i have a friend whose place of business has tons of throw-away lumber every week. I started collecting this lumber for this loft bed project. i love working with reclaimed lumber for several reasons:
(1) price! (FREE!!!)
(2) Easy on the environment - RECYCLE!!! GREEN! GREEN! GREEN!
(3) reclaimed lumber is usually "distressed" and i think that produces a more unique and aesthetically pleasing piece.
(4) Did i mention price? the lumber i scored were all 2x6x8 and they cost at least $4 each in home depot. i reclaimed over 30 boards - that's $120!

What's needed:
safety gear:
- eye protection
- gloves (to minimize splinters)
- close-toed shoes (things fall)
- respirator (not always)
- nothing loose fitting (to reduce snags)

tools:
- drill
- screwdrivers and/or screwdriver bits for drill
- dremel or similar (optional, but very useful)
- circular saw
- compound miter saw (optional, but is much faster than a circular saw)
- drill bits - i used 1/8inch and 1/4inch primarily
- wood chisels
- block plane (optional)
- wood sander
- tape measure, yard ruler, & combination square
- several clamps - the more the merrier. i use 3 clamps that have a 4.5 inch mouth and one clamp with a 12 inch mouth, but i wish i had more, and bigger.

supplies:
- wood - i used (as noted above) 2x6x8 unfinished pine (reclaimed). i know a loft bed can be made with 2x4's but in my view, that would require more wood in order to make it stable, so i would rather go with 2x6's

- - i also purchased 2x2x8's - two of them. they were construction grade (not finished grade) which makes them cheaper - only $1.52 each

- screws - i bought 2 pounds of screws (2 boxes), size 2.5 inch long (2 and 1/2 inches) phillips head (each box cost about $8). i've tried the more exotic head screws before (hex, square, torx, etc.), but the bit usually wears out too quickly and the screws rarely hold much better. yes, phillips head bits wear out just as quickly, but they're much cheaper to replace. the length is important - yes, they're more $$$, but a "2x" (two-by) board is actually 1.5 inches thick, and you need the extra 1 inch to grab the other board. i did not buy simple drywall screws - i spent a little extra $$ (about another $2 per box) to get the screws that resist rust. soft woods tend to streak nails and screws, and the rust resistant helps prevent this. final note: screws don't wiggle loose as fast as nails, so i use screws, but nails are MUCH cheaper and quicker - especially with a nail gun. if you choose to, you can substitute nails everywhere i use screws.

- bolts - if you build the loft bed in the room it will stay, then the bolts aren't necessary. BUT - even in that case, bolts are able to produce a much more sturdy frame, since they can snug 2 pieces of wood together much tighter than a screw. i bought 24 carriage bolts and 24 flat washers, lock washers and nuts to go with them. i selected the carriage bolt because its head is smooth so it won't snag the bedding, and also, the head is larger than a hex bolt, thus reducing the need for another washer (washers are required because soft wood like pine compresses too easily, and a washer spreads out the force onto a larger area of wood). the size of bolt i used was 1/4 inch in diameter and 3.5 inch length. they all cost me about $8 (bolts, nuts, flat washers, & lock washers). be frugal here - if you find other cheaper bolts that can do the job, then get those. keep in mind that sometimes what you want could be packaged differently and may be much cheaper. this happened in my case. the washers and nuts were crazy expensive if bought individually, but i found an odd little package designed for another purpose that had what i wanted for less. i bought the bolts individually.

Step 1: Find Lumber

Where to find reclaimable lumber?
Sure, pallets are the most commonly mentioned source, but i never waste my time with pallets - too much prep work for too little wood. instead, i look for manufacturers of commercial or wholesale goods. in my case, there are several window manufacturers in my area, and the glass is rarely made onsite so it must be trucked in. glass is fragile (duh) so it must be packed in heavy wooden crates that are then discarded. go to the industrial district of your nearest large city and just drive around for a while - be a little nosy, but not too much so. if you find even the slightest hint of discarded lumber, then ask the dock foreman for it. trust me, he (she) will be thrilled to have you take it. there is an etiquette to this, so follow these rules:
(1) if you turn away pieces that aren't "perfect" then the foremen won't be willing to let you come back. don't be a prima donna - that's just rude.
(2) do NOT make a mess! totally rude!
(3) don't just take one or 2 pieces (unless that's all they have) - stock up if you can. it helps them reduce their pile and helps you have more than enough so you can be choosy at home.
(4) if you do things right, then he/she will want you to come back, so ask when and how often.

