Build Plans • Up North
A 8'×8' box standing 10 feet off the ground on four 6×6 posts. Man door on the west wall, horizontal sliding windows on the north, south and east. Shed roof falling north to south so the snow lets go on the far side from the stairs. Everything below is dimensioned, squared and cut-listed — the numbers are the drawing.
Four 6×6 posts stand on concrete piers, tied together with 2×6 X‑bracing so the tower behaves like a rigid box instead of a card table. Two doubled 2×8 beams bolt to the outside faces of the north and south post pairs, and the floor joists hang between those beams. That one move is what makes the footprint land on a true 8'‑0" × 8'‑0" — the beams sit outside the posts and the joists sit between the beams, so nothing projects past the deck edge.
The walls are conventional 2×4 stud walls built flat on the finished deck and tipped up. The north wall is 8'‑4" tall, the south wall is 7'‑0", and the east and west walls are raked between the two. That 16" of drop over 96" is a 2:12 shed roof falling toward the south.
Three things drove the layout, and they are worth knowing before you change anything:
Post centres form an 84½" square. That is not an arbitrary number: 84½" on centre puts the outside faces of the 6×6s exactly 90" apart, and the two 3"-thick doubled beams bolted to those outside faces bring the total to a dead-on 96".
Check the layout by measuring the diagonals before you dig. Both should read 119½" (9'‑11½"). If they do not match, nothing downstream will square up.
Fig. 1 — Pier & post layout, plan view. North is up. Piers are 12" diameter, 4'-0" deep. The doubled beams sit on the outside faces of the north and south post pairs, which is what makes the deck land on exactly 96".
Twelve-inch tubes, 4'-0" deep — below frost. Set the tube so the top finishes 8" above grade; that keeps the post base up out of splash and out of the snow, which is the whole point of going with piers instead of burying the posts. Four #4 rebar verticals per pier, tied, held 2" clear of the form.
Cast a ⅝" anchor bolt in the wet concrete (or drill for a ⅝"×8" Titen HD after it cures) and set a Simpson ABU66Z standoff base. The 1" standoff keeps end grain off the concrete so the post can dry — that is what makes a PT post last thirty years instead of twelve.
Fig. 2 — Pier section. About 26 bags of 30 kg concrete mix pours all four piers (0.47 yd³). Let it cure a week before you load it.
This is a cut straight through the middle of the blind, north–south, looking west. Every controlling elevation on the job comes off this one drawing.
Fig. 3 — Section through the blind, looking west. Deck framing top is 10'-0" above grade; the finished floor is ¾" above that. Snow sheds off the south side, away from the stairs.
A post standing on a bracket is pinned at the base, not fixed. On its own it is a hinge, and 10 feet of leverage plus an 8×8 sail area is exactly the situation that walks a tower out of plumb over a couple of winters. The X-bracing is what turns four posts into a rigid frame.
Each face gets a pair of crossed 2×6 PT braces running from 18" above the post base to 18" below the post top — a diagonal of 113", cut from 10-foot stock. Lap them where they cross and bolt the intersection. Each end gets two ⅜"×4" structural screws into the post.
Add four 2×6 knee braces at the top, 34" long with 45° cuts at both ends, running from the posts up into the underside of the beams. Those tighten the one joint that carries everything.
Two doubled 2×8 PT beams, 96" long, bolt to the outside faces of the north and south post pairs with their tops flush to the post tops. Two ½"×10" hot-dip galvanized through-bolts per post — eight bolts total. Those bolts are in double shear and they are carrying the entire building, so do not substitute screws.
Joists run north–south, hung between the beams in LUS28 hangers. Clear span is 90", which a 2×8 handles with a very large margin. A row of blocking at the 48" line supports the plywood seam and keeps the joists from rolling.
Fig. 4 — Floor framing plan. Seven 2×8 PT joists at 16" o.c. hung between the two beams. The last bay closes at 14½" so the east rim lands flush at 96".
