A 15 ft x 5 ft framed jungle gym with a 6 ft peak (sized for ceiling-fan clearance), built from framing lumber, OSB, and sisal rope for two former-feral cats. The design follows the AAFP/ISFM environmental-needs guidelines and cat-superhighway rules: no dead ends, an exit at both ends of every lane, duplicated resting spots separated in space, hide boxes with two doors, and hop distances a cautious cat will actually use.
Drag to orbit, scroll to zoom. Four leg stations along the wall at 4.7 / 5.0 / 4.7 ft spacing, front and back rows 3.6 ft apart. The height stack is honest: 1.5 in sole plate + 66 in legs + 3.5 in on-edge top rail = 71 in structure, walking surface ~71.5 in, so a standing cat's head stays under a ~7 ft fan sweep. Every position has at least two ways out, every everyday hop is 24 in horizontal / 18 in vertical or less, and the one bigger move (the 18 in jump gap) has a bypass route.
If the frame above is blank, open cat-playground-3d.html from this folder directly. It needs internet on first load for the 3D library.
Every element, what it's built as, and the research or engineering that put it there. The sourcing here comes from the AAFP/ISFM Feline Environmental Needs Guidelines (2013) and the 2024 AAFP Intercat Tension Guidelines, published scratching and refuge studies, Jackson Galaxy and Kate Benjamin's Catification "superhighway" rules, cat-shelf manufacturer installation guidance, and standard deck-framing practice.
| Element | Built as | The research behind it |
|---|---|---|
| Rim highway | 15 ft OSB lane, 11 in wide, walking surface ~71.5 in, off-ramps at BOTH ends (crow's nest left, far perch right), two 14x24 in passing bays at the 5 and 10 ft marks | Jackson Galaxy's superhighway rules: ample lanes, on/off ramps, destinations, no dead ends. Shelf makers converge on 10–12 in minimum walking depth (a 1x8 is only 7.25 in). The 2024 AAFP guidelines' worked failure case is one cat blocking a single-lane chokepoint; passing bays and dual exits mean neither cat can pin the other on a 15 ft run. |
| Crow's nest | 16x24 in carpeted through-stop at 62 in with a side rail and fleece cushion, on the climb line between the 50 in platform and the rim | AAFP/ISFM verbatim: perches "wide enough and long enough to allow the cat to fully stretch" (an adult cat is ~18+ in stretched). Catification bans cul-de-sac perches, so it's a stop on the route, not a pocket. The side rail doubles as a roll-off guard and an AAFP visual barrier. |
| Far top perch | Second cushioned 24x16 in perch at 60 in at the opposite end of the run; one top perch staged in window sun, one shaded | International Cat Care's multi-cat rule: one of each key resource per cat, plus one, in separate locations; high resting places are explicitly listed as resources cats won't share. With one premium perch, two former ferals get a contested resource. The center pole and bridge break the direct stare-line between the two beds, per the 2024 AAFP visual-barrier guidance. |
| Diagonal bridge | 83 in OSB lane at 50 in crossing the interior in plan, with a 2x4 glued and screwed on edge underneath (T-beam) | Beam math: a 3/4 in board over a ~7 ft span deflects ~1.6 in under a landing cat; the T-beam cuts that to ~0.08 in for one $4 stud. Shelf-maker guidance is blunt that cats refuse surfaces that flex, so stiffness is a usability feature, not just safety. |
| Jump gap | 18 in horizontal gap from the 50 in center deck to a doubled-OSB landing at 47 in, with an onward step down and a taped landing mat below | 18 in is inside the published everyday comfort envelope (under 24 in horizontal). The landing is the highest-dynamic-load surface in the build: landing force runs 1.5–2x body weight, and the published rule is to rate cat shelves at 4x static weight with 50 lb hardware per mount, hence the doubled deck on two bearings. Catification bans single-route commitment points, so the gap always has a walking bypass. |
| Zigzag + mid-depth steps | Platforms alternating front row (31 in) and back row (50 in) with 41 in mid-depth steps between them | Installer guidance caps confident everyday hops at ~24 in horizontal with 12–18 in of rise; bigger gaps get the approach-calculate-walk-away treatment, and cautious ex-ferals are the worst case. As first drawn the front-to-back leap was ~60 in; the mid steps break every transition down to legal hops. |
| Climb pole | Two face-laminated 2x4s, sisal-wrapped full height, center of the run | Wilson et al. 2016 (JFMS, 4,105-owner survey): the ideal scratcher is sisal/rope substrate, upright, 3 ft or taller, and sturdy. It's also the fast vertical route between floor and rim for a confident cat. |
