I-Beam Saw Horses With Green Paint

Fujichrome Velvia 50 slide film (35mm)

  2018 January 11    Woodworking


You've probably seen pictures of I-beam sawhorses on this site and elsewhere.  I think Popular Mechanics and 50 other sites have done articles on them. 

Well, it's time for another look at this old reliable saw horse design.  That's because there are a couple things you can do to make I-beam sawhorses even better than they are.

And besides, you can never have too many sawhorses.

Caution:  Woodworking and similar tasks can be dangerous;  Disclaimer

Now let's get building!

A Quick Note

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In This Article

1.  Materials

2.  Tools

3.  Cut List

4.  Assembly

5.  Weatherproofing


1.  Materials

Get you some two-by-fours.  If you build these out of pressure-treated lumber, no extra weatherproofing will be necessary.  However, the saw horses will be just a bit heavier.

I built this set from Douglas Fir 2x4's.  If you buy 8-foot lengths, you'll need at least five of those.  (Buy an extra, just in case.)

Also get a box of 12d galvanized nails.  And some wood glue.  Get a water-resistant variety;  saw horses tend to be outside for extended periods.


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2:  Tools

You can use deck screws and impact drivers, but I built these old-school.  Hammer and nails.  You'll need some other tools as well:

- Circular saw

- An existing pair of sawhorses will make the job easier.  I would recommend it especially if you're using a circular saw instead of a miter saw.

- Two or three Clamps to hold 2x4's while cutting or gluing.  The 12" SL300's are a great all-around clamp. 

- Tape measure

- Carpenter pencil

- Speed Square.  An absolute must-have tool for almost every type of woodworking and metalworking.

Also I would recommend a drill with 1/8" bits;  you're far less likely to split the lumber if you drill pilot holes. 


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3:  Cut List

32 inches x 4 pieces.  These will be the flats or horizontal portions of the I-beams.

30 inches x 8 pieces.  These will be the legs. 

29 1/2 inches x 2 pieces.  These will form the uprights or "web" portions of the I-beams.

Mark these with a pencil, or label them or something so you don't mix them up.  Otherwise it's very easy to start nailing together the wrong lumber;  they all look so similar.


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4.  Assembly:  The I-Beams

You made all the basic cuts, but there's one more thing I'd recommend.  Using a table saw, remove the rounded edges on the 29 1/2" pieces and at least one pair of the 32" pieces.  This will make the I-beam fit together more solidly.  It will also make the lumber a bit narrower than 3 1/2" wide.  You need only remove about 1/8" or one blade-width off each edge.  So the final width might be 3 1/4", or thereabouts.

OK, first you'll assemble the I-beams.  Pick out one of the 32" pieces that you de-rounded with the table saw.  Scribe a line exactly down the middle of it, long-ways.  Do this on the flip side, too.  (Mark along the wide faces, not the narrow ones). Then set it flat on the ground.

Now, pick out one of the 29 1/2" pieces that you also de-rounded with the table saw.  Turn it perpendicular (while staying lengthwise) to the 32" piece that's already on the ground.  Center it exactly on the 32" piece.  Make a pencil mark at each end of the 29 1/2" piece.  Transfer the marks to the exact locations on the flipside of the 32" piece.  (It's easiest to do this with a combination square and a pencil).

The scribe line and marks on that opposite side will show you where to put the fasteners.

Drill three pilot holes, each about 7 or 8 inches apart, along that scribe line.  The middle one should be at the exact center of it. 

Glue the pieces together before driving the nails.  The galvanized nails will really cinch down the glue joints. 

When you get ready to attach the opposite "flange" of the I-beam, make sure the nail holes do not line up exactly with the first set of nails (you know, the ones that went in from the other side).  You'll want to stagger them by an inch or so. 

Now repeat this whole process for the other I-beam.


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5.  Assembly:  The Legs

If you de-rounded all four of the 32" pieces, then you can skip the next step.

If you de-rounded just one pair of them, each I-beam should have one "flange" or horizontal that's narrower than the other.  This narrower one is going to face downward, toward the ground, when the saw horses are put together. 

OK, now.  Whichever method you chose, the next steps will be the same.

Now, mark each 30" piece with 4 pilot holes near one end.  Where to locate these pilot holes is something that is best learned from experience, but basically, you want them close enough to the ends that they'll make a secure bond when nailed to the I-beams.  They should not be so close to the ends that the wood splits, though.

It also helps if you stagger the holes so they're not a perfect square.  This helps to avoid splitting down the wood grain. 

Look closely at the photo, top of page, and you'll see what I mean.  The nails don't really form a square.

Sometimes the wood will split anyway.  (Or maybe you'll miss with the hammer...)  That's what clamps and extra wood glue are for.  These are utilitarian sawhorses.  Though we like them to look somewhat nice... they're going to get scuffed and dinged up sooner or later. 


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6.  Weatherproofing

Here's why I like to use non-treated lumber for these.  We're going to paint them.

You can paint pressure-treated lumber, too, but the wood has to dry out first.  (Could take months, or more.)

House paint works great for sawhorses.  Here's one that looks similar, but nowhere near identical, to the color that I used for these sawhorses. 

Barn paint, such as this or this, would be another great choice.  Outdoor paints are very durable to weathering, so it makes sense for outdoor furniture.  And sawhorses.

Make sure to work a lot of paint into the end-grain of all the pieces, especially the ones that'll be on the ground.  Water that wicks into the end-grain is the #1 reason why sawhorses go bad when you leave them outside.  (Unless they're plastic sawhorses, in which case it's the sunlight that ruins 'em.)  You will have to paint the sawhorses in a couple stages, probably.


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This was an improved version of the common I-Beam Sawhorse.  My version has some of the rounded edges removed, so the I-beam goes together more solidly.  I also used galvanized nails, which make the saw horses surprisingly sturdy if you use pilot holes.

The way I built these, the saw horses should last.  They should be able sit out for a year or more-- probably several years-- in the direct sun and rain.  (This pair has been out for 8 months or so.)  The galvanized nails might get a bit loose over time, but you can always pound them back in. 

If you found this article helpful, please help me out by using the links on here to purchase your tools and anything else.   Your support is greatly appreciated and is the only way I can keep this website on-line and adding helpful articles to it.


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