Does Loft Insulation Reduce Noise?

noise reduction loft insulation

Last updated: June 23, 2022 at 13:38 pm

If you’re using your loft as an office, spare room or anything else, the most obvious thing to consider is whether your existing loft insulation will muffle any sounds sufficiently. After all, it’s very bulky, and mass does matter for soundproofing.

If you’re working in the main part of your home, there’s insulation there, too, in the external walls. However, this will do nothing to reduce the noise created inside your home and have a limited effect on external sounds.

Unfortunately, most standard insulation is designed to keep in the heat rather than block sound waves from passing through. Heat and sound waves behave differently and so must be blocked differently.

Does Loft Insulation Reduce Noise?

It may be partially effective at blocking high frequency sounds like talking, but impact noise such as walking around will likely still get through. Similarly, if you have kids playing video games or members of your family watching tv, the low frequency sounds will still be audible.

If noise is not a major issue and you want one product that will do it all, your best bet is mineral wool. It’s a lot more dense than standard insulation, so it is great at keeping in heat. It is also made of loosely packed fibres, so the sound loses a lot of energy trying to push through them.

What If I Add Extra Layers of Insulation?

If you use mineral wool, it might help a bit as it has some soundproofing qualities. However, other types of insulation will keep your home warmer rather than make any major difference to the sound that can get through.

Acoustic Insulation

If you’re working in the loft, have a child’s playroom there, or simply see it as a weak spot for sound ingress, then acoustic insulation is a possible solution. As explained above, keeping out sound and keeping in heat are two different goals; generally, one product will not do both.

So, if you want to lay acoustic insulation, you should aim to pair it with some thermal insulation to ensure your home stays warm and quiet.

This is how you lay the insulation:

  • Measure your loft to find how much insulation you need. Gaps reduce the quality of the soundproofing, so measure carefully to ensure a snug fit.
  • A lot of acoustic insulation comes in sheets, so you can easily cut them to size and lay them on top of your existing insulation. Use a sharp knife to do this.
  • For soundproofing to be effective, you need to seal up all gaps. Once the insulation is laid, use acoustic tape to seal the joins between each sheet and acoustic sealant around the edges where it meets the wall.

Other Soundproofing Options

If you already have thick loft insulation and don’t want to lose space by adding acoustic insulation on top, there are other products that will be equally effective.

Mass Loaded Vinyl

mass loaded vinyl example

Mass loaded vinyl is an excellent soundproofing material. It is thin and flexible, meaning it can be cut to any size and shape you need and can even be wrapped around pipes. It is doubly effective at soundproofing for two reasons. Firstly, it is designed to bleed away the sound wave’s power and reflects it back in the direction it came from. Secondly, it absorbs the sound wave and bleeds away its power.

Mass loaded vinyl comes in sheets which are usually 2-5mm thick. The sheet size varies, but 2 metres by 3 metres is a standard size. Here’s how you lay it:

  • Measure your floor and cut your MLV to size. Do this carefully as you want it to fit as snugly as possible
  • Although it’s a thin product, MLV is thick enough that scissors will not work. Use a Stanley or utility knife
  • Lay the vinyl across the floor of your loft. Nails, screws, and staples will all work to fasten the sheets onto the floor joists
  • Use an acoustic sealant to seal the edges where the MLV meets the wall
  • Use acoustic tape to seal all the joins between the pieces of MLV
  • If you want to stop noise entering the house from outside, you’re done, but if you plan to use it as a room, lay flooring on top

Sound Mats

Sound mats are soundproof panels made of layers of soundproof material. Many types use a sheet of mass loaded vinyl, a layer of closed-cell foam to absorb impact noise, and then a final layer of mass loaded vinyl.

Because a sound mat is thicker than other types of soundproofing and uses different types of material, it is excellent at blocking all kinds of sound. Unfortunately, it’s more expensive than mass loaded vinyl or many types of acoustic insulation. However, if you have a significant noise problem, it may be worth the extra expense.

Add-Ons

These options will not significantly block noise on their own but paired with the options above, they will enhance the soundproofing effect.

Thick Carpet

Laying a thick, deeply piled carpet will help keep the heat in and absorb some sound. Unless you’re trying to make an attractive room, you don’t need to worry about the colour or pattern.

Go to carpet warehouses and look for offcuts that are the right size. The thicker the carpet is, the better.

Old Gym Mats

Admittedly these may be too heavy to hoist into the loft, but gym mats are made from thick rubber that will absorb a reasonable amount of sound. The best part is that you can ask around gyms and schools in your area to see if they have any old mats. You could get them very cheaply or even for free.

If you lay these on the joists and have not laid a floor, please remember they are not as solid as they look. If you step on them between the joists you could end up taking an unplanned and expensive trip through your ceiling!

Acoustic Underlay

Acoustic underlay is only an option if you’ve laid a floor in your loft. If so, laying good quality acoustic underlay paired with a thick carpet will make a reasonable difference to the sound that can get through.

Acoustic underlay is laid the same way as regular underlay. As explained above, sealing all the gaps is key. Use acoustic tape on the joins.

Conclusion

If you have a problem with noise in your loft or entering the house through it, then standard thermal insulation will not help much, regardless of how much you use. Keeping in heat and blocking sound are different tasks, and you need to choose a product tailored to your goal. If you need to use just one product, then mineral wool insulation is your best option.

However, it is far better to use a product specifically designed soundproofing solution like mass loaded vinyl, acoustic insulation, or sound mats. Consider the space, your budget and how much noise you need to block and decide on the best option for your needs.

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About the Author: AJ

AJ is a self-confessed soundproofing nut. He has written full-time on Quiet Living for the past 3 years, and has a wealth of knowledge about living a quieter life, soundproofing and fixing loud noises.

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