How to build outdoor masonary steps with cinder blocks with stone cladding risers?

[ethanspeeds]

Hi All, 

I am looking to build an outdoor masonry stairs using cinder blocks and stone cladding as facia for the risers. Its located between a driveway and retaining wall. there is 4 steps  but i've broken up each step into 2 sections. The 1st section of the step would be a full block and the 2nd section would be a half height block, hopefully to reduce the amount of digging. the void area under the pavers and blocks will filled with drainage gravel.

Any idea if this would work?

I am also stumped on whether drainage is required but if i were to place a socked ag line on the first coarse, would the socked line would be placed behind the first block but at what height? Would the socked ag line be placed in the bedding sand layer or road base?

Any pointers and suggestions is welcomed

[MitchellMc]

Welcome to the Bunnings Workshop community @ethanspeeds. It's sensational to have you join us, and many thanks for your question about building a staircase.

I think your approach sounds quite solid overall, and it's great that you're thinking ahead about reducing digging and incorporating drainage. One thing I’d recommend is bedding your cinder (Besser) blocks onto a mortar base rather than just sand and gravel, particularly since you're working with tiers. While sand and gravel are fine for flat areas, using mortar will help ensure the blocks are firmly set and won’t move or tilt under pressure — especially when someone steps on the front edge. So once you've dug and compacted your tiers, lay a mortar bed on top and set the blocks into that for a much sturdier result. 

As for drainage, it’s only really necessary if you're already experiencing water issues in the area. If water tends to flow down that slope, then adding a socked ag line is a good idea. Ideally, you’d dig a trench behind the top tier deep enough to run the ag line along the base of the wall, backfilled with drainage gravel. This would intercept water before it reaches the steps. If that’s not feasible, placing the ag line just behind the first course, as you mentioned, is still helpful — ideally sitting it in the compacted road base rather than in bedding sand, as it will perform better and last longer there. 

Please let me know if you have any questions.

Mitchell
 

[ethanspeeds]

Hello Mitchell,

Thanks for the feed back. 

I forgot to mention once I dig the clay/fill out to the appropriate depth, I was going to pin down non woven geo fab over all the steps ending with wrapping the ag line with  20mm drainage gravel  over the dig to prevent any weeds and clogging up the pipe.

So do i then level out my  treads with 50 mm road base then sit the blocks on x thickness mortar to get the right height?

Would the blocks require stakes embedded into the mortar into the clay?

Would core filling the blocks with drainage gravel still required?

Regards

ethan

[EricL]

Hello @ethanspeeds 

Thanks for the added detail, you're clearly planning this thoughtfully, and your approach is on the right track. Here's a breakdown of your follow-up questions with some friendly, practical guidance:

Yes, using non-woven geofabric over the excavation is a great move. It helps stabilise the subgrade, prevents fine clay from migrating up into your drainage layer, and keeps weeds at bay. Wrapping the ag line with 20mm drainage gravel is also ideal, it allows for good water movement while protecting the pipe from clogging.

Now, regarding your treads and block placement:

Once you’ve excavated and laid your geofabric, you can build up each tread with around 50mm of compacted road base. From there, it’s perfectly fine to adjust your block height using a mortar bed typically anywhere from 10mm to 30mm thick to get the levels right. Just make sure the road base is well-compacted and level before laying mortar and blocks.

Stakes embedded into mortar or clay aren't necessary for this kind of masonry stair. The blocks themselves when properly bedded on mortar over compacted base will hold firmly in place. Instead of using stakes, focus on ensuring the base is solid and the blocks are level. If you want to go the extra mile, you can also backfill behind and under each tread section with compacted gravel for added stability.

Core-filling the blocks with drainage gravel is not required unless you're building a structural wall or using reinforcing bar (rebar) through the cores. In your case using them as stair risers with stone cladding, it’s better to leave the cores empty or fill them with mortar for strength, especially if they’ll be visible or supporting stone. If you're concerned about moisture retention inside the blocks, drainage gravel won’t help much inside a block core. Instead, make sure the steps are well-drained around the structure.

Final tip: Consider a slight forward slope on each tread (just a few degrees) to shed water. It doesn’t take much to prevent pooling and helps extend the life of the mortar, stone cladding, and paving.

If you need further assistance, please let us know.

Eric

[ethanspeeds]

Thanks eric for the pointers,

i've taken your advise and will be using mortar instead, but i have another question. because i didnt want the treads to higher than the drive way as its tight, this leaves me with a  bit of exposed soil under the thickness of the aggregate of 50mm. i want follow the stone cladding of my step risers to cover the clay. To do that i need some of backing plane im assuming so the stone cladding can adhered . Any ideas how i go about that? initially i was thinking a backside of a tile to hold back the clay and then tile cement to stick the cladding on and colored silicone to seal off the top edge, would the blocks pressed up against the tile be enough to hold it up against the clay under the driveway?

how to install cladding onto aggregate drive way

[JacobZ]

Hi @ethanspeeds,

Do you have any photos of the area where you are planning to install these steps? 

Your plans are fantastic, but I am struggling to wrap my head around things without seeing the actual area.

Any time you are retaining soil, you'll need something more substantial to resist the weight of it. A tile would not suffice. You're going to have to use something like a cinder block, retaining wall block or sleeper so the soil is suitably retained. The stone cladding can then be attached to this retaining structure. If you were to forego this, regardless of the fact that you have clay, which tends to retain its shape quite well and is less prone to erosion when compared with other soil types, over time, it will shift, and I fear that it will collapse.

A sleeper retaining wall could be as narrow as about 50mm, so this is likely your best option, considering there is limited space.

Do you have any thoughts on this?

Allow me to tag @Dave-1 and @Nailbag to see if they have any ideas.

Let me know what you think.

Jacob

[Dave-1]

Good Afternoon @ethanspeeds 

You have some impressive plans, and the suggestions from @EricL and @MitchellMc and @JacobZ make perfect sense. I am a liitlke confused as well about the step side 😕 I few photos of the area would certainly help out with us picturing the side of the steps. 

Some kind of retaining wall will be needed so depending on how much space you have the plans might need to be modified a little.

Dave

[ethanspeeds]

Hi all,thanks for the feedback, this currently the stage I am up to

 

[EricL]

Hello @ethanspeeds 

Thank you for the update, it's good to see you've started your project. Those steps are forming up nicely.

Eric