To paraphrase an old saying: The only constant in life is change. Life changes every day for every person in some way. The same hold true in the fire service.
Technology has lead to some significant changes to the tools we use to fight fires over the years. However the actual buildings we fight fires in is changing as well. It is essential that we the fire service understand that building materials and methods will always be changing, therefore we must be a constant student of buildings.
Recently in my attempt to be a constant student of building materials and methods I came across a new building material that truly is an example of wood framing no longer being what we think, when we think of a wood frame building.
That new building material is called TStud. This material is the marriage of wood and plastic foam to create a structural framing material.
The following information has been taken from several sources on the internet for TStud.
Standard construction today uses either 2×4 or 2×6 solid lumber generally spaced 16″ on center. Where energy conservation is a concern, most builders frame an exterior wall with 2×6’s. Up to 30 percent of the exterior wall (studs, top and bottom plates, cripple studs, window/door jams and headers) is solid wood framing. Thermal bridges are points in the wall that allow heat and cold conduction to occur. Heat and cold follow the path of least resistance—through thermals bridges of solid wood across a temperature differential wherein the heat or cold is not interrupted by thermal insulation. The more volume of solid wood in a wall also reduces available insulation space, and further, the thermal efficiency of the wall suffers and the R value (resistance to conductive heat flow) decreases. (2)
The most common way to minimize thermal bridging is to wrap the entire exterior of the building in rigid insulation to minimize heat loss and cold from entering the building. This effort significantly increases materials, carbon footprint and labor costs and can be undesirable in increasing the thickness of the building walls with non-structural materials.
A thermal break wall system comprised of 3×6 thermal studs each comprised of two non-dimensional lumber sections with a thermal break section of rigid foam insulation there between. The studs are 24″ on center. The studs are used for headers and sills and also may be used for top and bottom plates. The corners have an exterior all wood stud, an interior all wood stud and an interior all wood stud adjacent to the interior wood stud completing the interior corner for nailing gypsum board thereto. This corner has a thermal break space between the exterior and interior wood studs for insulation placement. The corners may also have two 3×6 thermal studs oriented 90 degrees from each other and an interior all wood stud for completing the interior corner for nailing gypsum board there to. This corner arrangement also has a thermal break through its construction.
A built-in foam core gives the Tstud™ three times the insulation of a conventional wood stud.
In construction, the R-value is the measurement of a material’s capacity to resist heat flow from one side to the other. In simple terms, R-values measure the effectiveness of insulation and a higher number represents more effective insulation.* The R Value through a typical 2×6 wood stud is 6.88. Any wood member causes there to be a transfer of heat and cold from the exterior of a home or a building to the inside of the same space; known as conduction. The only way to stop the transfer of heat or cold from one side of a wall to the other side is to purchase and install thick enough rigid insulation to the entire exterior perimeter of the structure.
The Tstud™ is the same depth as a 2×6 but offers an impressive stated R Value of 18 and has a 99.23% complete thermal break** through the stud. Meaning that there isn’t a need for continuous rigid insulation to meet and exceed the 2015 Energy Code in all of the climate zones in North America.
Typically, the maximum R Value of any continuous insulation is only 5 and is ¾” to a maximum of 1” in depth.
The Tstud™ has approximately 2-1/2” of rigid insulation and we are using a stated R Value of 14.25. Add in the R Value of wood at 1.25 per inch, times 3” of wood, and you get a combined wood and foam R Value of 18.
Regarding the 99.23% complete thermal break through the Tstud™:
The proprietary truss system that holds the 2 wood members together accounts for .77% of a thermal transfer of heat and/or cold.
The truss is non-metal and is fully encased in foam. Continuous rigid insulation is attached with metal nails and still has up to .5% of conduction through the foam, depending on the diameter of the fastener.
By using the thermally broken Tstud™ Wall Assembly, a reduction of 4-7 points on the HERS numbering system is garnered thus yielding the building an approximate 18% improvement (depending on heating or cooling degree days and the climate zone energy code currently in force) in energy efficiency over standard 2”X 6” wall construction. The Tstud™ will be an excellent LEED (Leadership in Energy and Environmental Design) product.
Fire Rated Benefits (Source https://www.tstud.com/)
90% of the Tstud™ remained intact after a 10 minute burn at 3500 degrees.
*Soon to be code compliant!
The foam core of the Tstud™ is currently used in the SIP (structural insulated panel) industry and already has industry acceptance. The adhesive that is used to secure the nonmetal truss inside of the wood members of the Tstud™ is also currently used in the construction industry and passes ASTM D2559, as a heat and moisture resistant adhesive. The ASTM D2559 is required for use in members that could and would be used in headers and top plates, for the protection of fire personal and the inhabitants of the occupied space. Underwriters Laboratory (UL) has tested the Tstud™ and has concluded that the Tstud™ passed as a Class A fire rated member. A testing program is being implemented with UL for use of the Tstud™ as a Fire Class Rated Assembly.
Until a E119 Assembly Test is completed, and additional E84 Steiner Tunnel tests are completed, the Tstud™ cannot be sold with a fire rating. More updates will follow.
TER Certification Letter of TStud Link: https://static1.squarespace.com/static/59cce8bba9db0941ea92e75f/t/59d258de4c326d7077339582/1506957534952/170808+TER+1603-06+Tstud+Certification+Letter.pdf
Additional Reports & Testing Links: https://www.tstud.com/testing-reports/#
The Tstud is just one of many ways our built-in environment is constantly changing and we need to be a student of our profession, more than ever before. It simply is not enough to “Put the Wet Stuff on the Red Stuff”. We must know that the buildings of today, are not going to be built to be fire safe, and as fire service professionals, we must push for home fire sprinklers to save the lives of those we swore to protect.
Please share this with all your brothers and sisters in the fire service in order to continue raising the awareness of modern building construction products that we will face in future fire fights.