ASTM Standard Seeks to Reduce Roofing Materials in Landfills

A new ASTM International standard will help reduce the amount of used roofing materials that go to landfills. ASTM’s Committee on Roofing and Waterproofing (D08) developed the standard, which is available as D8013-16, “Standard Guide for Establishing a Recycle Program for Roof Coverings Roofing Membrane and Shingle Materials”.

According to ASTM member Joseph Schwetz of Canton, Mass.-based Sika Sarnafil Inc., the new guide will help building owners who want to minimize their environmental impact by eliminating waste during roof replacement. The standard will help them and their contractors compare the costs for disposal versus recycling.

In addition, manufacturers will use the standard to determine whether recycled roofing materials could be a cost-effective ingredient in creating new roofing products.

To purchase standards, visit the ASTM website and search by the standard designation, or contact ASTM Customer Relations at (877)909-ASTM or sales@astm.org. ASTM welcomes participation in the development of its standards. Become a member here.

Attic Ventilation in Accessory Structures

Construction Code Requirements for Proper Attic Ventilation Should Not Be Overlooked in Buildings That Don’t Contain Conditioned Space

The 2015 International Residential Code and International Building Code, published by the International Code Council, include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands how the code addresses accessory structures, like workshops, storage buildings, detached garages and other buildings. What’s the answer? The code treats all attic spaces the same, whether the space below the attic is conditioned or not. (A conditioned space is a space that is heated and/or cooled.)

The 2015 International Residential Code and International Building Code include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands the code also addresses accessory structures, like workshops, storage buildings, detached garages and other buildings.

The 2015 International Residential Code and International Building Code include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands the code also addresses accessory structures, like workshops, storage buildings, detached garages and other buildings.


The administrative provisions of the IRC that set the scope for the code are found in Chapter 1. Section R101.2 and read:

    The provisions of the International Residential Code for One- and Two-family Dwellings shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height.

Let’s clear up any confusion about the code. The ventilated attic requirements in the 2015 IRC include the following language in Section R806.1:

    Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.

An accessory structure is actually defined in the IRC:

    ACCESSORY STRUCTURE. A structure that is accessory to and incidental to that of the dwelling(s) and that is located on the same lot.

The IBC also includes attic ventilation requirements that are essentially the same as the IRC. Section 101.2 of the 2015 IBC contains this text:

    The provisions of this code shall apply to the construction, alteration, relocation, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures.

This requirement for ventilated at-tics in accessory structures in the IBC and IRC is mandatory unless the attic is part of the conditioned space and is sealed within the building envelope. Unvented, or sealed, attics allow any ducts located in the attic to be inside the conditioned space, which can have beneficial effects on energy efficiency. For accessory structures, which are typically unheated, that provision does not apply.

It’s important to note the codes do contain detailed requirements for the design and construction of sealed at-tics to reduce the chance of moisture accumulation in the attic. These requirements have been in the codes for a relatively short time and remain the subject of continued debate at ICC as advocates of sealed attics work to improve the code language in response to concerns about performance issues from the field.

Traditional construction methods for wood-framed buildings include ventilated attics (with insulation at the ceiling level) as a means of isolating the roof assembly from the heated and cooled space inside the building. Attic ventilation makes sense for a variety of reasons. Allowing outside air into the attic helps equalize the temperature of the attic with outdoor space. This equalization has several benefits, including lower roof deck and roof covering temperatures, which can extend the life of the deck and roof covering. However, it is not just temperature that can be equalized by a properly ventilated attic. Relative humidity differences can also be addressed by vented attics. Moisture from activity in dwelling units including single-family residences and other commercial occupancies can lead to humidity entering the attic space by diffusion or airflow. It is important to ensure moisture is removed or it can remain in the attic and lead to premature deterioration and decay of the structure and corrosion of metal components, including fasteners and connectors.

In northern climate zones, a ventilated attic can isolate heat flow escaping from the conditioned space and reduce the chance of uneven snow melt, ice dams, and icicle formation on the roof and eaves. Ice damming can lead to all kinds of moisture problems for roof assemblies; it is bad enough that roof assemblies have to deal with moisture coming from inside the attic, but ice damming can allow water to find its way into roof covering assemblies by interrupting the normal water-shedding process. For buildings with conditioned space, the attic can isolate the roof assembly from the heat source but only if there is sufficient ceiling insulation, properly installed over the top of the wall assemblies to form a continuous envelope. Failure to ensure continuity in the thermal envelope is a recipe for disaster in parts of the country where snow can accumulate on the roof.

Accessory buildings, like workshops, that occasionally may be heated with space heaters or other sources are less likely to have insulation to block heat flow to the roof, which can result in ice damming. Ventilating the attic can prevent this phenomenon.

