Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.
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The following drawings:
The plans have a List of Materials, including size and number of the door trim and corner boards, studs, plates, trusses, joists, sub-floor, wood foundation, gussets for the trusses, OSB for the walls and roof; recommended adhesives for the sub-floor, fastenings for the hinges, etc., the framing, sheathing and roofing.
The Instructions include the following topics:
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There are three kinds of foundations that are practical for this type of shed—a concrete slab on grade, a concrete block on a concrete strip footing or a wooden floor supported on pressure treated 6x6s. The easiest and most mobile is the wood foundation. Once concrete is poured it is permanent.
Note:These plans are for a storage shed that is 12' wide and 16' long, but its length is totally up to you. If you need a shed that is longer than the side elevation, just add more studs and trusses and revise the foundation and floor accordingly.
See the shed foundation drawing. Place the anchor bolts on 4 foot centers or less around the outside perimeter. Make sure they are in the center of the 2x4 when placed flush on the edge and are at least 2" high. These bolts are usually placed after the concrete is poured. Depending on where you live and how cold the winters are, the perimeter of the slab should be built up in thickness, 12" being the minimum thickness and 12" in from the edge as well. Typical with any concrete slab or footing, make sure all top soil is removed and provide a base of well compacted sand, gravel or undisturbed non-organic soil under it.
To support a row of concrete blocks, you need a concrete footing. The blocks are 8x8x16" long. The footing is 6" thick by 16" wide, poured over well compacted gravel. The forms are made of 2x6s on each side nailed on the top with 1x3 cleats and fastened on the side with 1x3 pegs. After leveling the concrete, scratch out a key for the blocks to make a good bond with the mortar and concrete. The next day, at least, after pouring the footing, the blocks can be laid. Use regular blocks with the web in the middle, one row is sufficient. Place some concrete in the web and insert anchor bolts every 4' or so. After the concrete is set up for about day, bolt a 2x6 sill plate onto the top of the blocks, running their length. The box and floor joists are nailed onto this plate.
See the shed foundation drawing. The wood floor is typically 5/8" tongue and groove plywood on 2x6s at 16" centers on 6x6s, pressure treated to last for 40 years. Put these 6x6s on a bed of about 6" deep compacted gravel to help in drainage. Make sure the center one is level and true with the edge ones. The 6x6s are 16' long and placed 12' apart to the outside with a center 6x6 to support the mid span of the floor joists. Cut 2 - 2x6s 16'-0" and lay them both out together for the box joists. Start at the left end, measure 15 1/4" and place a mark with an X on the right of the mark. Now move the tape to this mark and continue to mark and place an X in the same manner at every 16" mark on your tape, until you run off the 2x6. Cut the 13 - 12 foot 2x6s to 11'-9" to allow for the combined 3" for the box joists on each end, as shown in the above drawing. When you nail the joists onto this box joist the left edge of the joist will be on the mark covering up the X.
After nailing on all the joists you should be able to place your tape on the edge of any joist, except the first one, and read a multiple of 16". This will enable the plywood to end on the center of the joist. When the joists are all nailed on, measure their diagonals to be sure the floor is square. Bump one 6x6 to the left or right until the diagonals are the same and the floor is square. Go ahead and nail the plywood on. When using 5/8" tongue and groove (T & G), start with the tongue flush with the outside of the floor and the groove towards the inside of the floor. Notice the stamp on the plywood, it usually says place this side down (the tongue is thicker on the bottom).
Nail on your first two sheets end to end, snug the end joints up. Just use a few nails to keep the plywood in place and mark where the joists are. Keep them back from the groove side by at least 6" to allow the next sheet to slip into the groove easier. Cut the third sheet in half - 4'x4' and start on the left, the way you laid out the joists. Place the tongue up to the existing groove get your helper to stand on the tongue and groove together while you hammer lightly with a sledge hammer against a 2x4 against the groove side of the third sheet. The sheet should slip into the groove of the one nailed on. Now install the fourth sheet (full size) next to the half sheet. Then install the other half to get to the end of the floor. This is called staggering your sheets so the joints are not in the same line the same way brick layers build a brick wall. Continue the next row with a full sheet and the last row by staggering your sheets again. Nail or screw on the plywood securely: nails spaced 6" apart on all joints and 12" apart in the middle.
