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How to build a planter box with seating?

Hi all

I'm working how to go about creating an outdoor planter box with seating. Got a few questions. I'll attach a pic of the space and what I hope to achieve.

Plan is to build with narrow besser blocks and rebar with 2 separate footing leaving sand ground between, filling with rocks, landscaping mesh and then soil for planting.

1. Will this be sufficient drainage?

2. How do I waterproof the exterior as I want to butt it up close to the garfen shed and fence?

3. What can I use to fill the gap between the fence and concrete so it doesnt fill up with leaves, nuts etc and create moisture against the wall?

First question

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Comments

JacobZ

Hi @michy81,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Is the idea to have your seating area where I have marked below?

Were you planning on having pavers or stones in the seating area like in your inspiration image?

Assuming the area is already fairly well-draining, having two parallel footings for your besser brick wall, where natural earth is left in-between, topped with drainage gravel, geotextile membrane and then soil, sounds like it will be more than fine in terms of drainage for the planter boxes, but it may be worth installing some sub-surface drainage in the form of agi-pipe to divert water that collects in the landscaped area between your planter boxes.

You might like to check out How to install garden drainage for some guidance on this.

You can use Bastion Exterior Waterproof Membrane, for waterproofing, however, it would be tricky to paint the backside of your besser bricks as it needs to be painted in one continuous membrane to be truly waterproof. Against the fence, you could temporarily remove fence panels to paint the membrane on and with the shed, you could temporarily move it before re-anchoring it.

To stop things falling between the fence and your planter boxes, you could use a product like this Saxon 180mm x 8.0m Black Plastic Gutter Guard.

It sounds like a fantastic project that is going to be very exciting to see come to life. As you're still in the planning stage, allow me to tag some of our helpful members to see if they have any advice or inspiration they can offer, @Dave-1, @Nailbag, @Codey.

Let me know if you have any further questions.

Jacob

Nailbag

Hi @michy81

as @JacobZ mentioned this is an exciting project. Following his guidelines will be the perfect plan to work by. Taking the time to get the ground work, drainage etc in place will be imperative in achieving the result in your vision photo. I would also consider things like any low voltage garden lighting that may require an cable runs if not solar powered.

Nailbag

Dave-1

Morning @michy81

I like your thinking and also your concerns. The suggestions from @JacobZ follow mine almost.

I am never keen to have anything against the fence, I just think it drops teh lifespan of the fence more then its worth so i would be factoring in how to keep debris away from the fenceline type deal (sealing it helps but having nothing against the palings are better. Id have a gully of at least 10cm wide and when you mow your lawn, you check the gully for debris.)

As I was thinking of going through and mentioning each of your questions I came up with a better idea, pretty much what I do for any project and that is to sketch it out. Makes no difference how bad you may think you are at sketching it really brings to mind any issues that are around.

For instance "Drainage", you know your yard, you know the wet areas after rain or even just normally. Does any of that area end up pooling? If so then the Age pipe is a good way to goas @JacobZ suggests tho were would you run that to? These ar the type of things taht I think sketching really helps solidify. Plus you ahve something to refer to when you get to an "issue" taht isnt going the way you expect. 🙂

Dave

michy81

https://www.workshop.bunnings.com.au/discussion/comment/42676#Comment_42676

Thank you so much. The area is fully sand and drainage is not an issue. I am planning to have pavers and stone on the sand for the base/floor so I'm thinking the stones on sand will also allow better drainage for the seated space as I will just compact the sand before laying the pavers to hopefully minimise the pavers moving too much. What are your thoughts on using expanding foam to fill the space between the fence and the wall?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/83614#Comment_83614

Hi @michy81,

Expanding foam could be an option or perhaps you could use a timber capping to cover the area. It's best to allow a certain amount of airflow as it will help to keep the area dry. If you seal it off and moisture still get's into the area it could create quite a humid environment.

Mitchell

michy81

https://www.workshop.bunnings.com.au/discussion/comment/106727#Comment_106727

Great idea on the timber capping. Thanks 😊

michy81

https://www.workshop.bunnings.com.au/discussion/comment/42713#Comment_42713

Hi @Dave-1

Sorry got distracted by life and am now up to sketching this out to price it.

Can I ask about besser blocks? The space is roughly 4m x 4m given I'm going to have it a bit off the fence and 2 walls for the planting, how slim a profile can I go with for the besser blocks?

The standard block is 390x190×190

Can I use a thinner profile like a 140mm or even a 90mm? If reinforced with rebar will these be strong enough for a seating area?

TIA

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/84019#Comment_84019

Morning @michy81

I dont see a problem other then strength. I know I lever the shovel fairly hard when I am turning the garden bed especially if its settled.

You could add reo and concrete inside the block to give it extra strength.

The way I see it, large area of a standard bessa block = better grip and resistance to stresses. You will need a foundation to have the bessa blocks sit on so you could incorporate the reo lengths into that.