| Part | Material | Qty | Cut length | Notes |
|---|---|---|---|---|
| Posts & bracing | ||||
| Post | 6×6 PT | 4 | 111" | Cut in place; top = 10'-0" above grade |
| X-brace | 2×6 PT | 8 | 113" | From 10' stock. Ends cut at 44°; lap and bolt at the crossing |
| Knee brace | 2×6 PT | 4 | 34" | 45° both ends, post to underside of beam |
| Floor | ||||
| Beam ply | 2×8 PT | 4 | 96" | Two plies each side; glue and nail, then through-bolt to posts |
| Joist | 2×8 PT | 7 | 90" | 16" o.c.; hangers both ends |
| Seam blocking | 2×8 PT | 5 | 14½" | At the 48" line |
| Seam blocking | 2×8 PT | 1 | 13" | Last bay, east side |
| Post-top blocking | 2×8 PT | 4 | 14½" | West bay, both sides of each west post |
| Post-top blocking | 2×8 PT | 4 | 13" | East bay, both sides of each east post |
| Deck | ¾" PT plywood | 2 | 48"×96" | Full sheets, long way east–west; glue and screw |
All four walls are 2×4 at 16" on centre. The east and west walls run the full 96" north–south and carry the raked top plate; the north and south walls are 89" and fit between them. That means the rafters bear on the north and south plates in the middle and on the raked east and west plates at the outside edges — continuous bearing the whole way across.
It also puts the two walls that carry the roof directly over the two beams, which sit directly on the posts. Snow load runs roof → rafter → north or south plate → beam → post → pier in a straight line, with nothing bending sideways on the way down.
The raked walls get a single sloped top plate, not a double. Cut it 97⅜" long with both ends at 9½°, and cut every stud in those walls with a 9½° bevel across the top. The lengths in the tables are long-point measurements — the short point is ¼" less on every one.
Fig. 5 — North wall. Tallest wall in the build. Six full studs at 95½", double top plate, window centred.
Fig. 6 — South wall. Same window layout as the north wall — only the stud and upper-cripple lengths change.
Fig. 7 — East wall. Drawn looking west at the outside face, so south is at the left. Every stud top is bevelled 9½°; table lengths are long points.
Fig. 8 — West wall. Drawn looking east at the outside face, so north is at the left — the mirror of Fig. 7. Check that before you cut. The door sits 24" off the north corner because that is the only stretch of this raked wall tall enough to take an 82½" opening plus a header.
| Part | Qty | North wall | South wall | Notes |
|---|---|---|---|---|
| Bottom plate | 1 ea | 89" | 89" | 2×4 |
| Top plates | 2 ea | 89" | 89" | 2×4, doubled |
| Full studs | 6 ea | 95½" | 79½" | 4 layout studs + 2 window kings |
| Window trimmers | 2 ea | 48½" | 48½" | Bottom plate to header underside |
| Header | 2 ea | 51" | 51" | 2×6 doubled, ½" ply spacer optional |
| Rough sill | 1 ea | 48" | 48" | 2×4 |
| Sill cripples | 4 ea | 27" | 27" | Under the sill |
| Header cripples | 4 ea | 41½" | 25½" | Header top to top plate |
| Part | Qty | Length | Position from south end | Notes |
|---|---|---|---|---|
| Bottom plate | 1 | 96" | — | 2×4, square cuts |
| Sloped top plate | 1 | 97⅜" | — | 2×4, both ends 9½° |
| End stud (south) | 1 | 81¼" | 0" | |
| Corner nailer (south) | 1 | 81½" | 1½" | Backs the south wall |
| Layout stud | 1 | 83⅞" | 16" | |
| King stud | 1 | 84¾" | 21" | |
| Trimmer | 1 | 48½" | 22½" | Square top |
| Header | 2 | 51" | 22½" | 2×6 doubled, top at 55½" |
| Rough sill | 1 | 48" | 24" | Top at 30" |
| Sill cripples | 4 | 27" | 24 / 39½ / 55 / 70½" | Square both ends |
| Header cripples | 4 | 31¼ / 33⅞ / 36⅜ / 39" | 24 / 39½ / 55 / 70½" | Bevel tops |
| Trimmer | 1 | 48½" | 72" | |
| King stud | 1 | 93½" | 73½" | |
| Layout stud | 1 | 94⅝" | 80" | |
| Corner nailer (north) | 1 | 96¾" | 93" | Backs the north wall |
| End stud (north) | 1 | 97" | 94½" | Cut from 10' stock |
| Part | Qty | Length | Position from south end | Notes |
|---|---|---|---|---|
| Bottom plate | 1 | 96" | — | 2×4; cut out 38"–72" after tip-up |
| Sloped top plate | 1 | 97⅜" | — | 2×4, both ends 9½° |
| End stud (south) | 1 | 81¼" | 0" | |
| Corner nailer (south) | 1 | 81½" | 1½" | |
| Layout stud | 1 | 83⅞" | 16" | |
| Layout stud | 1 | 86⅝" | 32" | |
| King stud | 1 | 87" | 35" | |
| Trimmer | 1 | 81" | 36½" | Sits on bottom plate; square top |
| Door header | 2 | 37" | 36½" | 2×6 doubled, top at 88" |
| Tapered filler | 1 | 37" | 36½" | Rip a 2×6 from ⅝" to 6¾"; bevel top 9½° |
| Trimmer | 1 | 81" | 72" | |
| King stud | 1 | 93½" | 73½" | |
| Layout stud | 1 | 94⅝" | 80" | |
| Corner nailer (north) | 1 | 96¾" | 93" | |
| End stud (north) | 1 | 97" | 94½" | Cut from 10' stock |
Seven 2×6 rafters run north–south at 16" on centre, bearing on the north plate at 100" and the south plate at 84". Sixteen inches of drop over a 96" run is 2:12 — a 9.46° angle, which for cutting purposes you set as 9½° on the saw.
