Skip to Main Content

How to read and compare window contractor bids

Windows Updated: June 7, 2023

Planning a new window install project

When you’re ready to hire a contractor to install windows in your home, it’s a good idea to seek bids from at least 3-4 different contractors. Reading and comparing bids for services can be a complicated task. Consider the following to help guide you through this process.

Sample bid


Inclusions are what the contractor is committing to complete for the quoted amount. Exclusions typically describe work related to the primary services that the contractor does not agree to perform. It’s also safe to assume that if a service is not mentioned at all, it probably means it’s not included. Remember, it’s your responsibility to have the services you expect in writing before signing the bid.

These services may include siding repair adjacent to the window opening(s), removing and reattaching security system devices, expectations around site clean-up at the end of the day/project and potential rebate/incentive support. If you see something called out on Contractor A’s bid, but not included with Contractor B, this is a good opportunity to ask why.

Comparing window options

As you compare the different bids you receive, you may find it difficult to determine which solution is the best fit for your home. Sometimes you may get a better understanding of the quality of your installer by reading online reviews or asking for referrals. But how do you decide between different window brands and types? The following are some common options you’ll be presented with, as well as guidance on how to narrow your options.

  • Frame choice: Vinyl? Wood? Metal? Composite? Choosing the right frame material depends on a combination of your budget and aesthetics. If your home is part of a Homeowners Association (HOA) or is considered a historic home, you may be limited in your window material options. Be sure to consult your local codes and rules before purchasing windows. Read more about frame choice in our article on signs your windows may need to be replaced.
  • Glass options: Some window locations are required to use tempered glass for safety reasons. This glass is typically more expensive than non-tempered glass and is required by code in areas where there is a higher risk of a person accidentally breaking the glass. This includes bathroom locations, windows immediately adjacent to door swings and windows low to the ground. Tempered glass is designed to break into small dull pieces to limit injury if a person makes contact with the broken glass. Window manufacturers offer a wide variety of performance options related to glass.
    • Panes of glass: You can choose between double-pane or triple-pane (pane refers to each layer of glass).
    • Glass coatings: Optional coatings on the glass can reduce solar heat transfer or UV light, reduce glare, offer privacy or provide additional security.
  • Sound transmission: For windows located near busy roads or other sources of unwanted noise, you may have the option of products designed specifically to reduce the transmission of sound.
  • Window type: Fixed windows, also known as picture windows, do not open and are typically the lowest-cost window type. Windows that are operable can come in a variety of forms, including awning, casement, single-hung and double-hung, sliding, etc. Costs vary significantly depending on the type of window you choose. Some window types are also determined by the location. If used in a basement bedroom, the window may need to meet egress requirements. If used in a room on the second floor, safety issues may help guide you to a window with a limited opening. Your window contractor will provide visual aids to assist you in your decision-making process.
  • Overall energy performance: Each window product you find in your bid(s) will have specific measurements of energy performance. The most common performance ratings are U-Value and Solar Heat Gain Coefficient (SHGC).U-value measures the insulation performance of the window. The lower the U-value, the better the window is at preventing the transfer of heat. A window with a low U-value will help keep the heat inside the home in the winter and outside the home in the summer. ENERGY STAR® certified windows in the Pacific Northwest have a U-value of .27 or lower. Solar Heat Gain Coefficient (SHGC) measures the amount of solar heat that passes through the glass. For homes in the Pacific Northwest, solar heat gain in the winter is a benefit, so be sure to discuss with your installer how coatings may perform differently when the sunlight enters at a lower angle (winter) as compared to a higher angle (summer).

Additional installation costs and considerations

Installation costs can vary significantly, both by contractor and across different conditions of the installation location. As referenced in the section above, be sure to thoroughly review the estimates provided by the contractors bidding on your project and compare what is and is not in the description of services. Additional factors that can impact your installation costs include:

  • Site preparation: Your installer may need to address site conditions prior to the installation of your new windows. This could include trimming back trees or bushes restricting access to the window openings, setting up scaffolding to access the second floor, etc.
  • Lead paint: Lead-based paint is very common in homes older than 1978 and may be disrupted during the process of installing windows. Be sure to ask your contractor if they’ll be checking for the presence of lead-based paint and if they’ll be following the Oregon Renovation, Repair and Painting rules to keep you and your family safe.
  • Asbestos cement siding: Asbestos cement siding is another potentially-hazardous material commonly found in homes. If you have asbestos siding on your home, ask your window installer if they’ll be disrupting the siding when they install the windows. If yes, be sure to confirm they’re following the state regulations for handling asbestos containing materials.
  • Mold and rot: If your previous windows were not preventing water infiltration, you may have mold and dry rot issues hidden inside your walls. If a window installer encounters these types of issues when removing your existing windows, there’ll likely be additional costs added to your project and perhaps the inclusion of an additional contractor to replace the wood framing.

Get started

Ready to enjoy the benefits of new high-efficiency windows? Energy Trust of Oregon proudly offers window incentives and can help you find qualified contractors near you.

mom and baby looking out window

Window savings

Find incentives for your new window install.

More resources