A Gothic window in Nantucket. Storm window inserts for the arched, round and otherwise odd-shaped window.

Acrylic opens up all kinds of possibilities. It’s lightweight, more transparent than glass and can be made into just about any shape imaginable. Which is why people with odd-shaped windows, from arched windows to those resembling batwings, have sought us out to make them interior storms.

When we bring a new dealer online, usually one of their first orders is from people with unusually-shaped windows. They didn’t think they were ever going to be able to block drafts on that funky little round window on the second-floor landing.

And then they found us.



How do we make custom-shaped window inserts?

We ask people to make a template by tracing their window onto paper. Tyvek is the best, because it’s strong and light still shows through. On occasion, people will trace their odd-shaped windows onto tissue paper, but that’s prone to ripping. We don’t always need a template. Every window is different – we just try to keep the process as simple as possible. 

Here’s a picture of our Operations Manager Brianna, reviewing some window templates on our conference room floor.

Operations manager Brianna reviewing odd-shaped window templates in the conference room.

After we trace the shape onto acrylic, we use a circular hand saw to cut it.

The circular saw cuts in small straight lines, kind of faceting it a little like a diamond. Then we sand that edge smooth, forming it into an arch or round, or the dips and peak of a window that resembles a fancy badge.  

This is a big departure from most of the inserts we make. For normal rectangular window inserts, we input measurements into a software program that tells our Computer Numeric Control (CNC) machine how to cut the acrylic.

Also, for normal, rectangular window inserts, we use a rigid ABS (Acrylonitrile Butadiene Styrene) plastic carrier with a silicone edge. But that won’t work for shapes that dip, peak, half-round and full circle!

For custom-shaped funky windows, we have to use pure silicone tubing all around the edge, like we used to for all inserts in the old days (which was just a few years ago!) It bends and molds nicely to the edge of round window inserts.

As well as these window shapes:

  • Half-round
  • Oval
  • Gothic
  • Eyebrow
  • Bell-top
    An odd-shaped window that looks like a badge.

Indow vs. other odd-shaped window solutions

It’s hard to find companies that make exterior or interior storms for odd-shaped windows. It’s labor-intensive to craft them of metal or wood, which makes them expensive. Plus, they’re hard to remove and put in.

“People are just generally surprised to find we do it at all,” said Brianna. “A lot of companies don’t. People tend to be surprised by how nicely they fit. They disappear into the frame.”

Have a funky window? We would love to see it! Share with us on social media on Facebook, Instagram or Twitter.

To see some great Indow customs, check out our Bowdoin case study.

Oh, and did we mention that these odd-shaped windows come in all our grade types, from Privacy to our UV-blocking Museum Grade? Check out our product pages to customize your order.

We’re happy to discuss your odd-shaped windows! Contact us here.


Do you have window condensation?

Window condensation is so. not. fun. First of all, there goes your view! And it’s not good for the windows or walls: all that moisture can lead to rot and problems with mold and mildew, as well as lift up paint and damage plaster.  To address the problem of window condensation, it’s important to understand why it’s happening.

Window condensation in a 1911 Craftsman bungalow.

How does it form?

Window condensation forms when the interior surface temperature of your windows is at or below the dew point temperature of the surrounding air in your house. What’s the dew point? That’s when the air is no longer able to “contain” all the water vapor mixed with it. Some of that water vapor has to say “see ya”, so it condenses into liquid on the window pane.

Think of the air as a sponge holding water: when the temperature drops, that squeezes the sponge onto the interior surface of your window.


Window condensation in a mid-century modern home.

What environmental factors affect it?

The inside and outside temperature, as well as the relative humidity of a space, determine whether your windows get foggy. As the air cools outside, it may cause the interior surface of your windows to fall beneath the dew point.

If all other conditions are equal, condensation will occur more quickly in a space that’s more humid. And all kinds of things increase the humidity of a home including breathing, pets, showers and plants to name a few.


Solving window condensation with Indow Window inserts.

Indow inserts are made of acrylic and press into the interior of your existing window frames. The silicone edging creates a near airtight seal so the moist interior air of your house can’t get to the glass window pane. The air in the cavity between the acrylic insert and your glass window also buffers the insert from the cold outside temperature

High-grade acrylic insulates better than glass: acrylic holds more energy and stays above the dew point more easily.   

