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How to Build a Simpson Shed

The tools you will need:

  • Measuring Tape
  • Pencil
  • Level
  • Clamps
  • Saw
  • Power Screwdriver
  • Hammer
  • Safety Goggles
  • Gloves


Before starting, prepare a level foundation. A concrete foundation, pier blocks or a treated wood substructure are all good alternatives as long as they are level. An uneven base will cause the structure to lean off center during construction.


This shed plan can be modified to meet your particular needs although this may affect the shed's structural integrity. If modifications are made to the 10' width or the 8'8 7/8" frame height, they should be carefully undertaken for this will affect the angle cuts and rafter lengths. If you do modify the 7'6" depth of the shed, you need to add additional studs, rafters and connectors and carefully recalculate your BUY and CUT lists. This shed can also be built using 2x3 lumber instead of 2x4's, however all dimensions should be recalculated before construction.

Skylights, windows and vents are features that can be added to increase light and ventilation. This shed can be used as a frame for a playhouse, spa enclosure, pool house, pet cage, deer blind, fishing hut or anything you desire.

Sheathing is necessary for maximum structural integrity. Alternative sheathing materials, from those suggested, such as acrylic panels or screen may be used, however they will not provide the rigidity of plywood.

Once your shed is built you may want to add trim to enhance it's appearance (see drawing on front of shed plan). 1x4 trim can be used to match the lumber on the doors. When trimming around doors it is a good idea to mount the door hinges on top of the trim.


The first phase of construction consists of building the four walls. Assemble each wall separately, and then attach each to one another to form a base for the roof (Fig. 1).

Assembling the walls while they are lying flat makes it easier to make precise connections and allows for nailing through bottom plate to stud. All connections should be clamped before fastening.


  1. End studs should be installed flush with the ends of the top and bottom plates using 16d nails through the plate into the stud.
  2. Check to see that the wall is square by measuring diagonally both ways from top corner to opposite bottom corner. Dimensions should be equal, adjust if necessary. Use this method for squaring all walls.
  3. Attach the 46" intermediate studs to the bottom plates using the RTT22 on what will be the inside of the wall. Refer to your specification kit for spacing of studs.
  4. Flip the wall to the opposite side and attach the intermediate studs to the top plates using the FWL2 on what will be the outside of the wall. Install the FWL2 so that Flange A protrudes over the top plate (it will anchor a rafter in a later phase). There are a total of six connections like this.
  5. On the ends of the walls, use a TWL2 three-way connector to anchor the end studs and top plate.
  6. Install an inside stud on each of the end studs using 8d nails. This will provide a nailing surface when walls are attached to one another. There are four connections like this.


  1. Install the two 46" end studs on each end of the bottom plate using nails through the bottom plate.
  2. Fasten two intermediate studs to the bottom plate using the RTT22 on what will be the inside of the wall 16¼" o.c. in from each end.
  3. Attach the two 90¼" studs to the bottom plate 32½" o.c. in from each end using the RTT22.
  4. In the center of the bottom plate attach a 46" stud using the RTT22 (Fig. 2).
    Note: Before fastening the top plate, make sure the wall is square and the top plate is level.

  5. The top plate will be in three pieces.

    1. The two 31¾" outside top plates will span from the end stud into the side of the 90¼" stud. Fasten the top plate to the end stud using nails, and to the intermediate studs using the RTT22. Attach the top plate to the long studs using the FWL2.
    2. The 46½" center piece of the top plate will install between the two 90¼" studs and rest on top of the center 46" stud. It will attach to the center stud with the FWL2 and into the 90¼" studs with the remaining flange of the FWL2 (Fig. 3).
  6. Attach the end studs on each end of the bottom plate, using nails through the bottom plate.
  7. Attach the 84 5/16" long stud for door fame at 18¼" o.c. from each end (using nails through the bottom plate).
  8. Attach a 17½" horizontal member on top of, and flush with the outside edge of the end stud and into the side of the long stud, making sure it is level.
  9. Nail the 79" inside studs for the door jamb to the inside of the long studs.
    Note: Before fastening the door frame header, make sure the wall is square.

  10. The door frame header consists of two 75" 2x4's turned on edge and resting on top of the inside stud of the door frame. Nail these two 75" members together to make one 3"x3½" member. Turning this double 2x4 on edge, position it between the long studs so that it rests directly on top of the inside studs of the door frame. Make sure that the header will be flush with what will be the front edge of the doorway studs. Nail through long stud into the end of the double 2x4 header to fasten it in place.

