Affordable Pet Doors Melbourne installs the following cat doors which are designed specifically for timber doors. They have a plastic frame and are fully weatherproof. These doors also have a silent action and transparent flap:
Pig In Mud Standard Cat Door – $210 including supply and installation
Dimensions: 
- Door Size: 18.4cm x 19cm
- Flap Size: 15.9cm x 15.9cm
Features:
- Impact-resistant frame made of super-strong thermoplastic
- Unbreakable LEXAN flap with felt seal and magnetic close
- 4-way locking mechanism: Door Open / Door Locked / In Only / Out Only
- Tamper-proof mounting system means door can’t be removed from outside
- Inner telescoping frame adapts to doors from 32mm to 44mm (standard door) thick
(Yarra Valley / Mornington Peninsula – an additional $40 travel surcharge applies)
Pig In Mud Large Cat Door – $230 including supply and installation
Dimensions: 
- Door Size: 20.6cm x 34.3cm
- Flap Size: 19.1cm x 26cm
Features:
- Impact-resistant frame made of super-strong thermoplastic
- Unbreakable LEXAN flap with felt seal and magnetic close
- 4-way locking mechanism: Door Open / Door Locked / In Only / Out Only
- Tamper-proof mounting system means door can’t be removed from outside
- Inner telescoping frame adapts to doors from 32mm to 44mm (standard door) thick
(Yarra Valley / Mornington Peninsula – an additional $40 travel surcharge applies)