How to Soundproof a Steel Door

Let’s assume for now that you didn’t go for the more expensive option of buying an acoustically rated door in the first place.

Like most people, you now realize just how much of a weak link your steel door is to your soundproofing efforts. All is not lost, though. There are some practical tips on how to soundproof a steel door that you can use.

That being said, here are some of the most practical ways to soundproof a steel door:

Find and Seal the Gaps or Cracks Around Your Door Frame

The simple rule of thumb here is that as long as light can travel through it, so can sound. So whatever cracks exist on the door frame or even on the door itself need to be sealed.

Some of the most obvious places to start looking would be on the door trim or casing.

One of the best ways to find out where those tiny cracks might be hiding include:

• Turning off the light in the room maned by the steel door, you intend to soundproof
• Ask a friend or family member to hold a spotlight on the other side, or you could leave the lights in the other room open
• You will see where the light is slipping through on your door frame

All you have to do then is mark the spot for further treatment. Here are the necessary steps you need to take once you identify the cracks in your steel door:

• Step 1: If you plan to reuse the casing trim, carefully remove it from the jamb. In some cases, you will find that the drywall goes all the to the jamb, and it is probably caulked. You will therefore find an empty gap
• Step 2: Depending on the size of the gap, you can use fiberglass, rigid insulation, backer rod, or rock wool to fill it. However, if the space is particularly small, you can insert mass loaded vinyl or neoprene rubber strips

If you find that the spaces letting in the light and noise are particularly small, you can use products such as Green Glue acoustic caulk to fill them in.

Use Door Gaskets or Weatherstripping

Once you are done with the door frame, the next point of attack will be the gaps between the door and the jamb. This is where most sound will leak through when the door is closed.

To fill in those gaps, you need to have weatherstripping, some scissors or utility knife, a tape measure, and the will to work because it’s going to take some force to jam that seal into those cracks. This is because the seal is intended to be compressed when the door closes and allows the door to easily pop open when you turn the knob. At least that will be the result if the job is done effectively.

Here is what you need to do when using Weatherstripping Tape:

• Step 1: Since weatherstripping tapes come in different sizes, you need to start by measuring the gap at the bottom of your door to the frame as well as the thickness.  If you buy tape that is too thick, it will interfere with how effectively the door can be closed; if it’s not thick enough, then it won’t do its soundproofing job properly. Finally, measure the length of the jambs on your door and buy appropriately sized weatherstripping tape.

• Step 2: Carefully measure and cut the three pieces that will come into contact with the jambs. This is so that you don’t leave any gaps at those points. While facing out, so the door pushes against the strip when it closes, begin with the top jamb. Peel the adhesive backing protection and stick it tightly at the right spot. Pull off as much paper as needed as you go along and be sure to push the foam tightly into the corner edge where the door stop molding meets the jamb.

• Step 3: Repeat the same process with the remaining jambs. Always start at the top and be sure to push the strips tightly into the header piece.

Door Gasket

This is yet another option you can use instead of weatherstripping tape. They will be pretty much the same, with the slight difference of door gaskets being just a bit more expensive. They do, however, work better with steel doors and allow the magnetic strip to get a good grip on the door, thus effectively sealing off any external noise. 

Soundproof or Mover’s Blanket

Surprisingly enough, using a soundproof or mover’s blanket does wonders for soundproofing your steel door. Mostly made out of fiberglass, you can hang these blankets over your door whenever you need to shut out the outside world and prevent noise from coming through.

Although, as effective as these blankets might be, they have a couple of distinct disadvantages:

• They are cumbersome to work with (hanging and all)
• They don’t look that good and probably won’t go with your decor

Other than that, they are very effective and quite affordable.

Use a Door Sweep

One thing that many people forget to do is to cover a crucial part of the door that often goes unnoticed – underneath. If you close the door and stay on the dark side of the room, you will see a beam of light shining through beneath the door.

That part also needs to be soundproofed if you are to achieve your goal. For the most part, you can’t use weatherstripping here.

You can, however, use a door sweep. These work well to keep the sound out but aren’t as easy to install as the door gaskets or the weatherstripping tapes. You might have to do some drilling.

These are some of the best and most practical methods of how to soundproof a steel door. The best part is that many of these methods are simple enough to implement even if you don’t have much DIY experience.