Forum Connect

1.  Guidelines for Historic Window Replacement

Posted 08-30-2017 11:54
We are currently working on an easement where there may be an economic hardship argument to be made for the full replacement of a number of the historic windows, which are a character defining feature. I would like advice from others with experience in determining when it is appropriate to allow for the replacement of historic windows in the face of economic hardship. Information about projects applying for preservation tax credits would be particularly helpful.

Angelina Jones
Conservation and Easements Manager
Chestnut Hill Conservancy
Philadelphia PA

2.  RE: Guidelines for Historic Window Replacement

Posted 08-31-2017 09:12

Not knowing the details of the situation, the building, or the economics, I can offer this:


Assuming a high-quality replacement window will be required, the cost will likely be equivalent to repairing the historic windows. Run the numbers for rehab vs. replacement and see how it shakes out. Alternately, is a compromise solution that requires rehabilitation of the windows on the primary elevations and replacement on the secondary elevations? Just a thought.




Devin A. Colman | State Architectural Historian

Vermont Division for Historic Preservation

One National Life Drive | Deane C. Davis Building, Floor 6 | Montpelier, VT  05620-0501


Phone: 802-828-3043




3.  RE: Guidelines for Historic Window Replacement

Posted 09-13-2017 17:13
Hi Angelina,

Full disclosure: I work for a small startup in Portland, Oregon called Indow that makes interior window inserts to improve the energy performance of historic windows. I wouldn't normally chime in on something like this, but what we make might help since our inserts allow people to keep their old growth wood windows.

Our inserts have gone into a pre-Revolutionary War house in New Hampshire, a Frank Lloyd Wright house and a Case Study house, just to name a few. We've also been on This Old House. In all cases, people wanted to improve the energy efficiency of their original windows without damaging them or visually altering the exterior in any way. Historic preservationists also like them because they are edged in silicone and press into the interior of the window without a track system leaving that old growth wood intact.

The inserts essentially help single-pane old growth wood windows perform like new double panes. The U.S. Department of Energy did this study out of Seattle.  Since most historic windows are out of square, we laser measure every window and then each insert is custom made for a precise fit.

Please let me know if you have any questions or if we can help in any way.

P.S. Periodically we hold Window Hero Webinars with window restoration experts to encourage people to restore their windows and learn different ways it can be done.

Carrie Sturrock
Portland, Oregon

4.  RE: Guidelines for Historic Window Replacement

Posted 09-14-2017 08:41
I'm a bit confused and find it inappropriate that commercial, for-profit companies like "Indow" are allowed to blatantly promote their products on this forum.I

The top source for best practices and energy efficiency for the rehabilitation of historic windows is the not-for-profit, peer reviewed "Window Preservation Standards". This book is being used by SHPOs, HPCs, window restorers, architects and preservation specifiers.

Our organization, "The Window Preservation Standards Collaborative" is gearing up for our bi-annual "Window Preservation Summit" in Pine Mountain Kentucky the week of September 24. We take no funding from any commercial products and are an objective,  science based organization of hundreds of dedicated energy efficiency experts, architects, window restorerers and HP staff  from all over North America. You can learn more at

Bob Yapp
Hannibal MO

5.  RE: Guidelines for Historic Window Replacement

Posted 09-14-2017 10:56
Edited by Rebecca Bice 09-14-2017 11:01

Hi Bob,

Thank you for your feedback; we will take your concern into account as this community grows. As it stands now, Forum Connect is open to everyone, and we allow organizations and companies to talk about their products, events, and work, as long as the post contributes constructively to the ongoing discussion. We monitor Forum Connect at all times and do take down posts that spam the community or inappropriately advertise products. I am happy to talk more about this with you if you'd like. You can message me directly on Forum Connect, or you can contact me at


Rebecca Bice
Associate Manager for Forum Member Engagement
National Trust for Historic Preservation
Washington DC