Do Inside Storms Offer a Good Opportunity?

John G. Swanson
August 20, 2012
THE TALK... | Products, Energy Efficiency, Markets & Trends

I've heard them called "inside storms" and "interior insulating panels" and they've been around in one form or another for many years. Some type of frame is put around a glazing panel–usually plastic–and is then attached to the inside of a window to improve energy performance, reduce drafts, and increase comfort. In this week's news, we have Indow Window, a relatively new entry into this arena, announcing plans to roll out its product and program to dealers nationally.

I'm no expert, but it seems that these products have found some success in the market.  They appear to enjoy some popularity for older homes and historic buildings.  I know they are also used in urban areas, where apartment owners will turn to such products to reduce noise levels coming in from outside.  But these inside storm products have never become hugely popular.  Could that change?

That's our poll question of the week.  And I know window manufacturers and dealers may be biased against such products–preferring instead to sell a replacement unit versus an interior panel–but I'd love to hear your thoughts on these products.  Do they represent a good, cost-effective alternative to window replacement?  What are the limitations of such products? What's prevented more widespread market adaptation?  Is there a big opportunity still out there?  Post a comment or email me and share your thoughts.  We'd love to hear from you, particularly those of you who sell or have sold both.  

Survey Results as of 08/26/2012:


Interior insulating panels...

Have potential, but available products have had limitations.




Do not present a cost effective alternative to replacement windows.




Are a cost effective alternative for many customers and a good opportunity for dealers.




Our survey results suggest many window and door industry folks see some potential for inside storms, but the numbers don't suggest many see a huge market for these products.  The comments below indicate some of the limitations people have encountered over the years.  In addition to the comments below, I heard from another reader who noted that he also has a concern about the use of these products on egress windows.

I don't know if the survey results reflect a bias against inside storm products or not.  Exterior storm windows were once a big market, but they slowly lost ground to replacement products.  There's reason to believe, however, the right storm product at the right price would be a success. It will be interesting to see if one emerges.


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We manufacture vinyl interior storms glazed with 1/4" laminated glass to attenuate unwanted exterior noise. Replacement windows have limited available air space and hence, limited STC ratings. Much larger air spaces can be had with interior secondaries. We can achieve improvements of 10 to 20 dB over the existing window's STC rating resulting in combined rating of 41 to 51. Try that with your replacement window! You can rech us at Quiet Window Mfg. (800) 448-9703.

Oh boy, let me get in the way-back machine and crank her up. When we manufactured and sold storm windows 20+ years ago we installed a few acrylic interior storm windows. The margins were very good and, I believe, we gave good value to the consumer with this product.

We found that most people did not want to bother with a panel that had to be removed in order to operate the sashes. Personally, I always liked the concept. It certainly can be a good product if the consumer wants to keep old historical windows. There definitely is a niche for this product. Will it become mainstream? I guess we'll know in a a few years.

One thing is for sure: change is a constant in the fenestration industry. Many that push towards their visions for will fail, and a few are going to be the marquee products as the market shifts like a sandbar in along the banks of the Mississippi river. Those that don't experiment with change, will be stranded on the a metaphorical sandbar: those that do adapt will be carrying the new load down commerce's river of acceptance.

Abe Gaskins, MGM Industries


You mentioned the noise reduction benefits of the interior "storms," for lack of a better word. This is real and even can be done in conjunction with a new window.

One potential issue for the interior storm concept is the potential for moisture to build up in the envelope created between the storm and the window, resulting in damage to wood. These are not sealed units, so moisture from the interior of the home can get through the barrier they create and condensate on the outside window. If used with an older, leaky window, moisture may enter from outside. Enough can cause damage greater than if there was no storm because the moisture is inhibited from evaporating into the room's air.

In other words, it is neither a good or bad idea. Just one which has to be used with caution and knowledge of the environment where it is being considered for use.

Phil Lewin V.P. Technical Marketing - Vinyl Window Designs Ltd.

Interior panels can offer very cost effective energy savings for those who can't afford full replacement, but the panels should be low-e to get the full benefit.