0
         Roof high side

Window __o  o  o  o  o__ Door 
         o--|--|--|--o
         o--|--|--|--o
         o  o  o  o  o 

         Roof low side

I'm planning a soundproof shed using pine posts, laid out in 3.6x2.7m as above. Grid = roof struts.

Each post is +-10cm diameter, each gap is 75cm. Wall plan is immutable (give or take a few cm). Height is 1.8m on high side and 1.7m on low side of roof (tilt is for rain, no snow here). Treated pine posts are cheap, and good for years in this mild coastal climate.

Noise insulation is key, as I'll be using powertools in the shed. Wall sections will be filled with sand; and posts should transfer vibration into the turf. I also want to prevent roof and floor from leaking much noise. Ventilation being at odds with noise and water proofing, I have some misgivings about this.

Floor seems to offer two options, either enclose wall sections...

  • right down to the ground, with packed sand inside to maybe 10cm + fine gravel or pavers on top, or
  • leaving 10-15cm space at bottom and do floorboards / joists up to same height, for air underflow.

Ceiling noise reduction is more of a challenge, as noise out the top may travel. Should be lightweight as possible. Grid shows where roofing posts could be laid using saddle notches, sectioning the roof. Insulation then goes into those sections (about 10cm high given post widths), or on top of framework.

How would you soundproof this? Bonus points: How would you soundproof this while optionally allowing natural light in through the roof on days where noise is less of an issue?

Note I am not in UK/US/CA/AU or the like, so no highly specialised solutions, please.

1
+50

There are a few approaches to soundproofing. One is a lot of mass, like you're describing with your walls. Another is mechanical isolation, two solid "walls" with no openings between them, a gap between them, which can be air, and no mechanical connection other than where they are fastened to the building structure.

You can use the same principle with the roof. Make it a double wall of clear material such as this clear corrugated plastic panel, which will provide light in the daytime:

corrugated panel

Those kinds of panels come in various lengths. A standard size is often 8', which might be a hair short for your dimensions. A 12' length can be easily cut to the size needed, and a little extra length will give you some protective overhang. The panels are self-supporting, you won't need a bunch of roof struts or posts. You also won't need to insulate the roof.

There are matching mounting strips that you would use at the high and low walls. The inertness of the walls will dampen noise transmission at those points.

mounting strip

Rip some angled strips of wood to put under the mounting strips to compensate for the roof pitch so that the mounting strips will be square with the panel.

You can improve the isolation even more with a layer of rubber or dense foam weatherstripping, or even a strip of wool felt, between the mounting strip and the panel.

To separate the two panel layers, you use two mounting strips back to back on top of the first panel (use long screws to go through everything and then into the top surface of the wall). The back-to-back strips will be offset by half a corrugation so the panel corrugations are parallel between the layers (uniform gap).

Between the high and low walls, there will be an air gap between the layers. The combination of the plastic material and the isolated layers will be very effective at blocking noise. It will also be very light weight.

At the two sides, you would need to seal in the sound. The side walls will need a wedge-shaped top piece to follow the roofline, and the height will need to match the panel at that point. The walls will dampen sound for any connection there.

The gap between the panels needs to be sealed on the sides, and both layers should be firmly fastened to the walls. How to fasten and seal the bottom panel to the side wall will depend on whether the corrugation is facing down, up, or transitioning.

  • If it's facing down, put a layer of rubber or dense foam weather stripping, or a strip of wool felt, between the panel and the top of the wall and screw the panel down.
  • If it's facing up, round a board to fit the corrugation (use the mounting strip as a guide). Alternately, if a standard diameter PVC pipe matches the curvature of the panel corrugation, cut a section as a mounting surface. Use silicone caulk to adhere it to the top of the wall and fasten through it.

  • If the corrugation is transitioning, cut up a few mounting strips to create pieces that fit the gap between the panel and the top of the wall. Position these every foot or so to serve as fastening supports. Adhere the supports and the panel to the wall with expanding exterior-grade foam, which will also seal the gap. You can then screw the panel down at the support points.

