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Hi,
I am looking for some advice on leveling and tamping the ground before building a deck.
After the plumber fixed the water leakage issue, a patch of my backyard has been left as shown in the photo. The patch is about 2x2m. I am planning to build a deck on top to 1) make a nice resting corner and 2) have an elevated platform to protect the PVC pipe down there.
My questions are,
1. What material should I use to fill and compact the area? Obviously want something to cover the pipes without putting too much load on them. The plumber suggested some soil and Tuscan on top.
2. What tools do I need for the project?
3. Any guidance for building deck?
Thank you.
Welcome to the Bunnings Workshop community @leijiang. It's wonderful to have you join us, and many thanks for your question about preparing soil for a deck.
I'd suggest laying weed matting over the area and placing at least 50mm of drainage gravel over that. That way, any water in the area can easily seep through the gravel and drain away. Also, how's the drainage in that area? Does water run away freely or pool there? If it does pool there, it might be an idea to install a drainage pit to collect the water and send it into your stormwater pipe. Any standing water under a deck can cause high levels of humidity and the early onset of timber decay.
The only thing I'd qualify about using sleepers for a deck is that they are not structurally rated, and therefore, their use is not permitted on a weight-bearing structure like a deck. Instead, use H3 timber, which is suitable for above-ground use and place it on footers.
Please let me know if you have any questions.
Mitchell
Hi @MitchellMc
Thank you for suggestion. A few follow-up questions
1. The drainage in this area is fine, never seen any pooling water. The area is a bit bumpy but not necessarily deeply sunken. I've attached a photo hopefully to make it clear. The area circled has the deepest spot about 40mm depth, while the surrounding is pretty ok. If I place 50mm gravel on top, would that be too much and need some sort of edging?
2. What type of gravel do you recommend to use? fine screenings or some crushed rocks?
3. On top of gravel, do I need to lay some sand as well? Some says this will help with leveling and compaction.
4. For decking, H3 timber as bearer?
5. I've watched Bunnings deck building DIY videos, are you suggesting to use footers vs stumps to support bearers? Footers seem easier as it removes hole digging and concrete.
Sorry for the barrage of questions. First time taking a challenge to build a small deck myself.
Appreciate your advice.
Hi @leijiang,
Drainage gravel is fine to use over that area. A layer of 50mm thick across the whole area should be fine, or you could just level the area with the gravel. It doesn't need to be a full 50mm above the height of the surrounding area. That drainage gravel is 10-20mm. Sand on top of it would help with levelling the area, and a paver and an adjustable pedestal foot for each support will allow you to account for an unlevel surface.
H3 timber is what you'd typically use as a bearer.
A footer is what goes in the ground, such as concrete, to secure the stump in place. You can use concrete footers and stumps, brackets, or a paver on top of the soil and adjustable feet. Sorry, I misspoke previously; that was a concrete foundation, which is also another option.
Mitchell
It depends on how high your deck is, @leijiang. Typically, you'd concrete a stump into a footer for an elevated deck. For this situation, if the bearer is less than 200mm from the ground, I'd go with a paver and pedestal feet. Generally, you wouldn't place a bearer on a footer, but you could concrete a stirrup into the footer and place it on that.
Mitchell
Hi @leijiang,
Could I please have some more context to your question? Are you trying to determine how many bags you'd need per square meter? If so, that would be around three to four. There's no equation I can use to work out how many drainage gravel bags are in a cubic meter.
Mitchell
