This question may seem trivial, but I want to be sure. I've gotten conflicting information thus far from a few different big box hardware stores.

We have a door that is in our garage that leads to the exterior of the house. I believe the previous owner installed a door that is not a solid door. From the parts of it that have degraded over time I can clearly see the border of the door to be solid wood and the inner area most likely be MDF? or something else, im not entirely sure. Regardless, the door needs to be replaced.

As I went to look at solid doors, I thought the doors that were completely solid were made out of pure wood. I guess I was wrong? So I guess there are 3 types of doors. The hollow interior doors. A door that has it's border made out of wood, but the entire is solid mdf. And doors that are made entirely out of wood.

Which type of door would I need for my garage door? Can anyone shed some light on the topic? The information you can give, the better.

  • Steel skins, wood frame, insulated core. Works for me anyway.
    – Ecnerwal
    Nov 1, 2020 at 0:17
  • I'm a little confused. One side of this door is the garage. Is the other side "the great outdoors" (i.e., "exterior of the house" meaning "exterior of house+garage") or is the other side "the house" (i.e., garage is outside the house and this is the door in between). That may be an important distinction as I believe there are some strict fire codes for doors between garage and house - i.e., to prevent a car fire from spreading quickly into a house. Nov 1, 2020 at 0:46
  • 2
    I bought a place with an outdoor shed equipped with 2 hollow-core interior doors. It's been 25 years and they are still in good shape. I'm not saying it's a good practice but upkeep makes a big difference and I keep them painted properly. The very best, most expensive exterior door will deteriorate if not maintained... Nov 1, 2020 at 1:01

2 Answers 2


You're mostly correct about the varieties of door, with the caveat that most manufactured wood core doors are probably particleboard inside. (Roughly speaking, the same properties as mdf, but larger chips of wood in particleboard. Probably not as hefty as mdf would be.) There's also fiberglass or steel skinned foamcore doors.

For an exterior door, solid is generally preferable. They're more secure, more durable, and better insulated (especially the foamcore). The amount of weather a door takes might drive you to a steel or fiberglass product. If the overhang is good and you don't get massive temperature cycling from the sun, you might take a cheaper particle core product. As a broad rule of thumb, the more you pay, the more durable a door will be, though regular painting will have a huge impact on how long a door lasts.

Whatever you choose, be sure to paint the top and bottom of the door. Those are the spots most prone to failure.

And last but not least, whoever installs the door should use at least one long screw through each hinge.


It sounds like an interior door was used. I used interior doors on a shed ; I screwed 3/8 " rough sawn cedar ( exterior grade ) to the outer surface . I thought the cedar would protect them but the doors deteriorated in a few years. My other exterior doors are steel with wood frames - no problems. Front door is solid wood - no problem ,but more expensive than steel.

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