People with single-pane windows often experience more window condensation than people with double-pane windows, but it can happen to both types of windows. Indow inserts can help solve condensation on both single and double-pane windows. *

Here is a great picture a customers sent of a clear window with an Indow insert right next to a foggy, wet window without an insert:

Window condensation in Boston.


Video: Indow inserts solving condensation.

And here’s a video our creative director did. Michael loves the inserts so much he actually came to work at Indow after buying them for his mid-century modern home in Portland. This video shows how the windows with inserts don’t steam up after a shower. Those without inserts get foggy!



Other methods of reducing it.

  • Lower the relative humidity in a room.
    Lowing the relative humidity can help, although you don’t want to go below 30 percent for reasons of comfort. To check the humidity levels in a house, you can use a hygrometer. According to the U.S. Energy Star program, indoor humidity levels between 30-50% are ideal. Below or above that can lead to problems with bacteria, viruses, fungi and respiratory infections among other problems.


Graphic of Optimal Relative Humidity levels that shows them to be 30-60 percent.


  • Be careful of blinds and drapes if you notice condensation.
    Air moving over a window surface slows the ability of moisture to form. Window coverings can reduce the surface temperature of your window below the dewpoint. And we know what happens then. Condensation!


  • Install and use ventilation fans.
    Control moisture in kitchen and bathrooms with ventilation fans. These fans will pull the warm, moist air out of your house so the “sponge” doesn’t get too full.


  • Buy a dehumidifier or make your own. If you buy one, follow best practices by placing the dehumidifier away from walls and in as central a location as possible in a room. Also, shut windows and doors so it doesn’t have to work to dehumidify the outdoors.

I don’t have window inserts but I do have storms: why do I have condensation?

Exterior storms contain “weep holes” and don’t provide a near airtight seal. In wetter, southern climates, the outside air can be more humid than the indoor air. In this case, the air pocket between the exterior storm and the primary window pane will have high relative humidity and so condensation can occur on the primary window pane when it cools to the dewpoint, typically due to air conditioning inside the home.
 In the case of interior storms made of glass, that can lead to condensation in the cavity on the interior storm itself as moist, exterior air gets into the pocket between the storm and the window pane through the leaky original window.  If the glass of the interior storm window is cooled to the dewpoint by air conditioning,  condensation happens. Indow window inserts, on the other hand, are made from acrylic which is a better insulator than glass and will not drop as significantly in temperature, thereby reducing the chance of condensation.
In northern climates with lower relative humidity, if an interior storm, regardless of glazing type isn’t airtight, moist interior air can enter and condense inside the cavity between the storm and the primary window pane.  Condensation will occur more readily if the glazing material is glass.  Indow window acrylic inserts prevent this from happening. They have a near airtight seal and the acrylic holds more energy so it doesn’t cool to the dewpoint as easily as glass. 

What if I have condensation between the glass on my double-pane windows?

We were recently inside a building with vinyl double-pane windows that had condensation between the panes. This was caused by a crack in the exterior pane that allowed moisture to get into the space between the two panes of glass:

Window condensation between the panes in a double-pane window.

If you have condensation between the glass panes on a double-pane window, then the seal is broken. There are people who specialize in trying to fix this particular problem. Often, though, the window must be replaced. Call your window manufacturer for advice.

*Indow window inserts will reduce or eliminate condensation in most cases, but not all. Sometimes structural issues can interfere with the ability of the inserts to solve the problem.

reduce your carbon footprint at home

Don’t despair if the groundhog sees his shadow – reduce your carbon footprint instead.

What should you do if the groundhog sees his shadow Friday and there’s six more weeks of winter?


Hiding is tempting, we know.  

We have a better plan. Below are six actions you can take to seal out the cold and create a more energy efficient built environment to reduce your carbon footprint. Did you know residential and commercial buildings account for 40 percent of energy costs in the United States? Now that the U.S. has pulled out of the Paris climate accord, it’s more important than ever for individuals and businesses to do their part to make the buildings we live and work in energy efficient.

