Finished Project

Materials

QuantityItemTotal Cost
11-1/2" x 4' x 8' foam insulation$16.00
21/2" x 4' x 8' OSB$20.00
84' 2x4$4
1quart of paint - brown #1$0
1quart of paint - brown #2$0
1quart of paint - brown #3$0
1quart of paint - brown #4$0
1quart of paint - gray$0
228-oz liquid nails$10
401.5" screws$0
Total$50

Instructions

Step 1

On the OSB, trace out the lines shown in the following figure. Then then use your skill saw and hand saw to cut out the pieces.

fireplace made of styrofoam

Step 2

Use your miter saw to cut the 2x4s as shown in the following figure.

fireplace made of styrofoam

Step 3

Screw the 2x4s to the OSB.

fireplace made of styrofoam
fireplace made of styrofoam

Step 4

Use the liquid nails to glue the styrofoam to the OSB.

We only did the front face, but you can wrap the styrofoam around the edges if you want. Seams in the styrofoam are hard to hide, so minimize the seams as much as possible.

Step 5

Sketch your rock pattern on the styrofoam.

Step 6

Use the drill with rotary rasp to carve out the rocks.

Start by carving out the grout lines.

fireplace made of styrofoam

Then round the edges of the rocks.

fireplace made of styrofoam

Finally, roughen up the face of the rocks with a block of wood.

fireplace made of styrofoam

Step 7

Vacuum up all the styrofoam mess.

fireplace made of styrofoam

Step 8

Paint the rocks. We used four different shades of brown that we had lying around. This step does not need to be very accurate. Just get the paint on there.

fireplace made of styrofoam
fireplace made of styrofoam

Step 9

Sponge the top coat of paint. We chose to use the two lightest colors of brown, but you can do whatever combination you choose.

fireplace made of styrofoam

Step 10

Paint the grout lines and the sides of the outside 2x4s.

fireplace made of styrofoam
fireplace made of styrofoam

Step 11

Install the bottom half of the fireplace on your wall.

Step 12

Set the mantle on top of the bottom half.

Step 13

Install the top half of the fireplace on your wall.

Step 14

Make the recessed fire area by painting the remaining OSB pieces black on one side then screwing them together to form four sides of a box.

While you have the black paint out, also paint the inside faces of the 2x4s on the inside of the fireplace.

fireplace made of styrofoam

Step 15

You're done!

Decorate with cheese cloth, PVC candles, skulls, busts, bugs, potion bottles, or anything you like.

You can also add a fake fire in the fireplace and a realistic looking cauldron.