Making a brick wall from styrofoam is really easy to do.  It is perfect for Halloween displays, haunted houses or movie and theater sets.  Or maybe your son or daughter just wants a medieval themed play area.  It is a really cool and realistic effect.  In the following tutorial I show how to make a cinder block pattern.  You are not limited to that pattern alone.  I have used my technique to make the foam look like granite, fieldstone, fired brick, dry stacked stone and many other variations.  You can mimic almost any stone wall type.  I have done this most often for theater sets for live performances where the script of the play called for either a certain time period or a certain type of look.  If this is something you are looking at trying, get some smaller pieces of foam and just dive right in.  Testing out some small panels gives you a good feel for the technique and helps you get a feel for how the foam reacts.  I have a list of tools and materials at the bottom of this article to help get you started.  A small warning, once you start it is oddly satisfying and rather addicting.  Let’s Begin!

 

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It all begins with expanded polystyrene foam, or EPS foam for short.  You can find this in the insulation department of your home improvement or building supply store.  It is traditionally used as a building insulator.  Four foot by eight foot sheets are the most common but smaller sizes are available as well.

 

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The pink or blue extruded polystyrene foam will not work with this technique.  So make sure it is EPS foam.

 

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If you can find it without a film coating on it you are one step ahead already.

 

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As building materials evolve, many manufacturers put a reflective film layer on one side and a mold/vapor barrier on the other.  It’s not a problem, as it peels off quite easily.

 

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If the cinder block wall pattern is the one you are going for, mark every 8″ vertically with a permanent marker.

 

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Using a drywall square ensures your 8″ lines will be nice and square to the edge of the foam.

 

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Measure for vertical lines every 16″ across.  Start the first row 16″ from the edge and the next row 8″ in from the edge.  This will give you the staggered cinder block pattern.

 

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If you started out with a 4’x8′ sheet like I did, you should end up with 12 staggered horizontal rows; each block measuring 8″ tall and 16″ wide.

 

 

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Now it’s time to carve the grout lines into the foam.  There are a few methods to do this.  The first one using a router and 1/2″ core box bit.  This is the quickest and probably the most consistent method.  It is easily the messiest method as well.  The flakes of styrofoam accumulate a static charge, attach themselves to things and get all over.  A built in dust collector or vacuum helps but isn’t perfect.  This is probably my second favorite method, and I only employ it when doing a high volume of panels.
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The second method for cutting in the grout lines is by far the most cost effective.  All you need is a snap style Olfa knife.  Cut 2 opposing 45° cuts to form a “V” channel and create the faux grout line.  TOOL TIP – Do yourself a favor and skip the bargain barrel $1 snap knifes.  They work for crap and the Olfa ones are a joy to use.  NT’s Red Dot is another great knife.  Even if you never cut a piece of styrofoam in your life, you will thank me as they make great all around shop knives.

 

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The last method for cutting in the grout lines is my favorite.  It is using a hot knife forming tool.  You can get them in a kit.  It uses electricity to heat up nichrome wire to melt it’s way through the foam.  If you aren’t going to be cutting much foam, it probably isn’t a cost effective option, but they do work well.

 

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The nichrome wire is nice because you can bend it to special shapes to get unique effects.

 

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I bent mine to mimic the concave shape of a real grout line.  Albeit slower than the router, it’s a cleaner cut than the knife and just plain fun to use.  You are melting the foam at this point, so make sure you do this in a well ventilated area and you are using appropriate breathing protection.

 

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Before any surface texturing, the three grout methods (knife, router & hot knife) look a bit unique to each other, but that will change shortly.

 

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This is the panel with all the grout work complete.

 

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After reforming the hot knife, I make random cutouts in the field of the brick.  This gives the final result a more organic look while adding depth.

 

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Cutting away certain areas give the appearance the pieces of the brick have split or chipped away over time.

 

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An Olfa knife or wire brush can be used to get very similar results.

 

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Using the actual hot knife to make slits in the foam will give the appearance of cracks later.

 

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Edges of the panel don’t need to stay true and straight.  Cutting them back sells the effect even more.

 

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And now for the star of the show, the heat gun!  The heat gun is the true secret to the process.  It will be used to melt the surface of the foam giving it the desired brick or stone look.

 

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Tool Tip – Buy the digital heat guns that have an auto cool-down feature.   At a previous job of mine, we had to use heat guns almost all day, no joke.  I had gone through more than 100 heat guns of every type and from almost every manufacturer.  I finally found these and have had the same 3 or 4 for over 6 years.  They work great for removing decals, old paint & finish, moulding plastics, melting waxes and the list goes on.  It will probably be the last heat gun you’ll ever buy!