After the shed foundation is made, start on the side walls. Lay them out in place, for an 8' ceiling use pre-cut 2x4 studs (92 1/4") with a single plate on the bottom and top and double plate on the top. For a concrete slab, start with the bottom plate and drill holes for the anchor bolts so that the plate will lay on the slab flush with the outside of the concrete. Don't fasten the bottom plate to the concrete yet. Now place the top plate next to the bottom plates and lay them both out together.
First, lay the studs out on 16" centers. If you are using plywood or OSB for sheathing, pay particular attention to the start of the first stud so that the 4' sheet will end on the center of the stud. I usually lay out the long walls first, with the ends of the plates flush with the outside of the slab, just like the sides of the plates. I then go to the shorter walls and lay them out with the plates against the plate of the longer walls. Now watch these walls for the stud layout; remember the sheathing will start at the edge of the intersecting wall plate so add 3 1/2" plus the thickness of sheathing, probably 3/8" = 3 7/8". What I do is just stick my tape measure out past the end of the plate by 3 7/8" then mark on 15 1/4" (3/4" back from the center of the stud). Now place the end of the tape on this point and continue laying out the studs on 16" centers. These points are the sides of the studs, so mark an X where the stud lies. Lay out the studs right through the doors and windows for now.
Now layout rough sizes of the door and windows, that is allow for the thickness of the shed door and window jambs plus 1/4" on each side for shims (to allow for settling and shrinkage). It is important to get the correct rough opening for the selected windows. Get these from where you are buying your windows. The rough openings vary depending on where the windows are made. On each side of the window or door is a double 2x4 consisting of the cripple and the stud. The cripple is nailed together with the stud, but is shorter allowing room for a beam or header (also called lintel) to be placed on top of the cripple. The size of the header depends on the span of the opening. Today most builders just use a 2x10 header over all the window and door openings. They put it tight to the underside of the top plate, therefore eliminating any window studs on top of the header. This also gives the right height to have the window installed. Please note that for a window narrower than 24", there is no header required. Once happy with the layout, let's build some walls.
Start with one of the long walls. Go to each end of the wall and on the concrete or wood floor, snap a line in 3 1/2" from the edge. This line is the inside of the plate line. Turn the plates up on their edges with the bottom plate in position along the line, roughly. Separate the top and bottom plate about the distance of a stud. Now nail the studs in position on both plates. Cut your cripples to fit the header and nail them together with their stud. Choose straight boards here. Nail in the header, doubled. Since the header's thickness is 3" and the wall is 3 1/2", nail the header flush with the outside of the wall, in other words lift the header up flush to the top of the studs and plate when the wall is laid down on the slab. Where you marked the studs through the window will be your window stud positions. Measure from the header down along the cripple the depth of the rough opening and add 1 1/2" for the plate. Get the length of this plate by measuring between the cripples on one of the plates. After cutting the plate to size, lay it down on one of the plates, between the cripples and mark off the positions of the studs onto this plate. Nail a window stud against each cripple and on each stud mark, then nail the plate onto the window studs. There is your window rough opening. The door opening is the same procedure, except you may need extra 'wood' below the header to make up the correct height and, of course, no studs in the door opening such as the window. Now cut and nail the double plate to the walls. Make sure to overlap the double plate onto the intersecting wall. There should be at least 4' between joints of the top and double plates. Layout the floor joist on top of the double plate starting at the same end as the studs were laid out, on 16" centers. (Easier now than when the walls are standing up.)