| Wrapped legs | Two legs wrapped to 42 in over screwed-on 1x4 face boards; two more carpet-wrapped until the cats vote | Cats scratch at full vertical stretch and mark at territory boundaries and near sleeping spots (they stretch-scratch on waking), so wraps sit at the entrance and beside the rest areas. The face boards steal the commercial bolt-on-refill trick: a worn wrap unscrews in minutes instead of a rebuild. |
| Ramp | 6 ft carpet-faced board at ~26° with cross cleats every 8 in, up to the 31 in platform | Cats use ramps reliably at 18–26° and slip or refuse steeper grades; a short-footprint ramp to 31 in would run 35°+. Six feet parallel to the wall hits the ceiling of the usable range, and cleats at roughly paw-to-paw spacing cover the rest. |
| Block stairs | Two offcut steps at 12 and 22 in at the far end | First-access guidance: a beginner entry at 18–24 in from the floor, steps 8–12 in apart. The lowest platform is 31 in, above that norm, so BOTH ends get a graduated ground entry; whichever cat is less athletic is never locked out. |
| Tunnel | 12 in form tube trimmed to ~36 in, strapped to a 30 in shelf, mid-length escape hole facing the room | Pam Johnson-Bennett's multi-cat tunnel rule, verbatim: "cut an escape hole halfway through so there's always an option for one cat to make a quick exit if halfway through the tunnel another cat enters." Builder threads document mid-span sag and roll-off as the tube's real failure modes, hence the straps and full-length shelf. |
| Floor hide | OSB box with two 6 in doors on different faces, in the corner farthest from the glass | Vinke et al. 2014: shelter cats given a hiding box had significantly lower stress scores and adapted faster, the single best-evidenced element in the build for ex-ferals. AAFP: multi-cat safe places need more than one entry so access can't be blocked; the 6 in door is the feral-shelter standard ("the width of their whiskers"), and doors on different faces mean one cat can't cover both from a single position. |
| Raised hide | Second two-door box with its floor at ~17 in, under the nap deck | A communal-housing refuge study (PMC4494404) found cats occupied refuges raised ~20 in about twice as long as identical floor-level ones, while very high effortful refuges went unused. One hide stays on the floor for the shyer cat; the two boxes' doors don't face each other. |
| Nap deck, bolster + hammock | 24x31 in deck at 30 in with a fleece bolster; fleece hammock slung under the bridge on velcro ties | AAFP/ISFM verbatim: "a hammock-style dip in the middle of the perch or shelf will aid the cat's sense of feeling hidden." Velcro because sun-room UV makes fleece a consumable; everything soft unclips and washes. |
| Scratch tray + catnip | Shallow 2x4-edged tray packed with corrugated strips at the main entrance; dried catnip or silver vine rubbed into every scratch surface on day one | Zhang & McGlone 2020: cardboard and rope were the heavily used scratch substrates (carpet was largely ignored), and catnip/silver vine attractants drove 85–90% of cats to actively use treated surfaces, the cheapest adoption lever for a structure two cautious cats have to choose to use. Refills are free shipping boxes. |
| Bird feeder | Suction-cup feeder on the glass within 3 ft of the pane, in view of the back platforms, rim, and crow's nest | A superhighway needs a destination or it doesn't get walked (Galaxy). The within-3-ft rule is bird safety: feeders within 3 ft of glass (or beyond 30 ft) prevent window-strike deaths because birds can't build collision speed. |
| Grass, water, feeding | Oat/wheat grass tray re-sown every 2 weeks; floor water mid-footprint; one small feeding shelf at 2 ft on an end leg, second feeding station across the room | AAFP Pillar 2: key resources multiple AND separated, at least one per cat; food never sits on traffic lanes or beds where eating invites guarding. The grass is non-toxic and the sun room grows it in place, a thing most indoor builds can't do. |
| Cool tile + thermometer | Loose 12x12 ceramic tile on a shaded platform; min/max thermometer at perch height | Vet guidance names sun rooms as heat-trap rooms where 85–90°F becomes dangerous in 15–30 minutes, and hot air stratifies to exactly the perch zone. Cats self-regulate only when the structure offers a thermal choice: sun bed, shade bed, tile. |
| Frame + bracing | 66 in legs, on-edge rails, 8 knee braces, 3 bay diagonals, OSB gussets, sole plates, wall anchors at all 4 leg positions into king studs | Deck-framing practice: metal corner braces alone act as hinges under repeated jump-and-brake loads, which is exactly why cat trees wobble. A 2x4 is massively overbuilt in compression; every real risk is joint stiffness and panel deflection, so the margin is spent there. Anything over 60 in tall gets wall-anchored; on a mostly-glass wall that means finding the king studs between windows. |
The reasoning behind the shape, the trade-offs taken, and what got rejected.
