Sonolok Acoustic Panels for the Living Room Wall

Sonolok acoustic panels come in boxes of four. 

The TV in my living room hangs on a wall that's about 3.3m (11') high x 6.7m (22') wide. That wall has had TVs and other things hung on it by previous owners of my condo, all of whom did less than professional repairs to the drywall. It looks awful. It also happens that the opposite side of that wall is my neighbor's bedroom, and it happens that my stereo speakers are positioned along that wall on either side of the TV with their rear radiation bouncing off and going through the wall.

 

This is what I started with. Is it really that hard to patch a hole in the drywall? And whose idea was it to just paint over it?

I've have been thinking about what to do about it for a couple years. I wanted something that would look nice and not seem out of place in the room/building. I considered just repairing the wall and painting it, or hanging wall paper or a wall paper mural. 

On my recent semiannual trip to Costco I saw something called Sonolok acoustic panels on sale for $30 for a box of four panels (they go for $90 per box on the manufacturer's web site and $40 per box at Wayfair). I looked them up and watched some YouTube videos about installing them and decided this was the way to go. The panels will theoretically reduce sound transmission through the wall, though the manufacturer provides no specs to that effect, and will provide some absorption and diffusion of the rear radiation from my speakers, all while looking pretty good and fitting with the look of the room/building. The panels get good reviews of their acoustic properties on amateur audio forums.

Each Sonolok panel consists of a dense synthetic felt pad 600 mm square x 10 mm thick with 27 mm wide x 13mm thick walnut veneered (really?) MDF strips stapled to it. The strips are spaced 13 mm apart. The wood strips are offset on the felt so that two edges of each panel will neatly overlap adjacent panels. Each box of four panels comes with two right side and two left side end-pieces to neatly finish the look of the wall. There are also black drywall screws and a bunch of round, black, felt stickers to hide the heads of the screws. 

My building was converted to condos about 20 years ago and uses steel studs, spaced 24" apart, covered with 5/8" drywall on both sides. I checked building codes to see what the allowable lateral loading on the studs would be (you can't just start putting heavy stuff on the walls without regard to the loading capacity!). This wall, like all the walls in my condo, are non load bearing (the rafters, posts, and beams carry all the load). I found that acceptable loading on non load bearing light gauge steel studs used in my walls was 10lbs/sqft. The wall is approximately 12' high x 22' wide, so 264 sqft. The 5/8" dry wall on both sides of the studs loads it to 4.4 lbs/sqft. The Sonolok panels add about 1.65 lbs/sqft, so the load on the studs will be a bit over 6 lbs/sqft, well within the allowable 10 lbs/sqft limit.  

Front side of one of a Sonolok panel. The felt backing is 600mm x 600mm (NOT 2'x2' as at least one Youtuber would have you believe). The wood slats are 587mm long x 27mm wide x 12mm thick, and are spaced 13mm apart. Don't worry, the dark area is the shadow of my head when I took the picture. The color of the wood slats is perfectly uniform.

The back of a Sonolok panel. The felt pad is 600 x 600 x about 10mm thick. The wood slats are stapled to the felt. Note: at least one YouTube reviewers says the panels are 2' square. NO they are NOT! 600mm is not 2'.

One of the panels with the right and left end pieces. 

When you put the end pieces in place, their slats are spaced the same as the others for a very neat look.

When the panels are installed, there will be neat, uniform horizontal gaps between the wood slats. This eliminates unsightly mismatches in the slat positions if the panels/slats aren't placed perfectly. One YouTube installer actually cut the felt at the top of the panels off so the slats would contact each other. Then he suggested hiding the resulting mismatches by using wood putty and sanding. That's insane!

The recommended mounting method is to put construction adhesive on the back sides of the panels then screw them to the wall to hold them while the glue sets up. I had a different idea. I decided to mount the panels on furring strips that would hold them away from the wall, allowing things like network, power, and speaker cables to be hidden behind the panels.

This is the wall that will be covered with the Sonolok panels. The plan is to start the panels at the top of the baseboard and go up from there. There are a couple electrical outlets and a TV mount that will have to be accommodated. Note: the light spots are reflections of the sun from the disco mushroom sitting in the window.

At the top of the wall there are unevenly positioned rafters. The top edge of the Sonolok panels  get close but won't require any trimming around the rafters.

As usual, I started the project by making a CAD model of the wall and the Sonolok panels so I could figure out the layout before starting the installation. 

This is what the wall will look like when it's done. The green thing is the wood structural post that stands forward of the wall by about 200mm. This image doesn't show the TV wall mount that I'll have to make cutouts for. There are 5 vertical x 11 horizontal Sonolok panels here, with right and left end pieces. The wall is a a few mm wider than the panels and end-pieces so I'll have to finish the right side with a custom end pieces to hide the furring strips.

