How to build a low-level deck for alfresco area?

[Vishuk]

Hi All,

I just Joined this forum so please excuse for any pointless question.

I am planning to build decking outside of existing alfresco floor to be sit on sand.  please refer attached frame layout and BOM. I removed grass patch and will put weed mat over it. 

Could anyone suggest for building decking post (Qty, type, length etc ) required to build decking frame as attached, Decking area is 5.1mx1.2 m. It is not exactly rectangle. I have considered 100x50 Split Pole type post currently available at Bunnings in 2.4m length. 

Is there any easy alternate to installing posts?

Additionally, The Existing Alfressco Floor is only 180mm from Soil that means I will have low clearance under frame. would that be alright. 

[JacobZ]

Hi @Vishuk,

A warm welcome to the Bunnings Workshop community, it is wonderful to have you with us.

You have put 75x50 as your framing material in your materials list. This is not a profile of timber that is commonly used for deck building, and unless it is structural grade timber with a span table we can reference, it is not suitable for the construction of a deck frame.

Typically, I would advise using 90x45 H3 Pine Framing as it is structurally rated, suitable for use outdoors and easy to design decks with as it is listed in the Hyne Bearer Span Table and Joist Span Table.

I'd suggest you have a quick read through How to understand deck components and How to understand deck span tables to ensure you understand the structural requirements around building a deck.

Unfortunately, 100x50 is not a suitable profile for vertically supporting a deck. Typically, you would use either H4 Posts or pedestal feet to support your deck. 

Using 90x45 framing with 19mm thick decking boards will give you 71mm of clearance beneath the frame. At this height, you could use timber posts or these Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet.

I am happy to work with you to design a deck that will be strong and last the test of time, so please let me know what you think.

Jacob

[Vishuk]

Hi @JacobZ 

Thanks for the information, 

Regarding Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet. These looks easy installation then post. Can these be installed directly on the soil or does these require concrete padding? how many of these required?

[JacobZ]

Hi @Vishuk,

They can sit directly on the ground, assuming it is fairly compact and won't move. If the ground is a bit soft, then it would be worth digging out a small hole and either adding compacted road base or a concrete paver.

The number of pedestal feet required will depend on the material used for your bearers and the advisable span of your bearers.

If you were to use 90x45 H3 Pine, they can span 900mm between support, meaning you will need 6 pedestals per bearer, 12 total.

Let me know if you have any further questions.

Jacob

[Vishuk]

Hi @JacobZ 

 Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet. is a great option but it is a problem in my case, refer picture. In Option-1 installing P/feet will clash with boundary fence on one side and Alfresco floor on other side. Installing P/feet under joist is not great , is that correct?

So i considered moving bearers (option-2) inside and creating protusions on both ends. Now, Bearer are sitting directly on P/feets. What do you think about this?

Also, Since bearers are 90x45 now can Joist and noging be low small crossection now? say 70x45.

[EricL]

Hello @Vishuk 

I would probably go with option 2 as the pedestals are supporting the joist properly. However, I suggest adding pedestals on the joist that don't have support underneath. This will keep your deck rock steady. For the noggings yes you can use 70x45, but I propose staying with the 90 x 45 for the joist to keep the frame stiff.

If you need further assistance, please let us know.

Eric