here's an uncommon source of good lumber: thrown away furniture. you won't yield a lot of wood, but most furniture is made with hard wood (well, not so much anymore, but they used to be) and if you tear it apart, you can score some beautiful woods for small jobs, like inlays or handles or...

another uncommon source: ever see a board along the highway? that may be a discarded timber from a truck driver. flatbed drivers who haul steel or heavy machinery need timber as props for their load, and soft wood like pine will just fall apart under 30 thousand pounds of steel, so they use a hardwood like oak. if one edge splinters then it isn't load worthy anymore, but there's still 5 feet of oak for you to use.

Step 2: Loft Bed: Frame

i tend to keep my designs simple. my loft bed consists of 3 sections: the bed frame, the legs, and the cross members & ladder & rail (i will put the rail with the cross members).

frame:
measure the mattress and add 3 inches to its width and length - for the width of the wood. mine was 38x71, so it became 41x74.
cut two 41inch boards and two 74inch boards.
cut notches in the ends to produce a corner halving joint - see pics. this type of joint is relatively quick to make and avoids having the screws all face only one direction (weaker).
since these joints require screws into the end of the wood, i highly recommend drilling a pilot hole for the screws to avoid splitting. all the screws in this loft bed were first drilled with pilot holes. i used a 1/8inch bit for the pilot holes, but your pilot holes should be a little smaller in diameter than the screws you buy.

after cut, flip over the two 41inch boards so that the missing black sections are on the ground and form the frame of the bed. the notches will line up and you can screw into the wood to hold it together. the screws go into the side of one board (the uncut white section) and into the end piece where the black section was. (remember, your measurements will be different if you use different sized wood - i used 2x6).

now cut as many slats as you think you need or want. i cut 8. the slats are the width of the bed - mine are 38 inches. sure, i could have used thinner and perhaps cheaper wood than 2x6's for slats, but my thought is if i make an extremely sturdy loft bed for my son, then when he goes to college years from now he can take it with him.

take the 2x2x8 boards and cut them 6 inches shorter than the length of the mattress - save the waste cuts. why 6 inches? to make room for the forthcoming carriage bolts (i didn't do this so i had to cut the 3 inches off each end after it was screwed to the frame - quite a hassle!). center this cut piece along the length of the long side of the frame at the bottom edge and screw it into the frame. it will provide a shelf upon which the slats will rest. screw the waste pieces at the head and foot for extra support.

the frame is complete.
next step: legs & ladder.

Step 3: Loft Bed: Legs

my son wanted to be able to sit up in bed - i wanted to be sure it would be versatile enough to go through several bedroom re-decorations. the space underneath needed to be able to convert to a desk, or shelving for storage, or (my son's current request) a reading nook. - so i had to get the leg height precise.

i measured the ceiling height in his room and did some math incorporating required headroom above and required seated headroom below (if a desk is put underneath) and concluded the legs needed to measure 60 inches.

i decided i wanted to use a "finger" joint for the legs, but they will be connected along their edge, rather than their ends (a finger joint is typically found on the ends of the wood). here is the math: 60 inches long boards and i want 4 fingers --- so 60/4 = 15 inches for each finger. cut them as shown in the pics.

then, take 2 boards, flip one over (end to end) and if your finger cuts were precise then the notches will match up with the fingers - remember, it's just like lacing your fingers together. now screw them together and you have a very strong joint.

do this for all 4 legs.

the legs are connected to the frame via the carriage bolts. here's how you do that. turn the frame over (upside down) and have a helper hold a leg at the corner of the frame and clamp it to the frame using 2 clamps. keep in mind you will be drilling very close to the clamps so placement is important.