Tools

 

Besides the usual electric drill/screwdriver and a tape measure, I used a couple special tools for this job:

Laser "tape" measure. IRIC it was about $30 a few years ago when I bought it. I have checked it against a couple different tape measures and found it to be very accurate.

3 axis laser level I bought from Temu for about $40. It projects horizontal and vertical lines so it can be used to check the squareness of walls, the level of floors, and to follow studs in the wall once they have been located using a magnet. I verified it's accuracy by marking a level line (as reported the this level) on the wall then rotating the laser level 180 degrees. The line remained in the same position, so I could trust the accuracy of this unit.

A razor knife with a fresh blade cuts the felt very neatly and I used a pull-saw to cut furring strips and most of the Sonolok wood slats. 

I added additional staples to the Sonolok slats to ensure that every piece would have at least two staples holding it to the felt backing before I sawed through the slats. 

Special considerations

I was planning to use the baseboard as the guide for placing the panels, but the laser level revealed that the baseboard that follows the floor is neither flat nor level. 

The green laser line is aligned to the baseboard at about the middle of the wall...

Left end of the wall at floor level. 

Level at the right end of the wall. The floor at the left side of the wall is about 30mm higher than the floor at the right side of the wall.

The left end-piece and panel had to be cut to fit around the bricks in the upper left corner of the wall.

There are three outlet boxes that had to be allowed for and a wall-mount for the TV. 

Decisions, decisions...

The original plan was to leave the baseboard in place and follow its top edge with the bottom of the first row of Sonolok panels. That wouldn't work because, like the floor, the baseboard's top surface is neither flat nor level. This install was over a wood floor that occasionally gets vacuumed and wet-mopped, so I couldn't just remove the baseboard and run the panels down to the floor because the finish on the MDF slats would not hold up against the vacuum cleaner nozzle or a wet mop. The baseboard hides gaps between the drywall and the floor, and protects the soft drywall from things like vacuum cleaner nozzles and wet mops, so it needed to be left in place.

I settled on mounting the Sonolok panels on furring strips. The furring strips are thicker than the baseboard, so the Sonolok panels overlap the baseboard. I just installed the bottom edge of the Sonolok panels along a level line overlapping the baseboard a little. That allows the panels to be high enough to protect them from the vacuum cleaner and mop. I didn't have to trim the bottom edge of the panels to fit the unflat floor or the baseboard.

This is how the Sonolok panels, mounted on the furring strips, overhang the baseboard. The gap between the Sonolok panel and the baseboard, and a few horizontal gaps between the furring strips allows me to bring speaker cables out from behind the panels. 

Preparations

I put masking tape on the floor at the baseboard and the right corner of the wall and painted the baseboard and right edge of the wall black. I also painted the left edge of the wall black right up to the bricks. Then the power outlet plates and TV mount were removed and the areas around them painted black, as well as the left and right edges of the wall.

Black paint on baseboard, surrounding power outlet, and on the right edge of the wall.

Black paint around power and CATV outlet boxes, TV mount, and baseboard. Note the vertical lines marking locations of studs. I replaced the original white outlets and cover plates with black ones.

I used a magnet to locate the studs (it sticks where there are screw heads holding the drywall to the studs) and drew vertical lines on the wall over the studs, using the laser level as a guide. I added horizontal lines on the wall to indicate where to mount the furring strips. The laser level makes all this very easy to do.

Installation

The next step was to mount the furring strips. I used 1x2" (actual measure 0.75 x 1.5"- why do they do that?) and 1 x 4" (actual measure 0.75 x 3.5") strips that I screwed to the studs using drywall screws intended for use with thin gauge steel studs. I left some gaps between the ends of the furring strips to allow for vertical cable runs in strategic places (close to the speaker locations and power outlets). Blue painter's tape on the baseboard marks the locations of the gaps in the furring strips so speaker cables can be brought out from the wall.

Wherever the ends of the furring strips were going to be visible I painted them black.

This is the layout of the furring strips with some of the Sonolok panels shown so you can see how they attach. The Sonolok panels are screwed to the furring strips without any glue so they can be removed to run cables as needed. The left end-pieces are glued to the furring strips and the ones on the right are screwed down.

I determined where the left edge of the panels would be, and placed the left edge piece and 11 of the panels and a right side end piece along the wall to precisely locate the right edge of the installation about 30mm from the edge of the wall on the right side. 

With all the prep and painting, it took two days work to get the first two rows of panels installed. They were the worst part of the job because they were closest to the floor and required a lot of bending over and sitting on the floor to work. They also involved making cut-outs for the power outlets and TV mount and that took extra time.

Installing the panels. I left horizontal gaps between the furring strips to allow power and CATV cables to go to the TV behind the panels. I considered lowering the TV enough to cover the outlets but decided against it as I need access to the power outlet for vacuuming, etc.

The first two rows almost complete. The left end-pieces are glued and the right end-pieces are screwed to the furring strips.

I used the green 09laser level to ensure the panels were aligned properly before screwing them down on the furring strips. 

