Sunday, November 7, 2010

Building a DIY Spray-Booth in the garage

I had an earlier attempt to build a painting booth in the single car half of this garagegarage and there wasn't much space with all the stuff that my friend was moving. Now with an open garage, I'm going to start from scratch on the other larger side. I'm going to leave the previous hours in the tally, but I'm going to return all the un-used products that I tallied before, and restart the actual costs for building the booth from scratch.

I started by screwing a 20' long 2"x4" ($3 each) to the support for the sliding garage door. You've got to do it high enough that it is above where the garage door starts curving and so it has ceiling space for your car; but low enough that the garage door can open and be above the booth (so you can spray with sunlight lighting your booth.) I set mine at 7 feet high.

On the other end of the 2x4, I screwed a 8' tall 2x2 ($2 each) so that it was level. I also put a short 1x2 brace at the middle of the 2x4 attatched to the ceiling to give it some vertical and lateral stability. (Note, this isn't the final position of  this vertical 2x2. It's just there to hold things up for now.)

Here is the same board on the other side of the garage door. (This garage door is 16 feet wide, which is just right for a spacious booth.) It is mounted to the garage door railing right where that red flag is.

Once the sides were mounted, I then had to put up the cross members. These would be three 16' long 2x4's ($2 each). There would be one just by the garage door (about two feet from the garage door), one in the middle, and one on the side furthest from the garage door. They are spaced 9 feet apart. (This is to give clearance for the garage to open, and also so that a 10' sheet of plastic will easily fit and have some overlap.) If you are working by yourself, you'd find it hard to get a 16' 2x4 suspended in place by yourself, and keep it there while you screw it in. I started by screwing a scrap of wood to the top of each side of the 16' 2x4, and lifted it into place where it hung until I screwed it to the 20' beam. I then removed the scrap wood. Here you can see that intersection and the scrap wood still there. I used 3.5" decking screws at all the joints.

The same thing is repeated on the back of the garage, and this one is also supported by the ceiling. I also moved the 2x2 floor supports to the corner, and cut their tops off so they can have plastic stretched over their tops. In this picture the 2x2 is cut down and in its final position.

I then mounted the front (near the garage door) 16' cross-beam, and gave it vertical supports in the corners as well. (You need to check that the garage door can open and close before you screw it closed. There is a metal pull bar on most garage door that needs to clear this cross-beam) These vertical supports are less about weight (since the long beam is attached to the garage door frame itself.) Instead, this vertical support will allow me to wrap one single long piece of plastic around the entire booth, minimizing gaps and staples to keep it in place. Doing all this framing took about 3 hours, and another 2 hours to sweep the floor and mop and squeegee it three times and do some other moving stuff and cleanup of the garage. (I should have built the booth first to keep all the sanding dust out of this half of the garage.)

Now that the framing is all done, it is time to put up the plastic. Instead of using the smaller sheets I had previously bought, I just decided to get a whole roll of plastic. I opted for the generic brand 12' x 100' x 2mil plastic sheeting in a roll ($26). I first rolled it out over the rear cross-beam. It took about 18 feet of tarp and easily spanned the 9 foot width. I made sure not to let it touch the ground which would have gotten it all dusty, even with the thorough cleaning. After tacking it with staples on one long side, I tacked it on the other stretching it just a bit taut. Then I pulled the short ends taut and stapled those. I used 3/8 inch staples in a small Stanley staple gun ($3). I put staples every 2 or 3 inches. Once the plastic was nice and taut I started on the second ceiling panel. I rolled out another section, supporting it on the central cross-beam. I connected the extension cord for my internal light, and then tacked the tarp first to the central cross beam. Then I tacked it to the garage-door side, and then the side beams. It ended up being very taut and let in plenty of light from the ceiling panels. It took 3 hours to do the ceiling plastic, and 1 hour to install the light.

For the sides, I started in the corner you can see in the picture below. I strung a rope through the roll of plastic and slowly payed it out as I tacked the top edge of the plastic wall to the beams. I worked around the whole booth this way until the whole wall was taut and tacked on the top. I made sure to tack between the staples that were already there for the ceiling plastic. I then tacked this wall plastic to the rear vertical supports, but not the front. (I needed to be able to lift the plastic in the front of the booth so I could pull the car in.) Here is a photo from inside the booth. (The car is still parked in the other half of the garage, outside the booth.) It took 2 hours to do the walls.

