Feedback wanted on low-level deck design

JesseS6

Hi All,

First time designing a deck and keen to get some feedback. Sketch is below.

In green, we have the posts, 100x100mm where the bearers will be set in also.

In Red Bearers – 190x45mm with 1318mm centres.

Joists in blue – 140x45mm with 395mm centres.

Deck it’s self will be 140x19mm Merbau with 4.5mm gaps.

A couple of questions, are there any issues running the Bearers as a single piece of timber? (5620mm)

And similar for the Merbau, any issues using 5700mm lengths cut to size?

The stumps will be 300mm above ground, noting the 190mm bearers will be set into the posts. So there will be 110mm from the bottom of the bearer to the ground, is this an issue? It will be 440mm from ground to bottom of the deck.

EricL

Hello @JesseS6 

Your deck design looks well thought out, but there are a few considerations to keep in mind.

For the bearers, using a single 5620mm length is structurally possible, but timber of that length can be prone to warping or sagging over time. Typically, it's better to join two shorter pieces with a staggered overlap (scarf joint or butt joint over posts) to improve stability and ease of handling. If you prefer to use a single length, make sure it’s properly supported and straight.

For the Merbau decking, using 5700mm lengths cut to size is fine, but consider staggering the joins for a more natural look. Long boards tend to expand and contract, so allow for proper gaps and fixings to minimize movement.

Having more space under the deck is always ideal, but a gap of 110mm should allow air to flow under the deck. 

Before you begin, I suggest checking the rules and regulations of your local council in regards to deck size and height limits. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric