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One person advised me that I'll cut down on the heat loss in my kitchen by installing a storm door. Another said I'd get better results by replacing the door itself, and then I can either install a storm or not, it doesn't really make any difference. I'm confused.

My existing kitchen door is well hung and with no drafts around the edges. However, I think it's at least 40 years old, maybe more. What is causing a problem is that it has some glass panels, and they are made of single pane glass. My infrared gadget, and my hand, are both telling me I'm losing a lot of heat in those glass panels.

aparente001
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4 Answers4

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I'm going to disagree with the other answers and say that a storm door will provide a very marginal insulation ability. It may not even be worth your time depending on what your actual problems are.

A storm door will protect the main door from high winds which can stop a lot of drafts if that is an issue. High winds can force cold air through the cracks of the door, but in this case, we're not actually insulating - we are providing a form of sealing. The additional physical door and the air gap will reduce air circulation.

A storm door can also help protect the door from debris and keep it cleaner. It can keep leaves, dirt, etc from accumulating on the threshold, and that can improve the life of the seal on the bottom of the door.

Cheap single pane windows on a storm door will do almost nothing for radiative heat loss. The window will feel very cold, and the window on your door will also be just as cold as it is now. A nicer double pane storm door will probably rival the cost of a new main door, so that seems like an odd choice.

If wind and a poorly sealed main door are big concerns, a storm door might be worthwhile, but for general "insulation" purposes... Probably not.

A few sources:

So, forget the storm door. Go with the caulk, spray foam, mastic, and weatherstripping first. Sealing the air leaks is the place to start.

Energy Vangaurd

Blocking wind is essentially mitigating forced-air leaks around the door.

However, the energy savings from storm doors are minimal. Aside from air leaks, doors aren’t a significant source of home energy loss.

Save on Energy

R value of metal storm door with single pane glass: 1.00

Colorado Energy Org

R value of 1. That's not much at all.

JPhi1618
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Does a storm door help prevent heat loss?

Yes, unequivocally. The closed storm door traps a pocket of air between the screen and entry doors. That trapped air significantly slows heat transference from indoors to the great outdoors. How much? From the ACCA Manual J, it looks like adding a storm to any door increases the R-value of the door by about 2.

Here are some better questions to ask:

  • Would a storm door or a new door prevent more heat loss? To answer this, we need to know what type of door do you have now, what type of door you'd replace it with (a steel or fiberglass insulated door?), and which storm door you'd choose. A typical wooden door has an R-value of about 3, whereas steel or fiberglass insulated doors are around 7. If your existing door is not insulated, you can gain about four R by replacing the door.
  • Which is the better value? This depends on your choice of doors. A good R-7 insulated exterior door with small windows can be had for about $250. Storm doors range from half that to twice that.
  • Which is the difference in cost between a storm door and a new insulated door with thermal pane glass? Use this to calculate the $/R of each choice.

I replaced one of my exterior wooden doors recently with an insulated fiberglass door. The before/after infrared photos can measure the difference. We can also hear the difference, insulation also blocks sound transference.

Depending on your climate, it might make sense to do both. In my climate (PNW), the convenience of not having another door to deal with upon every entrance/exit is certainly worth the potential loss of 2 R. Doors are a very small proportion of the walls so they don't make a huge difference in heating, unless they're not air sealed. In northern Michigan where I grew up, the winters are much colder and everyone has storm doors.

Matt Simerson
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If you replace the door with another wooden door with a single pane of glass, you won't see any significant benefit. Unless you go to an architectural salvage yard, you'll probably have a difficult time finding another wooden door with single pane glazing. You can find wooden doors at your local big-box, but they'll come with significantly improved glazing and eye-watering prices ($1500 is about the cheapest at my local favorite).

If you install a brand new door, you'll most likely get a steel or fiberglass door with a foam core. (Doors like this are available off-the-shelf at my local big-box for $150-$300). This will provide significantly better insulation. It will also come with better glass (double pane, low-e coatings, etc) which will show additional insulating improvement.

If you add a storm door, you'll get the added benefits of another layer of insulation (the door itself) plus the trapped air between the doors.

Doing both - replacing the door and adding a storm door - will give you the best possible insulation value.

The question is how much improvement are you willing to spend for and how long will it take for your investment to pay off (both financially and in comfort factor).

FreeMan
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Yes a storm door will help prevent heat loss. Heat loss is measured in resistance (r-value or u-value) and generally speaking the thicker an assembly the slower the heat will move through it.

Wood has an R-value of 1 per inch, so if you add an additional 2.75" of storm door plus the air space you'll add at least R2.75. Current triple pane 2 surface triple low-e coated windows can achieve close to R7.

But having both the old door and a new door in front of it would certainly prevent more heat loss than just replacing the old door.

Generally speaking if you are worried about energy you do air sealing first as that is the cheapest and most cost effective way to reduce heat loss. A good book is :

Insulate and Weatherize : For Energy Efficiency at Home

Also a link to energy.gov that talks about doors:

https://www.energy.gov/energysaver/design/windows-doors-and-skylights/doors

Fresh Codemonger
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