I installed the panels using seven screws each- 3 at the top and bottom edges and one in the center. 

Cutouts

The positions of the cutouts were determined as I installed the panels. I started on the bottom row, placing the panels from the left edge and working toward the right edge. When I encountered a power outlet, I laid out its location on the panels using blue painter's tape, then used a framer's square to draw the cutting lines on the tape (sorry, I didn't take any pictures). In places where cutting the slat would result in a piece of the slat being held by a single staple, I added staples to stabilize the positions of those slats (example- the short slats above the TV cutout) before cutting the slats.

At some cutout locations, and at the far right edge of the installation, when viewed from the side, the ends of the furring strips were visible. I painted those black before installing the panels.

Problems

When I bought the furring strips I selected straight, untwisted boards. By the time I got to putting up the third row of panels, the 1x2s that were sitting on the floor in my living room for two days warped so badly I couldn't use them. A couple of the 1x4s also warped to unusable condition. I was able to cut them into shorter pieces, leaving out the twisted parts, and got them to work OK, but next time (hah!) I'll invest in better quality wood. For this application, it would actually be better to use strips of MDF or even plastic because it won't warp. 

The top left side panel had to be trimmed to fit around the bricks up near the ceiling. The slats are held on the felt with staples, and are made of MDF, so it's impractical to try to trim the panel at the shallow angle that would be required to follow the outline of the bricks exactly. I painted 50mm or so of the wall black, up to the bricks, and cut the left end-piece and the panel squarely to fit. Then I marked and cut the two left-most slats and felt on the panel to lengths that would fit under the overhanging bricks. I think it came out pretty good. 

The upper left corner panel was cut to fit around the bricks. First I measured and cut the left end piece, the I measured from the wood on the lower panel up to the bricks following the edge of the wood on the lower panel and trimmed the two left-most slats and felt on the upper panel to fit.

I wasn't sure how I was going to close the edge of the panels at the right side of the wall. Then I looked at the many extra left end-pieces I had and found that the wood strips are just the right width to close off the opening created by the furring strips. I removed the wood slats from the felt and glued them to the right side end-pieces and it looks very professionally finished. If I ever need to run cables through the right side I can remove one of the right end-piece plus slat, cut it open enough to run cables and then put it back. Or just make a new one with some of the many extra end-pieces that were left over from this installation.

Detail of one of the right edge finishing pieces. I removed the slat from a left end-piece and hot melt glued it to the felt on a right end-piece using a simple jig to keep them aligned. The right end-piece with the left end-piece slat attached is just held in place with screws so I can remove it easily to run more cables if I ever need to. Note: I painted the wall and the end of the furring strip black, but didn't really need to.

Jig used to hot-melt glue the left end-piece slat to the right end-piece felt. I used spring clamps to hold the right end-piece against a board, taped off the slat, then applied glue to the felt. Masking tape prevented the glue from going to the wrong places. I set the slat (removed from its felt) from a left end-piece down on the glue.

Installing cables

I prepped a set of 12 gauge speaker cables (I bought a 250 ft spool of 12 gauge speaker cable via Craig's List for $15!) for this installation. I hung the cables using some thin plastic held in place with thumb tacks. The hangers are only there to keep the cables from getting in the way when installing the acoustic panels. I also ran a piece of black network cable to the left side of the wall where the WiFi router will be placed.

Cable hangers made from thin plastic strips tacked to the wall.

I bought a power-strip/surge protector with a flat, rotating plug so that I could route the power cable up the wall under the Sonolok panels. The end with the sockets will be installed on the wall behind the TV. I will use it to power the TV, Shield Pro, and Bluetooth transmitter.

Power outlet under the TV with flat plug that rotates so the cable can go straight up under the Sonolok panels. The other cables are HDMI and optical fiber that go from the TV to the amplifier.

 

Finally

 

It took about 4 days to hang all the furring strips, run the cables, and trim and mount the Sonolok panels. I used 14 boxes of the panels at $30 each, and spent $40 on the laser level, and another $50 or so on furring strips and screws, and maybe $15 for replacement power outlets and face plates, for a total cost of about $500 to cover this 3m x 6.6m (~10'x22') wall.

I don't yet know if the Sonolok panels reduce the sound transmission through the wall a meaningful amount. They will certainly help at least a little. I'll have to ask my neighbor if he notices any difference.

The newly paneled wall is on the west side of the room. The east side wall is mostly very large windows, with heavy velvet curtains that can open and close, and is very reflective for sound with the curtains open and very dead when the curtains are closed. With the curtains open, the stereo image from my speakers seems to be a bit more sharply focused than before the wall was paneled, but that may be because I'm paying more attention to it. With the curtains closed the sound seems less satisfactory, as if the room is just too "dead". 

Living room with Sonolok paneled wall. Windows on the left are the east side of the room, Sonolok wall is on the west side.

This is what it looks like with the curtains open during the day.