drill through the leg and frame using a 1/4 inch drill bit. if you make a template then the holes will be uniformly placed, but this isn't necessary. after drilling the four holes for the one corner (that's 4x4=16 bolts just for the frame) put the bolts in & tighten them before removing the clamps. then move on to the next leg. if you have 8 clamps then you can do this standing up, otherwise it will probably have to be upside down on the floor (as noted).

a note on bolt placement:
you probably want the nut end of the bolt facing out. yes, it's less sightly, but the threads will snag the mattress if you put the bolt facing in. the order is thus: push carriage bolt through from the inside so the threads are outside, then put on a flat washer, then put on a lock washer, and finally put on the nut and tighten.

next step: cross members and ladder and rail.

Step 4: Loft Bed: Cross Members and Rail

by now your frame and legs are attached - you can turn it upright and start cross member placement.

crossmembers:
cut four 41 inch boards and notch them as done previously for the frame. (there is some overlap in this instructable - hopefully you'll read the whole thing through and realize you can compress some steps). these will hold the legs together and the notches are for the long cross members.

cut two 74 inch boards and notch them as well. these long cross members will be attached using bolts.

cross member placement:
using a jig is important in this step. grab some scrap lumber and cut it to about 18 to 20 inches or so. mine ended up being 19 inches, and upon reflection i would have been happier if i had put more thought into the spacing, but at least with a jig it is consistent.

start with the 41 inch cross members that are notched. hold the jig in place along the inside of one of the head legs pressed upwards against the bottom of the frame and press the cross member against the other end of the jig and clamp the cross member in place. do this for the other end and repeat your measurements with the jig to be sure it is precise. with the 41inch cross member clamped in place, screw it to the legs - see pic - i used 4 screws as shown. remember to use a pilot hole - it reduces splitting. repeat on the two foot legs. now use the jig to repeat for the lower cross members - pressing the jig against the bottom edge of the mid-cross members. make sure the cross members are all the same orientation - that is, the notches should all be facing the same way. i choose "notch down".

a note on jigs: a jig is just a measuring device, and in the case above, it's simply a stick cut to the exact length i want to measure. jigs are useful because they produce consistent results, and your work won't look crooked and rickety.

now that the 41 inch cross members are in place, get out the long 74 inch cross members, turn these over so the notches fit (in my case, the long cross members need to be "notch up") and wedge them into the notches on the small cross members and clamp them. use a wood chisel to shape the notches if they don't fit. after they're clamped in place, then drill 1/4 inch holes for the bolts. i put 2 bolts on each end of the long board - for a total of 8 bolts. why bolts? because they're removable and i can't shove a completely put together loft bed through the doorway, so i need it to be modular.

why are the long ones "notch up"? my logic is this: due to leverage it would take less force to crack a long board than a short one, so i wanted to put the notches on the long boards "inside" the force - this is the same concept used when they make old fashioned long bows (you know: bow & arrow) - they shave & work the wood on the inside of the bow, leaving the wood uncut along the outside - it keeps the bow from splitting.

i could have put a ladder at both ends to make the bed more symmetrical and reversible but i was running out of wood and, frankly, feeling kinda lazy... cut 2 rungs to a length of 41 inches - no notches needed. and measure the gap to put the rungs in the middle of the space. i made a jig for this too. screw them on - bolts not needed, since the ladder is permanent.

rail:
i chose a 4 foot length for the rail - it's a round number and during mock up, it seemed to be the right size. i wanted the rail to be removable so the bed can be made easily and etc. so here is how i did it:
the width of the cross board of the rail is 5.5 inches (a 2x6) and based on the height of the mattress i needed it 6.75 inches above the frame, so i cut two 2x6's to a length of 6.75 inches and set them aside. i cut 4 2x6's to a length of 16 inches and sanded them and beveled them. i laid the 4ft cross rail sitting upright along one edge and clamped it to the table and made a 3-board sandwich as noted in the pic and screwed everything together - leaving a gap where the rail will be wedged onto the frame.

there you have it!
please leave a comment, and be sure to rate this instructable (on the right side of the screen) so i can improve it if necessary.