ᐅ Soundproofing – Differences in Interior Doors?

Hello dear forum members,
I would like to ask for your experiences regarding sound insulation in interior doors.

Last year, we had our own house built and also did a lot of the work ourselves. Among other things, my father (a longtime carpenter/joiner) and I installed the interior doors by ourselves. I have read a lot about home construction... but some topics, like the one mentioned above about interior doors, took a bit of a backseat. Honestly, we focused more on appearance and price than on function. In the end, we chose what we think are visually appealing interior doors with honeycomb core. After several months, however, I have realized the reason for the low price... in my opinion, the doors provide almost no sound insulation. Since we have a very open living area, a lot of noise carries into the upstairs rooms. I might be able to live with that if we didn’t have small children who are very light sleepers...

By now, I have come to the conclusion that “buying cheap means buying twice.” So at least I want to replace the doors on the upper floor. But how much improvement does such a replacement really bring? Since the doors need to fit the existing frame, the selection is limited. I have now found doors with a tubular chipboard core... does that already offer a meaningful improvement? Or do you need a solid core door?

With the current interior doors, I cannot notice much difference between closed and open. Does anyone have experience with how much sound insulation different door cores provide? For example:

- Honeycomb core / 20 dB
- Tubular chipboard frame / 40 dB
- Tubular core / 50 dB
- Solid core / 55 dB

The goal is to figure out whether it makes sense to choose a certain core type. If the difference between solid core and tubular chipboard frame is small, then tubular chipboard is enough for me... if only the solid core really improves sound insulation and the difference between tubular core and honeycomb core is barely noticeable, then I can save myself the tubular chipboard option...

What kind of doors do you have and how satisfied are you with the sound insulation?

Best regards,
Basti2709

We decided to use solid particle boards, and for the utility room and bathroom with washer/dryer, we even added an extra soundproof strip on the floor and opted for full-surface adhesive bonding of the door frames instead of point fixings.

We are satisfied, except for the spin cycle of the washing machine.

Side question: Do you have a controlled mechanical ventilation system? Because the weakest point lets the sound through. The noise passes through the air gaps, not through the door panel itself.

toxicmolotow schrieb:
We chose solid core panels, and for the utility room and bathroom with the washer/dryer, we even added an extra soundproofing strip on the floor and used full-surface adhesive bonding on the door frames instead of just fixing them at points.

Apart from the spin cycle of the washing machine, we are satisfied.

I see fewer issues in the utility room... although there is only an interior door with a honeycomb core installed there as well, because there is a second door in between, you barely hear anything from there in the living room (even with spinning). This second door is the only other one in the house, a sliding door... it is also much heavier and made as a solid core panel... in my opinion it blocks sound better than the honeycomb doors with frame.

toxicmolotow schrieb:
Quick question: Do you have a mechanical ventilation system with heat recovery? Because the weakest point lets the sound through. Sound passes through the gaps, not through the door leaf itself.

No, no mechanical ventilation system with heat recovery... I would need to measure the air gap under the doors... but at first glance, they don’t seem too large... what would be considered “normal” here?

Is it possible to check the specifications with the door manufacturers? Solid core doors are heavy, @toxicmolotow, how many hinges do you have there? Is it still feasible with just two?

Only two hinges. Even for the framed glass door, which carries the heaviest weight.

In general, I would always recommend using three hinges for solid particleboard doors, as this better distributes the door’s load and significantly extends the hinges’ lifespan. Regarding mechanical ventilation with heat recovery, the ventilation can also be routed through the upper door frame. This was discussed somewhere here before, but I can’t find the thread at the moment.