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  • non-functioning windows
  • uninsulated & drafty windows
  • Preserve the vintage charm
  • & More…

All while maintaining the original glass.

The Problem.

You love the look of your vintage windows, but they’re not aging gracefully. You’re torn because you could always replace them with brand new energy-efficient window replacements, but you don’t want to lose the charm.

Owning an old home can sometimes be challenging. While you love the charm of your vintage home, it can be costly and time-consuming to manage.

Some of the challenges of owning an old home can include:

  • Loss of heat and air-conditioning through leaky windows
  • Water damage and leaks around window frames
  • Difficulty installing and operating bulky storm windows
  • Single pane windows are ineffective at reducing outside sound
  • Expensive to maintain vintage windows
  • Replacing windows can affect original charm and value.

Did you know that the average home can lose up to 30% of its heat or air conditioning energy through the windows? SLIPs are designed to maintain the beauty of your original windows while protecting you from the elements and increasing the insulation of your home. In terms of insulation power, SLIPs are similar to insulated glass conversions.

Another key aspect is that SLIPs will ensure your window sash remains fully operable, without any need to open two sets of windows as you get with many types of traditional storm windows.


To solve this problem, we created Slim Line Insulating Panes to take your Single Pane and transform it into a Dual Pane! This allows you to update your windows’ efficiency while maintaining the character of your home or building.




The Slim Line Insulating Pane is a sleek, low-profile addition to your Single Pane Window.

We have made it possible to add a TEMPERED pane directly to each sash overlaying your current glass set up. 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 Single-hung, double-hung, 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 Benefits.

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

Our goal is to improve upon this by updating the window’s efficiency while keeping the windows true to the look and feel of the building. So how does the SLIP accomplish this:

  • 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

Learn how the window upgrade products can increase comfort, save money, and provide a positive return on investment.

Need more Reasons to Choose Window SLIP?

Before - Single Pane Window

Single Pane Window

Without SLIP
Increased bills due to high energy loss

After - Single Pane Window

Single Pane Window

Reduces Bills by up to 72%!


Once you submit your window measurements, we’ll assemble, and ship your custom-made DIY SLIP™ Kits. These kits contain all the custom-sized materials you’ll need for a successful installation.



DO I INSTALL THIS PRODUCT MYSELF? Yes, Don’t worry we’ve prepared video guides to walk you through every step. With the help of these guides, most of our customers are able to install the kits themselves. However, any handyman or contractor will have the skill set to assist you in the event you need a little help.

HOW DO I GET STARTED? Every kit we create is custom to the measurements you provide, so start by watching out guide on how to measure your windows, then submit those measurements when you request a quote.

WHAT IF I NEED ASSISTANCE? You can always reach out to our team at sales@windowslip.com or fill out our contact form, and we’ll be happy to answer any of your questions.


What do they cost?


Casement SLIP™ cost




Doublehung SLIP cost




Here are the top 10 Reasons to consider choosing a Window SLIP™ to upgrade your single pane windows.

The true mortise and tenon construction of antique windows is incredibly strong and even when it begins to weaken is easily repaired. Many unique window shapes were created because of the craftsmanship with wood joinery. Antique windows were built to last and not land in landfill.

Antique wood windows are constructed of old growth timber. The wood is much denser and more weather resistant than today’s tree farmed softwoods. Delicate profiles are possible because of the density of the wood. The reason these windows are still around, even with years of neglect, is because the wood is of very high quality requiring no cladding or additional materials to give them weather resistance. Minus all the ugly paint your wood windows are usually quite beautiful, graceful, and strong.

Even the glass in antique windows tells a story. It may be roundel or cylinder glass, each indicating a certain era of manufacturing. Old glass has varieties of color and texture that are a delight to the eye. Two layers of glass are better than one, and in an antique home that second layer of glass should be the storm window that protects the original window.

Poly vinyl chloride (PVC) is becoming one of the greatest concerns in the building industry. Not only does the production of it create an environmental nightmare, but the gases it emits over time are becoming a concern. Heaven forbid your house catches fire, and PVC burned will release toxic amounts of dioxin. If you are concerned about lead, please understand that it is used as a stabilizer in the manufacture of PVC. If you are concerned about our planet’s health you should read up on efforts to reduce the use of vinyl.

Replacement windows are set into the window opening, and the sash is smaller than the originals. You get less viewing area and less light. Who wants less light?v

According to the Field Study of Energy Impacts of Window Rehab Choices conducted by the Vermont Energy Investment Corporation, the University of Vermont School of Civil and Environmental Engineering and the U.S. Army Cold Regions Research and Engineering laboratory the estimate first year energy savings between a restored wooden window with a good storm window vs. a replacement window was $0.60. Yup, less than a buck. In their conclusions section they noted “The decision to renovate or replace a window should not be based solely on energy considerations, as the difference in estimate first year savings between the upgrade options are small.” Broken glass, failed glazing, no weather stripping – these small and repairable items are what really effect energy efficiency in windows.

Replacement windows are touted as a way to save energy. But when evaluated from the perspective of the entire production, shipping, installation and removal process replacing windows consumes a whole lot of energy, or viewed the other way an older building has a great deal of embodied energy. If the total energy expenditure to manufacture replacement windows is considered the break even period stretches to 40-60 years. In the words of Richard Moe, President of the National Trust for Historic Preservation

“We can’t build our way out of the global warming crisis. We have to conserve our way out. That means we have to make better, wiser use of what we have already built.”

With replacement windows it’s all or nothing. With repair and restoration we can do as little or as much as needed. Services like replacing broken panes and cords is inexpensive and quick. Even with complete restoration our services are often less costly than wasteful window replacement.

Chances are your windows have done their job for fifty or more years already. Sure, they may be a little creaky and may not be as attractive as they once were, but it’s a far better investment to repair a proven performer than to sink money into a new window that only has a 20 year warranty at best. Chances are your windows have done their job for 50-100 or more years already. Sure, they may be a little creaky and may not be as attractive as they once were, but it’s a far better investment to repair a proven performer than to sink money into a new window that only has a 20 year warranty at best. With proper maintenance your antique windows should last another 100 years. Replacement windows are most often set into the original window opening, and the sash is smaller than the original sash. You get less viewing area and less light. Who wants less light? Replacement windows have a rigid structure that fits within your window openings. Old houses move and shift over time and frequently the gaps that open up around replacement windows and the window openings result in more drafts that the original windows.


“The SLIP Was A Game Changer For Me And My Family.”


It’s ingenious and I would recommend it to anyone who’s wanting to keep their vintage windows but upgrade their insulation. I’m a PNW gal and they’ve just made a world of difference. Thank you Chosen for the great product – I couldn’t be happier!


“Very Good Product”


11 out of 10 these guys are very knowledgeable and they have a very good product their installers are excellent craftsmen I would definitely recommend them for all of your vintage wood window needs.


“Hats Off To These Guys!”


This product is amazing!! I live in a house built in 1930’s and Chosen was able make my windows more efficient, saving me money each month on my electrical bill.


“Would Give A Sixth Star If Possible!”


Wonderful product for my wood windows. Friendly associates.