Ask a question

The Bunnings Workshop community can help with your home improvement projects.

How to build a low-level deck over different levels?

Finding My Feet

How to build a low-level deck over different levels?





Hi all,


I'm hoping for some advice on decking over a sunken front porch?


The aim is to have one deck all the same height. I've read all the articles about low level decking but not sure how to go about the sunken part or the front step?


Any advice would be greatly appreciated!



Bunnings Team Member
Bunnings Team Member

Re: decking over multilevels

Welcome to the Bunnings Workshop community @Fitzhouse. It's wonderful to have you join us, and many thanks for your question about decking over uneven surfaces.

Creating a frame to raise the lower section will be a relatively straightforward process. To determine how high you'll need to raise the frame, first, we need to work out where the top section will finish. To do this, we need to determine what sized timber will be used on the top section for the frame. What is the working height there? Working height is measured from the concrete to the top of your door sill. The concern I have is that from your images, it appears you have a minimal working height. Typically, you'd use 90 x 45mm outdoor H3 timber for the frame. This would require a working height of 90mm for the frame plus 19mm for the decking. There doesn't look like 109mm worth of working height there. This is where you'll need to compromise on the structure by finding a configuration that allows you to build a deck within those confines. You could consider turning the 90 x 45mm timber on its face, so it is only 45mm high. This will work if you have 64mm of working height.


Once you let me know the working height, we can move on with the design stage.


Please let me know if you have any questions.



See something interesting? Give it the thumbs up!

Re: decking over multilevels

Thanks. The distance from the concrete to the top of the door sill is 60mm.

Re: decking over multilevels

That's a very limited height to build a deck within @Fitzhouse. It would be best to consider tiling that area and saving the deck for the lower portion. Here's a helpful step-by-step guide on How to tile an outdoor area.


For a 60mm working height, you'd need to use 90 x 35mm H3 outdoor framing timber laid on its face. That plus your decking will be 54mm, leaving only 6mm space under the structure for drainage. If you were to go ahead with this method, you should expect a significant decrease in the lifespan of the deck's structure. 


For the lower portion, you can use TuffBlock 300 x 300 x 90mm Instant Foundation System Deck Supports and 90 x 90 posts to level the area with the top. You'd then create the deck's frame and joists from 90 x 45mm outdoor framing timber


You'll need a transition area over the steps where you'd change from using the inadequate 90 x 35mm on its face to the 90 x 45mm timbers.


I've put a rough rendering together for you below that should better illustrate my suggestion.




See something interesting? Give it the thumbs up!

Why join the Bunnings Workshop community?

Workshop is a friendly place to learn, get ideas and find inspiration for your home improvement projects