How to build a low level deck on sloped land?

[RJ2]

Hello fantastic people of Bunnings Workshop,

After successfully completing my last VJ panel project with your assistance, I’m back with another challenge — building a low-level deck.

I’m engaging a professional to build a 25 sqm low-level deck (most likely using Ekodeck) on sloped land, with the lower side toward the house (see attached picture). Some excavation will be required to ensure the deck has a proper fall away from the house. However, I have a few issues I hope you can help me with.

1. Grass Maintenance Challenge

As you can see, after the deck is installed, there will be a fair bit of grass left on either side. I’m concerned this could be difficult to maintain (mowing/edging) due to the deck's proximity. I’d love to hear any suggestions on how to make maintaining this area easier.

The two options I’ve considered are:

• Expanding the deck — Building a larger, 50 sqm edge-to-edge deck to eliminate the need for mowing. However, this would double the cost and might require council approval.

• Synthetic grass — Installing synthetic grass around the deck, though I’m unsure how I’d feel about having that much artificial grass around me.

Are there any other alternatives you’d recommend to simplify maintenance or improve the design?

2. Low-Level Deck Considerations

In the picture you'd notice that the weep holes on the house wall are positioned quite low, meaning the deck will sit above them. The deck structure will not be placed hard against the weep holes and the deck board on the edge will be removable for easy termite inspections.

Is there anything else we should consider when installing a low-level deck in this situation?

Any advice or guidance would be greatly appreciated before we move ahead with this project.

Thank you in advance for your help!

Many thanks!

[EricL]

Hello @RJ2 

Thanks for sharing your question about your decking project. If you are worried about lawn maintenance, I suggest leaving enough room for a standard lawn mower to pass through the front and sides of your deck. You might also like to check your local council's rules and regulations in regards to how close you can build your deck to your fence. Just keep in mind that there should be enough room to run a lawn mower through and enough room at the end to turn around and go back.

I'm not a big fan of artificial turf so if you can manage to have real grass in your yard it would be much more environmentally friendly. One other option is to surround the deck in pavers totally eliminating the turf or use pebbles as a large border feature for the deck. If you build the deck as free standing and not anchored to your home, you can leave a gap between the decking frame and your house wall which will prevent moisture from being trapped and allow your weepholes to function properly.

My best advice is to make sure that the ground on which the deck will be built on has proper drainage. You don't want to have standing water under your deck, it must be sloped in such a way that rainwater drains away from your house wall. You can also use weedmat and gravel to help facilitate drainage. To give your decking frame extra layers of defence, I suggest coating the bottom of the frame with Gripset Betta 4L Bitumen Rubber Waterproofing Membrane. For the top portion of the frame, I recommend covering it with either Protectadeck 45mm x 50m Flexible PVC Joist or CAgroup 50mm x 20m Bearer Protector G-Tape. These will protect the surface of your frame and prevent water from sitting on the timber surface.

Should you decide to install a timber pergola over your deck, this would be the best time to prepare for it. The foundations of the pergola post must be defined first before you build your deck. In this manner there will be no need to disassemble your decking panels in order to dig for post foundations. I also suggest having a quick look at these guides - How to build a low-level deck by @Adam_W and How to build a deck by @MitchellMc. 

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

If you need further assistance, please let us know.

Eric

[Dave-1]

Good afternoon @RJ2 

Love making an area more useful. I do like the idea and by the look of it you have two brick courses above the grassline to start with.

Id work backwards with your plan for a deck. to get the distance down you will need.

- floorboards, commonly 19mm thick

- joists, commonly 90mm thick

- beams if needed 120mm thick

- TuffBlock 300 x 300 x 90mm Instant Foundation System Deck Support as an idea or stirrups in concrete.

So minimum I can see is 160mm and thats with concrete set stirrups with 50mm spacing above the ground. No beams as you would use more stirrups to support the joists. I would prefer 100mm gap between the ground and teh joist minimum. With the Tuffblocks I dont like them on soil as I think the soil could get washed away.

Second part. 

Im not a fan of mowing So Id actually mulch the area left over and have stepping stones access. Paving as @EricL could work especiallya s a path, even as a narrow garden path so a wheelbarrow wheel can run along it. Not having the deck up to the tree would be wise as roots do grow and could shift footings if you are too close. Plant some long lived shrubbery and it could be low maintence for sure.

Last thing id possibly do, get a plumber out to install a new tap near the water heater for watering the yard. Nothing is more of a pain then dragging a hose across the deck.

Id factor in some posts for a roof "just in case" when installing the footings. that way you dont need to tear the whole deck up down the track.

Dave