Overhang is 12" at the south eave and 6" at the north. The long side goes south deliberately: that is the low edge where water and sliding snow come off, and it is the far side of the building from your stairs. Each rafter cuts to 115⅝" overall — from 10-foot stock with 4" to spare.
The five interior rafters get birdsmouths at both plates. The two outer rafters do not — they lie flat on the raked east and west top plates, which are already in the plane of the rafter undersides. Screw them straight down through into the plate.
Fig. 9 — Roof framing plan. Roofing panels run north–south, down the slope, so there are no laps across the flow of water — which matters on a pitch this shallow.
Fig. 10 — South eave & birdsmouth. Mark the first birdsmouth 123⁄16" along the rafter from the low end and the second 109½" along. Cut one rafter, test-fit it on the walls, then use it as the pattern for the rest.
| Part | Material | Qty | Cut length | Notes |
|---|---|---|---|---|
| Rafter | 2×6 SPF | 7 | 115⅝" | Plumb cut 9½° both ends; birdsmouths at 123⁄16" and 109½" on the 5 interior rafters only |
| Bird block | 2×6 SPF | 6 | 14½" | Between rafter tails at the south eave |
| Sheathing | ½" plywood | 2 | 48"×96" | Full sheets, 96" run east–west |
| Sheathing | ½" plywood | 1 | 19⅝"×96" | Rip; fills the last course |
| Roof panel | 36" metal | 3 | 116" | From 10' panels; 2" overhang at each rake |
| Fascia | 1×6 | 2 | 96" | North and south |
| Rake board | 1×6 | 2 | 115⅝" | From 10' stock |
Three identical windows, one each on the north, south and east. Nothing to buy but the sheet of acrylic and some 1×2. Line the rough opening with ½" plywood to bring it to a finished 47" × 19", then build a bypass track out of strips ripped from 1×2 — three at the head and three at the sill, spaced ⅜" apart, which makes the two channels.
Rip the head strips ¾" × ¾" and the sill strips ⅜" × ¾", so the head channel is ¾" deep and the sill channel only ⅜". That difference is the whole trick: you lift a pane up into the head channel, swing the bottom in, and drop it into the sill. It goes in and out in seconds, and nothing holds it in but gravity.
Fig. 11 — Window assembly. Head channel ¾" deep, sill channel ⅜" — lift in, drop down. A single 48"×96" sheet of acrylic yields all six panes.
Quantities below include normal cut waste. The 2×4 count is the one worth reading twice — stick framing at 16" on centre eats studs. If you would rather not haul 60 boards up a bush road, see the note at the bottom.
