Lightweight Room Dividers, a Temporary Wall for Renters

We made extremely lightweight temporary walls by creating (nearly) floor-to-ceiling room dividers that aren’t nailed or screwed into walls or ceilings. They use tension from furniture levelers pushing against the ceiling to stay in place.

We have a large bedroom (nearly 20 across & 20 feet wide) shared by two teens/tweens who could use some visual privacy, but we rent. These panels can be moved or taken down in just a couple minutes. They should leave almost no trace once we take them out, just a little carpet flattening. These don't block sound - the kids can still talk to each other pretty easily. But they don't disturb each other's sleep anymore.

It’s not a super cheap project, but it’s cheaper than moving. It’s also cheaper - and feels more like real walls - than expensive room divider curtains we looked at.

Materials

• 1 inch XPS foam board insulation (1 4x8 sheet per panel)
• 1x4s (like these primed trim boards from Home Depot) (approx. 24 ft. per panel)
• 2x4s (18” per panel, plus 7”of waste per 2x4]
• Screws. We used:
• 1-¼” screws to attach 1x4s to each other
• 1-⅝” screws to attach bracing triangles to the 1x4 frames
• Paint (enough to cover the frame)
• Heavy duty furniture levelers (2 per panel)
• Felt furniture circles to stick to the levelers (2 per panel)
• Rigid desk chair mat, cut into strips (if dividers will be on carpet)
• Tacks (to tack chair mat strips to frame)
• Felt (or other wall covering, approx. 64 sq ft per panel)
• Wood glue
• Acoustic foam squares
• Double sided tape

Tools

• Saws (for cutting foam insulation, cutting dado grooves out of 1x4s, and cutting boards to length). This is what we used, but you could also do most of the cuts with a circular saw instead of the miter saw and table saw, and use a router for the dado grooves.
• table saw
• dado set on a table saw (but see step 2 below for a variation that wouldn’t need this)
• miter saw
• Drill (to pre-drill screw holes in frame assembly, to attach furniture levelers, and to drill holes in the chair mat)
• Screwdriver 
• Paintbrush
• Paint pan
• Rotary cutter, cutting mat, and ruler (optional, but made cutting the felt much easier)
• Foam brush

First, figure out where the panels will go; it may help to mark this on the floor with painters tape. 

Get a height for the panels by measuring the distance from floor to ceiling in a few different locations around the room (It wasn’t the same everywhere at our house!). Use the shortest measurement. Then we added ¼ inch to that number, even though we knew we’d need to tip the panel into place, because carpet squishes. 

We wanted all the panels making up a wall to be the same width, so next we determined the length of that wall, subtracted an inch for wiggle room, then divided by the number of panels.  

For us that meant our first three panels were all 94 ⅛” tall and 41 ¾” wide. But we made a single panel from start to finish and recommend you do the same, no matter how many you’re making. You may discover places you need to adjust a measurement or a process, and having to replace a piece of foam is expensive and inconvenient.

Getting the foam insulation from Home Depot to the house was possibly the most annoying part of the project. It’s 4’x8’, so it doesn’t fit inside even a large vehicle, you can’t strap it to the top without denting it (unless you want to buy a couple sheets of plywood to sandwich it between), and a pickup truck seemed… risky. We ended up renting a U-Haul van, which was still cheaper than having it delivered.

If you’re following the model here with dado-cut grooves to hold the foam in place,* the height or the width of the foam will be the width of the panel, minus the thickness of the remaining board on each side. In other words:

Panel dimension - 2 * (thickness of the uncut board - depth of the groove)

Since we’re using 1x4s (which have an actual thickness of ¾”) and a dado cut 5/16” deep, our frame pieces will be 7/16” thick at the cut part. So we subtract (2 x 7/16”) or ⅞” from our panel dimensions to get our foam dimensions, which gets us 93 ¾” tall and 40 ⅞” wide.

Cutting the foam can be frustrating. We tried a track system for our circular saw, but it ended up being a huge pain to set up, and its “one size fits all” attachment system didn’t really fit our saw. So we cut three panels that way, but later decided we preferred figuring out how much width we needed to remove (e.g. 48” - (40 ⅞” - saw loss)) and cutting that much off with the table saw. Pink foam sawdust got everywhere, regardless of method. The stuff is soft, so if you’re really patient you could even do it with an Xacto knife. Err on the side of cutting small, so your foam will fit in your frame.

Eventually, we got there: pieces of foam cut to size, 93 ¾” X 40 ⅞”.

*If dadoes aren’t an option for you, you could use this basic plan, but cut your foam so it fits entirely inside the frame and use molding strips or something to hold the foam in place. In that case your foam height and width would be 1.5” less than your panel. The nicer thing about the dado approach (besides how sturdy it is) is that you’re subtracting weight, rather than adding, which keeps the panels very light.