A piece of ½" plywood can be used as a spacer between the two 2x4's to make the header the same width as the doorway studs. This will allow the header to be flush with the doorway studs on the inside and outside of the doorway. This is only necessary if the inside of the shed is going to be sheathed.


The next stage of construction is fastening the walls together to make a square foundation upon which the roof will rest. Before fastening the walls together, use a level placed vertically against a stud of each wall to make sure the walls are plumb (i.e. straight up and down) (Fig. 4).

Fasten the walls together by nailing through the end studs of the front and back wall into the sides of the double end studs of the two side walls.

Make sure the outside edge where the walls meet is flush. Make sure all corners are square. Corner bracing may be necessary to maintain correct positioning during roof construction.


Now it's time to assemble the roof on top of the framed walls (Fig. 5).

  1. Insert a 40 1/16" lower rafter into Flange A of the FWL2 on the side walls so that the 22.5-degree cut is flush with the top of the top plate of the wall. Bend Flange A 22.5-degrees to match this angle and fasten. The lower rafters should angle towards the inside of the structure. Repeat for each lower rafter connection (Fig. 6).
  2. Pre-attach three FWL2 connectors onto the top of each of the three 2x4's which will become the ridges. Install the connectors so that they will align with the wall studs and rafters (22.5" o.c.) On the ends, make sure to use TWL2 three-way connectors.
  3. Install the lower ridges flush with the 22.5-degree angle cut on the top ends of the lower rafters. Flange C of the FWL2 on the ridge member will bend to straddle the lower rafter.


  1. After the lower ridges are fastened in place, install the upper rafters into Flange A of the FWL2. Install so the 22.5-degree angle cut on the bottom of the upper rafter is flush with the flat side of the lower ridge.
  2. Attach the center ridge between the upper rafters. The flanges on the FWL2's will bend down to straddle the upper rafters on either side of the ridge. The rafters should line up with the FWL2's pre-installed on the ridge member with a little adjustment (Fig. 7).
  3. The front and back ridge supports wedge under the ridge and raise the roof up a few inches to provide support as well as tighten the whole roof structure. On the back wall the 52 3/8" ridge support extends from the top of the wall to the bottom of the ridge. On the front wall the 17 3/8" ridge support will extend from the top of the double-header of the door frame to the bottom of the ridge.
  4. Connect the ridge supports to the ridge using an A21 angle on the edge of the support to the bottom of the ridge. Connect it to the middle of the top plate of the back wall using the FWL2. On the front wall, anchor the support to the header using an A21 on each side. After ridge support installation the frame will reach it's final height of 104 7/8".

The front and rear upper rafters will rest on the long studs of the door frame and the long studs of the back wall. Connect the long studs of the door frame and the long studs of the back wall to the rafters using the H2.5 ties (Fig. 8).



There are a wide variety of materials available for sheathing. Plywood is preferred due to it's strength, durability and various finishes and thicknesses. For this shed, ½" plywood is recommended. Thicker plywood can be used for additional strength.


  • If a more finished appearance is preferred, T1-11 plywood may be used. This type of plywood has grooves and a rougher surface on it's face. When using this material, care must be taken to align the grooves and fit the edges to achieve a "continuous sheet" appearance. In order to make all the grooves run vertically, special cutting and placement will be necessary in some spots and extra material will be needed.
  • To ensure fit, it is a good idea to clamp all the pieces in place before nailing. This allows for minor adjustment and trimming.
  • In situations where two pieces of sheathing meet over the 2x4 member, both pieces of plywood will be nailed onto that member. Therefor it is a good idea to move the nail a little farther away from the edge of the plywood and nail at a slight angle into the member. In addition, stagger the nails on each piece of plywood when they meet over the same member. These tips will help to avoid splitting the 2x4 member by driving too many nails into the same area.
  • Nailing lines are used to mark the location of a member behind the plywood. This ensures that when nailing, you fasten into the intended member. This is done by measuring from the edge of the plywood to the center of the member underneath. Scribe the lines onto the face of the plywood using these dimensions.
  • Recommended nailing is an 8d common or sinker nail every 6" on all edge nailing and a nail every 12" on intermediate nailing.


