HOW TO SOUNDPROOF A GARAGE

We are often asked how to soundproof a garage or a shed so that little Johnny can bash seven bells out of his drum kit without upsetting the neighbours. The principles of soundproofing these buildings is the same as studio soundproofing and that is a ‘room within a room’ principle. Basically this is as the phrase suggests, building a room within that is completely isolated from the existing structure and the easiest way to do this is with 3 x 2 inch (75 x 50mm) timber stud.

First of all though, windows and large doors for vehicle access should be blocked up as shown in the photograph on the left.

If the building is a shed then screw external grade ply at least 18mm thick to the outside of any windows and a layer of 12.5mm high density acoustic plasterboard over the inside.

Next infill between any wall supports with suitably acoustic mineral wool of suitable thickness then screw another layer of acoustic plasterboard to the shed walls encapsulating the mineral wool.

Now you can get on with building the internal stud and this will be relevant for both sheds and garages.

Assuming the structure is sitting on a concrete base fix the bottom plate of timber stud to the floor about 25mm away from the existing walls then add the uprights and ceiling joists so that the entire structure is self supporting. Noggins are not required because Resilient Bars are screwed to the uprights at 600m centres from floor to ceiling and these act as noggins.

With ceilings the Resilient Bars are screwed across the joists at 400mm centres but before you do any of this sound absorbing insulation must be installed into the stud framing. For this you will require 100mm of Acoustic Mineral Wool which should sit comfortably against the outside wall and flush with the front of the framework. If a greater degree of soundproofing is required the acoustic mineral wool can be replaced with SoundBlocker Quilt that has to be either stapled to the sides of the framing or secured with battens,

SoundBlocker Quilt is a unique sound insulation that not only acts as a sound absorber but also a sound blocker due to its unique layer of soundproofing mat sandwiched within it. This is why it is important to seal it into the framing so that no noise can leak around the edges of it. So now you have installed the acoustic infil and screwed on the Resilient Bars we can think about the cladding. For this 12.5mm high density Acoustic Plasterboard is again used but this time a double layer has to be screwed to the bars.

To soundproof the garage (or shed) to maximum effect 2mm SBM5 Soundproofing Mat should be sandwiched between the two layers.

floors

Now for the floor. A floating floor will have to be installed to reduce structure borne sound flanking under the walls of the building and this is easily installed as follows. Roll out 10mm of resilient recycled R10 over the floor wall to wall then lay on top 19mm high density QuietBoard acoustic flooring which in turn should be carpeted.

doors

The walls, roof and floor of the building have now been soundproofed so what about the entrance door? This is just as important a feature because a poorly soundproofed entrance door will dramatically reduce the effectiveness of your newly soundproofed garage – or shed so what to do? The easiest and cheapest method is to use 1 hour heavy fire doors installed with our Acoustic Doorseal Kits. One door may be OK for a shed but a masonry built garage may require a double door entry system as shown in the detail below.

ventilation

Now you have a studio style soundproofed building with no ventilation so it is going to get a bit hot and sweaty inside within a very short time so ventilation is essential. A good way to install this is to use Acoustic Vents and you will require two of these, one at the top of a wall and the other at the bottom diametrically across on the opposite wall.

If a forced air ventilation system is required then a slow spinning fan can be used and should be installed into soundproofed trunking made from 18mm MDF or ply and be extended as far as possible from the main vent on the outside, if possible with the fan near the entrance to the trunking. If the trunking is built on the inside of the room, the fan should be located close to the vent and as far from the entrance as possible. I hope this makes sense but if any doubt, give our technical department a ring. The inside of the trunking must be lined with our non-flammable black acoustic foam.

sound absorption

Now the job is done. Hang on a minute, the garage may have been soundproofed but what about reverberation on the inside? Little Johnny will be deaf in no time if he is regularly generating in excess of 100dB in a confined space so you will have to install some sound absorption to soak up some of this noise.

The best and easiest sound absorber I can suggest here is 30mm Echosorption Plus.

If these are glued across the entire ceiling and onto some of the walls the job really is done.

EXPECTED RESULTS

Before installing sound insulation as described above, your garage (or shed) would have a very poor insulation value that would no doubt, had your neighbours beating on your door in no time. As the windows are one of the weaker points, the original sound insulation of these would have been no more than 24dB with lower frequency noise being a particular problem.

So if music is being played at 110dB, 86dB of noise would penetrate any windows, which is loud and we want to keep the neighbours happy. After installation of the materials described above, windows have been blocked up, the window insulation value would now be improved to around 35dB and once the walls have been soundproofed, the overall insulation value of the building will be around 40-70dB depending on whether it is a shed or masonry built garage.

This means a lot less noise will now be penetrating the walls of the structure. A vast improvement and should reduce any possibility of falling out with the neighbours, unless of course, the drums are being played in the early hours. Any noise that can be heard during the night can be considered a nuisance no matter how quiet.

WINDOWS

If light through the windows is desired, they should be triple glazed with different thicknesses of laminated glass at staggered intervals and installed completely sealed.  The outside panes of the glazing should be the thickest and fitted as far apart as possible with the centre pane installed at an angle.

This has been a brief description on what is required to soundproof any building but in particular, a garage or shed. The same principles of soundproofing can be adopted wherever sound control is required.

ALL IMAGES ARE OWNED BY MARK MASON AND SOUND SERVICE (OXFORD) LTD AND CANNOT BE USED OR COPIED WITHOUT PRIOR PERMISSION. Mark Mason used our products to soundproof a garage for his son. His website can be seen here www.matthewmason.co.uk