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How To Build & Install Furring Strips In A Camper Van

DON'T screw directly into your van wall! This post will teach you a much better solution.

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In this post, we show how you can build and install furring strips in your camper van so that you can easily install walls and a ceiling in your camper van.

From start to finish, our step-by-step guide will teach you everything you need to know about how to create furring strips and how to attach them to your van.

(Hint: No screws were used in this post!)

“If you’re ready, let’s get to it!”

Learning Objectives

By the end of this section, you should be able to answer the following questions:

Want to build a camper van? Check out our
DIY Camper Van Build Guide

What Are Furring Strips?

Furring strips with cross nuts in a van conversion
Attaching a furring strip, with cross nut, in our van conversion

Furring strips in a camper van conversion are typically small pieces of wood that are attached to the van’s sheet metal frame. Once these furring strips are fixed to the van frame, you can easily attach your final camper van walls and furniture to these furring strips for a strong hold.

In the above picture, you can see an example of one of our furring strips; a white rectangular piece of wood that we bolted to the van’s metal frame. We have over 50 individual furring strips attached all throughout our van.

Later, we will screw our plywood walls to these white furring strips.

Benefits Using Furring Strips In A Camper Van

When thinking about how to install walls in a camper van, there are realistically only two ways to do it.

1. Fasten Walls Into Van's Sheet Metal Frame

This is the easiest and fastest approach. However, we this isn’t the best approach because not only are you screwing into metal and opening your van up to opportunities for rust buildup, but the screw cannot get a firm grip on the sheet metal because of how thin the metal is.

A strong grip is especially important in a camper van because there will be lots of vibration when you drive and screws with weak grips will simply get yanked out.

2. Fasten Walls Into Furring Strips

By first installing thick furring strips in your van conversion, you can then screw your camper walls into these furring strips. This allows the screw to get a much stronger hold.

Also, if you attach the furring strips correctly, you will not be creating any new and unnecessary holes in your van. More on how to do this further down this post.

So, perhaps you’re asking, “how can I make my own furring strips?”

How To DIY Furring Strips For Camper Vans

Creating your own campervan furring strips isn’t overly complicated and gives you an opportunity to use your leftover plywood. These are the following steps we used to build our own furring strips.

Step 1:

Select Wood & Cut To Size

Creating DIY furring strips for our camper van
Creating DIY furring strips for our camper van walls

We decided to make our own furring strips from all the leftover 1/3″ thick plywood that we had from when we made our camper van’s sub-floor.

Wood Quality Tip: You can also simply buy wood beams from any hardware store or lumber yard. But make sure you are getting a hardwood or semi-hard wood. Cheaper wood can often be soft, which isn't great for holding in screws and handling vibration from driving.

Furring Strip Dimensions (L x W)

The size of most of our furring strips are 4″ x 16″. However, we had a few different sizes (4″ x 8″) and (2″ x 20″) to fit some of the smaller areas in our camper.

So we traced the furring strip dimensions we needed onto our leftover plywood. In the picture above, you can see the furring strip tracings we made on the plywood.

Afterwards, we would take our jigsaw and cut along the tracings to create our furring strips.

Furring Strip Thickness

We felt good about using our leftover plywood for something useful. But, we felt that our 1/3″ thick plywood was too thin. We wanted our furring strips to be thicker so that we could use longer screws when attaching our future camper walls.

Longer screws would make a stronger grip.

To get thicker furring strips, we simply adhered two plywood furring strips on top of each other with generous amounts of wood glue to double the thickness. So instead of having 1/3″ thick furring strips, they were now 2/3″ thick.

This was perfect for us.

Step 2:

Anti-Mold Preparation

Creating DIY furring strips for our camper van conversion
Adding anti-mold primer to our DIY furring strips

Since these furring strips would be installed behind our final camper van walls, likely never to be seen again, we took extra precautions against mold.

We planned to be in hot and humid environments, so mold could be a problem in the future.

Materials Needed

Anti-Mold Spray

Mold Killing Primer

So after the wood glue dried on our plywood furring strips, we sprayed each piece of wood with a healthy amount of Concrobium anti-mold solution.

When the anti-mold solution dried, we gave each plywood furring strip two coats of anti-mold primer.

When we were finished, we would end up with over 50 furring strips, ready to be installed in our camper van conversion.

Install Cross Nuts To Van Walls

The next step is attaching those furring strips to the camper van’s metal frame.

But HOW to attach those furring strips to the van’s frame is an important decision.

Many choose to simply drill the furring strips straight into the sheet metal. But like we mentioned earlier, screwing into the van’s metal frame isn’t ideal because this does not create a strong grip. Plus, additional holes in the sheet metal increases risk of rust in the future.

“So what’s a better alternative solution?”

Cross Nuts

Cross Nut Product Picture
Cross Nut Sample

Our answer is to use cross nuts.

If correctly installed, a cross nut has over 1,215lbs of pull-out strength. Over 12x more strength than a standard screw through sheet metal.

And NO unnecessary drill holes are created in the van.

Convinced? We were. Let’s get stared!

How Cross Nuts Work

Cross nuts do not create new holes in the van because they conveniently fit into the hundreds of pre-fabricated holes all throughout the camper van’s sheet metal frame.

