How to Soundproof an Attic Floor


Soundproofing an attic floor might seem a bit difficult at first. But it’s actually very similar to soundproofing any other floor in a house or apartment. The only potential difference is the type of noise that you’re trying to block.

If it’s only airborne noise (like people talking) then simply adding some density to the floor with mineral wool batons placed between the joists will already help immensely. But if you also want to block impact noise (vibrations from footsteps, playing drums etc.), you will need a few more methods to block those sounds.

But it’s nothing too complicated, and it’s less than a days work for one person. So here’s a 5 step process you can follow:

1. Place floor floaters underneath the joists

I’ve only recently realized how effective this stuff is, so forgive me for not mentioning it in previous articles. Floor floaters (also known as joist isolators) are made from strong rubber and they provide additional support for the joists. Basically, they prevent the joists from vibrating, which makes a huge difference for preventing impact noise.

Floor floaters are very easy to install (check out the price on Amazon). They have standard dimensions for joists that are typically used in US floors. Place them under each joist and make sure that the distance is between 16 to 24 inches between each floater for best results.

2. Insulate the space between the joists

All of that empty space between the joists is an open playground for noise passing through. The standard material that’s used for covering this space are mineral wool batts. This is a standard soundproofing solution for both airborne and impact noise.

To install this material in the floor, simply cut it to size with a bread knife (if necessary) and place it between the joists until there’s no empty space left.

Here’s a tutorial for installing mineral wool batts between joists.

3. Use soundproofing tape on the joists

Before you install the subfloor, I recommend taping the top of the joists with green glue soundproofing tape. This is a really affordable way to prevent the noise produced by the space between the subfloor and the joists while you’re walking.

Here’s how the pros install this tape:

4. Install a subfloor (floor underlay)

Subfloor is a floor layer installed under the visible floor, as the name implies. It’s firmly attached to the joists using screws or nails. Some commonly used materials for subfloors are plywood, OSB and MDF panels.

A simple subfloor installation guide:

MDF panels provide the best sound insulation, but plywood and OSB are more affordable. All of them can be bought at Home Depot and various hardwood stores. Any of these three underlay materials will work great in addition to Green Glue.

5. Use Green Glue on the subfloor

Green Glue is the crucial ingredient here if you REALLY want to reduce the noise. It’s an awesome impact noise blocker, and makes a huge difference when used between the subfloor and the second layer.

To install Green Glue, simply spread it across the sub floor. Here’s a visual demonstration:

So once you’ve spread the Green Glue across the sub floor, screw or nail the second layer of panels into place.

6. Cover the floor with soft material

Once you’ve insulated the floor from the inside, we can focus on the outside. If you’re trying to prevent the noise from footsteps and make your floor warmer, covering the floor with a thick carpet or similar soft material can really help.

If you want to cover a larger portion of the floor, or cover it completely, there are 2 main options to choose from:

Obviously, the thicker they are the more effective they’ll be. Rug pads are the more popular option, but both are equally effective for protecting hardwood floors and for sound + thermal insulation.

Here is a very simple tutorial for installing a rug pad on your own:

Installing interlocking floor tiles is much easier. There’s basically no installation required. Just connect them on the floor like a puzzle set and you’re done.

Once you’ve finished your project by covering the floor with a soft (and dense) material of your choice, you’re all set! Your floor will be impenetrable for noise and the people downstairs will love you for it.

Additional Tips

Measure your floor first

Measure your floor first before ordering soundproofing material. You don’t have to be super precise, because most soundproofing products are sold in bulk and/or in large tubes anyway. But have an approximate estimate of how much of the stuff you’ll need.

Buy from proven sellers

I’ve linked most of the soundproofing material you can use for this project on Amazon for two reasons.

First of all, it’s much cheaper to buy online than in physical stores. And more importantly, there are real customer reviews (if it says “verified customer” by the comment’s username, it means that this person actually purchased the product before). That’s the most honest product review you can get – another regular person who used the product.

Other websites that sell soundproofing material lack customer feedback. So you have to trust the seller who’s hell-bent on making money off of you that the product works as intended. I rarely link to them unless I’ve used their product or they’re the original manufacturer.

For buying soundproofing products when quality control is really important (especially for walls and vehicle soundproofing), Amazon remains the safest choice.

Ask a friend to help you out

When you’re soundproofing floors you already have one friend – gravity. You don’t have to hold the material on the wall while someone else is screwing it in place and things like that. But it’s still a good thing to have one more person to help you out. Two brains are better than one, and you can finish the project faster as well.

Conclusion

If you follow through with ALL of these steps, you will get the best noise-reduction possible for your attic floor (or any other floor where you apply this guide).

But there’s no need to apply all of these methods to get decent results. If you install a subfloor and spread green glue on top of it, you can get away without inserting the insulation batts between the joists. As I said, not if you want the best results, but you’ll still get very satisfying noise-reduction so that you can walk, talk and play music louder without worrying about the folks downstairs.

If I was soundproofing a floor on a tight budget, I would place the floor floaters, sub floor and green glue installation on my list of priorities. And lest not we forget, cover the floor with a carpet or interlocking floor tiles to cut down on foot traffic noise afterwards.

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