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Window Replacement

Many home windows are inefficient and installed without sealing the air gap around the framed opening and flashing to avoid water penetration. Homeowners replacing windows must decide between a full-frame window replacement that includes sealing the air gap and adding flashing, or the much more common practice of minimizing replacement window cost by installing within the existing frame without sealing the air gap and adding flashing. Critical installation best practices need to be followed with either choice to ensure a successful project. Use this checklist to get the significant energy savings, enhanced comfort, and durability benefits possible with window replacement.

Old windows represent a substantial source of heat loss in winter and heat gain in summer because they provide 5 to 10 times less thermal protection than an insulated wall. With typical window replacements, the existing frame is left in place to minimize the disruption and cost. However, existing windows were often never air sealed behind the trim at the rough opening around the window frame and the window may also lack pan flashing. Homeowners who are replacing windows must decide whether to address these areas of potential air and water leakage by doing a full-frame window replacement or to minimize costs and leave the existing frame in place.

Checklist

This U.S. Department of Energy checklist includes important specifications that can contribute to a complete and quality installation. All work shall comply with these specifications, all relevant codes and standards, and all manufacturer installation instructions. The contractor shall check each box on the checklist below and sign and date at the bottom to certify the work is completed.

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Preparation

An ENERGY STAR certified or better window matched to the climate zone for this specific home shall be selected for all windows to be replaced.

Egress windows and safety glass shall be specified in accordance with local codes.

The presence of lead-based paint in pre-1978 homes shall be assumed unless testing confirms otherwise. The work shall comply with EPA’s Lead Renovation, Repair and Painting (RRP) Rule (40 CFR Part 745) in pre-1978 homes and proposed changes to this rule (Federal Register/Vol. 75, No. 87/ May 6, 2010).

Installation: Option 1 - Window Replacement in Existing Frame


Interior stops, sashes, parting strips, and pulleys shall be removed and the rough opening shall be cleaned and fully sealed.

Sealants shall be durable, pest resistant, compatible with their intended surfaces, have a weather-appropriate seal, and be applied in accordance with the manufacturer’s specifications.

Indoor sealants shall be low volatile organic compound (VOC) products that meet independent testing and verification protocols, such as Green Seal, GREENGUARD, or comparable certifications.

Replacement windows shall be installed in accordance with the manufacturer’s specifications, ensuring that the exterior stops are caulked and that the new window inserts are sealed at the existing frame.

Installation: Option 2 - Full-Frame Window Replacement (RECOMMENDED)


Replacement windows shall be installed in accordance with manufacturer’s specifications and with ASTM E2112-07(2016) Standard Practice for Installation of Exterior Windows, Doors and Skylights.

Exterior cladding or trim shall be removed as required to install exterior head, jamb, and sill flashing. Cladding or trim that is removed shall be replaced after flashing is installed to match existing exterior finishes.

Trim and finishes shall be removed as required to fully expose the rough opening on all four sides around each window and internal weight pockets used for older windows. If there are internal weight pockets, all hardware shall be removed. The rough opening and/or pockets shall be fully insulated and air sealed with non-expanding spray-in foam or blown-in insulation and sealants.

Head, jamb, and sill flashing shall be fully integrated with the weather-resistant barrier (e.g., house wrap, building paper, taped water- resistant sheathing, liquid-applied coating, or another approved material). Membranes shall be installed shingle-fashion where the top layer of the flashing or weather-resistant barrier laps over the bottom layer to prevent water from draining behind the bottom layer.

Add material or cut the existing weather-resistant barrier to create a flap at the top of the window opening. Tape the flap so that it is temporarily folded up, toward the sky.

Extend the weather-resistant barrier 4 inches into the frame opening and wrap around the opening toward the interior of the house. Trim the weather-resistant barrier if needed to ensure it will not be visible from the interior of the house after trim is installed.

Rigid, flexible, or fluid-applied pan flashing shall be installed at sills and extend to the face of the weather-resistant barrier.

Caulk the outside edges of the head and side jambs. Do not caulk the across the sill.

Windows shall be installed according to the manufacturer’s instructions including installing flanges over the flashed opening, or with metal clips provided by the window manufacturer for this purpose, or with 20-gauge metal tie plates screwed to the window first if metal clips are not provided.

Side (jamb) flashing shall be installed over window flanges and pan flashing and extend above the top (head) flange and shall be integrated with the weather-resistant barrier on the exterior sheathing.

Top (head) flashing shall be installed over and beyond the jamb flashing (and over the drip cap if installed) and shall be fully integrated with the weather-resistant barrier on the exterior sheathing. Install the top flashing so that it does not inhibit the flap created in the weather-resistant barrier from being folded down.

Flashing shall be integrated with the weather-resistant barrier at the top of the window (e.g., fold down and tape the house wrap over the head flashing).

All cladding or trim removed to install flashing shall be replaced with either wood, cementitious board, or composite exterior trim to match existing and shall be primed on all six sides.

All interior trim and finishes removed shall be replaced as required to match the existing trim.

Commissioning


Occupants will be notified of changes or repairs made and will be educated on how to operate and maintain windows.
Window Replacement

Tips to Sell Quality Installed Home Improvements

Home Improvement Expert is a valuable tool for organizations committed to quality installed work. The following tips help optimize the value of this tool when selling home improvements:

Trust Matters: Inform homeowners how your work conforms to this world-class expert guidance. Recommend they visit the DOE website as evidence these are indeed official best practices.

Knowledge Matters: Take advantage of the Building America Solution Center as a resource for becoming an expert on these projects.

Clarity Matters: Tell prospective clients to contrast your expert-recommended best practices with other contractors.

Value Matters: Advise prospective clients to insist other bids also include these checklists to ensure equivalent quality work.

Message Matters: Showcase on your website and marketing materials that your company uses the highest quality best practices specified on HIE Checklists.

Experiences Matter: Provide visual evidence contrasting the difference between poor and high quality work such as infrared images; pre- and post-energy bills; short and long warranties; and simple charts and graphics depicting performance advantages.

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Disclaimer

This content is a work created with funding provided by the United States Department of Energy under Contract no DE-AC05-076RL01830 for the operation of Pacific Northwest National Laboratory. The information and guidance provided by Pacific Northwest National Laboratory (PNNL) in the content are intended solely for educational purposes only and do not constitute formal training or certification. It is provided with the explicit understanding that neither the United States Government nor the United States Department of Energy, nor the Contractor, nor any or their employees, nor any jurisdiction or organization that has cooperated in the development of these materials, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or any information, apparatus, product, software, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Viewers assumes full responsibility for all actions that they may take from information provided in this content including ensuring the safety, code compliance, and proper functionality of any products they choose to install. Installation and use of such products should be performed in accordance with local regulations and manufacturer instructions.