Use this guide specification as a starting point for the structural thermal break section of your project manual. It is written to performance requirements with STB-1 as the basis of design, and can be placed under MasterFormat Section 07 21 00 (Thermal Insulation) or coordinated with Division 05 as your office prefers.
Edit to suit the project. Text in [brackets] requires a project decision. Download the STB-1 data sheet (PDF) for your submittal. Need the spec in Word format? Contact us and we will send it.
Part 1 – General
1.1 Summary
A. Section includes load-bearing structural thermal break pads, thermal break washers and isolation bushings at steel-to-steel and steel-to-concrete connections penetrating the building envelope, including [balcony and canopy connections] [shelf angles] [rooftop dunnage and posts] [column bases].
1.2 Related Sections
A. Division 05 – Structural Steel Framing.
B. Section 07 21 00 – Thermal Insulation.
C. Section 07 27 00 – Air Barriers.
1.3 Submittals
A. Product data sheets showing compliance with Part 2 performance requirements.
B. Shop drawings showing pad dimensions, thicknesses, hole patterns, washer and bushing sizes, and connection marks.
C. Fire test classification for the specified fire performance.
1.4 Delivery, Storage and Handling
A. Deliver parts labelled by connection mark. Store flat, off the ground, protected from damage.
Part 2 – Products
2.1 Basis of Design
A. STB-1 Structural Thermal Break by Benchmark, manufactured in Canada. Tel. 800-580-4195. [Or approved equal meeting the performance requirements below.]
2.2 Structural Thermal Break Pads
A. Material: thermoset, reinforced composite plate.
B. Compressive strength (ASTM D695): minimum 48,000 psi (330 MPa).
C. Flexural strength (ASTM D790): minimum 25,000 psi (172 MPa).
D. Tensile strength (ASTM D638): minimum 11,000 psi (75 MPa).
E. Shear strength (ASTM D732): minimum 16,326 psi (112.6 MPa).
F. Thermal conductivity (ASTM C177): maximum 1.06 BTU·in/hr·ft²·°F.
G. Surface burning characteristics (ASTM E84): Class A.
H. Reaction to fire (EN 13501-1): Euroclass B.
I. Operating temperature: -20 °F to +250 °F (-29 °C to +121 °C).
J. Thickness: [1/2″] [3/4″] [1″] [2″] as indicated on drawings.
2.3 Thermal Break Washers and Isolation Bushings
A. Material: same as pads.
B. Washers sized to cover steel washer bearing area; bushings sized to bolt diameter, hole diameter and exterior plate thickness.
2.4 Fabrication
A. Cut pads to plate dimensions and drill or machine holes to match the approved shop drawings.
B. Label each part with its connection mark.
Part 3 – Execution
3.1 Examination
A. Verify steel end plates and bearing surfaces are flat, clean and free of weld spatter before installation.
3.2 Installation
A. Install pads between steel components at locations shown, with full bearing over the plate area.
B. Install thermal break washers between the steel washer and the exterior steel, and isolation bushings through exterior steel holes, at each bolt.
C. Tighten bolts to the pretension or snug-tight condition specified by the structural engineer.
D. Do not field-modify pads without approval.
3.3 Protection
A. Protect installed connections from damage until enclosed. Replace damaged parts.
Related: STB-1 data · design guide · STB-1 vs Armatherm FRR
Request a Quote or Data Sheet
Send us your connection drawings, bolt schedule or load requirements and we will quote STB-1, TBF, washers and bushings cut and machined to your specification. Data sheets and design support are available for engineers and architects.
Call 800-580-4195 or use the form below. STB-1 typically ships in 5–7 days; TBF in as little as 3 days.