How to build a deck with stirrups?

[Whitetees]

Deck for Farmhouse

Hi, I'm building a deck on my farm and don't have much experience using post stirrups. Have always just put posts straight into the hole when building structures on property.

I've decided to use stirrups for this project to give me some extra height for my posts that I have on hand. 

I will be using  Pryda 600 X 90mm full stirrup post to support a 3.6m2 deck with the same post being used to support the same size roof.

Question:

1. What hole size is best?

2. How much gap between concrete and base of stirrup is maximum? ( Remembering I'm trying to maximise height)

3. Are stirrups a strong and safe option for my required use.

Regards

[JacobZ]

Hi @Whitetees,

Thank you for your questions and welcome to the Bunnings Workshop Community, it is great to have you with us.

I will start by saying that it is important when building multi-faceted structures such as this that you understand the relevant regulations in your local area. Active loads like uplift from the roofing structure need to be taken into account for your safety and those of its intended users. It will be worth contacting a consulting engineer to assist with the design of your deck as Pryda haven't provided engineering specification for all live load requirements. You may like to have a read through Pryda Post Anchors Guide and Full Stirrup Post Anchor Data Sheet as it provides a good starting point when designing projects with their products.

Stirrups are certainly a strong and safe option when used in line with the relevant engineering plans. Due to the size and complexity of your deck, it would be important to communicate with an engineer prior to their use.

I am hesitant to specify a size for the foundation pier holes as it would require calculation of the live loads that will be applied to the structure.  

With this being said, their post anchors guide states that,

"Design dead and live loads are likely to be limited by the capacity of the post, but should not exceed 16kN at the maximum stem height of 130mm and 24 kN for 75mm stem height or less. For all other heights, to be designed by consulting project Engineer."

My interpretation of this is that Pryda are comfortable with the stem protruding 130mm out from the concrete foundation assuming live loads, particularly wind load, do not exceed 16kN.  If you wanted to exceed this height, you will have to consult an engineer for design assistance.

Let me know if you have any further questions.

Jacob