When it comes to building, formwork is the starting point. Whether you are pouring a residential slab, forming column structures, or constructing a large commercial building, the shuttering material you choose plays a critical role in how smooth your journey is. At the centre of that conversation lies a question many first-time builders and contractors ask: What thickness of waterproof plywood should I use?
It’s a good question. But it’s not the only question that matters.
Because behind that question lies a deeper truth about material behaviour, lifespan, and long-term cost. And unless we understand where waterproof plywood excels and where it silently fails, we will find ourselves repeating the same expensive mistakes on every new site.
This guide walks you through how to choose the right plywood thickness for shuttering and why, in many cases, the answer might not be plywood at all.
Why Thickness Matters in Shuttering Work
Plywood used in concrete shuttering must be strong enough to resist the pressure of wet concrete and flexible enough to be used across varying slab spans, columns, and beams. The thickness of the plywood affects several things:
- Load-bearing strength
- Number of repetitions
- Risk of bending or warping
- Finish quality on the concrete surface
- Ease of handling by workers
Choosing a plywood sheet that is too thin can lead to deflection, poor finish, or even formwork failure. Choosing a sheet that is unnecessarily thick can increase cost and weight without much added value.
Common Waterproof Plywood Thickness Options
In Indian construction, the following thicknesses are most commonly used:
- 12 mm: Most widely used for slabs, beams, and general shuttering. Balanced strength and weight.
- 16 mm: Used for heavier loads or where additional support is not possible.
- 18 mm: Sometimes used for high-load areas or where a longer lifespan is expected.
- 8 mm: Rarely used for concrete shuttering, more suited for low-load interior applications.
If you are using waterproof plywood sheets or moisture proof plywood, 12 mm is the most common choice. But its actual performance depends on the build quality, not just its thickness.
The Challenge with Waterproof Plywood
Let us pause here and ask the next critical question.
What does waterproof mean in the context of plywood?
Most waterproof plywood is simply treated with resin-based adhesives like phenol formaldehyde. The external layers are sometimes coated with a film to resist water. But the core material is still wood.
In real-life construction conditions — where rain, curing water, and rough handling are part of daily site life — the weaknesses quickly emerge.
- Water absorption at edges
Even with sealed sides, once the sheet is cut or worn out, water finds its way in. - Delamination and warping
Repeated wetting and drying cycles cause layers to peel apart or the board to curve. - Short lifespan
Most sheets last 5 to 10 uses at best, especially if they are exposed to water and not stored properly. - Hidden replacement costs
The waterproof plywood price may seem affordable per sheet, but the real cost shows up when sheets are discarded midway through a project, leading to frequent repurchases. - Inconsistent concrete finish
As sheets age, the surface roughens, and the finish of the concrete degrades with every reuse.
Weather Resistant Is Not Water Immune
Another set of terms gets thrown around in procurement: weather resistant plywood, moisture proof plywood, and water resistant plywood sheets.
Each of these phrases sounds promising. But in reality, they all describe varying degrees of vulnerability.
Unless a board is entirely water-impermeable and non-biodegradable, it is only a matter of time before it begins to fail.
This is especially true in regions with long monsoons, humid air, or where construction extends across multiple seasons — in other words, most of India.
What Beginners Should Know Before Choosing Thickness
If you are new to the construction space, especially in shuttering or formwork work, here is what you should know:
- Thicker plywood does not mean waterproof
An 18 mm plywood will still fail prematurely if exposed to water without protection. - Site conditions matter more than catalogue specs
A sheet rated for 10 uses may last only 4 if stored poorly or used on columns with excessive nailing. - Weight increases with thickness
Thicker plywood is harder to transport, lift, and move between shuttering cycles. - No plywood lasts forever
No matter what the supplier promises, plywood is a consumable item — and a high-waste one at that.
So, What Should You Use Instead?
This is where WoWBoards come in.
They are not just another waterproof ply board. They are a new material category altogether.
WoWBoards are made from recycled plastic sheets. Unlike wood, plastic does not absorb water, does not rot, and does not splinter. These boards have been designed specifically to outperform traditional shuttering plywood in all the areas where plywood silently fails.
Here’s how WoWBoards compare:
| Feature | Waterproof Plywood | WoWBoards (Plastic Shuttering) |
| Water resistance | Limited to surface film | 100% waterproof |
| Recommended thickness | 12 mm and above | Available in 8 mm, 12 mm, 16 mm |
| Reuse potential | 5 to 10 times | 50+ times when handled well |
| Concrete surface finish | Degrades over reuse | Consistently smooth finish |
| Storage impact | Highly affected | Can be stored outdoors |
| Sustainability | Wood-based | Made from recycled plastic boards |
| Total lifecycle cost | High (frequent buy) | Lower cost per use over project |
Which Thickness of WoWBoard Should You Choose?
Unlike plywood, where thickness is often chosen to compensate for water damage, WoWBoards offer strength, resilience, and waterproofing across the board. Here’s how to decide:
- 8 mm WoWBoard
Ideal for vertical applications like column shuttering. Lighter and easier to handle. - 12 mm WoWBoard
Perfect for general-purpose slab and beam shuttering. Matches the strength of 12–16 mm plywood but lasts longer. - 16 mm WoWBoard
Recommended for longer spans or higher load areas. Offers robust support without compromise.
WoWMaterials also provides technical guidance on runner spacing based on thickness and application. This ensures you get the structural support you need without overengineering.
Conclusion: Make Thickness Count, Not Cost You
When choosing between waterproof plywood sheets and WoWBoards, the question is no longer just about thickness. It is about longevity, performance, and responsibility.
Yes, plywood may seem familiar and cheap. But if we zoom out, we realise it’s costing us more than money. It costs us forests. It increases site waste. It slows down our timelines with rework and replacements.
WoWBoards represent a new way to build — where formwork materials are not just functional, but future-ready.
They offer clarity in a space filled with marketing jargon. They give your site teams a material they can rely on. And they help you build with purpose, not just plywood.
Ready to explore formwork materials that are strong, waterproof, and built to last? Choose WoWBoards. Because the right thickness is not just about the board. It’s about how long it stands tall.