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How to Make a Simple Multipurpose Doorstep for Your Cat Flap From Decking

Updated on December 20, 2016
Nathanville profile image

I strive to balance aesthetics, functionality and quality with costs when planning DIY projects in the home and garden.

Doorstep for cat flap with adjoining plant potter platform hiding pipes and drain.
Doorstep for cat flap with adjoining plant potter platform hiding pipes and drain.

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Ease of Access

Like humans, cats like to walk in and out of doors rather than have to struggle through them because the opening is too small or they are too high or too low. Ideally the base of the cat flap should be a little below leg height, and the top no shorter than shoulder height; so the cat can just walk straight through without clambering, bending or stooping.

Where a cat flap is fitted to a door this is generally not a problem in that there’s usually a doorstep on the outside to a similar height to the internal floor level. Under UK building regulations, the internal floor must be above the DPC (Damp Proof Course) which is a minimum height of 150mm (6 inches) above ground level.

On building our new conservatory, the cat flap I made through its wall is close to being the correct height on the inside, but with the additional drop of 6 inches for the DPC, the stepdown outside was far too high.

Considering My Options

The obvious option to me to resolve this issue was to install some kind of cat step; the questions being what materials to use and whether it should be made from wood or a permanent structure e.g. brick.

To consider these options carefully I took a leaf from my Project Management training and applied the principle of the ‘five options’ from ‘do nothing’ to ‘do everything’:-

  • Do nothing e.g. let your cats’ struggle each time they want to go in or out.
  • Do a little e.g. put a wooden box or a brick on the outside just below the cat flap.
  • Do a little more e.g. make a temporary structure with a patio slab placed on a few bricks just below the cat flap.
  • Do most of it e.g. build a semi-permanent structure from wood, such as decking.
  • Do it all e.g. make a permanent step from bricks and cement or a concrete step.

As is so often the case with Project Management, you generally consider and quickly dismiss the first option of ‘do nothing’, unless there is a good reason to do nothing.

Then generally, quickly dismiss the last option of ‘do everything, on the basis of it being too expensive and too elaborate for you budget and or requirements.

Usually, it’s one of the middle three options that gains favour. In my case, building a semi-permanent structure from decking seemed the ideal solution; and for the purpose of this article is the one I will be describing in detail.

Choosing the Build Materials

I had a choice of building the cat step from brick or wood. I chose wood, specifically decking, because:-

  • Brick would be too permanent e.g. if we changed our minds or future needs changed, then dismantling a brick structure tend to be a major operation; whereas a wooden structure can easily be dismantled or modified.
  • A wooden structure is no more expensive to build than brick and can sometimes be cheaper.
  • It’s easier and quicker to build from wood.
  • Wood allows for a more flexible design e.g. I also wanted to find a way to hide the drain and drain pipes in the corner, right next to the cat flap.
  • Using decking in particular means it’s long lasting in that the decking and timber used for the decking frame are pressure treated so they don’t rot quickly in the British climate, and
  • Decking is quite an attractive material that adds to the aesthetics of the design.

Making the Design Multipurpose

I love making things multifunctional. In this case the cap flap from our conservatory is close to the drain and drain pipes; so I instantly saw the option of extending the cat flap platform to cover the drain and pipes. In doing so I also saw the opportunity of extending the multifunctional use of the platform by designing it to also stand plant potters on; adding to the aesthetics and functionality of the design.

Basic Design

My design is in two parts:-

  • Cat flap doorstep, and
  • Adjoining plant pot platform, that also conceals the drain and drain pipes.

Each part is made up of four elements:-

  • Frame
  • Support Posts
  • Skirting, and
  • Decking

Design Requirements

My brief to myself for designing the multipurpose cat step was that the decking should be:-

  • Aesthetically pleasing and functional.
  • Floating i.e. not fixed to any structure or the ground but supported in place entirely by its own weight.
  • That as it would also be concealing a drain that it should be easily removable in the event that access to the drain is required e.g. to clear a blockage.