After all the studs, headers, window studs and double plates are nailed in, position the wall on the snap line to get the bottom plate straight. Measure the diagonals of the wall, making them the same, to square up the wall (this makes the wall ends plumb when standing up). Now decide whether you want to put the sheathing on now or later. I always put the sheathing on at this stage and get the necessary help in raising the walls. If you want to put it on later that's fine too, except it is more work. If using OSB make sure you leave a 1/8" space between all sides of the board up against other sheets of OSB. Just tack a spike between the sheets. Start sheathing at the bottom of the wall and the edge from where you laid out the studs. On the joint, bring the stud half-way onto the sheet. The sheets go across the studs not with them. On the next row of sheathing stagger the sheets by 4'. As you go, mark on the sheets where the openings are so you can snap lines easily and cut out the opening after the sheathing is down. Stand the walls up as close to their proper position as possible. Watch the anchor bolts. Use a crow bar to lift and move the plate over the bolts and drop them into position. Tighten up the bolts when the wall is straight and on the snap line. Brace this first wall with stakes driven in the ground. For a wooden floor fasten the bottom plate to the top of the floor, flush with its edge by nailing into the box or rim joist.
When all the shed walls are standing, nail the corners together on the studs and on the sheathing. The outside corners should be plumb, so run a string from one end of the plate to the other or eye ball it to make sure the walls are straight. Nail braces to securely hold the walls straight while you are building the attic floor.
Hopefully the shed floor joists are nicely laid out for you on top of the wall. Cut your floor joists to length. They should be 12' less 3" for box joists. Check the measurement out before cutting them too short. Another trick that the framers use is to have the box joist come out flush with the wall sheathing to eliminate the need to put a small piece of sheathing on the box joist later. So figure this in with your joist length.
Nail the 2x8 joists in place along the box joist. Keep the crown up on the joists. Nail the box joist into the joists and nail the joist into the double plate. (Toe nail on each side). Nail solid bridging between all the joists in the center of the span. Nail a 2x6 along the long side, one side for now, off the floor on top of the floor joists and overhang the 2x6 by 2". This will form your overhang for the roof. Nail on the sub-floor, 5/8" tongue and groove plywood, with the tongue side against this 2x6. Use ring nails and construction adhesive. (This makes the floor one unit and very strong.) Proceed with the sub-floor until you have reached the other side. Cut the sub-floor back enough to allow the 2x6 to be placed on this side as well. A trick to get the tongue and groove (T & G) tight together is to start the tongue into the groove and continue by hammering a 2x4 held against the sheet (to protect it) with a sledge hammer.
Next layout the shed trusses, full size on the floor. Layout from the measurement on the Truss Layout drawing. You should have 8 trusses with gussets nailed to both sides and 2 trusses with gussets nailed on the inside only. Also, cut four 2x4s with the proper plumb cuts on them at the end of the sheathing at both ends.
Snap a line for the shed roof where it sits on the 2x6. This line should be longer than 12'-4". Label it line #1.
Snap line #2, up 67 1/8" and parallel to line #1. Mark in the center of this layout a point up 19 7/8" from line #2. Square a line down from this point to the bottom line. This is the center line of the shed truss.
From the center line measure 47 3/8" along line #2 each way from center and mark these points. From the center line and along line #1 in both directions mark points at 6'-2". Connect these three points on each side of the center line. This is the outside line of the truss. The measurements of the 2x4's shown on the shed plan should be 51 1/2" and 72 1/4". You need 8 trusses with two trim trusses for the overhang. That's 24 pieces of each length of 2x4 including 4 for each length for support at the end of the sheeting. Cut the 2x4s to match the layout lines and lay them on the layout when assembling them with the gussets.
Make your gussets from 1/2" plywood (don't use OSB, K-3 particle board or multicores). Cut them 12" long with the grain running length ways. Nail each side of the gusset with 8 - 2" galvanized nails, spreading them out and making sure the joints of the 2x4s are tight. Glue isn't required here as there's too much expanding and contracting due to temperature changes.
Just follow the above layout rather than using a definite pitch. Get your angles from the full size layout, not the drawings. The actual pitches that I get from my full size layout is closer to 5/12 and 12/4 3/4. Check yours out.
