Is your house too hot in the summer or too cold in the winter? Do you suffer with drafty of windows? Most of us can probably answer yes, and if that is the case then the solution is simple. Add storm windows. The truth about replacement windows is that they are expensive and the payback takes decades whereas storm windows are a lower cost option that help you realize the benefits, both financial and comfort, more quickly than a replacement window could dream of.
Storm windows not only save you money on your heating bill, but they also cut down on noise, protect the prime window (in the case of an exterior storm), eliminate drafts, and a whole lot more.
There are a lot of options when it comes to choosing the right storm window for your house. Do you need exterior or interior storms? Wood or aluminum or vinyl? Press-fit or magnetic frames? Can you make modifications to the frame or does it have to be preserved? There are so many options and manufacturers I thought it would be helpful to give you a guide to storm windows so you can acquaint yourself with the different designs, manufacturers, and options you really have.
Why Do You Need Storm Windows?
While noise and thermal improvement may be issues for certain folks, the biggest advantage is by far their ability to stop air infiltration.
According to a 1999 University of California Berkley study:
“Walls, infiltration, and roofs are the biggest contributors to heating loads in the old, uninsulated buildings.” – Source: Simulation Research
According to the study, infiltration accounts for approximately 28% of heat loss in older buildings and a major place in which that occurs is around ill-fitting doors and windows.
Another important study by The Center for Resource Conservation in Boulder, Colorado in 2011 showed that:
“It is possible to improve the overall energy performance of existing window systems by well over four fold through repairs, weatherization and installing storm windows with insulated frames.”
How Much Could Storm Windows Save You?
This depends on a lot of variables that can’t be determined without a personalized inspection of your house. Questions like climate, HVAC equipment, local power costs, issues with your individual house all make the calculations difficult, but the savings can be significant and the payback is quicker than most other home improvements.
Here’s the proof: Keith Haberern, a professional engineer in New Jersey, performed an energy audit study related to historic windows called “Old Wood Window Replacement Window Energy Analysis” in which he was trying to determine if replacement windows or storm windows would provide better performance and financial savings.
His findings were astonishing!
“The payback period for the new windows is 40.5 years. The payback period for the storm window is 4.5 years.” – Source: Window Preservation Standards Collaborative
Ultimately, the savings are greater in the more extreme climates. Especially heating climates like New England and the northern tier states in the US.
The savings are still there for warmer climates too. Whether the storm is helping to keep the air conditioning in or freezing temps out, they are helping to seal up your house more than most other options available. And they do it with minimal alteration to the original structure.
A typical un-restored, un-weatherstripped double-hung wood window could have an average CFM (cubic feet per minute) of about 0.5. Which means that every 2 minutes, your window leaks about 1 CFM of air.
Compare that same window with the addition of a storm window and you get 0.05 CFM. That means that instead of 2 minutes to lose 1 CFM ,it takes a full 20 minutes. That is a 90% decrease in infiltration!
The other area where you’ll find significant savings with storm windows is in stopping conduction of heat through glass. Glass is a terrible insulator. Duh! It’s not designed to insulate, it’s designed to let in light.
Double-paned windows try to resolve this conduction problem by putting a small airspace between the panes of glass. Sometimes that space is filled with argon of some other gas to improve performance even more.
Storms take the air space to the extreme! The air space between the panes of glass on a storm and the main window is much larger than in any double-paned sash which greatly increases its insulating ability.
What Material is Best?
There is no best material when it comes to storm windows. Come on, you knew I was going to say that right? It depends on the application and your needs. A commercial hotel vs a small bungalow certainly don’t have the same needs, and the same applies to a cabin in Maine vs a Floridian beach house. Different climates and applications need different storm windows.
Here is a quick run down of some of the more popular materials that storm windows are made of and their benefits and drawbacks
Aluminum has been a popular material for the frames of storm windows since the mid 20th century. Most commercially available storm window options (especially for exterior application) are made using aluminum so you’ll have a lot of options to choose from in this material.
- Excellent strength and rigidity
- Factory painted for longevity in a variety of colors
- Wide variety of operability options
- Not historically accurate
- Frames provide poor thermal insulation
A classic material for storm windows that’s been used as long as there have been windows to protect. Wood has endured for centuries and is readily available anywhere you live.
- Strong frames
- Historically accurate
- Readily available material
- DIY friendly option
- Frames provide excellent thermal insulation
- Susceptible to rot and insect damage
- Heavy and difficult to handle
- Very few design options for operability
The newest kid on the block and most common on interior storm windows vinyl is popping up everywhere due to its great availability and relatively low expensive.
- Great flexibility
- Good thermal performance
- Must be install on interior
- Low strength and rigidity
Exterior Storm Windows
The standard storm window for hundred of years was a wood frame with one or two pieces of glass putty glazed in place and hung from storm/screen hangers installed on the window casings. This very simple design is a classic and still very effective. In the mid 20th century manufacturers began looking to aluminum which was lighter and stronger than wood and so the triple track storm window was born.
These storm windows were extremely popular for years because, unlike their wood predecessors they could be opened and closed without climbing up on a ladder. The fact that the first versions were poorly made and very leaky didn’t seem to matter compared to the convenience they provided.
Fast forward a couple decades and the aluminum storm window has really come of age. Though not a historically appropriate option they are very effective. I’ll go through some of the benefits and drawbacks of exterior storms below.
- Protects the Prime Window – Adding a layer of protection to your window is always a great idea. It’s cheaper to maintain a wood storm window than the prime window and aluminum storm windows really need little to no maintenance other than cleaning, so exterior storms really shine here.