Previously, I’ve designed and built all my decking in our garden to be floating e.g. free standing; rather than embedding the support posts in the ground with concrete or tying the structure to walls with bolts. It’s my preferred option, which works extremely well in that once built:-

  • The weight of the decking holds it firmly in place, so it doesn’t need anchoring
  • It’s easier, cheaper and quicker to construct.
  • There’s no risk of the support posts rotting around the base, and
  • Air flow is maintained between the decking and walls, to prevent the build-up of damp on the adjoining structure, such as the house wall.

Ventilation for Airflow

Ventilation aids airflow which reduces the build-up of damp. Therefore to ensure adequate ventilation the decking should:-

  • Not be fixed to the walls, to leave a small gap for ventilation. Important for airflow that prevents the build-up of damp which would otherwise cause the wood to rot and risk damp penetrating the house and conservatory walls.
  • Stand on a patio that slopes gently away from the house with the frame being held off the ground by support posts; to aid water runoff from the patio slabs when it’s raining.
  • Have an inch gap at the bottom of the decorative skirting; leaving ventilation underneath the decking to keep the frame aired and dried.

Construction Guide

Building the Frame

The first thing to do is carefully measure and cut all the required timber for the frame.

In this design the frame is in two parts:-

  • A larger structure to fit around and over the drain pipes and hide the drain, which also doubles up as a platform for pot planters, and
  • A simple frame for the cat flap doorstep.

The cat flap doorstep only needs to be a few inches off the ground so it’s the right height for our cats to be able to walk through the cat flap without having to crouch down or clamber up. The plant potter platform needs to be a little higher so the underside of the frame is slightly above the guttering down pipe laying on the ground, and not touching it. The frame for the plant potter platform also needs to be designed to fit around the down pipes.

Normally I would use a minimum of 2x4 inch timber for a decking frame, spacing the beams about 400mm (15 inches) apart. However, as this structure doesn’t need to take the weight of a normal decking, and with the space restrictions, I used mostly 2x2 inch pressure treated timber.

After making all the measurements, sketching a design and making a cutting list, I cut all the required pieces to size; then laid them in place to test fit.

Once I was satisfied all the pieces were correct, I screwed them together with suitably long screws. I would recommend a minimum of 4 if not 5 inch screws; using two for each butt joint.

All the pieces for the decking frame cut to size and laid out to test fit.
All the pieces for the decking frame cut to size and laid out to test fit.

Ease of Access to Drain

To ensure easy access to drain, if and when required, I designed the frame to fit around the soil waste pipe and rainwater down pipe like a piece of jigsaw puzzle; so that by simply unscrewing the first piece of decking the whole structure will simply lift off.

Decking frame designed to fit around soil waste and rain water down pipe.
Decking frame designed to fit around soil waste and rain water down pipe.

Adding the Support Posts

Using pressure treated timber I cut the support posts to length as required and fitted them to the inside of the frame.

In this design, as the plant potter platform is higher than the cat flap doorstep I used a couple of support posts of the plant potter platform as support for the cat flap doorstep. Therefore I only needed to fit a couple of additional support posts on the other side of the cat flap doorstep.

Two of the support posts for the plant potter frame also supports one side of the cat's step.
Two of the support posts for the plant potter frame also supports one side of the cat's step.

Fitting the Decking and Skirting

The fun part is cutting the decking to size and fixing it to the frames. The last piece cut to fit around the rainwater downpipe locks the whole unit in place; and it’s only this one piece that needs to be unscrewed in the event that access is needed to the drain below.

The final touch to complete the project was cutting decking to size to fit along the front and side of the plant potter platform to act as decorative skirting.

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Decking fitted to base, last peice locking platform in place around the rain water down pipe.Multipurpose cat step and plant potter platform concealing drain and pipes.
Decking fitted to base, last peice locking platform in place around the rain water down pipe.
Decking fitted to base, last peice locking platform in place around the rain water down pipe.
Multipurpose cat step and plant potter platform concealing drain and pipes.
Multipurpose cat step and plant potter platform concealing drain and pipes.

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    • Larry Rankin profile image

      Larry Rankin 8 months ago from Oklahoma

      Wonderful DYI!