Drafty Windows? Lack of Energy Efficiency? Update your windows to modern standards with this reliable long-term solution.

Introducing the Slim Line Insulating Pane | SLIP™

Over 20 years of experience restoring wood windows have made this product come to life. Modernize your single pane windows and make your home more comfortable, with the SLIP™ (Slim Line Insulating Pane). This update is an innovative and cost-effective way to retain your original, and valuable, wood Windows, while making them more efficient, saving you money, and enhancing the comfort of your living space.

Single Pane to Dual Pane Transformation!

                                                               WE SHIP TO YOU!

How it Works

We have made it possible to add a TEMPERED pane directly to each sash overlaying your current glass setup.  This essentially turns your single pane window into a simulated double-paned window. The frame of the SLIP™ is an attractive, low-profile, pressed metal extrusion. This simple solution can rejuvenate Singlehung, doublehung, casements, and more.  This modernization is a long-term solution that does not seasonally need to be reinstalled.

SLIPs are highly effective, well designed, and well-priced, giving you superior value compared to alternatives. SLIPs have a sleek look and feel with a low profile that blends into the sash; you’ll hardly know they are there. Another key aspect is that SLIPs will ensure your window sash remains fully operable, without the need to open two sets of windows or remove any components as you sometimes get with storm windows or inserts.

The SLIP™ is a tested and proven product that yields great results for the performance of your windows! Click to see the energy results and product studies

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Benefits of the SLIP™

  • Increased energy efficiency
  • Sound reduction
  • Less expensive than a window replacement!
  • Maintains original window glass
  • Windows can stay historically accurate and functional
  • Solid, well-designed construction and material
  • Interior or exterior install
  • Options of Clear, Obscure, or Low-e
  • Tested and proven product (Click to check out Large Projects)
  • low future maintenance costs

We understand windows are an extremely rich aspect of a buildings overall feel and character, and the view to the outside world. Our goal is to improve upon this by updating the windows efficiency while keeping the windows true to the look and feel of the building. Learn how the window upgrade products can increase comfort, save money, and provide a positive return on investment by following the link.
Click Here

Cost Savings

Adding SLIP™ to the windows in an average household will result in a cost reduction of 72.9% for the windows.

Average Energy Consumption Associated with Heat Gain/Loss of Windows at a Typical U.S. Household:

  • Single pane windows…454 THERMS and 474kWh
  • Single pane window with added SLIP™…123 THERMS and 129kWh
  • Single pane window with SLIP™ and weatherstripping…93 THERMS and 97kWh

A therm is a unit of measurement of energy (more specifically, thermal energy). The therm is used to measure gas consumption as well as consumer cost.

The overall U value of a test window wall assembly reduced 61%, from 0.44 to 0.17 BTU, from the base case to the final configuration. The U value reduction from baseline for each improvement is as follows: 18% for weather-stripping, 15% for wall insulation, 26% for SLIPs, and 28% for the double pane.


The creator and manufacturer of the product, Chosen Wood Window, has been installing SLIPs on commercial and residential buildings in the Northwest for over a decade.

For people further out who are looking to modernize their windows, we highly recommend our SLIP™ Kit. We assemble, sell, and ship custom-made DIY SLIP™ Kits. These kits contain all the custom-sized materials that are needed for a successful install. Contractors and handy homeowners are highly encouraged to purchase these kits! We have a full-length installation instruction video as well as a tutorial video on how to measure for your custom-sized SLIPs. Please visit our YouTube page Here.

To get a quote on a SLIP™ kit please fill out our online quote form.

Request a Quote


SLIPs are extremely low-cost and of excellent value. Standard clear tempered SLIPs start at $30/sqft.

This square measurement is not the whole window opening but, less actually, rather the square footage of the perimeter of the glass setup.

Check out our video showing off a SLIP™ project

Residential Homes

Over 20 years of working with homeowners with vintage windows and encountering problems have motivated us to develop this product. We have listened to vintage homeowners’ problems and concerns with their windows, and we took action. Our mission was to create a quality product that would resolve insulation, noise, functionality, and protection, all while being aesthetically pleasing at a reasonable price.

There are a couple of ways to get SLIPs on your windows-

  1. Buy directly from us for self-install…  CLICK HERE

  2. Have a handyman, window, or carpentry contractor install for you

Learn More About SLIPs

Commercial Buildings

SLIPs have successfully been put to use in many commercial buildings, and results have been outstanding. Building occupants noticed how much warmer the building is and how much smoother windows operate when letting fresh air in. Building owners will definitely notice the month-to-month savings in energy bills.

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Awning window with SLIP
Vintage Window Weatherstripping