Top Six Things To Reduce Your Carbon Footprint:

  1. First air seal your attic.
    Then insulate it. Before you do anything else. The U.S. government’s Energy Star program has a
    handy guide a to help you determine if your house needs this and whether you should hire a contractor.

  2.  Install Indow window inserts.
    The U.S. Department of Energy found that Indow inserts reduced the heating and cooling costs in a Seattle home by
    20 percent. That’s a big deal. 

  3. Clean or replace furnace filters once a month.
    Dirty filters can force the system to work harder, reducing its efficiency.

  4. Install a programmable thermostat 
    Thermostats like NEST will automatically turns down the heat when needed.

  5. Turn down the water heater
    By turning your water heater down to 120 degrees Fahrenheit, you will conserve energy while still enjoying a hot shower.

  6. Contact the non-profit Building Performance Institute (BPI)
    BPI will help you find a home performance contractor who will do a home energy audit and find ways to reduce your energy usage whether it’s through weather stripping or a ductless heat pump. That person will assess your home and figure out what works best for you.



Mandi Gubler Solves Her Noise Problem

Nationally acclaimed blogger and DIY expert Mandi Gubler of Vintage Revivals could hear traffic noise coming through the century-old mercantile she’s turning into a home and office in a historic building renovation. It was way. too. loud.  

As Mandi knows, noise can be a real problem. One of the building blocks of a comfortable home is quiet – so you can think. And no drafts – so you don’t shiver. And good design for everything inside it. Fortunately, Indow window inserts delivered all three for Mandi.

Thank goodness she discovered Indow window inserts! She made this nifty video to talk about why Indow Acoustic Grade inserts were the answer for her storefront windows.

Mandi doesn’t just know how to tear down walls and install flooring. She’s also got a eye for good design. She knows how to make a space sing. So when she turned to Indow inserts for the mercantile’s huge front windows and said they actually made the existing historic windows look better, we were really happy.

Happy holidays everyone! Who doesn’t love beautifully crafted old windows? And who doesn’t love to cut out snowflakes? Especially super pretty ones. So to bring those two things together, our creative director Michael made five paper snowflake designs for you to gussy up your windows for the holidays. You can download the templates below.

You and the kids will enjoy our paper snowflake designs

Russ’s daughter Ember making snowflakes for her old windows!

Is there a property with amazing old windows near you? Make some for those windows too! There is not a window in this country that won’t look more fun and festive with these snowflakes on the glass! One of them looks like a heart (see Ember in the picture at the left) and was designed by local Portland snowflake artist Pippa Arend  who also works at P:ear, an incredible organization that mentors homeless youth. 

We love what Pippa has to say about her art, “I am a flake. We all are. We have small, repeating patterns in our lives, things that when highlighted are funny, endearing, pathologic, and revealing.”

How very true. 

We also love this holiday decoration because most people already own what it takes to make it: paper and scissors. And it’s easy to recycle and reuse. 

Please send us photos of your windows and house decorated in snowflakes! (Send to [email protected]) We would love to post them. 

Below are a set of the snowflake templates in color and black and white:





Making historic renovation approachable 

There are a heck of a lot of historic renovation/home renovation blogs out there but we’ll wager there aren’t any with as much heart as Mandi Gubler’s. For years now, Mandi has renovated and redecorated newer homes and chronicled the process in her blog Vintage Revivals  for readers who love her unabashed enthusiasm.

Whether it’s finding just the right color of paint. Or just the right piece of furniture. Or why it’s important to make the front entryway stand out, she makes it fun:

Mandi Gubler is making historic renovation approachable

Mandi Gubler, excited to take on historic renovation!

“The entryway is currently rocking a Beatles piece of art and THE MOST AMAZING FRONT DOOR EVER.”




“ I mean this project will cost you $8. Booyah!”

But more recently she has done something different. She and her husband Court bought a 100-year-old mercantile in their town of Santa Clara, Utah. It had been a grocery store and a gas station and a post office. For a time, it was the last stop for gas and supplies on the way to California in their neck of the woods before I-15 in St. George went in.