In the middle you can see a florescent light fixture the I hooked up inside the booth to the central cross beam.

Here you can see that I've started to duct tape the edge of the plastic to the ground. I didn't tape it all the way to the garage door because I still need to lift the plastic to drive the car in. You can also make out one of the hooks I rigged to hold up the plastic so I could drive the car in. it is just half a hanger and some duct tape:

For ventilation, I've got three fans. Two box fans are just cheap 20"box fans that I picked up at Home Depot. They were $15 each. I used duct tape to connect a 20"x20" air filter ($5 each) to the box fan to filter out dust. These fans are pretty wimpy and I got better air movement putting the filter in the input side, and the fan blowing directly into the booth. This assembly was then supported at the intersection of the central cross-beam and the side beam and taped into place. Then the ceiling plastic was cut, and the edges sealed to the fan with duct tape. I put one fan on each side of the booth. This should help keep a downdraft in the booth and keep floating paint particles going towards the floor. It took 1 hour for both fans.

Here is a look at the fan from the inside:

Here is the completed booth from the outside. You'll see the plastic of the ceiling bulging because the fans are on, which is a good indication of the positive pressure in the booth. It took 1 hour to get the car into the booth in the right spot, and set up all the other parts on boxes and saw horses for painting, and to lay down masking paper for the floor under the parts.

With a booth 16 feet wide, there is tons of space on the passenger side for me to stand while painting (about 3 feet):

There's also about 3.5 feet at both the front and the back of the car for clearance. The "X" is a hole I had to make in the ceiling to plug in the light which I'd forgotten to plug in. Afterward it intentionally got left plugged in and on, and the hole taped back up:

Here you can see there is lots of space on the driver side for walking, and space for all the extra parts to get laid out. You can also see I've started masking up the car, which I'll cover in the next post.

The two box fans didn't provide nearly enough air movement to keep the over-spray and clouds of paint down in the booth. I decided to add a real fan to the mix. This is a pretty powerful fan that I borrowed from a friend. It provides a strong blast of air that is a little too powerful, so I opted to put the filter on the outbound side to soften the flow up a bit. I then used some plastic sheeting and a bunch of duct tape to cover the side of the filter and the most of the fan until there was good airflow going through the filter. (Set of three filters, $12; Two rolls of duct tape $7) This fan took one hour to tape up and then mount into the wall.

Here is a back view of that fan. I then taped the filter-side of this fan to the middle of the front side of the booth, facing the nose of the car. (You can also see the heater in the background that I had to put in to get my booth (and car surface-metal temp) up to 70 degrees F. This is about as cold as the manufacturers recommended temp for my paint. I also took a digital kitchen thermometer and stuck it on the light in the middle of the booth so I can make sure the temp is always just right.

I made some holes for the compressor hose to enter the booth, and positioned it just outside the booth so it is pulling in clean air, and made another small hole that I could stick a dowel through to turn my compressor on and off. I also made a hole that I could use to open and close the garage door which I will use for lighting and ventilation. I also set up 2 outgoing air filters in the bottom left and right corners of the booth next to the garage door through which the air will exit the booth and then the garage. It took 1 hour to place holes correctly and set up the outgoing air filters.

I left one corner of the booth loosely taped for an entrance, though I later saw a cool thing at Home Depot in the paint section. It is a 7 foot length of duct tape with a zipper in the middle. Stick it to your booth, open the zipper, and cut the plastic in the middle. Voila, instant re-sealable door for $10. I wish I had bought it.

I re-mopped and squeegeed the floor of the booth again, and am very happy with my makeshift DIY paint booth in my garage.

Time spent: 15 total (3 framing, 2 cleaning, 3 ceiling, 1 central light, 2 walls, 2 fans, 1 exit filters, 1 move parts and car into booth)
Money spent: $106 total ($18 lumber, $26 plastic, $3 staples, $7 duct tape x 2, $30 fans x2, $22 filters)


  1. Cool, thanks for the ideas.

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