  1. Place a full sheet of plywood (4'x8' or 4'x10') on the back wall so that the center of the sheet aligns with the center of the center stud. Ensure that the bottom of the sheet aligns with the bottom of the bottom plate and overlaps half of the 90¼" studs to which it will be nailed and clamp in place.
  2. Scribe along the roof line to make where the top corner needs to be cut. Unclamp and cut (Fig. 9).
  3. If a 4'x8' sheet is used for the center, a small triangle above the center sheet will remain unsheathed. The 8 7/8"x48" piece that was cut from the drop-off (scrap) of one of the sheets of door plywood is to cover this space. Clamp the piece in place so that it covers the area and scribe along the roofline on the back of the plywood. Cut along the line for a good fit (Fig. 10).
  4. To sheath the side of the wall, place a full sheet of plywood next to the center sheet (the two sheets should meet flush over the stud) making sure that the edges are flush with the bottom of the bottom plate; clamp in place. Scribe along the wall and roofline and unclamp. Take a straight edge (a straight piece of wood is fine) and align it with the lower rafter line. Continue to scribe along this line until it runs off of both edges of the plywood. Cut along this line first, and then cut along the other two lines to achieve the correct shape. Using this method leaves a large enough piece of drop-off (scrap) to use for part of the front wall sheathing. Repeat for the other side of the wall.
  5. Once all pieces are fitted and clamped, nail in place.

FRONT WALL (Fig. 11):

  1. To get the two pieces of sheathing for the sides of the front wall, cut a full sheet of plywood in half lengthwise. Make sure to measure accurately and cut along the line. This will give you two pieces 23 15/16" wide x 96" long. Place the plywood on the wall so that it covers the space between the doorframe and the side of the shed. Make sure to align with the bottom plate and the side wall. Scribe a line along the roofline and cut along lines for a good fit. Repeat for the other side.
  2. The two triangular pieces of drop-off from the side pieces of the back wall will yield the pieces to cover the space over the doorframe. To do this, the two pieces must be butted up against one another (shortest sides meeting over the ridge support) to form a larger triangle. In order to allow pieces to fit over the doorframe and meet over the ridge support, each smaller triangle must be cut to 36" wide so that it will fit between the sheathing on the sides of the front wall.
  3. Align the piece over the doorframe so that is aligns with the bottom of the doorframe header and covers half of the front ridge support. Clamp in place and scribe along the roofline on the back of the plywood. Cut along the line for a good fit.
  4. Once all the pieces are fitted and clamped, nail in place.


  1. Align one of the 48" x 91" pieces of plywood along the side wall so that it aligns with the bottom of the bottom plate and the sides of the wall. The sheathing is 1" shorter in height than the wall to prevent the sheathing from interfering with the roof overhang.
  2. Nail into place. Repeat for other side.


  1. Align a full sheet of plywood lengthwise along the upper portion of the roof. It should cover half of the lower ridge and half of the center ridge. It will protrude approximately 2½" over the front and back of the shed. Clamp in place. Repeat for other side, making sure that the two pieces meet flush over the center ridge. If your shed is longer than 8', refer to your specification kit for sheathing placement.
  2. Nail into place.
  3. Align a full sheet of plywood lengthwise across the lower portion of the roof so that it meets flush with the plywood on the upper portion of the roof over the lower ridge. Ensure that there is a approximately 2½" overhang off of the front and back. Clamp in place.
  4. Nail in place. Repeat for both sides.


Once the roof is sheathed, roofing material should be applied to keep the weather out and prolong the life of the shed. There are a variety of roofing materials available. This plan will outline installation of composite shingles due to the fact that they are readily available, easy to work with and come in a variety of colors (Fig. 12).


Before installing the shingles, a felt underlayment must be applied to the roof. The felt underlayment has white lines printed on it for use as guidelines for the overlap.

  1. Since the shed roof is relatively small, it will be easier to cut the lengths needed instead of rolling them out on the roof. Felt paper is typically 36" wide, so cut 6 pieces 8 feet long. Starting at the bottom of the roof, apply the paper making sure it is flush with the edges of the roof and fasten every 2-3 feet along the upper half with roofing nails.
  2. Moving up the roof, each sheet should overlap the previous sheet by two inches. Continue in this manner up to the ridge.
  3. Both sides of the roof should be done in the same manner. The top pieces will overlap at the ridge. Fasten the overlap with roofing nails.
  4. For added weather protection, drip edge flashing may be installed at the edges of the roof over the felt underlayment.


Most readily available composite shingles are three tab shingles that have three cutouts. They are 12" wide and 36" long. They usually have a half cut-out at each end so that when butted up to one another they form a whole cut-out.


This plan will use what is called a six-inch pattern. This means that each course will be staggered 6" to the left of the course below it. To achieve this stagger, the first shingle in each course must be trimmed in 6" increments. Working from left to right you will cut 6" off the first shingle of the second course, 12" off the first shingle of the third course, etc. Continue in this manner through the sixth course when you will have removed 30" off the first shingle. After the sixth course you start again with an untrimmed shingle. This pattern will ensure adequate stagger to avoid leaks. It also ensures that the cutouts in every-other course of shingles will align with one another for a uniform appearance. Leave a 5" exposure between shingles (i.e. five inches of shingle is exposed before the next one overlaps on top of it).