It was old, far from perfect, but it had that something that you can’t find in a new house. The original windows were wavy, single-pane glass made by a glassblower and they needed attention. It had history, past lives and a sense of continuity and Mandi just new – immediately – that they needed to buy it. Even though her husband’s first reaction was “No way!” which, we should point out, is not an unusual reaction. People often shy away from historic renovation because they think it’s going to be too hard, or too expensive or not “new” enough in a culture that celebrates new.

Mandi’s husband Court helps with the historic renovation project at the Merc by working on the historic windows.

Fearless Historic Renovation

The cool thing is that Mandi is showing how doable it is and why it’s worth the effort. She’s detailing every last turn of the screw for a reason: she wants people to know what they’re getting into with historic renovation so that they stick with it, because the payback is tremendous. She writes: 

I just wanted to drop in a quick thanks for being so supportive of all of my nitty gritty detail sharing on the boring behind the scenes stuff. I know it’s not the funnest to talk about (can we get to the design stuff already?!!) But it’s really important for me to share that there are actual real life issues that we had to deal with and overcome. That way if you ever find yourself on this journey, you won’t be discouraged by the quirks and roadblocks that come from saving an old building. Because man alive are they worth saving. There is almost 100 years of history here and it’s safe to say that none of the previous owners thought “I shouldn’t sign this easement because in 20 years someone might want to buy it and rip out the parking lot and turn it into a yard.” and guess what? That’s ok.

Next steps for this historic renovation project

And now she and Court are in the trenches turning this old building with a past into a home and office, bringing back to life something that had been so important to this town. And Indow is happy to be helping! The Merc is on a busy road, the noise of which goes right through The Merc’s single-pane windows. Mandi knew right away the windows were key to the spaces character and so she wasn’t about to remove that wavy glass.

So she’s using Indow Acoustic Grade inserts and keeping the windows intact!

Learn how they fit into the journey of reinvigorating the Merc. Please join us Dec. 7 at 1 p.m. PST for a Facebook Live Q & A with none other than Mandi herself.

Historic window restoration in action

Replace? Think again. 

There is a community of people out there quietly working to restore and save America’s old windows. These people know how to repair pulleys and ropes. They can repair rotted sashes. They know the value of rippling old glass and grab it whenever they can to repair cracked panes. Historic window restoration is their life.

They do not subscribe to today’s accepted wisdom that to save energy and do the right thing, you should rip out your old windows and replace them with new double-panes. That is the same voice that has razed historic buildings across the nation to construct strip malls that have made so much of this great and varied country, “Anywhere USA.” That way of being needs to stop. It’s possible to have energy-efficient historic buildings.

We need to value what we already have, including the windows. Character and uniqueness is what helps create a sense of place. And a sense of place is a prerequisite for economic vitality.

Old Window Restoration

These craftspeople quietly toiling on windows the nation over are a tight-knit community. Most are in something called the Window Preservation Standards Collaborative and they wrote the book: Window Preservation Standards.

This is not something they dashed off. To submit a technique to be considered as a “standard” a person must have:

“Used the method at least 100 times, and have been using the method for at least 10 years (20 years is better), and have gone back to check on at least ten projects to learn how the work is holding up, and be willing to share its failures and successes and how you have improved the results.”

We think that’s impressive.

Not only that, every couple of years, they hold a Window Preservation Summit, this year at the Pine Mountain Settlement School in Pine Mountain, Kentucky. At the summit people from around the nation who work on original windows learn techniques for bringing windows back to life so they can live on indefinitely. Sam, Indow’s CEO, attended the most recent one.

Energy-efficient Historic Buildings

He invented the Indow insert to preserve the original windows in his 1906 craftsman home. He wanted to block drafts but he didn’t want to damage the old growth wood. It’s one tool in a big tool box for window preservation experts to use.

“I came away from the Window Preservation Summit with a deeper appreciation of the historic design and functioning of windows,” said Sam. “And the need to be sensitive to what will help windows last through the ages. It does appear that preventing interior condensation is a good thing and a place where Indow inserts can help.”