 

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I like starting on the grout lines.  With the heat gun set to just over medium heat, move the heat gun along the grout lines.  I would say I am moving along at about one foot every two seconds or so.  There is really no perfect formula to it but it is pretty easy to see the results and adjust if needed.  Melting the foam in this fashion doesn’t give off any harsh smell like the cutting tool does, but error on the side of caution and do this outdoors or in a well ventilated area.

 

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A little bit difficult to see in this picture, but on the left one light pass with the heat gun and the right side has yet to be formed.

 

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After doing all the grout lines move on to the field of the brick.  The longer you remain in one spot the more dramatic and deeper the texture will be.  Make sure and keep it random and somewhat organic looking.  Most people that I have shown this to pick up on it rather quickly.  If you don’t like the initial results, go back over it again to add deeper texturing.

 

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After all the texturing, you can now see how each of the grout cutting methods look rather similar.  Personal preference I suppose.

 

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The heat gun isn’t the only way to texturize expanded polystyrene.  Spray paint, or aerosol paint can be sprayed on the surface to chemically melt the foam.  I don’t like this method for various reasons.  Spray paint can be pricey and the finished texture is too consistent to pass off for brick or stone.  Additionally, once the paint is dry, it forms a protective layer limiting any further texturing.

 

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What in the spray paint makes the foam melt?  Most likely its acetone content in the paint formulation.  So another method is to put acetone in a spray bottle and spray it directly onto the foam.  The fumes are noxious and nauseating, and it is super easy to melt completely through the foam.  Also, there is little control over the reaction and often times the effect is too pronounced.  I recommend sticking with the heat gun.

 

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With the panel fully textured the end is in sight.  Applying the base coat of paint dramatically changes the appearance and it starts to look a lot like brick.  For panels this size, a small paint sprayer using compressed air makes quick work of getting the paint on.  You can use a paint brush and/or roller but those seem to minimize the texture and make the overall effect less believable.  Either way you do it, a water-based paint should be used.  Most oil based and aerosol paints will chemically melt the paint just like the acetone.

 

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Again, I prefer to start with the grout lines and then move on to the field of brick.  One base coat should be fine, and heavy coverage isn’t really necessary.  Spray just enough to cover the white.  Also worth noting: with this particular and similar sprayers, the paint needs to be thinned down with water.  Your results may vary, but 3-4 parts paint to water works pretty good.  If it is not flowing correctly consider thinning the paint a bit more.

 

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Here is the panel with all the base coat applied.  I randomly picked a medium tan for this example but just about any color in an earth tone can be used to still look like brick.  Play around with different paint colors to see what works well for your application.

 

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I left this part of the panel in several stages for illustration purposes.  Hopefully this gives a you a better idea of the stages and how much or little texturing you can add.

 

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Making the panel appear to have more depth is done with and airbrush.  I merely added some black paint to the base color to make a slightly darker color.  This can then be painted into the grout lines and heavier texture areas to make the whole thing pop!
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The above picture shows the panel with base paint only, grout lines airbrushed, and finally the deeper texture areas.  Yes it is subtle, but I think it really makes the difference between believable and so so.  What do you think?

 

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If the panel is going to be at ground level, I like to add a very subtle green to the bottom to mimic moss and/or mold on the bottom.
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Depending on the overall look you are going for, foliage (like vines or ivy) can be added.  Cut some floral wire into small pieces and bend them into a staple shape.

 

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Simply push the floral wire “staples” into the foam to secure your greenery of choice.  Not the best job at applying ivy that I have ever done.  Check out the video below for a 2 story tall tower I did for the musical Shrek.  The ivy on that one is a whole lot better.

The Shrek tower video is what prompted me to get further in depth on my styrofoam process.  Thank you for taking the time to check everything out.  If you would like to see any other type of brick or stone wall in the future, or have any questions or comments on the process please feel free to leave those down below.

 

List Of Items Used

Digital Heat Gun

Hot Knife Kit

Drywall Square

Olfa Knife

Styrofoam

Wire Brush

Router

Router Bit

Small Air Brush

Small Paint Sprayer

Floral Wire

 


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6 Responses

  1. Greg

    On the foam wall do you have to put any fire retardant application on it to meet fire marshal requirements

    Reply
    • Nick

      that depends on what you are using it for and your local codes – you’d have to check into that as different areas vary

      Reply
  2. August

    is styrofome suitable for an exterior wall? Building a birdhouse and like this idea but not sure if it will last

    Reply
    • Nick

      it won’t hold up all that long outside – you want to think about coating it with something

      Reply
  3. Ganesh N

    Nick,
    Thanks for this YouTube post. One quick question is what paint you used for this? Can latex wall paints be used for this?

    Appreciate a quick response as I am working on a project that requires this.

    Thanks
    Ganesh

    Reply

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