- DIY friendly – While aluminum storms are not DIY friendly, wood storms are very simple to make yourself if you are handy. I’ve included a video in this post showing you a simple design and process to make a storm window yourself.
- Huge Variety – Compared to interior storm windows there are more options for exterior storms. With more manufacturers and more styles you have a better chance of finding exactly the style and price you want.
- Operability – There are operable interior storm windows, but there is greater flexibility in exterior storm window options. Some manufacturers have options where you can swap out glass panels for screens in the warmer months without having to completely remove your storms.
- Professional Install – For aluminum storm windows you will usually need a professional to measure and install them. Once they are installed this isn’t an issue, but the initial expense and trouble is an issue sometimes.
- Appearance & Approval – Installing an exterior storm window means having to get approval from a historic district if you are in one. They may only approve certain types of storm windows or none at all. Be sure you check what the rules are in your area before you end up with a bunch of paid for storm windows you aren’t allowed to install.
Exterior Storm Window Manufacturers
Below is a list of some of the most popular makers of exterior storm windows and a little bit about their products. This is just a small sampling of some of the larger manufacturers since there are literally hundreds of quality makers out there.
- MonRay – MonRay has been making storm window since 1947 and they make have made a ton of them. Made from premium aluminum frames these storms have a range of operability options and have been installed on residential projects as well as huge commercial projects around the country.
- Allied – Allied makes interior storm window too, but they are best know for their exterior aluminum storm windows. Again, lots of style, operability, and color options to fit your needs.
- Larson – Larson makes windows, doors, and storm windows. Similar to the above options they manufacturer aluminum storms and also have a new ComfortSeal interior option.
- QuantaPanel – QuantaPanel makes interior and exterior aluminum storm windows with operability and changeable screen and glass panels available in over 250 colors.
If you are a DIYer like me then I have a tutorial and woodworking plans for you to make your own DIY wood storm windows with a few basic shop tools.
Interior Storm Windows
While storm window shave traditionally been installed on the exterior of a window there is a growing segment of the market that prefers interior storm windows. You might be asking, “Is it really a storm window if it is on the inside?” The short answer is yes!
Storm windows typically served two purposes. 1) To protect the prime window against the weather 2) To improve the energy performance of the prime window. It’s this second purpose where interior storm windows really shine. They can be very effective at improving the efficiency of old windows without compromising the exterior aesthetics.
Some of the key benefits and drawbacks of interior storm windows are below.
- Ease of Installation – No more climbing up on a ladder and precariously installing your storms. Interior storm windows can be safely installed from indoors. Plus most of these windows require only minimal mounting hardware since they are not subject to the exterior elements and some like Indow have zero hardware and just press-fit into place which makes installation about as easy as it can be!
- Better Air Sealing – Exterior storm windows need some venting to perform well and not have moisture issues (or rot if you’re using wood storms). Interior storms don’t have this issue and generally have extremely tight seals compared to exterior storm windows.
- Lower Prices – Less complicated installation coupled with a storm that doesn’t have to be as tough as an exterior version usually equates to a lower price point for interior storms compared to exterior storm windows.
- Historic District Compliance – No need to get approval from a historic district for interior storm windows since they are treated much the same as other interior window covering likes drapes and blinds. Unlike exterior storms, interior storms of any style are permitted for historically significant properties.
- Lack of Protection – Sadly interior storms do nothing to protect the prime window from the wear and tear that mother nature subjects it too.
- Moisture Issues – Some interior storms can cause moisture build-up between the storm and the prime window. The cause is based on a lot of potential issues like high indoor humidity, leaky prime windows, improper installation, HVAC design, etc. It doesn’t happen to all interior storms but it is a potential side effect that needs to be considered depending on your windows and weather.
Interior Storm Window Manufacturers
Below is a list of some of the most popular makers of interior storm windows and a little bit about their products.
- Indow – Indow makes a compression fit storm window that requires absolutely no mounting hardware! Check out the video below to see how easy the installation process is. They are a vinyl frame around acrylic glazing with a silicone compression tube. They have a lot of different grades to choose from like Acoustic, Shade, Sleep Panel, etc. that allow you to customize according to your needs, but they do not have an operable option. Disclosure: Indow is a sponsor of this post, but the opinions expressed are my own.
- InnerGlass – Innerglass makes an interior storm with a vinyl frame around your choice of glass (tempered, low-e, standard, etc.). It has a compression fit technology and requires minimal mounting of hardware. They do have operable interior storm windows to work with double-hung windows and slider options which are an added convenience.
- Allied – Allied manufactures aluminum interior and exterior storm windows. They have several options when it comes to operable or non-operable storms, different glass options up to 3/16″ thick and different colors of the aluminum frames. Installation of these effective storms requires a bit of skill and is not in the DIY category in my opinion.
- Magnetite – Rather than using a compression tube magnetite windows have a magnetic frame that is installed onto the window casing and then the storm window is held in place by the magnets on the perimeter. Magnetite is acrylic glazing in various grades like Indow to focus on Sound, UV-blocking, Privacy, etc.
Again if you don;’t want to go the route of purchasing interior storm windows I have a tutorial and plan for making your own interior storm window which is slightly different and a little bit easier than the exterior storm windows I mentioned earlier. You can find that DIY Interior Storm Windows tutorial right here.
Maybe one of these options is right for you or maybe it’s another type of storm window, but the main thing is to realize the comfort and savings that storm windows can provide. You’ll not only retain the original historic windows, but you’ll get your investment back in years rather than decades like replacement windows.
What kind of storms do you have? What do you like or dislike about them? I’d love to hear your thoughts in the comments below.
Founder & Editor-in-Chief
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.