Every cut, every angle, every length. Bring this sheet to the lumber yard. All measurements are in inches unless otherwise noted; nominal lumber dimensions are used for labels (a "2×6" is actually 1½" × 5½").
§1. Master Cut List
For this build: 2' tail overhang, 12' polycarbonate panels
Part
Stock
Qty
Finished length
Key cuts / notes
Post
4×4 × 8'
3
92-⅝" (cut from 8' stock, ~3-⅜" waste per board)
Plumb-cut top to 92-⅝". Bottom sits in the APVB44 saddle, which buries ~5" of the post bottom in the base structure and provides a 1" standoff from the slab. Matches the existing pergola's post geometry.
Beam (sandwich pair, continuous)
2×8 × 16'
2
192" (full stock, zero waste)
Plumb-cut both ends square. No rafter seat cuts — rafters sit on top.
Rafter (2' tail overhang)
2×6 × 16'
9
168-½" (cut from 16' stock, ~23½" waste per board)
High-side plumb cut (85.24°) + bird's-mouth at low side + 2' tail. See §2 and §3.
Shade support blocking (optional)
2×4 × 8'
2
80.5" × 2 (cut 1 board per shade; ~3" waste each)
Mounted behind rear 2×8 to support shade brackets at top of opening. See §5.
Note: every rafter, beam, and post in this list is identical to its peers — gang-cut them on a single setup for the best consistency. Cut one rafter, use it as a template, then stack-and-cut the other eight. Total rafter waste for 9 boards: ~17.6 ft (the off-cuts are useable as short blocks, shims, or fire-starter).
§2. Rafter Plumb Cut (High Side, into the 4×12)
The high end of every rafter terminates against the face of the existing 4×12 beam inside the LSSJ26 hanger. The rafter's end cut is the "plumb cut" — its face stands vertical when the rafter is laid on the 1:12 slope.
Angle to mark:85.24° from the horizontal, OR 4.76° off vertical. On a Speed Square: 12" on the tongue, 1" on the blade.
Don't know what "tongue" and "blade" mean, or how to hold the Speed Square to mark the angle? See §2. The Speed Square in the Carpentry 101 page for a full walkthrough with a diagram.
Plumb cut at the high side. The face of the cut mates flush against the existing 4×12 inside the LSSJ26 hanger. The cut line is tilted 4.76° off vertical to be perpendicular to the sloped rafter.
Lay-out steps
Lay the 2×6 on sawhorses with the crown (if any) facing up. Mark the high end (the end that goes against the 4×12).
Set a Speed Square (or Swanson Speed Square) with the 12" mark on the tongue and the 1" mark on the blade. The resulting line is your plumb cut.
Scribe the line across the top edge of the 2×6, flip the board, and connect the marks on the bottom edge with a straightedge.
Cut with a circular saw. Stop just short of the line on the back side, finish with a hand saw or jigsaw to keep the line clean.
Sand or plane the cut face flat if needed. The face must sit flush against the 4×12 inside the hanger.
Critical: every rafter's plumb cut must be identical. Cut rafter #1, dry-fit it in the LSSJ26 hanger, confirm the fit, then use it as a template to mark and gang-cut rafters #2–9. Inconsistency here will show as a wavy rafter line at the high side.
§3. Rafter Tail & Bird's-Mouth (Low Side)
The low end of the rafter sits on top of the new double 2×8 sandwich beam with a bird's-mouth seat cut. The tail past the beam is the decorative front overhang.
New to the term "bird's-mouth"? See §3. Rafter anatomy in the Carpentry 101 page for a labeled diagram and the full vocabulary (plumb cut, seat cut, heel, tail).
Geometry: rafter total length 168-½" (cut from 16' stock, ~23½" waste per board). High plumb cut to bird's-mouth heel = 144.5" along the slope. Bird's-mouth heel to tail end = 24" along the slope (your 2' tail overhang) → ~24" horizontal past the new beam, dropping ~2" below the top of the front 2×8.
Bird's-mouth cut
The bird's-mouth has two cuts meeting at a 90° inside corner (the seat). The seat cut is horizontal (parallel to the ground), the plumb (heel) cut is vertical (in the wall plane of the rafter). The seat cut is short of the rafter's full width — typically 3½" wide on a 2×6 — to leave the rafter's bottom edge intact outside the seat.
Seat cut angle (from horizontal):4.76° — i.e., 1" of rise over 12" of run. On the Speed Square: tongue at 12, blade at 1, same as the plumb cut but oriented across the rafter width.
Heel (plumb) cut angle (from horizontal):85.24° — same as the high-side plumb cut.
Seat depth: 1½" (so the rafter still has 1" of wood — half its 1½" actual width — at the heel, and the 2×6's outer ½" remains uncut). If your local code requires a full-width seat, increase to 2½" and ensure the rafter still has at least ½" of uncut wood outside the seat.
