Noise control

[Morag Jones]

Been setting up dust extraction in my little shop and thanks everyone for helpful advice on ducting and design in recent weeks. Have mounted the extractor outside under the adjoining car port to save space (and ears) but I do have neighbours to consider.

Does anyone have tips for sound deadening materials please?

 

[Alasdair]

Have a look at fibreglass or rockwool wall slab insulation. You get 50mm and 100mm slabs. Its not too expensive If I remember it comes in 1200mm x 400 / 600mm
Alasdair

 

[RichardG]

If you get on well with the neighbours then I'd ask them first, no point in doing anything if they're ok as is. Otherwise the only way of cutting the sound down, from my experience, is to build a solid enclosure with the minimum amount of venting, point the vents away from the neighbours. As it's undercover then you could just make a large box out of 18mm exterior ply. If its still too loud then you can try lining the box with acoustic material, or put another skin of plywood on, what ever is cheaper.

This may be of use.

30 Types of Soundproofing Materials Explained

 

[JobandKnock]

Fiberglass is nowhere near as good as mineral wool - mineral wool batting is generally better than loose roll stuff for noise suppression not to mention being a lot easier to install. Cement mineral board also has good sound deadening properties as well as being relatively weatherproof (which is why it is used a backer board in bathrooms and cladding on buildings - recently did a big job where it was incorporated in the floors to give additional sound and fire protection, 12mm thick though - SNR 31)

 

[MarkAW]

Incorporating a baffle into the vents may help

 

[Inspector]

Fully enclosing the DC and using sound absorbing materials like the mineral wool, resilient channel (Z shaped sheet metal that you put between the studs and sheet goods to break sound transmission through the solids) sealant at all seams and a baffled/tortured path exhaust vent with the opening of at least twice (triple or more is better) the area of the air entering the enclosure through the ductwork. The exhaust vent inside path being lined with sound absorbing material.

Pete

 

[baldkev]

recently did a big job where it was incorporated in the floors to give additional sound and fire protection, 12mm thick though - SNR 31)

I did a block of flats nearly ten years ago, using the knauf cement based acoustic flooring, jeez, that stuff was heavy. We formed a chain gang to pass it up the stairwells.

 

[gcusick]

Mass is the only thing that really works. So, ideally, perhaps concrete blockwork. Otherwise, a double skin of 18mm or thicker ply, with rockwool batts between, and, as others have said, either a convoluted or baffled exhaust port.

 

[Morag Jones]

Great ideas thanks - sounds like the box around is the way to go. And I’ll be out scrounging!

 

[JobandKnock]

I did a block of flats nearly ten years ago, using the knauf cement based acoustic flooring, jeez, that stuff was heavy. We formed a chain gang to pass it up the stairwells.

Last year we cut and laid about 15,000 square feet of it (mostly 12mm stuff) for the upper floors of duplexes on the back of having put about 30.000 square feet of fire cladding on the walls in public areas (timber-framed, double frame soundproof construction). Everyone bitched about the weight - it was a real killer. The thing is, though, it is relatively affordable and it just screws onto a timber frame (with piloting), it is almost impervious to water but the soundproofing it provides is amazingly good. I'm sufficiently convinced that my next shed will have a layer of cement fibre board in it, plus mineral wool inside the walls - warm and good soundproofing!

Mass is the only thing that really works. So, ideally, perhaps concrete blockwork. Otherwise, a double skin of 18mm or thicker ply, with rockwool batts between, and, as others have said, either a convoluted or baffled exhaust port.

If you look at the figures you'll find that 12mm cement fibre board outperforms 18mm plywood on both insulation and sound attenuation and it won't rot if it gets wet (and termites don't like it much, either)

 

[Morag Jones]

Last year we cut and laid about 15,000 square feet of it (mostly 12mm stuff) for the upper floors of duplexes on the back of having put about 30.000 square feet of fire cladding on the walls in public areas (timber framed, double frame soundproof construction). Everyone bitched about the weight - it was a real killer. The thing is, though, it is relatively affordable and it just screws onto a timber frame (with piloting), it is almost impervious to water but the sound proofing it provides is amazingly good. I'm sufficiently convinced that my next shed will have a layer of cement fibre board in it, plus mineral wool inside the walls - warm and good soundproofing!


If you look at the figures you'll find that 12mm cement fibre board outperforms 18mm plywood on both insulation and sound attenuation, It also won't rot if it gets wet (and termites don't like it much, either)

Is that the same stuff you use for tile backing? And what is the best way to cut it please?