Each three tab shingle should be fastened with four roofing nails. One nail an inch from each end in the center, and one nail above each cutout. If your shingles have a self sealing strip, place the nails below it, not in it or above it.

  1. At the bottom edge of each side of the roof lay a course of shingles upside down so that there is a ¼" overhang off the bottom. This is called the starter strip. This double thickness is necessary because the bottom course does not have the protection of an overlapping course like the other courses do.
  2. Begin shingling at the lower left hand corner of the roof. Lay and fasten the first shingle so that it aligns with the starter strip. Lay the rest of the course working from left to right making sure they are straight and nailed properly. The last shingle in each course may hang off the end of the roof. Leave them all hanging of until the whole roof is complete. Then cut them all off at the same time making sure to follow a straight line even with the edge of the roof.
  3. Lay the rest of the courses moving left to right working your way up the roof. Make sure to follow the trimming pattern and leave a 5" real. Shingle both sides of the roof in this manner. When shingling over the lower ridges it may be necessary to add nails into the bottom of the shingle or use roofing cement to make the shingle conform to the curve of the roof.
  4. Now that you have worked your way up the ridge on both sides it is necessary to use ridge shingles to cap off the roof.

Lay a ridge shingle at each end and draw a straight line along one edge to provide a placement line to keep your shingles straight. Work from the outside-in using 5" reveal and overlapping as you work toward the middle of the ridge. The overlapping shingles should meet the middle of the ridge. The final ridge shingle should be nailed over both courses when they meet in the center of the ridge. The nails should be covered with roofing cement to prevent leakage.



  • There are a number of different styles of doors. Many can be purchased and cut to fit. The doors outlined here are simple to make and relatively easy to install.
  • These doors are designed to leave a ¼" gap between the door and the frame at the top and bottom and the sides. These gaps are to account for hinge thickness, and clearance for the doors to open and close.

TIPS: When fastening the 1x4 to the plywood, use a #8x1" wood screw through the back of the plywood into the 1x4 every 12" (Fig. 13).

  1. Fasten a 35½" piece of 1x4 across each end of the 78½"x35½" piece of plywood.
  2. Fasten a 71½" piece of 1x4 along the long edge of the plywood. It will fit between the two pieces at the top and bottom.
  3. Fasten a 28½" piece of 1x4 across the middle of the partially assembled door. The bottom edge of the 1x4 should be 34" from the bottom of the door.
  4. At the inside corners where the 1x4 members meet, install a RTA12 for rigidity. Two RTA12's should also be installed on each end of the middle bracing.
  5. Install the hinges on the outside of the doors 8" from the top and bottom. The hinges will attach to the door frame on the outside of the sheathing to allow the greatest range of motion. Install the hinges so that the doors will swing out when open.
    Note: Doors may be installed with the 1x4 and connectors on the outside or inside of the door according to preference.

  6. Align the doors in the frame using wood shims to achieve correct spacing between the door and the door frame. The spacing should be approximately 1/8"-¼" between the door, the frame and the other door. Make sure that the doors will swing shut without jamming. Attach the hinges to the door frame.

Tips: Hanging a door requires some minor adjustments. If the door does not operate smoothly, a belt sander or circular saw can be used to trim off wood where the door binds. In particularly wet areas it may be a good idea to increase the clearances between door and frame to avoid binding when moisture causes the wood to swell.



To increase the structural integrity of this shed it is recommended that it be anchored to the foundation upon which it was built. Anchoring to the foundation will help the shed resist forces generated by high winds, seismic events and any other force which could potentially move the shed off it's foundation. Depending on the surface upon which your shed was built there are different options available.

Wood Foundation: Attach a ½"x5" lag screw through the bottom plate of the shed into the wood substructure beneath it every 2'. Make sure that when driving into the substructure the lag screw fastens into a member. Fastening through plywood only will not provide a strong anchor.

Concrete: Attach a ½"x6" anchor every 2' along the bottom plate, with 3½" embedment in the concrete. A piece of threaded rod fastened into the concrete with an epoxy adhesive, or a mechanical wedge anchor should be sufficient.

Note: The same methods of fastening into concrete may be used when fastening into asphalt. However, asphalt is considerably softer than concrete and will not yield the same loads.

Fig. 1

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Fig. 13


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