Adding sound and heat insulation to the floor

Horse stall mat, vinyl coin matting and closed cell foam make a good sound damping combination over the factory wood floor of the van. Flanged l-track holds the three layers in place.

We painted the metal van floor and reinstalled the wood floor with some closed-cell foam underneath it. That wasn’t enough insulation though.

For a combination of heat and sound insulation, we went with a layer of closed cell foam (Low-E foil faced 1/8″ foam), 3/8″ rubber stall mat and 2mm (~1/16″) hard-wearing non-slip vinyl coin-grip flooring.

The three layers of flooring we added, held in place with flanged l-track
Each of these layers serves a different purpose. The closed cell foam is a heat insulation layer and it also lets the stall mat float freely above it. This makes the stall mat into a great sound dampening layer. Car audio fanatics use mass loaded vinyl in a similar way. The stall mat has a similar density to mass loaded vinyl but is much thicker. The non-slip vinyl layer on the top provides some protection for the floor and is more visually appealing than the rubber stall mat.

Tracing out the low-E foam on the wooden floor before we reinstalled it

All of these products come in four foot widths, but the van floor is around six feet wide. To hold the three layers down without needing to glue them in, which would ruin the sound dampening effect, we ran strips of l-track from the front to the back of the van about 12″ in from each wall. This lines up really nicely with one of the raised areas in the metal floor.

Installing stall mat - the second layer of our flooring

You can get l-track installed in the van from the factory, but that is recessed into the wooden floor and glued in place. We wanted our l-track to sit on top of the wooden floor. The space behind the flanges is 1/2″. That’s just right for the three layers of flooring material we are using when they are compressed together. The flanges of the l-track hold the layers in place really firmly.

We bolted the l-track through the wooden floor, through the metal base of the van, and through Unistrut steel channel under the van to add strength to the bolts and also to provide a mounting point for anything we want to attach under the van.

Unistrut channel under the van, with stainless bolts and fender washers coming from the l-track inside

The floor feels firm to walk on but slightly cushioned. It cuts down considerably on the road noise coming in to the van. There are some wrinkles in the top coin layer from where it was rolled up so tightly but they are smoothing out as we use the van.

10 Replies to “Adding sound and heat insulation to the floor”

    1. I got the coin flooring from Amazon. It ended up being the cheapest place when you factor in shipping. The stuff I bought does not have the felted back, but it glues down just fine. I used 3M 80 spray glue when I was gluing it to cabinetry. The floor is not glued down.

  1. Great job! Appreciate your website as I am planning a future DIY. I’ve saved your website to my reading list. Are you an electrical engineer? I feel comfortable doing most of it except for the electrical planning. I’m planning this next year to purchase a 170 wb 4×4, what features would you strongly recommend from the factory? I see that you recommend the blind spot alert, I didn’t know about the seats being a air cushion as a factory option either, do they come with rotating base from factory too? Do you know if I order a cargo van if I can customize the windows? Thanks for sharing!

    1. Hi Dave,

      I’m not an electrical engineer. I had done house and vehicle wiring before starting the van but I had to do a lot of research into the right components to use and how they all fit together. There are lots of helpful people, including some electrical engineers, on the Sprinter forum.

      I’ve written a bit about choosing the right van options. You can no longer get the factory suspension seats, apparently because they interfere with the airbags that Mercedes now puts inside the seats. 2015 was the last year that the factory suspension seats were available. I think that also prevents you from getting the factory-installed swivel seats, but I’m not sure.

      If you work with a good dealer, you can add windows to a cargo van. However, it’s also possible to add aftermarket windows by cutting holes in the metal panels if you prefer. That allows you to have vents in the windows that open for more airflow.

  2. Huge fan of the site – very interested in mimicking most of your setup, particularly the interior and your electrical system.

    I currently have a 2016 170″ 2500 “Worker” (no factory floor installed) and am looking to copy your floor setup.

    In your opinion, is the wood “subfloor” in your van necessary for rigidity of the floor/does it assist in keeping the horse stall matting and vinyl coin from wrinkling and possibly slipping out from under the L-Track?

    In other words, do you think I could install the same combo (Low-E, matting, coin) on top of a polyiso/spray foam combo laid onto my metal floor or should I put in a plywood subfloor to keep things rigid?

    Last question, is the L-Track alone sufficient to keep the flooring in place or do you recommend any additional fasteners (perhaps the D-Rings with longer bolts) to keep the flooring in place near the walls?

    Thanks!

    1. Hi Cam,

      I don’t think the wooden layer is absolutely essential in the van. The stall mat is strong enough to prevent anything from puncturing it. The wood layer *might* be better at protecting the floor if you happened to drop something heavy and pointy on it.

      You could install the low-E, stall mat, and coin on to a polyiso board layer. However, you’d need to find a way to securely attach the l-track. I would not personally trust the l-track if it was just rested on/bolted through the layer of polyiso. I imagine you’d need a solid strip of material under the l-track.

      Our flooring stays in place with the l-track and a couple of the D-rings. We also have edging strips at the rear and sliding door and at the back of the cab floor area. The coin layer does move a little in hot weather, but it’s not been an issue for us.

      Hope that helps!

      1. Ah yes, I forgot to think about the L-Track and how it might sink into the polyiso without some sort of rigid piece underneath. Might be worth the hassle to just make a subfloor rather than try to flush mount some kind of rigid piece of material under the L-Track.

        Thanks for the insight!

        1. If you are looking for heat insulation more than noise insulation, the polyiso layer is a great idea. Our floor still gets cold in the winter. A 1″ polyiso layer would probably help considerably. Like you say though, creating 1″ deep rigid strips to lie beneath the l-track could be hassle.

  3. Can you advise me on the hardware that you ordered for mounting your L-Track, specifically how long of bolts are needed and what are the dimensions. Any help is appreciated

    -Eric

    1. Eric, we used metric M6 size flat head countersunk bolts. If you are using imperial size ones, the L-track you can buy in the US is normally drilled for 1/4″ bolts. Be aware that the default countersink angle is different for metric bolts and imperial bolts. Either you use imperial, try and find metric with the right countersink angle, or just go for it with whatever metric bolts you find.

      The length of bolt you need will depend on how you mount your L-track, and even what brand and style of track you buy. For instance, some of the discount L-track has a much thinner base. We mounted our L-track over the factory floor, with a 1/8″ layer of foam under the factory floor. For that, we used 40mm length bolts. That gave us just enough room for the Unistrut, a fender washer, and a nyloc nut under the van. We drilled through the ridges in the floor that point up, not down. If you had to use the downward pointing ones for your attachment, you’d obviously need longer bolts.

      Be sure to only use stainless steel bolts, nuts, and washers. Tighten them by hand rather than using a drill-driver, and use an anti-seize paste or at least a good grease in the countersink area of the bolt head and on the bolt threads. Stainless steel has a tendency to gall, which makes it lock together in a way that you just can’t get it undone if you aren’t careful when you assemble it.

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