Does a storm door help prevent heat loss?
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.