This week's question comes from a customer looking to create an outdoor concrete table with a sage green colour. This is a fantastic project, but there are a few key considerations when working with concrete for outdoor use, including choosing the right construction method, ensuring proper support, and protecting it from the elements.
Two Approaches: Cast-In-Place vs. Precast
When making a concrete table, you have two primary methods to consider: Cast-In-Place and Precast. Each has its own advantages and is suited to different project needs.
1. Cast-In-Place
This method involves building the tabletop directly on-site. It’s a great choice if you want a seamless fit and don’t want to move a heavy slab after it’s cured. The process typically involves:
- Constructing a sturdy formwork on top of your chosen base.
- Mixing and pouring the concrete in place.
- Smoothing and finishing the surface while the concrete is still wet.
Pros:
- No need to transport a heavy slab.
- Can be tailored exactly to the outdoor space.
- Less risk of damage from moving the tabletop.
Cons:
- Requires on-site work and precise formwork setup.
- More difficult to achieve a high-polish or detailed finish compared to precast.
Here is a link to our Cast-In-Place Mix.
2. Precast Concrete
With this method, the tabletop is cast in a controlled environment (such as a garage or workshop) and then moved to its final location after curing.
Pros:
- Easier to control the finish and colour consistency.
- Less mess and disruption in the outdoor space.
- Can be made in ideal conditions for better curing.
Cons:
- Requires moving a heavy slab into place.
- Must ensure it fits the base exactly.
Here is a link to our Precast Concrete - GFRC Worktop Mix.
Supporting Your Concrete Tabletop
Concrete is incredibly strong, but over time, unsupported slabs can bend and sag, especially when exposed to outdoor conditions. A well-designed base is crucial for longevity. Here are a few key considerations:
- Opt for a sturdy base – A metal or solid wood frame with multiple support points will distribute weight evenly.
- Avoid long spans without support – If the table is large, consider adding a centre support beam.
- Use reinforced concrete – Our Concrete Lab mix doesn’t require vibration and is already reinforced with glass fibres, but adding further reinforcement (such as fibreglass bars) will further prevent sagging.
Outdoor Durability: Protecting Your Table from the Elements
Since this table will be outdoors, it needs to withstand rain, sun, snow, and temperature fluctuations. Here’s how to ensure longevity:
- Thickness Matters – The concrete tabletop should be at least 30mm thick to withstand seasonal stress without cracking.
- Seal the Surface – Using a high-quality concrete sealer such as the one we sell will protect against moisture, UV exposure, and staining.
- Winter Storage or Covering – If possible, store the table during winter months or at least use a protective cover to minimize exposure to extreme weather.
Achieving a Sage Green Colour
For a sage green finish, there are two primary options:
- Pigmented Concrete Mix – Using a high-quality pigment in the mix ensures the colour is consistent throughout. We offer a range of concrete pigments, including green tones that can achieve the sage look. Sage is coming soon!
- Concrete Stains or Dyes – Applying a penetrating stain after curing can enhance the surface while allowing some of the concrete’s natural variations to show through.
Final Thoughts
Creating an outdoor concrete table is a rewarding project that, when done right, can last for years. Whether you choose Cast-In-Place or Precast, ensuring proper support and weather protection will make all the difference. And with the right pigment or stain, you can achieve the perfect sage green finish for your outdoor space!
Need help selecting the right products? Get in touch, and we’ll guide you through the best materials for your project or use our handy calculators to work out what you need.