Bird's-mouth at the low-side rafter end. The rafter seats on top of the front 2×8 of the sandwich. The H2.5A hurricane tie wraps both the rafter and the 2×8 to resist wind uplift.
Lay-out steps for bird's-mouth + tail
From the high-side plumb cut (already made), measure 144.5" along the rafter's top edge and mark a point. (Use a tape pulled along the slope, not just projected horizontally — the slope adds 0.5".)
Square a line down from that mark to mark the heel (plumb) cut location: 85.24° from horizontal, OR square to the rafter's top edge, then trim 4.76° off the bottom so the seat is horizontal.
From the heel line, measure 1½" toward the tail and mark the seat cut: 4.76° from horizontal (parallel to the ground).
Remove the wedge of wood between the seat and heel cuts with a circular saw (finish with a chisel). Test-fit on a scrap 2×8 to confirm the seat sits flat and the heel is plumb.
From the heel, measure 24" further along the rafter and cut the tail end with the plumb cut (85.24° from horizontal — end face perpendicular to the ground). Same Speed-square marks as the high-side plumb: 12" tongue, 1" blade. Sand or plane the tail end clean.
§4. Decorative Tail Templates
The exposed rafter tails at the front (low side) are a major aesthetic feature — they define the "DIY craftsman" look. The tails can be left as plain square ends, cut perpendicular to the ground, or shaped with one of the templates below.
Option A — Plumb cut (perpendicular to ground) — your choice
Cut the tail end so the end face is vertical (perpendicular to the ground), not perpendicular to the rafter. This is the same angle as the high-side plumb cut.
Cut angle:85.24° from horizontal (or 4.76° off vertical) — the rafter's slope angle.
Speed-square marking: 12" on the tongue, 1" on the blade — identical to the high-side plumb cut.
Visual result: the end-grain line of each tail runs straight up-and-down. Clean, deliberate, and it visually echoes the plumb cut at the 4×12. The end face is the full 5½" depth of the 2×6 (you see the cross-section of the board).
Three tail end options. The skew transform (-4.76°) simulates the rafter's 1:12 slope so the rafter shape matches reality. The red line is the cut.
Option B — Square cut (perpendicular to rafter) — alternative
Cut the tail end truly square (90° to the rafter's top edge). The end face will be tilted 4.76° to follow the slope. Cleaner / more minimal look. Same Speed-square setting as before (12" tongue, 1" blade) but measured off the rafter's top edge rather than the vertical.
Option C — Shaped tail (decorative) — optional upgrade
After making the Option A plumb cut, draw a decorative profile on the end-grain (chamfer, cove, or stepped) and shape it with a jigsaw or oscillating multi-tool. Sand smooth. See the earlier decorative template section for the three common profiles.
Option D — Shadow-line cleat (works with any tail profile)
Add a 1×3 (¾" × 2-½") or 1×4 (¾" × 3-½") horizontal cleat screwed to the front face of all rafter tails, just above the tail's bottom edge. This creates a strong horizontal shadow line and visually "ties" the tails together. Cleat length: full 14' (so it runs across all 9 rafters in one piece, or in 2 pieces butt-joined at rafter #5).
§5. Beam & Post Cuts
Posts (3 × 4×4 × 8')
Top cut: square, plumb. Cut to 92-⅝" finished length (matches the existing pergola's posts, which are cut the same way). Field-verify with a laser before fastening the beams.
Bottom cut: square. Bottom of the post sits in the APVB44 saddle (1" standoff from the slab). The post extends down into the saddle with the bottom ~5" of the post buried in the base structure; this is what makes 8' stock work for a ~98-⅝" AFF post-top target.
Why 4×4 and not 6×6? The existing pavilion uses 6×6 because it FREESTANDS and has to resist all the wind and seismic loads on its own. The new extension is attached to the existing pavilion on one side, which means it inherits lateral stability from the pavilion's already-braced structure — the new posts only have to carry their share of the gravity load plus the small amount of wind that lands directly on them. The connection details (12 SDWS screws at the beam-to-post sandwich, 9 LSSJ26 hangers at the high side, 9 H2.5A hurricane ties at the low side) provide the lateral resistance; the post itself is mostly in compression.
Quick load check: 84 sq ft of roof tributary per post × 5.2 psf dead + 10 psf snow = 1,277 lb. With LRFD load factors: 1,868 lb demand. 4×4 S4S redwood (3.5" actual) at 92-⅝" with K=0.7 effective length factor: 2,793 lb allowable axial load. **Safety factor 1.49** — enough for the structure, tight enough to discourage silly overloading. The 6×6 would give a safety factor of 8.0, which is engineering over-conservatism, not safety. Savings by going with 4×4: **~$150-190** in lumber, plus the post is half the weight (easier to handle, easier to cut, doesn't need a helper to stand).