 

[dzj]

My DC vents outside. The unit itself is in a small room in the shop, so that isn't an issue noise-wise, but the ducting that goes outside made a lot
of unpleasant hissing noises. I made a muffler (plans found on the internet somewhere) and increased the duct diameter.
It made a noticeable difference. A phone app that measures noise levels said it was ~5 dB less.

 

[JobandKnock]

Is that the same stuff you use for tile backing? And what is the best way to cut it please?

Pretty much, yes. These days it is used for weatherproof cladding, sound insulation, heat insulation and of course fire boarding. The difference is possibly the thicknesses we use - mainly 12mm, 15mm and 18mm. (mainly Versapanel and some Versarock). Use an acoustic caulk on the joints, something like AC50

For bulk cutting, I use a Bosch GKT55CE plunge saw (circular saw on a guide rail) fitted with a 4-tooth PCD cement board blade. You can pick the blades up on eBay for around £20 to £25. You don't need a fancy saw, but you do need a guide. This stuff kicks back easily, so don't position yourself behind the saw. You also need a good P3 mask and a vacuum cleaner hooked up to your saw as this stuff is really dusty, ideally a class L or class M vac. Haven't tried a pre-filter cyclone, but a colleague who had one fitted to his saw said it worked really well as cement dust is quite heavy.

For other processing, it drills well with HSS-G drills, although they don't last too long - I prefer to use a TCT drill/countersink to pre-pilot holes when needed as they last far longer than the HSS ones. Bi-metallic holesaws work well, but carbide grit last a lot longer (again). HSS jigsaw blades work on it, but have a very short life - it really require TCT jigsaw blades (the cheap ones from Amazon - less than half the price of Bosch, 60%+ the life span). The jigsaw needs to be corded and it will run hot, The other thing we used for rough cut-outs was a carbide grit cutting wheel (Bosch - from Toolstation) in a 115mm cordless angle grinder - very dusty, but quick. Note that Versapanel can certainly be nailed to a timber framework using a gas nailer and 50mm ring shanks - the only proviso is that the nails need to be at least 25mm in from the edge to prevent cracking. Lastly, I had reasonable success screwing it using a collated screw gun and flooring screws (no piloting) - but it does require a corded screw gun as cordless guns have insufficient power

That's the sum total of a fair few months handling the stuff other than to warn you that it is really heavy.

 

[Morag Jones]

Wow that’s super helpful. Thank you.

 

[baldkev]

The stuff we used was about an inch thick.... it was in sheets of 600 x 900 i think. Knauf brio something, t and g edges like chipboard.... had blue glue!

 

[Hornbeam]

Mass is the only thing that really works.

Mass is the best way to absorb low pitch noise but the other approach is to build a twinskin enclosure around the extractor, with limited connections between the inner skin and the outer skin and mineral wool between the 2 skins. (This is the approach taken with steel cladding systems)

 

[tomlt]

Just remember that your outside shed will need to breathe a little. I have a felder af22 in a little 6 x 4 shed outside, not too loud, but the air pressure inside causes the shed doors and walls to bow out when turned on - I don't have any venting other than the natural gaps in the doors/roof. If you have a vacuum based system these generate a lot more heat too which needs removing.

Cheers, Tom.

 

[Gavlar]

Noise suppression ideally needs mass and absorbency. It will be most effective either close to the source (i.e. as an enclosure) or close to the receiver (i.e. as a noise screen - you could add absorbency or mass to the side of the car port adjoining the neighbours, for example). If going the enclosure route, although no gaps are good, remember your extractor needs air flow to keep it cool otherwise it will overheat. As others have said, baffled vents, bendy air paths and internal fluffy stuff. Don't forget gap sealing around the edges of the access panel.

 

[Woodernhift]

Hi, I looked into sound proofing my workshop so the neighbours would not be trouble. I went to the local college and read the various architectural texts that dealt with soundproofing. There is a big difference between soundproofing for say a recording studio and soundproofing to prevent sound being heard outside. As far as I could tell it comes down to 2 things. Mass and no holes. That is heavy or rather dense material that will not resonate such as high density breeze blocks. The other is no holes, apparently if the total area of gaps comes to more than about 6.26 sq cm then most of the sound proofing is negated, one book likened it to water, gaps equals big leaks. So I lined my workshop with high density breeze blocks, works a treat, but don’t forget the ceiling, reinforced mine with multiple layers of fireproof plasterboard.

 

[Inspector]

There is probably a made in Britain version of Sonopan that could be part of the solution for you. A 4'x8'x3/4" sheet at the Borg store is just under $30Cad/18pounds.

Pete