ALTERNATIVES TO XPS FOAM: A couple of commenters have voiced concerns about fire safety. That was something we weren't thinking about when we made these, but I've added a section at the end with some videos where we tried to see how flammable these walls are. According to one commenter, Thermax would be a fire resistant option. I was unable to find an online source that would give me weight or cost information, but your local building supply may be able to help.

I also looked at 4x8 cardboard sheets, which you can order from multiple sources, like Office Depot. Cardboard is still flammable of course, but it may be easier for some folks to obtain. if you went that route, you could do two sheets separated by an air gap, which might give you better noise reduction.

First, make the dado cuts.* For us, those were 5/16” deep, a little less than half the thickness of the board. Err on the side of cutting them a little deep, so the frame fits together around the foam. The grooves need to be just over 1” wide, because they’re holding foam that’s 1” thick. On our table saw setup we can’t cut that wide, so we did two slightly overlapping dado cuts to get there. Alternately, you could use a router for the dadoes instead (in fact, there are multiple Instructables on making dado jigs for a router).

We also did some sanding of rough spots at this stage. Buying pre-primed trim boards meant there wasn’t much sanding needed.

*See note above at end of step 2 about a variation that would skip dado cuts.

Second, cut the boards to length. In our frame, the top and bottom pieces of the frame run the full panel width, and the verticals run between them, so the top and bottom pieces are as long as the frame width (in our example, 41 ¾”). The vertical pieces are the same height as the foam, because of the rabbet joints explained next, so they’re panel height minus ⅞” again, or 93 ¾” in our example.

Third, cut the rabbets on the ends of the vertical pieces: ¾” wide (the thickness of the vertical frame board) and 5/16” deep (the same depth as the dado grooves). 

Then your corners will fit together in a rabbet joint, like in the photo above.

One corner at a time, drill two holes per joint and add screws, being careful not to split the boards. If the frame won’t fit around the foam, you may need to trim your foam down a bit, or deepen your dado cuts. Once I also just pinched the heck out of an edge of a foam piece… YMMV.

The foam + 1x4s alone have more flex than we liked, and they don’t leave a lot of options for holding the panels in place. Cutting triangles from a 2x4 to place in the upper corners of each panel fixed both of these problems.

First, we thinned the 2x4 using the table saw, so it wouldn’t stick out so far past the depth of the frame (2 2x4s @ 1.5” each, + 1” of foam = 4” total thickness. That’s ½” thicker than our 1x4 is wide, or ⅛”  of each triangle sticking out on a side). This is entirely optional, and actually made it tougher to attach the furniture levelers in step 7.

Then we cut the triangles from the 2x4 using a miter saw. The long side of the right triangle is the natural edge of the 2x4, so we just flipped the board over for a series of perpendicular 45 degree cuts. The short side ended up being just under 5” long, and the hypotenuse is 7”.

Next we cut a lip along one of the short edges of each triangle, to make sure the gripping lip of the furniture levelers in step 7 would fit (this could have been shallower if we hadn’t thinned the 2x4 in the first place). The levelers need a ⅜” lip. We did half on the left short sides the triangle, half on the right, so that the lip would always be at the top of the frame.

Then we attached the triangles to the corners using 4 1-⅝” screws, 2 from the top and 2 from the side. We placed (but did not attach) a leveler when drilling the holes for these screws to make sure we didn’t place them where they’d be in the way of the screws attaching the levelers in step 7.

We used pre-primed 1x4s (knot free! Relatively warp-free!) so they were already mostly white. But they weren’t evenly or entirely white, so we painted the 1x4s along with the corner triangles.

As you may notice in some of the photos, we only painted the surfaces that would be visible once the panels were in place, which saved on paint.

These furniture levelers are how the panels stay in place even though they’re free-standing. They’re designed to raise the corner of an object by pushing against the floor. Here, they’re pushing against the ceiling. They’re attached to the bracing triangles using the screws that came with the levelers. We used two per panel, on opposite corners, and this seems to be plenty.

They have hard plastic feet, so we added felt circles to give them a better grip and be more gentle on the ceiling.

At first we used an equivalent stick-on foot that was advertised as anti-skid, pictured in the second photo, but we DO NOT recommend this. They started breaking down and left gross black bits of themselves on the ceiling, even when they’d been in place less than a week.

These panels might stay in place pretty well with a smooth surface on the bottom board, but we wanted to give them some grip. We had an old office chair mat lying around that we knew was good at not sliding on carpet. With this attachment they're definitely still nudge-able (as we re-discover every time a kid bumps into one too hard), but they don't slide easily.