Dave

michy81

https://www.workshop.bunnings.com.au/discussion/comment/106996#Comment_106996

Hi Dave

What if I build it out on poured concrete? Would it still need to be waterproofed? Hubby is in the concrete pumping business so I'm now thinking might be easier to just form up the 2 walls?

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/120905#Comment_120905

Good Evening @michy81

Wooooo 🙂 Now that opens up options for sure! 😀

If you are considering that I would really suggest to sit down with a sketch pad and start scrolling through pages like this and cruise through some pages just to get ideas. The forms you could make, especially with reo inside might change what you have planned.

For instance I saw some bench seats at work that were made from poured concrete with styrofoam in the large foot at one end (to save concrete and keep the seat lighter I presume) and slatted timber boards on top. It looks stylish and functional.

Ive only ever done some concrete repair and concrete footings for lamp posts but for sure the other members will have some brilliant ideas 🙂

Mind is running off with ideas! 🙂 Just rem if you are going to have a garden bed make sure water can exit 🙂

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/129328#Comment_129328

Hello @michy81

In regards to the overall construction of your planter box, I would encourage you to build it as free standing with four walls to keep the soil inside the planter and not touching your fence. I recommend sealing the inside of the planter, this will prevent hydrostatic pressure from occurring on the outside of the planter. This will allow you to paint the outside of the planter with whatever colour you want, and it won't peel off.

Building it out of poured concrete pretty much allows you to almost create it in whatever shape you want. But as @Dave-1 said make sure you provide a drain point for the water.

If you need further assistance, please let us know.

Eric

michy81

https://www.workshop.bunnings.com.au/discussion/comment/129328#Comment_129328

Hey Dave I'm not really understanding the Styrofoam bit. But loving your enthusiasm. One of our good mates forms up skate parks so I'm sure he can form up 2 walls for me. Can you find the Styrofoam post and tag me. I can't see the point of the Styrofoam if you put timber on it. My thoughts were to form up 2 walls with rebar slotting out to bore the timber slats to. I think if we do this I'll just to ve sure chuck a couple of poly pipe angled dains in to capture any run off to under the paver/rock area. Is soft sand as we're near the beach and never had an issue with drainage but prepared to chuck some in as contingency

michy81

https://www.workshop.bunnings.com.au/discussion/comment/134662#Comment_134662

Thanks for the feedback Eric. I'm still in the thinking it out stage. I've sketched up dimensions. I've taken everyone's advice and will have it 10-15cm off the fence and shed. Are you certain there's a benefit from water proofing? I'm planning on only putting Mondo Grass on the top. So, rock fill between walls, landscaping mesh, soil then Mondo. Any further thoughts with this knowledge?

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/138113#Comment_138113

Good Evening @michy81

Will try and remember to take a pic of the benches at work tomorrow so I can explain easier 🙂

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/138113#Comment_138113

Hi @michy81

When soil and water area placed in a container, the soil absorbs the water and usually flows down in all directions. The trapped moisture in the soil now needs to evaporate or get out somehow and it will find every exit available. This includes the porous surface of the poured concrete. When water passes through the wall of the concrete any paint product you have on top of the planter will literally get pushed off. But by sealing the inside walls of your planter moisture can only evaporate through the top and your paint is preserved.

If you need further assistance, please let us know.

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/140451#Comment_140451

Morning @michy81

These are the "concrete" seats or bases for garden beds I was describing.

The fat end is 1/3 to a half of styrofoam in the middle. You save on the amount of concrete needed plus its lighter. (No way could you move these bty, they are heavy!) They made the seats insitu with formwork. and I saw them using styrofoam to fill the voids.

For your instance you could go the same route and have the fat end taller to enclose the garden beds?

01 22-11-2024.jpg

at leats half is styrofoam on the inside.

02 22-11-2024.jpg

Even the short leg had styrofoam within it.

03 22-11-2024.jpg

They have been there for at least 5 years.

Dave

michy81

https://www.workshop.bunnings.com.au/discussion/comment/140451#Comment_140451

Ok this now makes sense. Next couple of questions

what waterproofing membrane do you recommend and

Given the space between the two walls will only be about 25-30 cm wide to maximise space and given I'm only planting mondo on top, how on earth do I apply the waterproofing on the inside of the walls. Some sort of applicator with a long handle?? Can you get waterproofing stuff in a spray form? Wall is going to be about 1.5m high.

Michelle

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/142155#Comment_142155

Hi @michy81,

You can use the Bastion Exterior Waterproof Membrane. An extension pole paint roller would likely be the best applicator tool for your project. The long pole will allow you to get to where the waterproofing is needed.

Please note that you'll need to use the primer since the surface is porous.

I'm not aware of any waterproofers in spray form that would be suitable for your project.

Mitchell

michy81

https://www.workshop.bunnings.com.au/discussion/comment/143367#Comment_143367

Awesome! 😊

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