I’ve previously discussed fire-rated doors and hurricane-rated doors here on the blog. Those are the most well known and loved door ratings , but did you know there are more ratings than those?

In fact, even within those ratings there’s quite a bit of differentiation that’s actually pretty detailed. If you’re new to the door and lock industry, now is a perfect time to go over some of that basics that come with door ratings.

Door Ratings: The Basics

Sound Transmission Class (STC) Rated Doors

Sound transmission class (or STC as I’ll refer to it from here on out in this post) is a much fancier way of saying “soundproof” and if you’ve ever wanted to soundproof a door, you’ll need an STC door to accomplish that.

The STC ratings were developed by ASTM International. With their methods, they determined a rating to depict how much sound will pass through a door at any given time.

The higher the STC rating on a door, the less sound able to be transferred through the door material.

There are certain materials (such as wood) which  naturally have sound-dampening qualities, whereas other door materials—such as metal—lack them.

However, certain steps can be taken to increase the STC rating of a door. For example, metal can be filled with insulation to help reduce the amount of sound that travels through the door. This, in turn, raises the STC rating on the door.

Fire-Rated Doors

Fire-rating is the most well-known type of door rating, and with good reason. Fire-rated doors keep fire from passing through an opening for a specified period of time.

Certain buildings require fire-rated doors and different locations in those buildings can require different ratings.

There are six fire-rating classifications:

• Class A: Three hour rating for walls separating buildings or dividing a single building into fire areas.
• Class B: One and a half hour rating for enclosures such as stairwells or elevator shafts
• Class C: 45 minute rating for corridors and room partitions.
• Class D: One and a half hour rating for exterior openings subject to extreme fire exposure.
• Class E: 45 minute rating for exterior openings subject to moderate or light fire exposure.
• 20 Minute Fire-Rated Door: These doors don’t fall into a class but are typically found on interior rooms.

There are quite a few rules that come along with fire-rated doors and you can find more information about them here.

Windstorm-Rated Doors

Windstorm-rated doors get their most use in tornado- and hurricane-prone areas, but they’re used all over. These doors are rigorously tested to make sure they stay latched when met with high winds and hit with blunt objects.

They also have a range of pressure and water infiltration ratings that are calculated as part of the overall door rating.

Blast-Resistant Doors

Blast-resistant doors are doors which are rated to do exactly what you might expect—remain latched during a blast. These are most common in hazardous material facilities.

Blast-resistant doors are grouped into one of the following four categories:

• Class A: Provides life safety.
• Class B: Protects equipment and supplies.
• Class C: Protects against communication of detonation.
• Class D: Protects against mass detonations.

There’s a very informative technical bulletin by Overly that gets into the nitty gritty of blast-resistant door ratings. Check that out for more detailed information if you’re interested.

If you have questions about any of these ratings, we’ve got plenty of people at LockNet who would love to talk to you more. Just contact us anytime!