What is LTTR R-value?
The Long-Term Thermal Resistance (LTTR) is a scientifically supported, consensus-based method used to estimate the thermal resistance for insulation products with captive blowing agents at an age of 5 years (which corresponds closely to the average thermal resistance over a 15-year service life).
Is LTTR the same as R-value?
Sometimes these terms are use interchangeably. However, they actually mean something different as the R-value refers to the materials current thermal resistance while the LTTR references the R-value of the product over a designated period of time.
Does polyiso lose R-value?
The trapped gases in the cells of polyiso and XPS foam assist to provide an initial high R-value. During the life of these foams, air from the atmosphere diffuses in and the trapped gases diffuse out. The result is polyiso and XPS lose R-value over their lifetime.
What is the R-value of 1.5 polyiso?
Published Polyisocyanurate R-values Not all industry stakeholders are in agreement with the R-6/in. LTTR value published by polyisocyanurate insulation manufacturers for 1 and 1.5 inch thick samples. Since 1987 the National Roofing Contractor’s Association (NRCA) has recommended designers use R-5.6/in.
What does LTTR stand for?
LTTR. Long-Term Thermal Resistance. LTTR.
What is LTTR of polyisocyanurate?
New LTTR Values and What They Mean for Roofing Industry Professionals. As a result, LTTR values for polyisocyanurate (polyiso) roof insulation will change from a design value of 6.0 R per inch to 5.7 R per inch, which will impact the amount of polyiso needed to meet building-code requirements.
How thick is polyiso 30?
0.5” to 4.5”
Polyiso roof insulation is typically manufactured in incremental thicknesses from 0.5” to 4.5” with versatile options for meeting energy code requirements.
Is Polyiso a EPS?
The two most common types of insulation for commercial roof systems are Polyisocyanurate (Polyiso) and Expanded Polystyrene (EPS). Both are available in a variety of thicknesses and can be used in multiple applications. Polyiso is used in new construction designs more than EPS, though EPS still has it’s advantages.
How thick is R25 Polyiso?
0.5”
The high R-value and light weight of high-density (HD) polyiso cover boards provide important contributions to the design of a durable roof system. A typical 0.5” thick HD polyiso cover board adds R-2.5 to the total R-value of the roof insulation system.
What is the R-value of 2.5 ISO?
R-Value Chart for EnerfoilTM Rigid Foam Faced Insulation
| Thickness (Inches) | R-value (in I-P/Imperial) | RSI (R-value in Metric) |
|---|---|---|
| 2.0 | 12.4 | 2.16 |
| 2.5 | 15.5 | 2.7 |
| 3.0 | 18.6 | 3.24 |
| 3.5 | 21.7 | 3.78 |
How thick is r30 insulation?
Typical R-30 fiberglass insulation is 10-inches-thick. Prior to buying fiberglass insulation, it is important to measure the joint spacing you are working with. Note that the actual space between the framing members will be less than 16 or 24 inches, but the foam batts can easily be stuffed between these lengths.
What is long term thermal resistance (LTTR)?
Long Term Thermal Resistance (LTTR) is a relatively new value used to measure thermal resistance of polyiso insulation. On January 1, 2014, the ASTM C1289 Standard (Standard Specification for Faced Rigid Polyisocyanurate Thermal Insulation Board) was changed.
What are the new LTTR values for polyiso products?
The new LTTR values are compared to the old values in Table 1. It is important to note that the polyiso products will not change; only the LTTR test method is changing. It should also be emphasized that 5.7 R/inch is only the design value or guideline.
What is the LTTR value for polyisocyanurate insulation?
As a result, LTTR values for polyisocyanurate (polyiso) roof insulation will change from a design value of 6.0 R per inch to 5.7 R per inch, which will impact the amount of polyiso needed to meet building-code requirements.
What is polypolyiso LTTR certification?
Polyiso is the only roof insulation to be certified for its LTTR value by this unique program. FM Global® administers the program. PIMA recently announced that its QualityMarkCM certification program will begin reporting LTTR values in accordance with the updated ASTM C1289-13 standard on Jan. 1, 2014.