then see temperatures at lunchtime on a hot day during installation with a black roof of 150 ºF, your ΔT = 75ºF. If no humidity increase is expected, your ΔRH = 0%. Looking at the table you would gap every 4’x8’ panel by .08” or every 4’x4’ panel by .04”.

So our recommendation is to butt board edges and ends loosely in typical installations and for long, uninterrupted runs, there should be some slight gapping due to changes in temperature and moisture. More tips to help ridging on roofs include installing dry materials into a dry roof, storing boards on the rooftop to avoid thermal swing, and always consulting a design professional and use industry guidelines before installation.