Patent Application
20140245696
This application is related to fire resistant construction members.
Wood-based construction members can be vulnerable to fire damage. For example, some unfinished basement floor/ceiling assemblies are constructed using wood-based load-bearing construction members, such as I-joists. When a fire occurs in a basement having an unfinished floor/ceiling assembly that includes such construction members, the floor/ceiling assembly can be severely damaged by the fire and fail prematurely. There is therefore a need for construction members having improved fire-resistance.
Exemplary fire resistant construction members disclosed herein can comprise a wood-based I-joist, such as comprising an engineered wood product, and at least two panels comprising gypsum board secured to the I-joist. The member can comprise a first gypsum board panel secured to a first side of the member and a second gypsum board panel secured to a second, opposite side of the member. In some embodiments, gypsum board panels are secured to opposite sides of a web of the I-joist. In some embodiments, gypsum board panels are secured to opposite sides of upper and lower flanges of the I-joist. Wood-based members other that I-joists can also be protected with gypsum board panels to provide fire resistance.
In some embodiments, gypsum board panels are secured to opposite side of the web only, leaving the flanges exposed. The gypsum board panels can have a height about equal to the height of the web. The thickness of the gypsum board panels can vary depending on the amount of fire-resistance required
In other embodiments, the gypsum board panels are secured to the flanges, such that each panel spans from an upper flange to a lower flange, one on each side of the flanges. This can leave a hollow cavity between the gypsum board panels and the web. The height of the panels can be about equal to the overall height of the I-joist, such that the flanges and the web are protected by the panels.
The gypsum board panels can be applied to an I-joist in the field using, for example, nails or screws. Some panels can be nailed or screwed directly to the web, while other panels can be nailed or screwed directly to the sides of the flanges. Some embodiments can comprise one or more web holes passing transversely through the web and the gypsum board panels, such as to allow for plumbing and wiring.
The foregoing and other features and advantages of the disclosure will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatuses, and systems should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatuses, and systems described are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved.
Although the operations of some of the disclosed methods are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures and descriptions may not show the various ways in which the disclosed methods can be used in conjunction with other methods.
As used herein, the term “coupled” generally means physically coupled or linked and does not exclude the presence of intermediate elements between the coupled items absent specific contrary language.
Unprotected light-frame wood buildings do not have the natural fire resistance achieved with heavier wood members. Recently, language was added to the 2012 International Residential Code (IRC) requiring passive membrane protection in an effort to increase the fire-resistance of unprotected basement ceilings. Specifically, section R501.3 of the 2012 IRC requires that floor assemblies include a 0.5″ gypsum wallboard (GWB) membrane, a 0.625″ wood structural panel (WSP) membrane, or equivalent on the underside of the floor framing member. Section R501.3, however, provides certain exceptions to this rule, including wood floor assemblies using dimension lumber or structural composite lumber (SCL) equal to or greater than 2″×10″ nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.
Within the membrane protection requirement, equivalence may be shown by comparison to 0.5″ GWB or 0.625″ WSP. Equivalence may also be shown by comparison to 2×10 assembly framing. Recent work by the American Wood Council (AWC) has sought to define the performance of a 2×10 assembly and define the test method for making any kind of equivalence comparison. The “AWC Policy and Guidelines on IRC Membrane Protection Equivalency” (October 2011) suggests that “to be considered equivalent to 2×10 sawn lumber or SCL, the framing members should support a load corresponding to 50% of the full bending design of the framing members, while being subjected to an ASTM E 119 time/temperature heating regime. All components utilized in the manufacture of the framing members (fasteners, plates, hardware, etc.) should be utilized during testing. The test end criteria should be structural member failure.” The AWC further suggests that “the most straightforward and accurate means of determining the required minimum fire resistance time would be to estimate that time using the calculation methodology specified in National Design Standard (NDS) Chapter 16 for unprotected solid-sawn 2×10 floor joists assuming: a 3-sided exposure, a nominal char rate of 1.5 inches/hour, a bending strength to allowable strength design (ASD) ratio of 2.85, and supporting a load corresponding to 50% of full bending design.”
The calculation methodology specified in NDS Chapter 16 and the AWC assumptions above can be used to establish a fire-resistance benchmark of approximately 15 minutes for 2×10 joist, as shown in Table 1 below. The result shown in Table 1 assumes a 3-sided exposure, nominal char equal to 1.5 inches per hour, strength to ASD ratio of 2.85, and 50% of full bending design.
The calculation methodology specified in NDS Chapter 16 and the AWC assumptions above can also be used to estimate the fire resistance of an I-joist flange element, as shown in Table 2 below. The results shown in Table 2 assume a 4-sided exposure, nominal char equal to 1.5 inches per hour, strength to ASD ratio of 2.85, and 50% of full tension design.
The calculation methodology specified in NDS Chapter 16 can also be used to estimate the fire resistance of an I-joist web element, as shown in Table 3 below. The results shown in Table 3 assume a 2-sided exposure, nominal char equal to 1.5 inches per hour, and that the web is completely or nearly completely consumed at failure. At lower applied loads, the web element primarily functions to maintain the distance between the tension flange and compression flange and to brace the compression flange against bending failure.
Disclosed herein are methods of increasing the fire resistance of wood-based construction members, such as engineered wood construction members (e.g., I-joists). These methods can involve application of gypsum board to the wood-based members. The following examples can be used to provide equivalent fire-resistant performance per Exception 4 to Section R501.3 of the 2012 IRC (see above).