The first draft was a wall run: towers connected left to right. The rebuild treats the 15 x 5 ft footprint as a volume, and that's what makes it work for two cats. The 5 ft of depth buys independent front and back lanes at every level, so two cats can circulate without a head-on meeting; the diagonal bridge and mid-depth steps make front-to-back movement part of every route instead of an afterthought. The 15 ft of length is the other asset: it's what lets duplicated resources (two top perches, two hides, two ground entries, two feeding stations) be genuinely separated rather than adjacent, which is the difference between "one resource per cat plus one" and one clustered pile a confident cat can guard from a single vantage.
Former ferals resolve conflict by fleeing and hiding, so the whole structure is designed around the timid one: every position has two exits, hides outrank open beds in priority (the hiding-box study is the strongest evidence in the whole build), one refuge is raised, the tunnel has a bail-out hole, and no route ever forces a jump. A useful check on how much the visual-barrier features matter: if the two cats allogroom, allorub, or sleep touching, they're one social group and will share freely; if not, treat them as two groups and the sight-line breaks and separated duplicates carry real weight. Also worth stating: this room must not become the only territory worth holding. Keep at least one bed and one scratcher per cat elsewhere in the house.
Cats sample a surface once, and a plank that bounces or a frame that racks gets abandoned permanently. Every structural add (knee braces, bay diagonals, the bridge T-beam, four wall anchors, doubled landing pad) exists because roughly $50 of lumber and hardware decides whether the other $400 gets used. The members themselves were never the problem; a single 2x4 carries thousands of pounds in compression. Joints and panels are where cat structures fail, so that's where the margin went.
The room is the reason this build is better than an indoor cat tree: free warmth, live bird TV through the glass, and enough light to grow cat grass in place. It's also the hazard: heat stratifies to exactly the perch zone against the glass, and UVA through the windows embrittles sisal and fades fleece in months, not years. The answer is the same in both cases: choice and consumables. Every height tier offers a sun option and a shade option, and everything soft or fibrous is attached to be swapped, washed, or rewrapped without tools.
Catnip or silver vine on the scratchers day one, treats on the low platforms, and then patience: carrying a cat to the top teaches nothing except that being grabbed happens near the new thing. Expect the tunnel, hides, and low tiers to get adopted in days and the rim in weeks. Watch which legs actually get scratched and move rope there; watch which bed each cat claims and put the second thermometer check there. If either cat is still refusing a specific hop after a month, add an intermediate step; the same modification (more steps, a board across the jump gap) is the planned aging path when they're seniors.
Prices checked at Home Depot, Lowe's, and Walmart in late August 2026. OSB is the most volatile line ($8–45 historical range), so treat that one as a snapshot. Nothing here is pressure-treated; reject any stud with green or brown tint, incising marks, or a treatment tag.
| Item | Qty | Est. unit | Est. total | Notes |
|---|---|---|---|---|
| Structure | ||||
| 2x4 x 8 ft whitewood stud | 34 | $3.85 | $131 | Legs, rails, sole plates, knee braces, bay diagonals, bridge T-beam, laminated climb pole, support posts, spare |
| 7/16 in OSB, 4x8 sheet | 4 | $11.61 | $46 | Platforms, hide boxes, gussets, and all walkways ripped at 10–11 in (replaces the 1x8s). Three sheets only works with zero waste; buy four |
| 1x4 x 8 ft furring strip | 3 | $4.00 | $12 | Sacrificial rope face boards on the wrapped legs; worn wraps unscrew and swap |
| 3/8 in twisted sisal rope, 100 ft, UNOILED | 4 | $16.21 | $65 | SGT KNOTS untreated at Home Depot; 100 ft rolls beat bulk spools per foot. No manila (oiled), no jute (fails in months). Covers the pole + two legs; see rope math |
| 12 in x 48 in concrete form tube | 1 | $17.00 | $17 | The elevated tunnel; trim to ~36 in so both mouths land clear on the shelf |
| Hardware and finishing | ||||
