Quick answer: An outdoor catio tower needs weather-resistant timber such as cedar or exterior-grade plywood, stainless steel screws and brackets, outdoor sisal rope, a pet-safe exterior finish and fixings to anchor it. To compare with store-bought, divide the full cost, including replacement sisal and finish, by the years it lasts.
Indoor cat trees are not built for rain, frost and summer sun. Particle board swells, carpet holds water and mildew, and plain steel screws rust and stain the wood. An outdoor catio tower has to be built differently, which changes both the materials list and the true cost over time.
This guide is the materials companion to our comparison of an indoor DIY cat tree versus store-bought by cost per year, adapted for a catio. It sits in our DIY cat tree hub. At CozeCats we judge any cat furniture by what it costs for each year it is actually used.
The Design This Outdoor Catio Tower List Is Based On
The list below is for a simple tower about 150 cm tall: a square base, two posts, three platforms at roughly 50, 100 and 145 cm, and a covered top platform. Adjust quantities for your catio size.
Keep platforms at least 40 × 40 cm so a cat can turn and lie down, and fit a lip on the top platform. Anchor the tower to the catio frame or a wall so wind and jumping cats cannot tip it.
Timber and Boards
| Item | Quantity | Notes |
|---|---|---|
| Cedar or other rot-resistant posts, 7 × 7 cm | 2 at 150 cm | Naturally weather-resistant |
| Exterior-grade plywood, 18 mm | 1 sheet, 122 × 244 cm | Base and platforms |
| Cedar boards for platform lips | About 4 m | 2 to 3 cm high |
| Exterior-grade plywood offcut | 60 × 60 cm | Roof over the top platform |
Avoid particle board, MDF and indoor plywood, which swell when wet. Be cautious with pressure-treated timber: modern treatments differ, and older timber treated with chromated copper arsenate should not be used where cats chew or lie. If you are unsure what a product contains, choose naturally rot-resistant wood instead.
Fixings and Hardware
- Stainless steel wood screws, about 100 in mixed lengths.
- Four stainless steel angle brackets per platform.
- Two heavy stainless steel straps or brackets to anchor the tower to the catio frame.
- Stainless steel staples or small screws to secure sisal ends.
- Rubber feet or pavers under the base if it stands on soil.
Stainless steel costs more than zinc-plated hardware but does not rust or leave black stains on cedar. Our tower anchoring checklist explains how to test the anchors once fitted.
Sisal, Finish and Comfort
Sisal rope weathers outdoors, so plan to replace it. For two posts of 7 × 7 cm wrapped over 100 cm each, a 10 mm rope needs roughly 28 cm per turn and about 100 turns per post, so about 28 m per post, or 56 m plus 10% spare, around 62 m in total.
| Item | Quantity | Notes |
|---|---|---|
| Sisal rope, 10 mm | About 62 m | Untreated, no oil finish |
| Pet-safe exterior wood finish | 1 small tin | Check label for pet use once cured |
| Outdoor cushion or washable pad | 1 per platform | Bring in during heavy rain |
| Exterior-grade wood glue | 1 bottle | For joints only, not under sisal |
Let any finish cure fully before the cat uses the tower, following the label. The EPA's guide to volatile organic compounds explains why low-VOC products and good ventilation matter while finishes cure.
Tools and Build Time
Most of the build is straight cuts and screwing, so a basic set of tools is enough. Many timber yards will cut the plywood sheet to your platform sizes, which saves the hardest part of the job.
- Circular saw or jigsaw, or store cutting for the plywood.
- Cordless drill with wood bits and a countersink.
- Spirit level and tape measure.
- Clamps to hold platforms while fixing brackets.
- Sandpaper to round every edge a cat will touch.
- Gloves for handling sisal and cedar, which can splinter.
Allow a weekend: one day for cutting, assembly and the first coat of finish, and a second for wrapping sisal and anchoring once the finish has cured. Wrap sisal tightly, securing each end with a stainless staple, so the rope does not slip down the post when wet.
Cost Per Year of Use: DIY vs Store-Bought
Prices vary a lot by region, so the figures below are illustrative examples rather than quotes. The method is what counts: add the upfront cost to expected upkeep, then divide by the years of use.
| Option | Upfront | Upkeep over life | Years of use | Cost per year |
|---|---|---|---|---|
| DIY cedar tower | $220 | $60 (sisal twice, finish twice) | 6 | $46.67 |
| Store outdoor tower | $260 | $20 | 4 | $70 |
| Indoor cat tree used outside | $90 | $0 | 1 | $90 |
In this example, the DIY tower costs $280 over six years, which is about $46.67 a year. The store tower costs $280 over four years, $70 a year. The indoor tree is cheapest upfront but most expensive per year, because it rarely survives one outdoor season. Run the same sums with your local prices before you decide.
When Store-Bought Makes More Sense
If you do not have the tools or the time, a well-made store tower designed for outdoor use can be a fair choice, especially if it uses replaceable sisal and weatherproof materials. Check the product description for outdoor suitability; many cat trees are indoor-only even when photographed in gardens.
A small catio may not need a tower at all. A few wall-mounted shelves fixed to the catio frame give height for less money. Our wall shelves and perches hub has designs that can be adapted.
Maintenance That Extends Its Life
- Check every fixing and anchor at the start of each season.
- Brush off leaves and dirt so platforms do not stay damp.
- Re-coat bare wood with finish once a year, or as the label recommends.
- Replace sisal when it is frayed or holds water.
- Bring cushions in during wet weather and wash them regularly.
Regular maintenance is what moves a DIY tower from two years of use to five or six, and that is where most of the cost-per-year saving comes from. Our guide to replacing sisal without rebuilding shows how to rewrap a post.
Catio Safety Around the Tower
Position the tower so it does not give the cat a step to the top of the catio enclosure or over a fence. Check the mesh near each platform for gaps and sharp ends. Keep toxic garden plants out of reach of the catio, since cats may chew leaves that poke through.
Provide shade and water on hot days, and a sheltered spot when it is cold. The ASPCA's toxic and non-toxic plants list helps you check what is growing nearby, and our guide on taking an indoor cat outside safely covers introducing a cat to a catio.
Outdoor Catio Towers
What wood is best for an outdoor cat tower?
Naturally rot-resistant timber such as cedar is a good choice for posts and lips, with exterior-grade plywood for platforms. Avoid particle board, MDF and indoor plywood, which swell when wet. Be cautious with pressure-treated timber, and do not use old wood treated with chromated copper arsenate.
How much sisal rope do I need for a catio tower?
For two 7 × 7 cm posts wrapped over 100 cm each with 10 mm rope, allow about 28 m per post, or 56 m in total. Add around 10% spare, so buy roughly 62 m. Use untreated sisal, and expect to replace it more often outdoors than indoors.
Is a DIY catio tower cheaper than buying one?
It often is when measured by cost per year of use. In our illustrative example, a DIY cedar tower works out to about $46.67 a year over six years, against $70 a year for a store outdoor tower lasting four years. Run the sums with your own prices and expected lifespan.
Can I use an indoor cat tree in a catio?
Indoor cat trees are usually made from particle board and carpet, which absorb water, swell and grow mildew outdoors. They rarely last a full season outside. If your catio is fully roofed and dry, one may cope for a while, but outdoor-rated materials last much longer.
How do I stop a catio tower from tipping over?
Anchor it to the catio frame or a wall with heavy stainless steel straps or brackets, and give it a wide, level base. Check every anchor at the start of each season and after storms. Position the tower so it cannot become a step to climb out of the enclosure.