Accessory buildings, like workshops, that occasionally may be heated with space heaters or other sources are less likely to have insulation to block heat flow to the roof, which can result in ice damming. Ventilating the attic can prevent this phenomenon.


For unheated buildings in the north, ice damming is less likely to occur, unless the structure is occasionally heated. Accessory buildings, like workshops, that might be heated from time to time with space heaters or other sources are less likely to have insulation to block heat flow to the roof. In these situations, a little heat can go a long way toward melting snow on the roof.

While the ice damming and related performance problems are a real concern even for accessory structures, it is the removal of humidity via convective airflow in the attic space that is the benefit of ventilated attics in accessory structures. We know that moisture will find its way into buildings. Providing a way for it to escape is a necessity, especially for enclosed areas like attics.

There are many types of accessory structures, and some will include conditioned space. Depending on the use of the structure, moisture accumulation within the building will vary. For residential dwelling units, building scientists understand the normal moisture drive arising from occupancy. Cooking, laundering and showering all contribute moisture to the interior environment.

The IRC and IBC include requirements for the net-free vent area of intake (lower) and exhaust (upper) vents and also require the vents be installed in accordance with the vent manufacturer’s installation instructions. The amount of required vent area is reduced when a balanced system is installed; most ventilation product manufacturers recommend a balance between intake and exhaust. The IRC recommends that balanced systems include intake vents with between 50 to 60 percent of the total vent area to reduce the chance of negative pressure in the attic system, which can draw conditioned air and moisture from conditioned space within the building. This is less of an issue for non-habitable spaces from an energy-efficiency perspective, but moisture accumulation is a concern in all structures.

PHOTOS: Lomanco Vents

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ASHRAE and IES Release Guidance on New Compliance Path for Standard 90.1

A newly published document from ASHRAE and IES gives users of their energy-efficiency standard immediate access to an optional third path for compliance, providing more flexibility for the industry.

Standard 90.1-2013 Appendix G: Performance Rating Method is an excerpt from ANSI/ASHRAE/IES Standard 90.1 (I-P), Energy Standard for Buildings Except Low-Rise Residential Buildings. The document gives users immediate access to selected addenda slated to be published in the 2016 version of the standard. The majority of the document is comprised of addendum bm, which allows Appendix G to be used as a compliance path within the standard.

“This document is being provided at the request of users,” says Drake Erbe, chair of the Standard 90.1 committee. “This is the first time ASHRAE and IES have made available an interim clean publication of a portion of Standard 90.1, and we are doing so now because users have expressed a critical need for this guidance. Several entities have expressed interest in developing programs based on the revised appendix. This release also gives advanced notice to software developers that may be interested in automating the process of creating the Appendix G baseline.”

Erbe notes that the guidance in addendum bm had two significant impacts on Appendix G.

“Previously Appendix G was used only to rate ‘beyond code’ performance of buildings but could not be used to demonstrate compliance with the base 90.1 standard,” he says. “Now the standard provides that compliance path and gives credit for integrated design resulting in energy savings, such as efficient use of building mass, optimized building orientation, efficient HVAC&R system selection and right sizing of HVAC&R equipment.”

Using this new version of Appendix G to show compliance with the 2016 version of the standard, the proposed building design needs to have a Performance Cost Index (PCI) less than that shown in Table 4.2.1.1 based on building type and climate zone.

The second change is that the baseline design is now fixed at a certain level of performance, the stringency of which is expected not to change with subsequent versions of the standard. By this, a building of any era can be rated using the same method with the same baseline of compliance. The intent is that any building energy code or beyond-code program can use this methodology and simply set the appropriate target for their needs analogous to those in the table. Therefore, a beyond-code program may wish to set a target less than is shown in the table (a target of 0 is a net zero building), while compliance with a previous version of the standard may wish to set a target above what is shown. Because unregulated loads are not included in the compliance target in Table 4.2.1.1, beyond-code programs that encourage improvement in unregulated loads may wish to modify the target to include those loads.

Other addenda included in the excerpt are:

  • Addendum k directs the modeler to use the default assemblies in Appendix A for baseline opaque envelope assemblies.
  • Addendum r establishes the hierarchy of the decision-making process for selecting baseline HVAC systems.
  • Addendum z provides detail on the simulation of base-line building heat pumps, including how auxiliary heat is used in conjunction with heat-pump heating.
  • Addendum aa provides direction regarding when it is appropriate to model a heating-only system in Appendix G.
  • Addendum ad clarifies when baseline HVAC systems should be modeled with preheat coils.
  • Addendum dx makes changes to the baseline lighting power allowances in Appendix G.

Erbe noted that while it is likely that the version of Appendix G published in the 2016 edition of the standard will include additional changes to Appendix G, it is not likely that they will be as extensive as those included in addendum bm. The primary focus is to make the new methodology with a fixed baseline available so users become familiar with it.