Install 2x8 PT joists across the 3 beams at 12" OC MODIFIED (plan called for 16" OC). Attach with Simpson H2.5AZ hurricane ties. Apply Trex Protect joist tape after installation.
Joist Layout
Top-down. Joists (brown) run PARALLEL to pool, resting on top of 3 beams (red/perpendicular). ~15-16 joists at 12" OC across the depth. Outer joists become the LEFT and RIGHT rim joists.
Original plan calls for 11 joists at 16" OC. We're using 12" OC for firmer Trex Transcend Lineage composite feel. That's why the invoice shows 16 joists (11 from Order 1 + 5 from Order 2) — matches the tighter spacing.
Hardware for This Phase
Item
Quantity
Source
2x8 PT SYP at 14'
16 pieces total (11 from Order #1 + 5 from Order #2)
On hand
Simpson H2.5AZ hurricane ties
Need ~45-48 (3 per joist × ~15-16 joists). 50 on hand — tight buffer of 2-5, so don't waste any.
On hand
Simpson SD9 x 1-1/2" Strong-Drive Connector Screws (SD9112)
~480 (10 per tie × 48 ties). 500-count box = ~20 buffer.
NEED TO BUY
Trex Protect Joist Tape 1-5/8" x 50'
Use most of 5 boxes
On hand
Trex Protect Joist Tape 3-1/8" x 50'
Use 1 box for beam tops
On hand
Screw type matters: H2.5AZ hurricane ties are designed for 8d common nails (0.131" × 2-1/2") OR Simpson SD9 × 1-1/2" Strong-Drive Connector screws (part SD9112). Do NOT use SD10 (those are for post bases like ABA66Z) or generic wood screws — Simpson only warranties SD screws as nail replacements in these connectors.
J-roller, rolling pin, or firm hand pressure (for tape adhesion)
Part A: Layout Joist Positions on Beams
Do the layout BEFORE applying joist tape. Once the tape is on the beam tops, chalk marks won't hold well. Mark joist positions on the SIDES of the beams (a small vertical tick mark on the beam face) so the marks stay visible after taping.
Step 1: Mark First Joist Position
1Mark the first joist position at the back edge of the deck.
The first joist runs along the back edge of the deck (farthest from pool)
Draw a tick mark on the SIDE of each of the 3 beams at that position — vertical mark on the beam's face, extending down about 1"
Do this on all 3 beams so the marks line up when the joist is placed
Step 2: Mark Remaining Joist Positions at 12" OC
2Mark tick marks along each beam at 12" intervals.
Measure 12" from the first tick mark, and make another tick mark on the beam side
Continue at 12" intervals along the full length of each beam
Do this on all 3 beams so joist positions line up perfectly across all beams
Result: ~15-16 tick marks per beam, spanning the 14'-8" deck depth (one tick per joist)
Tick marks must line up across all 3 beams. If layout is off on one beam, joists will sit crooked. Verify by measuring from a common reference (like the back edge of the deck) to each tick mark on each beam.
Step 3: Cut Joists to Length
3Cut each 2x8 joist to length.
Joist length depends on final beam positions plus any cantilever
Typical: about 14 feet long (deck width + small overhang each side)
Use Speed Square for square cuts
Part B: Apply Joist Tape to Beam Tops
Why joist tape: Trex Protect tape prevents water from sitting on top of the joist/beam, which causes rot. Especially important on a pool deck with constant water exposure. Apply BEFORE setting joists so the joist bottom sits on top of the tape.
Step 4: Apply 3-1/8" Tape to Beam Tops
4Apply Trex Protect 3-1/8" tape to the top of each beam.
The 2-ply beam is 3" wide — the 3-1/8" tape covers the top edge with a small overhang on each side (about 1/16" each side)
Clean beam top with a rag (remove sawdust and debris)
Peel backing 6-12" at a time (avoids the tape sticking to itself before you get it in position)
Start at one end of the beam, press tape down along the top
Roll firmly with a J-roller, rolling pin, or press hard with your hand to activate the adhesive
Continue along the entire length of each beam
Repeat for all 3 beams
Your tick marks on the beam sides should still be visible below the tape
Part C: Install Joists
Step 5: Check Each Joist for Crown
5Sight along each joist to find the crown.
Look along the length of the board from one end — you'll see a slight bow (concave on one edge, convex on the other)
The "crown" is the convex edge — the one that bows upward when the concave edge is down
Mark the crown side with an arrow pointing UP toward the crown
Always install joists CROWN UP — deck load will flatten the bow over time
Step 6: Set Each Joist on the Beams
6Place each joist on the beams at its tick mark, crown up.