The people who wrote the above-mentioned book are on a mission. They know the window replacement industry has deep pockets. They know it’s a Sisphyean task to tell America not to rip apart their homes even though it destroys the character and also creates unnecessary landfill waste. But they persist, because they also know it’s the right thing to do. The Window Preservation Standards Collaborative has this to say about what’s happening:

The quicker we put this effort into play, the less time the replacement window industry has to spend their tens of millions in marketing money to discredit this critical and objective effort. The window replacement industry’s aggressive marketing has bamboozled homeowners, contractors and property developers into believing window replacement is the only option.  Just because they claim their products are superior does not make it true. Act now or lose your historic windows forever.

Historic Window Restoration

Steve Jordan, a window preservation expert who has done a Window Hero Webinar with us, talked at the summit about the history of window glass which started with glass blowers, evident in the ripples and “seeds” or bubbles. Jim Turner talked about how to repair steel windows. Gordon Bock, co-author of the book The Vintage House, talked about how the historic preservation efforts have been influenced over the last 100 years: the rise of the automobile and freeways helped empty inner cities which lead to a decline in old building stock and then urban renewal bulldozed down historic structures. At the same time redlining skewed the demographics unfairly.

The summit has been called the Woodstock for window preservationists. Sam encourages anyone interested in historic windows to attend. It’s an education on what’s happened and is happening to America’s homes and buildings. Many of the people who spoke are also members of the Window Preservation Alliance, which has a directory of window preservationists and also window preservation events around the country.

Said Sam, “I learned so much from all these experienced people who have been working in this area for so long.”


home energy score

Jason Elton leads quality management system development for Enhabit

A Home Energy Score is a measure of home efficiency that reveals opportunities for energy-saving improvements and gives homeowners, buyers and sellers an objective way of comparing a home to others in the community. It’s a quick way to get a professional, certified rating that does not involve extensive diagnostic equipment.

The Home Energy Score developed by the U.S. Department of Energy,  uses a 1 through 10 scale where a 10 represents the most energy efficient homes. The scale is adjusted for the local climate and utilities, so the score number really represents how your home compares to the least and most efficient homes in your city.

Anyone can benefit from a home energy score. But, what’s driving a lot of attention here in Portland, Oregon right now is that the score is required for homes listed for sale in starting January 1, 2018. The score will allow home buyers to compare similar houses based on long-term operating costs, which have not been easy for buyers to see. And there’s evidence buyers are interested. A recent National Association of Realtors Sustainability Report shows that 71 percent of realtors said information about energy efficiency is valuable to clients looking for a new home.

What is assessed to create the home energy score?

The score is a rating of the home based on its building characteristics — the “assets” the home contains. For example, assets such as the type, age and condition of the heating system, water heater, ducting and air conditioning are important. So is the leakiness of the structure, and insulation levels in the attic, floors and walls. Window type and panes are a factor, because double and triple-pane windows have a positive impact on a home’s score. Roofing type and color are also factors.

The size of the home is a big influence. Small homes are inherently more efficient because there is less space to heat or cool. A large home, even one that’s built to be as efficient as possible, will tend to have a lower score. It’s like an SUV that uses a lot of fuel. It might be well-built and comfortable, but it just can’t operate as efficiently as a compact hybrid.

A home’s utilities are factors (whether your home uses gas, electric or both, and the source of the power for those utilities). There’s a calculation that takes into account cost of energy and carbon use depending on the utility’s energy sources.

If the house has any solar panels, those are also considered.

The score does not consider lighting, appliances or the number of people living in the home. The scoring software makes estimates on those items based on the size and the number of rooms in the home. This allows a more “apples to apples” comparison of the building characteristics themselves, rather than how the home was used by previous owners.

What you can do to improve your score.

Fortunately, there’s no guesswork when it comes to determining what to do to improve a score. Included in the score is a report with  recommendations to improve efficiency and reduce the home’s carbon footprint. Those recommendations can include any combination of upgrades tailored to the specific home. Some homes may need an extensive home energy retrofit, while others may require just one or two changes.

The building envelope (the walls, ceiling and floor that together enclose the living space) can range from well-insulated and tight to hollow and leaky. Recommendations might include installing or adding to wall, attic, floor and ceiling insulation, and sealing up leaks.

Using interior window inserts like Indow inserts, or exterior storm windows, can favorably impact the score because they essentially convert single-pane wood or metal windows to double-pane. If all the windows are fitted with window inserts or storms, it can positively influence the score.

