Have you heard? There have been some important changes to walk door testing requirements upon which the latest commercial energy codes are based. This post aims to give you a quick breakdown of the key update we think is most important for builders to know.
First Thing’s First: Total Door Testing
Old door test methods utilized a small cutout of a door leaf, which was supposed to serve as a representation of the entire door – after all, it is the largest component of the opening. While this manner of testing lasted many years, recent codes recognize the limitations of what we’ll call the “cutout method”. Now ASTM requires the entire opening of the door to be tested, which includes the door, frame and weatherseals. This certainly makes sense to us.
As you can imagine, test results are quite different for the cutout method vs. total door. Below are the thermal values of a steel door assembly using the latest total door testing.
U/R Values of Steel Door Assembly
Results of the evaluation and tests to the requirements contained in the following standards:
- ASTM C1199‐09 Test Method for Measuring the Steady‐State Thermal Transmittance of Fenestration Systems using Hot Box Methods
- ASTM C1363‐05 Test Method for Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
- ASTM E1423‐06 Practice for Determining Steady‐State Thermal Transmittance of Fenestration Systems
|Material Tested||18/20 gauge polystyrene core door; 16 gauge frame, standard hardware and accessories|
|Result||U‐Value (Btu/hrft2•°F) .39 Measured Overall R‐Value (ft2•hr•°F/STU) 2.58|
|Material Tested||18/20 gauge polyurethane core door; 16 gauge frame, standard hardware and accessories|
|Result||U‐Value (Btu/hr•ft2•°F) .36 Measured Overall R‐Value (ft2•hr•°F/STU) 2.74|
Polyurethane vs. Polystyrene: What’s the Difference in a Door Opening?
Nothing has changed in the way of testing a door’s core, but we get asked this question a lot, so let’s address it. The short answer: Not much under the current code requirements for testing. When it comes to thermal values, or thermal resistance, polyurethane and polystyrene cores perform quite differently; ultimately, polyurethane provides a much higher R/U. However, the core material of the door does not have a large effect on the overall thermal value of the opening. Why? Because the door and the frame are made of metal, through-and-through. Additionally, don’t forget that door leafs contain holes to allow for hardware, and doors in general have gaps that are necessary for the door to be able to open and close. We add weatherseals to contain as much air infiltration as possible, but in the end, a metal door is designed to open and close, and it’s up to the rest of the building envelope to provide thermal resistance.
If you have questions about any of the information I mentioned in this post, send me an email or give me a call at 877-735-3667.