"The air barrier material of an envelope assembly shall be joined and sealed in a flexible manner to the air barrier material of adjacent assemblies, allowing for the relative movement of assemblies due to thermal and moisture variations and creep."
--Massachusetts Building Code 780 CMR Appendix 120 AA--Stretch Energy Code.
The Stretch Energy Code is the International Energy Conservation Code (IECC) 2009 with Massachusetts amendments.
Empire State Building Uses BACKERSEAL around windows as part of $550 million energy efficiency retrofit: Joint sealants around the 6,500 refurbished windows are installed from swing stages on the Empire State Building.
Expansion Joints and Joint Sealants in Air Barrier Assemblies:
COLORSEAL and BACKERSEAL installed as offered and intended in conjunction with a field-applied, low-modulus, liquid sealant is compliant with the ABAA air barrier performance requirements. This is because the COLORSEAL and BACKERSEAL/sealant system are impermeable and airtight when tested according to ASTM E 283*.
The highlighted sections of the Mass. Code recognize the ability of liquid sealant systems to be airtight (zero permeability) and require their use a outlined in the highlighted parts of the code.
502.4.0 Air Barriers. The building envelope shall be designed and constructed with a continuous air barrier to control air leakage into, or out of the conditioned space. An air barrier system shall also be provided for interior separations between conditioned space and space designed to maintain temperature or humidity levels which differ from those in the conditioned space by more than 50% of the difference between the conditioned space and design ambient conditions.
The air barrier shall have the following characteristics:
2. Materials used for the air barrier system shall have an air permeability not to exceed 0.004 cfm/ft2 under a pressure differential of 0.3 in. water (1.57psf) (75 Pa) when tested in accordance with ASTM E 2178. Air barrier materials shall be taped or sealed in accordance with the manufacturer's instructions.
3. It shall be capable of withstanding positive and negative combined design wind, fan and stack pressures on the envelope without damage or displacement, and shall transfer the load to the structure. It shall not displace adjacent materials under full load.
4. Air barrier materials shall be maintainable, or, if inaccessible, shall meet the durability requirements for the service life of the envelope assembly.
5. The air barrier material of an envelope assembly shall be joined and sealed in a flexible manner to the air barrier material of adjacent assemblies, allowing for the relative movement of assemblies due to thermal and moisture variations and creep.
Connections shall be made between:
a. joints around fenestration and door frames
b. junctions between walls and foundations, between walls at building corners, between walls and structural floors or roofs, and between walls and roof or wall panels
c. openings at penetrations of utility services through roofs, walls, and floors
d. site-built fenestration and doors
e. building assemblies used as ducts or plenums
f. joints, seams, and penetrations of vapor retarders
g. all other openings in the building envelope
502.4.0.1 Air Barrier Penetrations. All penetrations of the air barrier and paths of air infiltration/exfiltration shall be made air tight.
Given that the COLORSEAL or BACKERSEAL/liquid sealant system will be sealing control and expansion joints and other penetrations in the air barrier assembly, it would be necessary that the BACKERSEAL be “airtight”.
BACKERSEAL is installed as part of a system comprised of the BACKERSEAL and low-modulus liquid sealant--usually silicone. Like BACKERSEAL, COLORSEAL is an acrylic impregnated, precompressed foam with the silicone factory applied and cured.
Given that liquid sealant (usually silicones) tooled to typical thicknesses of ¼-inch or more are airtight and that the silicone is applied over the BACKERSEAL, the sealant system created by these two components is airtight in compliance with the part of the Mass. code referenced above.
The bottom line is that COLORSEAL, or BACKERSEAL used in conjunction with a field-applied liquid sealant, is compliant with ABAA guidelines and will not be detrimental to the overall performance of a compliant wall assembly.
*Using the results reported in our Test Report “1990-01-23EMSEAL_COV_BKS_ASTM283-331-330ReportNo90-38-B0020.pdf”, the relevant results are reported on Page 4, Item 5.0 Test Results.
At the relevant pressure 75 Pa and the Flow of 0.97 cu.m/hr converts to 0.0453 L/s.m2 which compared to the requirement of ABAA Compliance Alternative B or 0.2 L/s.m2 is 5-times below the ABAA requirement**.
**NOTE: this measurement is based on the air leakage of the particular compliant wall assembly in which the COLORSEAL and BACKERSEAL/silicone sealant was tested. It is safe to assume that if tested in any other ABAA compliant wall assembly, the COLORSEAL or BACKERSEAL/silicone would not have a detrimental effect on the performance of the assembly.
Double-Sided SEISMIC COLORSEAL provides the designer with additional options. SEISMIC COLORSEAL-DS can be customized to suit the entire depth of a wall or window mullion for example. And because both the interior and exterior faces are factory-coated with silicone the R-Value is increased by both the addition of depth and the addition of another layer of silicone.
R-values for the use of any of these systems installed from both faces of the wall with an air gap between the two systems can be expected to more than double the R-Value and insulating effect.
Expansion joints and
sealants by EMSEAL
Last Modified: March 07, 2014