An exemplary construction member 10 is shown in
The web 12 can have a thickness T1 of any size, such as from about 0.25″ to about 1″, and a height H1 of any size, such as from about 9.5″ to about 21″, or larger. The flanges 14, 16 can have a width W1 of any size, such as at least about 1.5″, or at least about 3.5″, and can have heights H2, H3, respectively, of any size, such as at least about 1.125″, or at least about 1.5″. The panels 20, 22 can have thicknesses T2, T3, respectively, of any size, such as from at least about 0.25″ to about 0.75″, or larger. In some embodiments, the panels 20, 22 can comprise plural layers coupled together to form a single panel. For example, a 1″ thick panel can comprise two 0.5″ thick panels layered together. The panels 20, 22 can have a height about equal to the height H1 of the web 12, such that the panels 20, 22 substantially cover the entire height of the web 12 between the flanges 14 and 16 and/or provide a snug-fit between the flanges.
The panels 20, 22 can be secured to the web 12 in any suitable manner, such as with fasteners, adhesives, positive locking mechanisms, friction fits, other manners, or combinations thereof. In the illustrated example, the panels 20, 22 are secured to the web 12 with fasteners 24 and 26, which can comprise nails, screws, bolts, other fasteners, or combinations thereof. For example, the fasteners 24, 26 can comprise Type W drywall screws. The length of the fasteners 24, 26 can be selected based on the values of T1, T2, and T3. In the illustrated example in
The construction member 10 can be constructed, such as in the field, by securing the gypsum panels 20, 22 to a wood-based I-joist. Because the gypsum panels 20, 22 primarily protect the web 12, the flanges 14, 16 can remain exposed to fire damage. Thus, sufficiently sized flanges can be provided in addition to the gypsum panels to provide the required level of overall fire resistance. Based on testing results, in order to provide “equivalent fire-resistant performance” and/or in order to survive for the duration of the fire test described above, the flanges 14, 16 can have a minimum width W1 of about 2.3″, about 2.5″, or about 3.5″, and/or minimum heights H2, H3 of about 1.5″.
As shown in
The fasteners 24, 26 can be positioned at various vertical locations along the height H1 of the web 12. For example, in the example of
As shown in
Table 4 below provides exemplary ratios relating how much raw material (gypsum board) is required on a per square foot basis of floor area using the web-protected members 10 versus installing the membrane protection currently required in the International Residential Code. A ratio greater than one indicates that it takes more gypsum board material to protect the web than to install a ceiling.
Another exemplary construction member 40 is shown in
The web 42 can have a thickness T4 of any size, such as from about 0.25″ to about 1″, and a height H6 of any size, such as from about 9.5″ to about 21″, or larger. The flanges 44, 46 can have a width W2 of any size, such as at least about 1.5″, and can have heights H7, H8, respectively, of any size, such as at least about 1.125″. The gypsum panels 50, 52 can have thicknesses T5, T6, respectively, of any size, such as from at least about 0.25″ to about 0.75″, or larger. In some embodiments, the panels 50, 52 can comprise plural layers coupled together to form a single panel. For example, a 1″ thick panel can comprise two 0.5″ thick panels layered together. The panels 50, 52 can have a height about equal to the sum of H6, H7, and H8, such that the panels 50, 52 substantially cover the entire side surfaces of the flanges 44 and 46.
The gypsum panels 50, 52 can protect both the web 42 and the flanges 44, 46 from fire and/or high temperatures. Because the flanges 44, 46 are not exposed, as in the member 40 above, the size of the flanges is less significant to the overall fire resistance of the member. Thus, a wider variety of sizes of I-joists can be used to construct the member 40 while still providing sufficient fire resistance.
The construction member 40 can be constructed in the field by securing the gypsum panels 50, 52 to a wood-based I-joist. The panels 50, 52 can be secured to the flanges 44, 46 in any suitable manner, such as with fasteners, adhesives, positive locking mechanisms, other manners, or combinations thereof. In the illustrated example, the panels 50, 52 are secured to the flanges 44, 46 with fasteners 54, 55, 56 and 57, which can comprise nails, screws, bolts, other fasteners, or combinations thereof. For example, the fasteners can comprise Type W drywall screws or 5d cooler nails. The length of the fasteners can be selected based on the values of T5, T6, and/or W2. In the illustrated example in
As shown in
The fasteners can be positioned at various vertical locations along the heights H7, H8 of the flanges 44, 46. For example, in the example of
As shown in
Table 5 below provides exemplary ratios relating how much raw material (gypsum board) is required on a per square foot basis of floor area using the web and flange protected members 40 versus installing the membrane protection currently required in the International Residential Code. A ratio greater than one indicates that it takes more gypsum board material to protect the web and flanges than to install a ceiling membrane.
Regarding the described gypsum protected members 10 and 40, the gypsum panels can contribute in various ways that limit the growth of fire damage on the web and/or flange material. Some examples can include: 1) preventing surface burning of wood material, 2) reflecting/absorbing significant amounts of thermal and radiant energy, and 3) reducing the availability of oxygen and ventilation.
In some embodiments, a member can comprise an increased web thickness, such as from about 0.5″ to about 0.0875″, in combination with gypsum panels over the web and/or flanges, to provide increased fire resistance.
In view of the many possible embodiments to which the principles of the disclosure may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is defined by the following claims. We therefore claim all that comes within the scope of these claims.
This application claims the benefit of U.S. Provisional Patent Application No. 61/772,284, filed Mar. 4, 2013, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61772284 | Mar 2013 | US |