Mechanical systems like heating systems, air conditioners, duct work and water heaters are sometimes targeted for upgrades. New systems are far more efficient than older, inefficient models. High-efficiency technologies like heat pumps and ductless mini-splits can make a big difference in efficiency and comfort.

Getting started with energy-saving improvements.

Because most energy efficiency work requires specialized knowledge, you’ll most likely want to work with a contractor to find out what it will take to implement the recommendations that come with the score’s report.

Look for contractors with staff certified by the Building Performance Institute (BPI) and are Home Performance with ENERGY STAR qualified. These contractors are trained in techniques to help you get the most out of energy saving upgrades. If your home is located in Oregon, search for contractors who are Trade Allies of the Energy Trust. Another option is to contact Enhabit for independent non-profit advice and access to certified, quality contractors.


Jason Elton leads quality management system development for Enhabit, a non-profit offering homeowner advising and home upgrade services. He has played a critical role in evolving and implementing building science in Oregon, to the benefit of both contractors and homeowners. His interests in energy efficiency developed while working with a local construction company building and remodeling homes, ultimately leading to his career promoting residential energy efficiency.

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Hot windows?

Do you need to know how to block sunlight heat from windows? You walk in and it’s almost hard to breathe it’s so stuffy and you think, “I could roast a chicken in here!” Beth Bryan in Alabama had something like that with her upstairs attic, which was also her office. It’s a lovely space with white walls and dark wood floors, a globe, wooden stars and a sign that says “Let it be.” It’s where she writes her blog Unskinny Boppy in which she muses on everything from her children to the eclipse to how to throw a stylish and inspiring Outlander party. She is all things home, comfort and family.

Cool Down with Shade Grade Inserts

Beth’s office desk faces a window due West, which can make it hard to muse when it’s roasting hot. We supplied her with a Shade Grade window insert that blocks solar heat gain and reduces UV light coming through a window by 90 percent. It took 10 minutes to unpack and install. Beth couldn’t have been happier that she now knows how to block sunlight heat from windows, lowering the temperature from 91 to 75 degrees.

“My attic-turned-office is a nice cool place to work now!” she writes in her blog.

Top Considerations for Treating Windows for Solar Heat Gain

  • Window faces West
  • Climate is southern and hot much of the year
  • High air-conditioning bills
  • Room needs to be cool for sleep


One Comfortable Blogger

Beth loved how the insert blended into the window frame so it’s hard to notice it’s there. We’re just happy she’s more comfortable so she can keep the blog posts coming!

If you have a super hot room that’s making your air conditioner work overtime, think about investing in some Shade Grade window inserts that will help keep your space cool without spiking your energy bills.


If your neighbors don’t love your awesome noisy drumming, it’s OK: there’s a way to quiet the sound so no one has to stop rocking out. Indow Acoustic Grade window inserts will damp the sound. One professional drummer named Dan found the quiet he wanted and made a video to prove it:


The Hows of Noisy Drumming

Most noise leaves or enters a house through the windows. Sound is energy. When you play, the drum vibrates, sending sound waves through the air that can penetrate gaps and cracks in your windows. Anywhere air can get in, sound can too. And it goes both ways, so that sounds from a leaf-blowing neighbor can buzz right through your practice space.

The average double-pane window has an STC or Sound Transmission Class rating of 28. Placing an Acoustic Grade insert over that window will quiet the noise by 50 percent yielding an STC rating of 42-45, according to tests done at the British Columbia Institute of Technology. You’ll get approximately between 50- 70% reduction in noise coming through an operable single-pane window.*

Stay Cool 

Playing drums takes stamina. Dan also bought Shade Grade inserts to block the solar heat gain so his living space stays cool while he plays. 

Indow supports drummers and the parents of drummers the nation over. We also support neighbors of drummers and will help you find quiet and energy efficiency too!


*Note, overall noise reduction performance depends on how much noise is coming through walls, ceilings, floor, and doors. The window noise reduction will be less when Indow inserts are placed over double pane windows. Indow inserts are not recommended to reduce noise coming through laminated double pane windows.