| Item | Qty | Goes into |
|---|---|---|
| Pressure treated | ||
| 6×6 × 12' | 4 | Posts — cut to 111" |
| 2×8 × 8' | 14 | Beams (4), joists (7), blocking (3) |
| 2×6 × 10' | 8 | X-bracing |
| 2×6 × 8' | 2 | Knee braces |
| ¾" PT plywood 4×8 | 2 | Deck |
| 1×6 × 8' PT | 4 | Skirt board over the floor framing |
| 1×4 × 8' PT | 16 | Corner boards, window and door casing |
| Framing (SPF) | ||
| 2×4 × 8' | 56 | Wall plates, studs, cripples, trimmers, sills |
| 2×4 × 10' | 6 | Raked top plates (2) and the four 97" end studs |
| 2×6 × 10' | 7 | Rafters |
| 2×6 × 8' | 6 | Headers, tapered door filler, bird blocks |
| 1×6 × 8' | 2 | North and south fascia |
| 1×6 × 10' | 2 | Rake boards |
| 1×2 × 8' | 6 | Rip to ¾"×¾" window track strips |
| Sheet goods | ||
| ⅜" T1-11 or ½" plywood siding 4×8 | 9 | All four walls + fillers |
| ½" plywood 4×8 | 3 | Roof sheathing |
| ½" plywood 4×8 | 1 | Window jamb liners, misc. |
| Item | Qty | Notes |
|---|---|---|
| Foundation | ||
| 12" × 48" tube form | 4 | |
| 30 kg concrete mix | 26 bags | 0.47 yd³ total — rent a mixer |
| #4 rebar × 10' | 6 | Cut to 16 verticals @ 44" |
| ¾" clear stone | ½ yd³ | 6" base under each pier |
| Simpson ABU66Z post base | 4 | Standoff type — do not substitute a flat base |
| ⅝" × 8" Titen HD or J-bolt | 4 | With nut and washer |
| Structural connectors | ||
| ½" × 10" HDG hex bolt | 8 | + 8 nuts, 16 washers — beams to posts |
| Simpson LUS28 joist hanger | 14 | + hanger nails |
| Simpson H2.5A hurricane tie | 14 | Rafter to plate, both ends |
| ⅜" × 4" structural screw | 60 | X-bracing and knee braces |
| 3½" framing nails / 3" screws | 10 lb | |
| 2" deck screws | 5 lb | |
| 1¼" siding nails | 5 lb | Hot-dip galvanized |
| Roof & envelope | ||
| 36" metal roof panel, 10' | 3 | Cut to 116" |
| Eave drip edge, 10' | 1 | South |
| High-side wall cap, 10' | 1 | North |
| Rake trim, 10' | 2 | East and west |
| Foam closure strip | 2 packs | Top and bottom of the panels |
| Butyl seam tape | 1 roll | Every side lap — not optional at 2:12 |
| Roofing screws w/ washer | 150 | |
| Synthetic underlayment | 1 roll | ~100 sq ft needed |
| Exterior caulk | 4 tubes | |
| Construction adhesive | 4 tubes | |
| Openings & finish | ||
| 32" × 80" prehung steel exterior door | 1 | R.O. 34" × 82½". Order it in-swing — there is no landing outside |
| 3/16" acrylic sheet, 48" × 96" | 1 | Yields all 6 panes at 24½" × 18½" |
| Adhesive UHMW or felt tape | 1 roll | Line the track channels — quiet slide |
| Exterior paint or stain | 1 gal | Plus 1 qt flat black for the interior |
| Indoor/outdoor carpet or rubber mat | 64 sq ft | Deadens every footfall — worth more than it costs |
Everything about the height of this build comes off one number: the post cut length of 111", which puts the deck framing 10'-0" above grade. Want it at 12 feet? Cut the posts at 135" and lengthen the X-bracing to 133". Want it at 8 feet? Cut at 87" and the braces at 91". Nothing above the beams changes at all.
The floor is heavily over-built for what it is: 2×8 PT joists at 16" o.c. over a 90" clear span are good for far more than four people and a heater. The roof is the one to think about — 2×6 rafters at 16" o.c. spanning 8'-0" carry well over 50 psf of snow, which covers anything Ontario is going to put on it. The governing question is not strength, it is the 2:12 pitch: see the roofing warning above.
At 64 sq ft this is under the 10 m² threshold that exempts an accessory structure from a building permit in most Ontario municipalities — but "most" is doing work in that sentence, and height and setbacks are separately regulated almost everywhere. One phone call to the township office before you dig. Ask specifically about height, because 19 feet is tall enough to trip a rule that 64 square feet does not.
Do not do the beam lift or the wall tip-ups alone. The walls in particular: a 89"×100" sheathed wall is heavy, it catches wind like a sail, and you are standing on an 8×8 platform ten feet up with no railing. Tip the walls up before you sheathe them, brace everything you stand up, and put a temporary 2×4 guardrail around the deck perimeter for the duration of the framing.
The bones already work for both. Three things turn it from a blind into somewhere kids will actually want to be: a real railed landing at the door instead of stairs straight to the threshold, a hinged hatch in the floor for hauling things up on a rope, and a fourth small window low on the south wall at kid height. All three can be added later without touching the structure — the landing cantilevers off extended floor joists, and the extra window sits between the existing studs.