The framing under the front and back gables are, of course, from the sub-floor up to the underside of the shed truss. Frame in whatever size door you have room for up there. The total height of the shed is 16'. The headroom in the attic is 8' less the joists and sub-floor and trusses, about 7'.
Now brace up the two outside shed walls so they are plumb and straight. Notice the Side Elevation drawing and the layout of the trusses to enable the plywood or OSB ends to rest on the center of the truss.
On the top of the walls layout the trusses as shown on this drawing. Extend your tape out 6" from the end of the wall and mark a point at 23 1/4". Place an "X" next to this point so that this point represents the edge of the truss and the truss sits on top of the X, centered on 24". From this point continue marking points along the wall at 24" and an X where the truss will sit. The X's should be on the same side of all the points. Remember to put a gable truss flush with the outside of the wall at each end (with the gussets facing the inside of the shed).
To hold the shed trusses in place before you sheet the roof, nail a 1x4 along the trusses near the ridge. This is where a friend comes in handy to give you a hand. Leave the two overhang (trim) trusses on the ground for now.
To hold that first awkward truss up, brace it temporarily either to a stake pounded into the ground or to the inside of a wall. Nail the bottom of the truss securely into the 2x6 with 3" nails. When all the shed trusses are up and tied together with a 1x4 near the ridge and braced up nice and plumb go have a coffee.
Now let's finish off the back wall. With the trusses forming the shape of the roof, just nail studs to the underside of the truss to a plate nailed on the floor. If the shed is not going to be insulated, place these 2x4s on the flat. If insulated place them on edge in the wall. They should be placed at 2' centers and kept flush with the outside of the truss.
On the front end lay out the door jamb for the loft, keep it plumb and use straight 2x4s. The header over the loft door should be as high as possible. Make the header long enough so you can nail each end of it to the bottom edge of the truss. It's best to put the header board up and mark its ends along the actual sides of the truss so you are sure to get an exact fit. Make up the door as explained for the main shed door.
Apply the wall sheathing when the shed framing is complete. The wall sheathing should go over the trusses as well. Nail it well to the truss and to the header, especially around the joints. This is why you didn't put gussets on the outside of the truss, the sheathing takes their place.
Start ripping the roof sheathing to the measurements required. Start at the bottom, allow an extra 1" for the first row of sheathing to overhang the truss where it sits on top of the 2x6. It isn't necesary to miter the joints in sheathing, butt joints are good. Keep the sheets separate from each other the thickness of a 3" nail to allow for expansion (about 1/8").
Nail up the sheathing at about 12" center in the middle of the sheets and about 6" centers along the ends. Get your friend to help you again by holding up the overhang trusses flush with the end of the roof sheathing, forming a 6" overhang, with the gussets on the inside.
Install your choice of roofing. I prefer fibreglass/asphalt laminated shingles. Follow the manufacturer's very explicit instructions included with their shingles.
Now nail the 1x6 trim on the ends of the shed trusses at the front and back, flush with the top of the roof sheathing.
Nail the 1x4 trim on around the shed door.
Nail a 1x4 on the inside of the latch-side jamb (the side opposite the jamb the door is hinged to). Offset the 1x4 so it extends about 3/4" out from the door-opening edge of the 2x4 (all along the length of the 2x4). This makes a door stop on the latch side of the door so the shed door can be securely latched close.
The door can be made of a framework of 2x4s on the flat and sheathed with OSB to match the shed walls as shown in the front section drawing. Nail 1x4 trim over the sheathing in the same locations as the 2x4s.
Attach the shed door to the frame with 3" galvanized strap hinges screwed to the door trim and jamb trim with 2" screws.
For security, I'd recommend a 6" hasp and padlock or heavy duty padbolt (barrel bolt that accepts a padlock).
Build a little ramp to the shed door to ride a mower in and you are all set.
Enjoy your new shed!
Dave(Ask Dave) (About Dave)