You simply slot a cross nut into one of the many pre-fabricated holes and compress the cross nut until it sandwiches the sheet metal wall, creating a firm holes.

The inner portion of the cross nut is threaded, allowing you to thread a bolt into it.

To understand how a cross nut works, check out this informative short video below.

Now we’ll discuss how to choose the correct size cross nut for you and how to install them in your campervan.

Step 1:

Purchase Your Correct Cross Nut Size

But different vehicles have different sized prefabricated holes punched into the vehicle frame. See below for your vehicle.

Which Cross Nut Do You Need?

Ford Transit

For those with a Ford Transit, we recommend the 1/4″ – 20  Cross Nut to fit the prefabricated holes.

Sprinters & Promasters

For a Mercedes Spriner or Dodge Promaster, we recommend the 5/16″ – 18 Cross Nut

Step 2:

Installing The Cross Nuts

When installing these cross nuts into your camper van, there are two ways to do this:

  1. OUR way,
  2. The BETTER way

Our Way: Cheap, Time Consuming, and Very Hard

We began by purchasing 100 Cross Nuts  and laboriously hand cranked each of them into the prefabricated holes all throughout the frame of our Ford Transit.

If you’re looking to save a few dollars and want to build up your hand strength, this is the method for you. Below, we list all the products you need to install cross nuts into your camper van’s frame.

What you need

locking pliers

Steel Cross Nut

Carriage bolt

K-Lock Nuts

5/16" Washer

5/16-Inch Wrench

7/16 Inch Wrench

DIY Cross Nut Installation Diagram

In the diagram below, we illustrate how each of the items we listed above work together to install a single cross nut.

Cross nut installation diagram using DIY tools
Diagram for installing a cross nut in a camper van

Looks confusing? We totally understand. We describe the DIY cross nut installation process below, step-by-step.

DIY Cross Nut Installation Steps

This gets confusing. It’s best to follow the steps below in conjunction with viewing the diagram up above.

  1. Fit the K-Lock Nut around the carriage bolt
  2. Insert the 5/16″ washer into the carriage bolt
  3. Insert the box end of the 5/16″ wrench around the carriage bolt
  4. Lastly, fit the cross nut on to the carriage bolt
  5. Fit the carriage bolt and cross nut, together, into one of the van’s pre-fabricated holes
  6. With your left hand, hold BOTH the 5/16″ wrench and the locking pliers, which grip near the head of the carriage bolt.
  7. With your right hand, fit the open end of the 7/16″ wrench around the K-Lock nut and rotate the nut clockwise.
  8. Keep turning the K-Lock nut. This compresses the backside of the cross onto the sheet metal.
  9. Keep turning the K-Lock nut until it refuses to rotate any more.

When you are done, the cross nut should adhere tightly to the van’s sheet metal frame. Below is an example of a successful cross nut installation.

Finished cross nut installation
Finished cross nu installation in a van wall

The Better Way: Astro Pneumatic Cross Nut Installation Tool

Cross nut installation tool - installing camper van walls
Cross Nut Installation Tool

It took us 3 days of hard work to install 100 Cross Nuts with our budget-conscious, DIY method. And with the cost of the wrenches, locking plier, and additional hardware, we actually didn’t save that much money in the end.

In hindsight, we should have purchased this Astro Pneumatic Cross Nut Installation Tool, to save us time and lots of hand cramps.

Cross Nut Installation Video With 'Official' Tool

The video below shows just how easy it is to install a cross nut with the proper tool.

Attach Furring Strips To Van Wall (via Cross Nuts)

Furring strips with cross nuts in a van conversion
Attaching a furring strip, with cross nut, in our van conversion

To attach the furring strip to our van’s frame, we put a bolt through the furring strip and into the cross nut. In the above picture, you can see how we bolted the furring strip to one of our cross nuts (hidden behind the furring strip).

To do this, we drilled a hole, just large enough to fit our bolt, through the furring strip. Then, with a washer, we bolted each furring strip to the cross nut.

The resulting hold is very tight and strong.

But…we would do things different if we had a second try.

Getting A Flush Fit

Because we want to mount our plywood walls to these furring strips, we want the bolt heads to be as flush as possible to the plywood surface.

This will create stronger adhesion and eliminate air space.

What We Recommend

Sidewalk Bolts

Sidewalk bolt for installing furring strips in a camper van
Sidewalk bolts for furring strips

If we could install our camper van walls again, we would likely have used these Sidewalk Bolts. The unusually flat and low-profile heads of these bolts are better than what we had actually used.

However: These Sidewalk Bolts only work for the 1/4"-20 cross nuts, used in Ford Transits. They do not seem to be available in the 5/16"-18 sizes for Sprinter and Promaster cross nuts.

Post-Furring Strip Installation Result

Completed furring strip installation in a camper van - installing camper van walls
Furring strip installation complete in our camper van.

When we were done attaching all our white furring strips in our van, we were finally ready to start working on our plywood camper van walls.

How many furring strips can you spot in the picture above?

Hint: We also put thin furring strips on our roof to install our cedar plank camper van ceiling.

Did You Know? This post is Part 4 of our 7-part camper van 'foundation' series. Check below to view the entire series. Or...simply return to our camper van build guide.

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