The new chair mat I tried buying for this project would not have worked - it’s too bendy! It would not have gone through the table saw well, nor would it have stayed flat when tacked to the bottom of the panel. The mat we had is no longer sold, but the one I’ve linked to in the materials list claims to be stiff.

We cut the mat into strips about 3” wide (enough to get a good number of spikes, but narrower than the 3.5” width of the 1x4) using the table saw.

Then we drilled four holes in each strip, and attached a strip to the bottom of each panel by hammering in a few tacks.

After working with the foam enough to build a frame, I abandoned my initial plan to paint the foam. It dents and scratches too easily, and would have looked shabby within weeks. I decided to cover the foam with felt instead. It’s pretty cheap, and because of its texture and thickness it hides minor blemishes (like holes from these hooks we're using to hang posters). The kids loved the idea because then they could each pick their own colors, even though I was insisting on beige for the common area.

The felt was only available in 72” width. I could have done single sheets 90-some inches long, but that would have resulted in a lot of waste (and extra cost). So I did a 40 ¼” wide by 72” tall piece at the top of each panel, overhanging a 40 ¼” by 20” tall piece at the bottom. At least, the math says the pieces should have been 40 ¼” wide to cover the exposed part of the foam (panel width minus 1.5”, the thickness of two 1x4s). Felt is stretchy, wood bows, cuts get a little off… I measured the exposed foam before cutting each piece of felt to fit, just to be safe.

Did I mention felt is stretchy? Also squishy. It’s kind of a pain to work with if you want a geometric ideal of anything. A giant rotary cutter and mat and fancy ruler helped, but I still always had pieces to trim here and there, plus the corners.

You can’t use just anything to glue stuff onto foam insulation. Some things, like a regular spray adhesive, will melt the foam (thank you for the warning, internet)! I started out with a special XPS-safe spray adhesive, but that stuff was expensive, and honestly, kind of a pain to work with. After the first couple panels, I switched to wood glue.

I diluted the wood glue - 1 cup glue to ¼ cup water - to make it more spreadable. Then I used a foam brush to spread it around. Spread it about as thin as you can manage, because anywhere it’s too thick it’ll soak through the felt and leave a brown spot.

If all you care about is sight lines, this is unnecessary. We were also trying to isolate light between a night owl and a morning person, so it was important to us.

I had already purchased some acoustic tiles that were about the right thickness for a little square porthole I was making in one of the panels. I cut that into strips, and attached it to the top of the panel with double sided tape.

Finally, they were ready to go! Put the base where it belongs, tip the panel up, and adjust the furniture levelers until they’re pressing against the ceiling.

They’re super light, and one person can easily carry a panel around. However, the foam on top tried to roll off against the ceiling when pushing a panel upright, so we always needed two people to position them. One person stands the panel up, and the other pushes on the acoustic foam strips with fingers or a ruler. It’s also handy to have one person on the ground nudging the base and checking a level while someone else can reach to adjust a furniture leveler.

We had slight gaps here and there where we couldn’t make things line up quite perfectly. We mostly ignore them, but we stuck felt scraps in the larger ones to block light between “rooms.”

We didn’t just want a few dividers, we wanted the feel of whole rooms. So we also made frames to hold tension rods for curtains. With longer curtains or a shorter ceiling, you could just hang the rod between two panels, or between a panel and a wall.

Our doorway panels follow the same basic steps as the wall panels. The differences are that 1) they only have a small rectangle of foam insulation at the top so the dado cut doesn't go the whole length of the vertical pieces, and 2) they have a piece of hardwood threshold cut to length along the bottom, instead of a 1x4. The measurements around the small panel were a little fiddly, and custom tailored to the curtains we bought. If you want them, leave a comment or question and I can flesh this part out.

Multiple commenters voiced concerns about fire safety, because XPS foam is flammable. One suggested the possibility of treating the felt, rather than the foam, and I found a flame retardant spray that seemed worth a try. Here are some things we (complete amateurs with no expertise in flammability testing) tried out.

We cut two squares of plain felt, sprayed one with the flame retardant, and burned both with our serious firestarting butane torch. It turns out that polyester felt burns away to nothing at the site of a flame and then goes out pretty quickly, treated or not.

Next we made a tiny model wall, and sprayed one side with the flame retardant. Then we used the torch to burn each side. The torch had no trouble burning through the felt on either side (it's a pretty serious torch), and the foam burns pretty easily. However, the fire we started on the flame retardant side went out on its own pretty quickly. The fire on the other side seemed happier to keep going.

Candles were a particular scenario a commenter asked about, so for our final test we assembled another tiny wall and treated both sides of the felt with the flame retardant. We then did our darndest to set the thing on fire with a candle, and didn't have very good luck.

The spray leaves a slightly slimy residue on the felt, but the results of these tests were reassuring enough we'll probably use the spray on some of our panels, particularly those near electronics.