How to build a low-level deck on concrete and grass?

[Mizzms]

Hi Community!

I am building a low level, small deck (approx 15sqm). It will sit on a combo of existing concrete path and grass.

It is 4.1 x 3.1 and I am using an aluminium and adjustable pedestal decking kit. The finished height will be 140mm. I am using 140mm x 19mm merbau boards.

Lastly, I would say soil type would be moderate clay.

I've attached photos of my deck plan, the pedestals and where it will be going.

Here are my questions.

1. Do I need to clear the grass?

2. I estimate I will need 24 footings for the pedestals on the grass. I am trying to work out what to use for footings and keep them budget friendly.

I've come up with the following options but I'm a bit unsure about which way to go and what other options there might be.

Concrete spot footings. A LOT of digging!

Concrete paver on road base.

Concrete pad on road base.

I would be grateful for any advice anyone can give.

Thanks in advance ☺️ 

Marie

 

 

 

[Dave-1]

Goodmorning @Mizzms 

I havnt built a low level deck (So cant really suggest a good footing) but have built a higher one. I used  Stirrups and set them in concrete. I was told I went overboard with the amount of posts and supports (Tho still think they are the right amount) and my footing were less in number then yours. 

I then rain rails across these to support the deck itself. From Memory the rails were 600mm ish apart. Its been standing there for a decade.

For you, less footings then your design I would suggest, and probarly not concrete them in. I have seen the concrete Foundation Blocks and would be tempted to use them in your situation. The area of my deck is about 4m by 4m. 

Just for an indication of the span between the boards. 

Hope these help in sorting the way you want to go. I always find it surprising when you sit down and work out the costs for materials. I was shocked at the price for the tin roofing once I got to that point. Shouldnt have been but it was an expectation it would be cheap but wasnt.

Dave

[Akanksha]

Hello Marie (@Mizzms)

Many thanks for your questions on deck construction. Great to see you've received some advice from @Dave-1. Our resident D.I.Y. expert @EricL will also be online later this afternoon and will be happy to assist with your questions.

In the meantime, you might like to read through experienced Workshop member @Adam_W's article on How to build a low-level deck and and How to build a deck by D.I.Y. expert @MitchellMc. I'd also encourage you to look through the most popular decking projects our members have contributed. For more inspiration, you can also look at our Featured Projects section which contains different types of decking projects.

Keep us updated as your project progresses. We'd love to see the final result.

Akanksha

[EricL · Accepted solution]

Hello @Mizzms 

Thanks for sharing your question about your low-level deck. Looking at the photo you posted it seems that it already has a natural slope in the land which is fortunate. This means that you won't have to do a lot of landscaping to create a slope. 

One of the most important things to take into consideration when making a low-level deck is drainage. Water has to flow out of the bottom of your deck to prevent it from getting damaged by trapped moisture. To answer your first question, it's not necessary to remove the grass in the area. I often recommend putting in weedmat on the ground to facilitate drainage. 

In regards to footing, I recommend using concrete pavers on road base. I suggest having a close look at this guide - How to build a deck by @MitchellMc. It shows a very good example of pedestals installed on top of pavers along with drainage gravel. This would be a cost-effective method and will not require a great deal of construction effort on your part

I also recommend having a look at this discussion - Low-level composite deck over concrete and soil by @oninpena. Again, a very good example of a low-level deck frame transitioning from solid concrete base to soil.

If you have any other questions we can help with, please let us know.

Eric

[Mizzms]

Hi @EricL 

Thank you for taking the time to answer all my questions and sharing links to similar projects. I had done some searching but got a bit overwhelmed!

Luckily there is good slope on the ground for water run off but also room for a French drain if it looks like it's needed.

After many Google searches and getting nowhere I was starting to feel stressed! But now I am excited again and looking forward to getting my project underway.

Thanks again 😊

Marie

[Mizzms]

Thanks @Akanksha for sharing all that info. It was very helpful

I'll be sure to share the finished project when I'm done.

Marie

[Mizzms]

Thanks @Dave-1  for sharing your experience! That sounds like a solid, well built, deck to, especially given its still going strong

I was tempted to use those concrete blocks but my kit came with the pedestals, it wasn't cheap! So I'd like to use them if I can.

You are so right, everything works out more expensive than expected!

Marie

[shauny]

Hi @Mizzms what did you draw your deck plan up in? I

I absolutely recommend weed matting at a minimum for your design.

[Mizzms]

Hi @shauny 

I bought the deck as a kit and the place I bought it off drew up the plan so I am not sure what they used.

My plan is to scalp lawn, weed kill then lay weed mat. 

Cheers

Marie