Between the two panel layers, see if the gap is the same as a standard diameter PVC tube. The tube can be glued to the bottom panel and act as the spacer (fasten through the tube at the support points). Another option is to use foam pipe insulation of a slightly larger diameter than the gap, with a PVC tube inside it to maintain its shape (fasten through the tube). The insulation will seal the gap between the panels.

pipe insulation

If you plan to use the shed at night, put fluorescent or LED lighting inside. You can fasten it to the top of the walls.

If your goal is to block noise, take the walls all the way to the ground. Then put whatever flooring you want inside.

Ventilation will be a problem because any opening will compromise the noise control. If there will be a wall facing away from your house and not facing neighbors, you could put a small window or two in that wall (triple pane will provide better noise control). You can open them to get some air and close them while you're working. From your description of sand-filled walls, you would need to frame out the openings.

If you want a "sealed system", you may need to just open the door occasionally for fresh air. You can condition the temperature, though. If you will be working and using equipment, there might be little need for heat, even in the winter, because it will be well-insulated. In the daytime, you will also have a lot of heat gain from sunshine through the roof.

For cooling, you could use either a portable AC unit with an exhaust vent to the outside (put the hole on the least problematic wall, like the one facing away from your house, close to the ground; run a duct through the wall and use a self-closing exhaust vent to keep critters out), or a two part AC unit that needs only a small pass-through that can be easily sealed.

  • In 7 years of using the SE sites, I've rarely had such a clear, well-explained, step-by-step answer that takes all of my considerations into account. If you don't teach - you should consider it. Few have this knack. – Engineer Jul 8 '17 at 6:57
  • @ArcaneEngineer, thanks. This was an interesting question and sounds like a fun project. Good luck with it. – fixer1234 Jul 8 '17 at 8:10
  • BTW, it occurred to me that the corrugated panels are made of different materials and have different thicknesses. It's possible that certain frequencies might pass through the roof. If you find that there is some noise getting through, there's something you can retrofit that will cost you all or most of the light. Remove some of the upper panels for access and temporarily put some of the screws back to hold the bottom layer in place. Then lay some dampening material on the bottom layer. It doesn't need to cover every square inch; you can leave some gaps for a little light. (cont'd) – fixer1234 Jul 8 '17 at 16:24
  • You want something thin enough to leave a little space to the top panel (no mechanical connection between the layers), that conforms to the corrugations, and is not ridiculously heavy. If the bottom panels are too thin to support the weight, add a panel layer to double the thickness of the bottom layer (which will also add noise reduction). The ideal material would be something soft and dense like rubber, the more gel-like the better. I'm thinking something like certain roll-up exercise mats or a type of carpet padding. (cont'd) – fixer1234 Jul 8 '17 at 16:25
  • Open-cell or closed-cell foam isn't likely to make much difference. Those are mostly trapped air, which you already have. If you can't find anything gel-like or rubbery, a number of layers of wool felt would be better than foam. The kind of material mouse pads are made of would also work. – fixer1234 Jul 8 '17 at 16:32
0

The standard way to soundproof is to weave insulation through the joists (you double up the joists, half for the roof, half for the ceiling). So if you were using 2x6s, your roof would be 8 or 10 inches wide.

As for light - if you have access to double pane windows or skylights you could use those.

Note that noise going directly up may not bother people as much as noise going sideways.

weave insulation

  • Hm. Interesting. You didn't pay specific attention to the floor i.e. my two methods described - which would be best? - and the fact that it is an outdoor building. Interesting as the weave is - I don't have, and can't afford due to constraints (mainly weight) two layers of joists. Thus, weaving's out of the question, at least for ceiling. Wasn't clear in the question, I know. – Engineer Jul 7 '17 at 19:05
  • 1
    The point of the weaving is to create a mechanical separation between the two layers, which greatly reduces the ability of sound waves/vibrations to travel through. There are some other ways to do so, like a resilient channel system (soundproofing.org/images/ceiling_proof.jpg), but you might have trouble sourcing that. In general, you want to maximize your mass in each layer, separation between the layers, and number of layers. Mass-loaded vinyl is a good way to increase mass, but it's expensive. – Robert Nubel Jul 7 '17 at 19:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.