| 2 1/2 in construction screws, 1 lb | 1 | $11.00 | $11 | General frame joints |
| #9 x 2 1/2 in structural screws, 1 lb | 1 | $10.00 | $10 | Two per leg-to-rail and rail-to-rail joint |
| 1 1/4 in screws, 1 lb | 1 | $9.00 | $9 | Platforms, cleats, boxes, gussets |
| Corner braces, 20 pack, 2 in zinc | 1 | $10.50 | $11 | Everbilt; platform-to-leg connections |
| Heavy L-brackets (50+ lb) + 1/4 x 3 in lag screws | 4 | $3.00 | $12 | Wall anchors at all four leg positions |
| Liquid Nails LN-901 (low-VOC latex) | 1 | $3.50 | $4 | Rope ends only, never continuous under scratch zones. This exact product; solvent adhesives off-gas for weeks |
| Water-based polyurethane, 1 qt | 1 | $20.00 | $20 | Seals cut OSB edges; hard-cure 24–72 h before cat access |
| Sandpaper, 80 + 120 grit | 1 | $6.00 | $6 | Every edge a cat touches |
| Plumber's strap (galvanized tape) | 1 | $5.00 | $5 | Straps the tunnel tube at both ends |
| Non-slip rug pad or double-sided rug tape | 1 | $10.00 | $10 | Under both landing mats; an unanchored mat skates on landing |
| Velcro straps / ties | 1 | $5.00 | $5 | All fleece attaches removably for washing; never stapled |
| Soft goods | ||||
| Fleece throw blankets, light colors | 4 | $4.00 | $16 | Walmart Mainstays 50x60; light colors run cooler in sun. Hot-wash any thrifted fleece |
| Carpet remnant / samples, SHORT CUT PILE ONLY | — | — | $0–25 | Flip each piece: sheared tips yes, loops no. Loop pile and berber snag claws and are banned from this build |
| Rug remnants, landing mats (cut pile) | 3 | $8.00 | $24 | Under the jump gap, the hammock, and the den end |
| Enrichment extras | ||||
| Suction-cup window bird feeder | 1 | $18.00 | $18 | On the glass behind the structure, within 3 ft of the pane |
| Min/max thermometer | 1 | $10.00 | $10 | Mounted at top-perch height; see heat section |
| Dried catnip or silver vine | 1 | $6.00 | $6 | Rub into sisal and the scratch tray on day one; ~85–90% of cats respond to one or the other |
| Oat/wheat cat grass seed | 1 | $4.00 | $4 | Sown in a shallow tray every 2 weeks; the sun room grows it in place |
| 12x12 in ceramic tile | 1 | $2.00 | $2 | Loose-laid on a shaded platform as a cool pad |
| Total | $450–480 | Plus tax | ||
Drill/driver with a #2 bit and countersink, circular saw or jigsaw (or have the store make the long OSB rips), keyhole/compass saw (~$10) for the 6 in round doors using the drill-a-starter-hole method, staple gun with 3/8 in staples, tape measure, speed square, level, stud finder (critical on a mostly-glass wall), and a sanding block.
| 2x4 pieces | Qty | Length |
|---|---|---|
| Legs | 8 | 66 in |
| Top rails, on edge: mid spans + end spans (splices land on legs) | 2 + 4 | 60 / 56.5 in |
| Top cross rails, front to back, on edge | 4 | 47 in |
| Sole plates: mid spans + end spans (splices land at leg positions) | 2 + 4 | 60 / 56.5 in |
| Knee braces, 45° ends (4 long-plane + 4 end-plane) | 8 | 24 in |
| Back-plane bay diagonals (angle-cut in place) | 3 | ~85 in |
| Bridge T-beam (on edge under the bridge) | 1 | 83 in |
| Center climb pole: two face-glued + screwed 2x4s | 2 | 68 in |
| Support posts: 62, 60, 50 x3, 47 x2, 45, 41 x2, 34 in | 11 | varies |
| Support posts, low (tunnel shelf, nap deck) + raised-hide posts (2 @ 17 in), from leg offcuts | 4 + 2 | 30 / 17 in |
| OSB pieces | Qty | Size |
|---|---|---|
| Rim highway rips (splices land on legs) | 2 + 1 | 56.5 / 60 x 11 in |
| Passing bays on the rim | 2 | 24 x 14 in |
| Diagonal bridge | 1 | 83 x 11 in |
| Ramp (carpet-faced) | 1 | 72 x 10 in |
| Crow's nest + far perch | 2 | 24 x 16 in |
| Nap deck | 1 | 31 x 24 in |
| Center front deck | 1 | 24 x 22 in |
| Zigzag platforms | 2 | 22 x 18 in |
| Mid-depth steps | 2 | 18 x 16 in |
| Jump-gap landing (two layers, glued + screwed) | 2 | 20 x 12 in |
| Onward step + rim step-down | 2 | ~15 x 14 in |
| Tunnel shelf | 1 | 43 x 16 in |
| Hide box panels (floor box + raised box) | 11 | ~17–24 in |
| Triangular gussets (from scrap) | 8+ | 12 in legs |
Run the whole cut list in one session and label each piece in pencil. Sand or round over every cut edge a cat will touch, especially both 6 in door rims (body-rubbed on every pass), walkway ends, and platform perimeters. Seal all cut OSB edges with 2 coats of the water-based poly and let it hard-cure while you frame; everything must be cured and aired out at least 72 hours before cat access.