The joist sits on top of all 3 beams simultaneously (perpendicular to the beams)
Align the joist edge with the tick mark on each beam side (visible below the tape)
Joist bottom rests on the Trex Protect tape covering the beam top
Step 7: Install Hurricane Ties at Each Beam Intersection
End view showing the joist sitting on top of the beam with an H2.5AZ tie wrapping from joist side to beam side. 5 screws per flange × 2 flanges = 10 SD9 × 1-1/2" screws per tie. Every hole gets a screw.
7Install a Simpson H2.5AZ hurricane tie at each point where the joist crosses a beam.
Position the tie so one flange wraps against the joist's side and the other flange wraps against the side of the beam
Per Simpson's spec: the H2.5AZ has 5 fastener holes per side (10 total)
Drive Simpson SD9 × 1-1/2" Strong-Drive Connector screws through EVERY hole:
5 screws into the joist (through the joist-side flange)
5 screws into the beam (through the beam-side flange)
10 screws total per hurricane tie
Each joist gets 3 ties total (one at each beam it crosses)
~15-16 joists × 3 ties = ~45-48 ties total = ~450-480 SD9 screws total
Fill EVERY hole in each hurricane tie. Per Simpson's data sheet, skipping holes reduces the tie's rated uplift capacity below its 415 lb rating. Simpson only guarantees the load rating when all fasteners are installed.
Step 8: Repeat for All Joists
8Install all ~15-16 joists at 12" OC across the deck.
Work systematically from one end of the deck to the other
Verify each joist is at its correct tick mark before installing hurricane ties
Check crown orientation on each joist before setting it
Part D: Apply Joist Tape to Joist Tops
Step 9: Apply 1-5/8" Tape to Joist Tops
9Apply Trex Protect 1-5/8" tape to the top edge of each joist.
Joist is 1-1/2" wide (nominal 2x) — the 1-5/8" tape covers the top with slight overhang
Clean joist top with a rag
Peel backing 6-12" at a time
Press tape onto joist top, starting at one end
Press or roll firmly to activate adhesive
Continue along the entire length of each joist
Trim excess with utility knife at joist ends
Repeat for all ~15-16 joists
Apply tape AFTER all joists are in position and hurricane ties are installed. The tape then covers screw heads and hurricane tie tops, sealing them from water intrusion.
Part E: Verify Joist Tops
Step 10: Check Joist Tops for Coplanarity
10Set laser at joist-top elevation and verify all joist tops are at the same level.
Sweep laser line across joist tops
Any joist noticeably high or low needs adjustment
High joist: plane top with hand plane
Low joist: shim between joist and beam with hardwood shim (before tape)
Small variance (1/8") is fine
Part F: Mid-Span Blocking (Recommended)
Step 11: Optional Blocking Between Beams
11Add 2x8 blocking between joists at the midpoint of each beam span.
Cut blocks 10-1/2" long (fits between 12" OC joists with 1-1/2" gap)
Install at the middle of each beam span (~2'-8" from adjacent beams)
Screw to each joist on both sides
Stagger blocks in alternating pattern so screws don't collide
Blocks reduce joist twist and stiffen deck
Completion Checklist
3-1/8" joist tape applied to all 3 beam tops (before joists)
All ~15-16 joists at 12" OC installed
Each joist crown-up
3 hurricane ties per joist (one at each beam intersection)
All hurricane tie holes filled with SD9 screws
1-5/8" joist tape applied to all joist tops (after hurricane ties)
Joist tops coplanar (verified with laser)
Optional mid-span blocking installed
Common Problems & Fixes
Joist won't sit flat on all 3 beams
One beam is high or low. Address the beam issue first (shim or trim), then install joist.
Joist looks bowed after installation
Normal if crown is UP. Deck load will flatten it over months. If severe, replace that joist.
H2.5AZ tie flanges don't wrap around 2-ply beam
H2.5AZ is designed for 2-ply beams (up to 3" wide). Verify orientation — flanges should wrap around the top corner of the beam and the side of the joist. If flanges are too short, verify you have H2.5AZ (not H1 which is for single 2x).
Joist tape won't stick
Surface may be wet or dirty. Wipe clean with dry rag. If PT lumber is still wet from treatment, let it dry a few days before taping. Warmer temperatures help adhesion.
Joist tape tears while installing
Peel backing more gradually. Press tape into place as you go rather than trying to align a long piece at once.
Missed a joist position — spacing is off
Remove the misplaced joist, reset at correct 12" OC location, reinstall hurricane ties. Better to fix now than after Trex is on.