Are Storm Doors Insulated? (Answered)

Depending on where you live in the US, investing in storm doors like we’re considering can be a must. But do you need to compromise on insulating your home if you also want to protect it?

Most storm doors have an R-value of 2, and these values are additive. So, if you have a solid, 2-inch wooden door, the R-value will be around 4. If you add a solid storm door with no glass, then your front doors have a combined R-value of 6.

Let’s dig down into the topic of insulated storm doors in greater detail, and find out if they can help insulate your older doors whilst also providing that all-important severe weather protection…

Do Storm Doors Keep Cold Out?

At first glance, storm doors may not seem substantial enough to keep the cold out. They aren’t very thick and they may be partially – or even all – glass. And, there are mixed reviews out there about whether they will really help lower your heating bills.

So what gives? We consulted an office of the U.S. Department of Energy, the Office of Energy Efficiency & Renewable Energy. They have an Energy Saver Office that has lots of advice for homeowners.

The Energy Saver office says that you might help with your heating bills if you add a storm door to an old, energy-inefficient door. But if you plan to add a storm door to a new, energy-efficient door, then you probably won’t get your money back.

Their point is that new doors are pretty good at keeping the cold out. Today,  front doors come in either solid wood or are foam-cored. A 1.75-inch solid wood door has an R-value between 2 and 3. If you choose a 2-inch thick wood door, then the R-value goes up to 4.

Foam-cored entry doors can either have skins of fiberglass or steel. Most new foam core doors have an R-value that ranges between 5 and 6, unless it has a lot of glass, then the R-value goes down. 

But let’s say that you have a beautiful, hand-carved wooden front door that you cherish but that the wind sometimes whistles through. A storm door may be the perfect solution. 

A good quality storm door with a professional quality installation will seal up those drafts, save you some bucks on your heating bill and protect your valuable wooden door.

Here’s the link to the Energy Saver Office advice on doors.

Will a Storm Door Help With Drafts?

Yes. Adding a storm door to an old or poorly fitting door is perhaps the best value that a storm door brings.

It’s surprising where the draftiest spots in houses are. You might think that doors and windows are big sources of leakage in a house. But doors and windows – put together – still don’t add up to the number one source of drafts in a house. 

According to the U.S. Department of Energy, doors account for about 11% of the drafts in your house. Windows account for another 10%. Added together, that’s around  22% of the drafts in your house. 

The largest source of drafts in your house are the gaps around the floors, walls and ceilings, accounting for around 31% of all the drafts. In addition, ducts account for 15%, fireplaces 14% and plumbing holes 13%. Together, these building-type drafts account for 73% of all drafts.

Surprised at the air draft statistics? Here’s a good source.

Drafts are hard to stop around old doors. Many times, they are significantly out of square. One of the best ways to stop the drafts around an old door is to install a storm door. 

First, buy a medium to high-quality storm door. If the door location gets more than a few hours of direct sunlight, experts say to avoid full glass storm doors. In a sunny location, the air between the glass storm door and your old wood door gets trapped. The trapped air tends to superheat and can damage your old wood door.

Then, unless you are an experienced DIYer, consider a professional installation to get the best airtight seal. 

What Is the R-Value of a Storm Door?

We looked for R values for storm door models sold in big box stores. They are pretty hard to find. So, we consulted home improvement experts for their opinion. The best answer we found was that most storm doors have an R-value of around 2.

But, door R values are additive. So, if you have a solid, 2-inch wooden door, the R-value will be around 4. If you add a solid storm door – no glass –  then your front doors have a combined R-value of 6.

Glass storm door on house

Do You Need a Storm Door in Winter?

If your front door is subjected to cold windy blasts and blowing snow, then the answer is yes. Front doors are expensive, but they can last up to 30 years. If you have an unprotected front door and you can see wear from the elements, then the investment of a storm door may be worth it.

Do Glass Storm Doors Help With Insulation?

Glass is a poor insulator, even low E glass (more on that later). However, glass storm doors will help keep drafts at bay. 

Do Storm Windows Help With Insulation?

Windows are notoriously bad insulators. But, storm windows do add another layer of R-value and help with drafts.

If you have an old house, you may have single-pane windows. A single pane window has an R-value of around 1. For double-pane or triple-pane windows, the R-value depends on the gap between the panes. But most double-pane windows have an R-value of around 3, triple-pane windows around 4.

So, if you have an old house with single-pane windows and add double-pane storm windows, your R-value goes from 1 to 4. If you can only afford to add single pane storm windows, you will still double your R-value.

How Do You Insulate a Storm Door?

Storm doors come from the manufacturer with insulating foam cores. If your door has glass, consider applying a UV and infrared film.

How Do You Winterize a Storm Door?

You can winterize a storm door the same way you do a wooden or foam-cored front door, with weather stripping, door seals, and sweeps. For small gaps around the frame, use caulk. For large gaps around the frame, use some spray foam.

Is a Low E Storm Door Worth It?

If you are getting a storm door with glass lights, then invest in the low E glass.

What is low E glass? The E stands for emissivity. Mirriam-Webster defines the word emissivity as the power of the surface to emit (or give off) heat by radiation. Low E glass has an extremely thin coating of metallic oxide. The metallic oxide bounces UV and infrared rays back where they came from but allows natural light through.

Low E glass is like a thermos. On the inside of a thermos, there is a reflective silver coating. The reflective coating bounces the heat waves coming from the hot liquid back into the bottle, keeping the temperature hot for a long time. 

The same thing happens with low E-glass windows. Low E glass on the outside of the storm door prevents UV and heat rays from coming in but allows natural light to pass through. On the inside of the door – inside the house – the heat (or the cooling) coming from inside the house bounces back into the house, like in a thermos.

The only caution here is when you have a sunny front door and a lot of glass on your storm door. On the inside of the storm door, next to your front door, air is trapped in a pocket between the two doors. 

In the trapped space, the low E glass will bounce back the heat rays onto your front door. In some cases, the air becomes so hot it can warp wood or trim. 

If you live in a sunny climate, consider cracking open one of the doors. Or, if your storm door has a screen, lower the glass so the heat can vent through the screen.

Here’s a video on how to winterize your house. It’s pretty long – about a half-hour – but we guarantee you’ll learn a bunch about your house.

Final Thoughts

In certain climate zones across the US, storm doors are a necessity, but this doesn’t mean we have to compromise on home insulation when we fit one.

Doors are notorious for letting in drafts, but the good news is that the R-value of your storm door will be additive – resulting in an extra layer of cold-weather insulation for your home.

Looks like we should get ours fitted as soon as possible. 🙂