Build four goal-post end frames flat (two 66 in legs + a 47 in cross rail on edge across the tops), stand them at 4.7 / 5.0 / 4.7 ft spacing, then tie them with the long top rails on edge, not flat, splicing only over legs (that's why the rail pieces are cut 56.5 and 60 in). Screw sole plates across the leg bottoms front and back with rubber pads underneath so the leg ends can't walk or squeak. The stack is 1.5 in plate + 66 in legs + 3.5 in rail = 71 in, which is what keeps a cat on the rim under the fan. Use two #9 structural screws at every leg-to-rail and rail-to-rail joint. Face-glue and screw the two 68 in pole halves now so the lamination cures while you work.
Corner brackets alone hinge under repeated jump loads; this is why cat structures wobble, and cats refuse surfaces that flex. Add the 45° knee braces at the four corner legs (front and back planes), one full-height 2x4 diagonal per back bay, and glued-plus-screwed 12 in OSB gussets at interior leg-to-rail joints. Push hard on a top corner: the frame should feel dead.
One 50+ lb L-bracket per leg position, lagged with the 1/4 x 3 in lags at least 1.5 in into the king studs between the windows. Find real studs with the stud finder and slide brackets along the rail to wherever the studs actually land; never into window frames and never drywall-only anchors. A 6 ft frame with a running cat braking on top needs all four.
Each platform bears on a 2x4 cleat or post plus corner braces, with 2+ screws per bearing so the deck acts as a shear panel. Order: tunnel shelf, nap deck, zigzag pair, mid-depth steps, onward step, center deck, jump landing (the doubled one; it takes the hardest landings in the build), rim step-down, far perch, crow's nest, then the rim highway boards and both passing bays screwed down to the back rail. Load-test each with a firm two-hand shove before moving up.
Both boxes get two 6 in doors on different faces (drill a starter hole, cut with the keyhole saw, sand the rim well), and the two boxes' doors must not face each other. The right-end box mounts raised, its floor ~17 in up on posts under the nap deck; the left box sits on the floor in the corner farthest from the glass. Keep the floor corridor under the structure open end to end. For the tunnel: trim the 48 in tube to ~36 in so both mouths land clear on the shelf, cut one 6 in escape hole at its midpoint facing the room, strap it to the shelf at both ends with plumber's strap, and keep both mouths open with clear landing space.
Wrap the laminated center pole full height first (~190 ft, nearly two rolls). Then screw 1x4 face boards to the two chosen legs and wrap those to 3.5 ft (~80 ft each); worn face boards unscrew and swap in minutes instead of a rebuild. The other two candidate legs get carpet wrap until the cats show a preference, then add a roll ($16) per leg. Start and end every run with a screw plus fender washer clamped over the rope, buried under the final 3–4 wraps; a dab of LN-901 under the first and last few wraps only, never continuous under the scratch zone. Wraps tight enough that a fingernail won't slide between them. No staples anywhere in the scratch zone.
Carpet every platform top in short cut pile, wrapped over the edges and stapled on the undersides only, every staple hammered dead flat. Tape or pad both landing mats so they can't skate. All fleece attaches with velcro or ties for washing. Light colors on anything in direct sun.
Two cats means one of each resource per cat plus one, separated in space; adjacent copies count as one location. Water station on the floor mid-footprint, away from food. At most one feeding spot on the structure (the small end-leg shelf at 2 ft, bowl fastened down) with the second at the opposite end of the room; never on highway lanes or beds. Scratch tray (a shallow 2x4-edged tray packed with corrugated strips from shipping boxes, swapped when shredded) at the main entrance by the ramp. Grass tray on the floor off the lanes. Bird feeder on the glass. Cool tile loose-laid on a shaded platform. Keep at least one bed and one scratcher per cat elsewhere in the house so this room isn't the only territory worth holding.
Countersink every screw flush and confirm no point can protrude through the far face (check screw length against the stack). Then run a bare hand slowly over every platform edge, underside, rail, both box interiors, and the tube interior; one missed point catches a paw at jump speed. Verify every gap between boards is under 1 in or over 4 in so a leg can't wedge. Rub catnip or silver vine into the sisal and the scratch tray, sprinkle the low platforms, and let the cats discover the rest on their own; carrying a cat to the top teaches nothing.