When 6×6 would be the right call: very tall post (over 12'), heavy roof (real tile or snow), freestanding with no house attachment, or local code explicitly requiring 6×6. None of these apply here.
Beams (2 × 2×8 × 16')
Ends: square cuts, plumb. The beams run continuously across all 3 posts; no scarf joints or splices. The 16' stock gives exactly 12" overhang past each outer post centerline (1' tail each end).
No rafter seats: rafters sit on top of the front 2×8 with a bird's-mouth. The beams themselves have no cutouts.
Shade support blocking (2 × 2×4 × 8', cut to 80.5" each)
Cut 80.5" from each 8' board (1 piece per board, ~3" waste each).
These blocks mount behind the rear 2×8 at the top of the openings, providing a clean mounting surface for the roller-shade brackets and ensuring the rolled-up shade fabric has solid backing.
Not part of the initial build. Saved here for reference in case TK wants to add decorative 2×6 gussets to the post-to-beam joints after the structure is up. The new structure is laterally stiff without them — this is purely a visual match to the existing pavilion's craftsman look.
If you do decide to add them later:
Stock: 2×6 × 8' redwood, rough-sawn. One 8' board yields 5 braces (~17" hypotenuse each, ~1" scrap per board). Buy 2 boards to get 10 brace positions, install 6 (2 per post × 3 posts), keep 4 as spares.
Cut per brace: ~17" long-point-to-long-point. Two 45° miter cuts on the ends (Speed-square: tongue at 12", blade at 12", or miter saw set to 45°). The brace is a right triangle with 12" legs and a ~17" hypotenuse.
Position: right-angle vertex sits 1.5" in from the post face and 1.5" below the beam underside. The hypotenuse spans diagonally away from the post/beam corner. One brace on the front face of each post (3 total) is the minimum to match the existing pavilion. Two per post (front + back, 6 total) is the full craftsman look.
Fasteners: 3" exterior structural screws (Simpson SDWS 3" or equivalent). 2 screws into the post, 2 into the beam, per brace. 24 screws total for 6 braces.
Cost: ~$48 total ($37 lumber + $11 screws). Time: 1-2 hours to cut and install all 6.
§6. Final Post-Height Calculation
This is the only number that must be resolved on-site. Work from the top down, using the high-side reference (existing 4×12 underside = 108" AFF).
Step
Dimension
Notes
Top of existing 4×12
119.5" AFF
108" (underside) + 11.5" (actual 4×12 thickness)
Rafter top, high side (flush with top of 4×12)
119.5" AFF
Target reference: rafter top should be flush with or slightly below top of 4×12 for a clean visual line. Adjust LSSJ26 hanger height to suit.
− LSSJ26 hanger seat drop (5-⅞" nominal)
5.875"
Rafter top is 5-⅞" below top of 4×12. Mount hanger with top edge at 5-⅝" below top of 4×12 (centered on the 4×12 face).
Rafter top, high side (actual)
113.625" AFF
Per Simpson LSSJ26 spec
− 12" drop (1:12 over 144" run)
12"
Low-side rafter top = high-side rafter top − 12"
Rafter top, low side
101.625" AFF
Bird's-mouth seats on this elevation
− 2×8 sandwich thickness (1.5" + 1.5")
3"
Front + back 2×8 = 3" of beam sandwich
Top of post (post cap elevation)
98.625" AFF
Top of post must equal 98.625" for the rafter to seat correctly. (This matches the existing pergola's post-top elevation, so the new beam line will be flush with the old.)
APVB44 post base height (1" standoff — same as existing posts)
1"
APVB44 has a 1" standoff from the slab, matching the existing pergola's post bases. The post bottom is at 1" above the slab. Verify the actual base height with the part in hand before cutting.
Post length needed (net)
≈ 92.625"
Post bottom to post top. Cut the 8' stock down to this length, OR keep the post full length and shim the base up 3.375" to compensate (not recommended — shims work loose). Field-verify with a laser level before cutting. The geometry matches the existing pergola's posts, which were cut the same way and work fine.
Recommendation: cut all three posts to 92-⅝" finished length, then stand them in the post bases at the slab and verify the math against a laser level or transit before the beams go on. Adjust ±¼" with shims under the post base if needed. The 3" field-trim gives a clean, predictable stack-up. (The geometry matches the existing pergola's posts, which were cut the same way.)
Don't skip the field verify. The 4×12 underside is the only fixed dimension; every other number above depends on the actual Simpson LSSJ26 hanger seating height and the actual APVB44 saddle geometry. Measure twice, dry-fit once. The 92-⅝" target matches the existing pergola's posts, which were cut the same way.