Air Sealing Modular Home Marriage Joints

Scope Images
Marriage joints between modular home modules at all exterior boundary conditions fully sealed with gasket and foam
Marriage joints between modular home modules at all exterior boundary conditions fully sealed with gasket and foam
Scope

Air Sealing

Air seal the marriage joints between sections of a modular or manufactured home with gasket material or spray foam.

  • Install a gasket along the entire seam of the exterior boundary where modules are attached together.
  • When modules are in place, seal the edge of the gasket to the module.

See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Certified Homes, and Indoor airPLUS.

Description

In modular or manufactured homes that are delivered to the site in two (or three) sections, the joint where the sections of the structure are joined together is called a marriage joint. (It is sometimes also referred to as a marriage line or mating joint.) Marriage joints can be significant sources of air leakage. They should be properly gasketed and sealed to avoid leakage and maintain indoor air quality. Air leakage leads to heat loss in the winter and cooling losses in the summer.

Double-section modular homes are transported to the site as two separate sections. The marriage joints, beam joists, and walls are aligned and connected at the site. The roof, walls, and floor along the marriage line must be properly aligned, sealed, and supported.

Modular home manufacturers offer two options for delivery of manufactured homes to the home site: turn-key or rough set. With the “turn-key” option the manufacturer constructs the foundation, delivers the home, sets the home on the foundation, seals the marriage joints, and performs all finishing work. With the “rough-set” option, the home is delivered to the site by the manufacturer and placed on a foundation built by a third party (Steven Winter Associates 2001). The third-party contractor is responsible for ensuring the marriage joints are properly gasketed and air sealed.

A typical two-section modular home installation on a pier and ground anchor system. The middle line between the modules is the marriage joint
Figure 1 - A typical two-section modular home installation on a pier and ground anchor system. The middle line between the modules is the marriage joint. 

How to Air Seal the Modular Home Marriage Joint 

  1. Install a gasket along the entire seam of the marriage joint. If the manufacturer has already installed the gasket, ensure that each step below was performed.
    1. Install the gasket to the ceiling, walls, and floor prior to joining the sections together.
    2. Fold the gasket in half and fasten along the mating surface with nails or staples. Fasten at intervals of 6 inches on center (NFPA 2013).
      A gasket is installed along entire seam of the modular home marriage joint
      Figure 2 - A gasket is installed along entire seam of the modular home marriage joint. 
  2. After the sections have been put in place and attached, air seal the entire perimeter of the gasket to the section walls, floor, and ceiling. Use an appropriate sealant such as caulk, foam, or silicon. 
Ensuring Success

Marriage joints between portions of modular homes should be visually checked to ensure that a gasket is installed along the entire seam of the modules and the outside portion of the gasket is fully air sealed.  An experienced technician can also check for air leaks with a smoke pencil or by feeling with the back of the hand. Air barrier effectiveness is measured at the whole-house level by blower door testing, which may help indicate whether marriage joints have been successfully sealed. To ensure indoor air quality and code compliance, air sealing strategies must be accompanied by whole-house ventilation systems and local mechanical exhaust.

Climate

No climate specific information applies.

CAD

Compliance

The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

ENERGY STAR Certified Homes, Version 3/3.1 (Rev. 09)

Rater Field Checklist

Thermal Enclosure System.
4. Air Sealing (Unless otherwise noted below, “sealed” indicates the use of caulk, foam, or equivalent material). 
4.1 Ducts, flues, shafts, plumbing, piping, wiring, exhaust fans, & other penetrations to unconditioned space sealed, with blocking / flashing as needed.
4.8 In multifamily buildings, the gap between the common wall (e.g. the drywall shaft wall) and the structural framing between units sealed at all exterior boundaries.

Please see the ENERGY STAR Certified Homes Implementation Timeline for the program version and revision currently applicable in in your state.

DOE Zero Energy Ready Home (Revision 07)

Exhibit 1 Mandatory Requirements.
Exhibit 1, Item 1) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.

2009 International Energy Conservation Code (IECC)

The 2009 IECC does not specifically address sealing the marriage joints between modular home modules. Table 402.4.2 Air Barrier and Insulation Inspection Component Criteria, Walls: Corners, headers, narrow framing cavities, and rim joists are insulated.

2012, 2015, and 2018 IECC

The IECC does not specifically address sealing the marriage joints between modular home modules. Table R402.4.1.1 Air Barrier and Insulation Installation, Walls: Junction of foundation and wall sill plates, wall top plate and top of wall, sill plate and rim-band, and rim band and subfloor are sealed. Corners, headers, and rim joists making up the thermal envelope are insulated.

Retrofit: 

2009, 2012, 2015, 2018, and 2021 IECC

Section R101.4.3 (Section R501.1.1 in 2015, 2018, and 2021 IECC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

2009 International Residential Code (IRC)

The IRC does not specifically address sealing the marriage joints between modular home modules. Table N1102.4.2 Air Barrier and Insulation Inspection, Walls: Corners, headers, narrow framing cavities, and rim joists are insulated.

2012, 2015, and 2018 IRC

The 2012 IRC does not specifically address sealing the marriage joints between modular home modules. Table N1102.4.1.1 Air Barrier and Insulation Installation, Walls: Junction of foundation and wall sill plates, wall top plate and top of wall, sill plate and rim-band, and rim band and subfloor are sealed. Corners, headers, and rim joists making up the thermal envelope are insulated.

Retrofit: 

2009, 2012, 20152018, and 2021 IRC

Section N1101.3 (Section N1107.1.1 in 2015 and 2018, N1109.1 in 2021 IRC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

More Info.

Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

References and Resources*
Author(s)
U.S. Environmental Protection Agency
Organization(s)
EPA
Publication Date
Description
Guide describing details that serve as a visual reference for each of the line items in the Thermal Enclosure System Rater Checklist.
Author(s)
National Fire Protection Association
Organization(s)
National Fire Protection Association
Publication Date
Description
Standard for installing manufactured homes, including specifications and procedures, for installation of utility connections of a manufactured home.
Author(s)
Steven Winter Associates
Organization(s)
Steven Winter Associates,
SWA
Publication Date
Description
Document describing advancement in factory built housing innovations.
Author(s)
U.S. Environmental Protection Agency
Organization(s)
EPA
Publication Date
Description
Website providing the technical specifications and related documents for home builders, subcontractors, architects, and other housing professionals interested in certifying a home to the EPA's Indoor airPLUS program requirements.
*For non-dated media, such as websites, the date listed is the date accessed.
Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

Building Science Measures
Building Science-to-Sales Translator

Tight Air Sealed Home = Comprehensive Draft Protection

Image(s)
Technical Description

Poorly air-sealed homes are less comfortable and cost more to maintain because they provide a pathway for drafts, cold spots, moisture, and insects into the home. Comprehensive draft protection includes a continuous air barrier around the whole house along with caulking and sealing in all holes and cracks. This includes around wiring, plumbing, ducts, and flues; where wall framing meets flooring; around windows; where drywall meets top plates and sill plates; where rim joists meet foundation walls and subfloors; etc. Spray foam insulation can be used at rim joists, floors above unconditioned space, and in attics to insulate and air seal at the same time.

Comprehensive Draft Protection
Sales Message

Comprehensive draft protection minimizes air flow that can undermine a complete high-performance insulation system. What this means for you is less wasted energy along with enhanced comfort, health, quiet, and durability. Wouldn’t you agree it would be a shame to only get a partial return on your investment in advanced insulation?

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