Thermablok^® Technical Support

Thermablok Physical Properties

0.40 in (10 mm)
390°F (200°C)
White
9.4 lb/ft³ (0.15 g/cc)
Yes
57 in (1,450 mm) wide     3/8" X 1.5" X 4' long
R-Value = 10.3 / inch

Thermablok Standards Organization Test Results

Property

Thermal Conductivity via Guarded Hot Plate
Thermal Conductivity via Guarded Hot Plate
Thermal Conductivity via Heat Flow Meter
Flame and Smoke Spread
Reaction to Fire Performance
Compressive Stress / Strain
Specific Heat
Water Vapor Transmission Rate
Linear Coefficient of Thermal Expansion (@ 10°C)
Water Vapor Sorption

Common Insulators: R-Value / U-Value - Energy of Mfg / CO₂ (Environmental Impact)

Notes: R-value is expressed in ft²•h•°F/Btu. U-value is expressed in W/m-K per standard convention.

• Thermal conductivity, k, is the property of a material that indicates its ability to conduct heat. It appears primarily in Fourier's Law for heat conduction. Thermal conductivity is measured in watts per kelvin per metre (W•K⁻¹•m⁻¹). Multiplied by a temperature difference (in kelvins, K) and an area (in square metres, m²), and divided by a thickness (in metres, m) the thermal conductivity predicts the power loss (in watts, W) through a piece of material.
• Wall assembly R-values are computed and expressed in the U.S. in (ft²•h•°F/Btu). Thermablok U -value expressed using this measurement is 0.0971 (BTU-in/ft²•h•°F).
• Metric U-factors are defined as Watts per square meter per degree Celsius. To convert inch-pound Imperial U-values to metric U-factors, multiply by 5.678. To convert metric U-factors to Imperial inch-pound U-factors, divide by 5.678. To convert Imperial inch-pound R-values to metric R-values, multiply by 0.1761. One inch = 2.54 cms. One (RSI) U-factor coefficient = 5.678; one R-value = .1761 RSI.
• USA R Value X 0.176 = Metric R Value

Wall R-Value losses from Thermal Bridging

Simple ORNL Whole Wall R Value Calculator

Notes:

Zone Method - The Zone Method is a variation on the Parallel Path Method designed to account for steel's impact on adjacent insulation.

The Parallel Path Method sums the R-Values for the various components in a wall assembly through two paths – one through the CFS stud and one through the center of the cavity.

The sum of the R-Values through each path are inverted to obtain a UFactor for the path and then weighted based on the area of the wall the paths represent.

In the Zone Method, the CFS flange width is increased by two times the total thickness of all finish material layers on the thicker side of the CFS member. This has the effect of increasing the amount of area that is assumed to be influenced by the steel member.

The result is a whole-wall U-Factor that can be inverted to yield an effective R-Value for the assembly, although from a code compliance perspective, the main interest is in the U-Factor.

The Zone Method tends to underestimate the effective R-Value of a steel assembly, or overestimate the U-Factor. Thus it should be acceptable for code compliance but may unnecessarily penalize a steel assembly. It is currently the only method permitted for calculation of U-Factors for CFS walls in California. The Zone Method is described in more detail in the 2004 ASHRAE Handbook of Fundamentals.

Modified Zone Method - The Modified Zone Method was developed by Oak Ridge National Laboratory as a follow up to a test program funded by AISI in the early 1990s. The Modified Zone Method is sometimes called the ORNL Method because of this fact.

With this calculation method, the flange width is widened by increasing its dimension by a term called "zf" that is defined as a ratio of thermal resistivity of finish material to cavity insulation. Thus, the Modified Zone Method is similar to the Zone Method in that it widens the assumed width of the flange, but the width size is smaller than in the Zone Method.

The Modified Zone Method calculation again breaks the assembly into two paths (framed and non-framed) and performs the path calculations on each. The Modified Zone Method is believed to be the most accurate calculation method based on comparison to test results and finite element analysis conducted by ORNL.

It is the method recommended in the ASHRAE Handbook of Fundamentals for metal framing. This calculation method is limited to C-shaped steel members and should not be applied to other shapes. It is also limited to clear wall assemblies, which can be a significant issue given that many walls are not clear wall assemblies.

Meeting ASHRAE 90.1-2007 Building Envelope Requirements for U.S. Climate Zones

Basic Thermal Definitions

Thermal conductivity is an intensive property of a material that measures its capacity to sustain heat flow. The units of thermal conductivity are often provided in metric values of Watts/meter-degree Kelvin or W/m-K. The symbol used to denote thermal conductivity is k (or lambda, λ).

• There are many different unit conversions to Imperial and others:
      1 BTU/ft hr F = 1.73 W/m-K or 1730 mW/m-K
      12 BTU-in/ft2 hr F = 1 BTU/ft hr F = 1.73 W/m-K
      1 BTU-in/ft2 hr F = 0.144 W/m-K or 144 mW/m-K
• The reciprocal of thermal conductivity is thermal resistivity; an intensive property of a material to resist one-dimensional heat flow. Thermal resistivity has units of m-K/W.

Thermal Resistance (R value)

• R is thermal resistance, which is the capacity of a material to impede heat flow over a given area and at a specific temperature. The greater the value at a given set of conditions, the better the material will perform as a thermal insulator.
• The units of thermal resistance are provided in m²-K/W (or ft² hr °F/BTU).
• Thickness/k value = R value.
• Resistances of insulators in series can be added.
• R-value can be for whole thickness or normalized (e.g. R-value is 12 per in or 24 for 2 inches of R-12 per inch material).
• R/in = 144/k (in mW/m-K) -> 12 mW/m-K = 12 per inch R value.
• The reciprocal of thermal resistance is thermal conductance (also known as the heat transfer coefficient), with units of W/m² K. This value is frequently measured in systems as the overall heat transfer coefficient (OHTC).
• Thermal resistance values are often used in the building and construction markets as a relative measure of thermal insulation performance for materials and systems.

Heat Transfer Coefficient (U Value)

• U values measure thermal conductance, a measure of a material or system to permit power flow per unit area and temperature change (W/m2 K).

• U-value is heat transfer coefficient.
• Low U values mean good insulation values (very similar to thermal conductivity k).
• OHTC -> Overall heat transfer coefficient; frequently used to measure the thermal conductance of systems.
• In the world of systems thermal engineering – U value and OHTC are often used synonymously.