Hot Dipped Galvanised Steel vs Painted Steel: What Is Best?

Investing in a new shed is always a large decision. A question we get asked often is:

Hot dipped galvanised steel vs painted - what is the right one for me?

In this article, we compare the two and what we recommend for different shed types.

What Is Hot Dip Galvanised Steel?

Hot dip galvanised steel, is steel covered in a zinc coating to protect the steel from corrosion.

The galvanising process involves cleaning the steel and dipping it in a 'bath' of molten zinc solution at temperatures around 450 degrees. The liquid zinc adheres to the metal and when you pull the metal out of the bath the zinc hardens. This results in a really hard outer coating of zinc, protecting the inner steel core from moisture and other corrosion.

Galvanised Farm Shed

Does Galvanized Steel Rust?

Technically yes, however, hot-dipped galvanized steel resists corrosion in numerous environments for much longer than uncoated steel.

Whether it is paint or galvanised steel, any coating is designed to protect the base material. The coating corrodes instead of the core material. Any moisture and corrosive materials (including oxygen in the air) will eat away the coating first before oxidising the metal underneath.

When you have a galvanised coating the zinc will oxodise instead of the metal it is coating.  Zinc oxidises slower than uncoated steel, preserving your sheds structural integrity.

Galvanised Steel Columns

How Does It Compare To Shed Paint?

Paint is the more traditional and cost effective way of protecting your shed against the elements. The steel is sand blasted to clean any mill-scale and to roughen it the surface so the paint will stick. The paint is then sprayed onto the clean steel surface of the metal to provide a protective layer.

The thick zinc rich paint we use providesr a layer of the zinc on the materials surface to further help with corrosion resistance.

However, paint is softer and thickness can vary. This means that the painted coating is susceptible to chips and scratches, exposing the underlying metal to corrosion.

Galvanised vs Painted Steel: A Snaphot

Galvanised

  • Average thickness is 85 µm.
  • Durable, scratch-resistant coating.
  • Galvaising is a more expensive process than painting
  • Galvanising is submerged on molten zinc to ensure complete coverage & protection.
  • Provides cathodic and barrier protection to steel, ensuring longer lasting protection.
  • Greater hardness and corrosion resistance means less maintenance over time.
  • Galvanising is only available in silver

Painted

  • Thickness varies between 64 µm to 90 µm.
  • Generally, not resistant to scratching.
  • Our painting process is factory-controlled to ensure complete coverage & protection.
  • Barrier protection only. When scratches occur, corrosion of underlying steel is limited.
  • An enamel top coat will provide longer lasting protection.
  • Painting provides infinite color choices

Painted Steel Shed

Painting Galvanised Steel: Can It Be Done?

Paint will stick to anything, including galvanised steel. If you are wondering how to paint galvanised steel, it involves a number of steps. Simply put:

  • Firstly, we clean the surface of the metal and leave it to dry. 
  • Galvanised steel has a shiny surface. In order for the paint to stick, a "whip blast" is often used to roughen up the surface.
  • Applying an "Etch" primer will also provide improved paint adhesion to a galvanised surface
  • Finally, the top coat is applied to the structure and set to dry.
Painted Steel Column

What Do We Recommend?

There are advantages and benefits for both painted and galvanised sheds. The choice comes down to you and your needs.

Painting is no doubt the most cost effective coating system we provide. Whist it provides adequate protection many situations there are some applications where galvanising is strongly recommended. These Include:

  • If you live near the coast it is a good idea to use hot-dipped galvanised steel in your building. Salt in the air corrodes things quicker, so extra protection is needed.
  • Animal waste can be corrosive. If you are building a livestock shelter we recommend galvanising to protect your shed from corrosion.
  • If you wash your shed often, and it is regularly wet, we also recommend a galvanised shed to ensure longevity.

If you still have questions about which option is best for you give us a call on 1800 350 450 or contact us today. Our expert shed designers will take the time to understand your needs and offer the best solution for you.