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Setting a letterbox post

Read the installation instructions provided by the letterbox manufacturer and then follow these simple steps to use the recommended concrete product to install your new letterbox.

Tools you will need:

  • Spirit level 
  • Tape measure 
  • Post shovel or long handled shovel
  • Measuring jug
  • Hose or bucket
  • Rod for tamping

Materials you will need:

  • Bags of Rapid Set Concrete 20kg
  • Letterbox & post
  • Drainage material: gravel 
  • Clean water

 

 


Recommended products

Although you can use any product from the Cement Australia concrete range, we recommend Rapid Set Concrete for ease & speed.

If you want to render a letterbox, we recommend our new PRO-Mix render.

Rapid Set Concrete

Hardens within 15 minutes, ideal for use where the surface won't be left visible

Before you get started

  • Read the Hints & Tips section
  • Use our simple Calculator to work out how much Rapid Set Concrete you will need for the project.
  • Ensure there are no pipes or services below the ground; contact Dial Before You Dig on 1100 or via their website www.1100.com.au for advice on the locations of submerged pipes and cables.
    get advice from Dial Before You Dig on the location of cables or pipes on your property
  • Rapid Set Concrete will harden in 15 minutes or even faster on a hot day. Be prepared to complete your project quickly. Take the time to read these instructions carefully before getting started.
  • Check with Australia Post for any particular restrictions on where you can place a letterbox on your property.

 

Safety

Before you begin any project, please ensure you protect yourself with the following:

Look after yourself properly

  • Protect your skin and eyes.  Cement based products are alkaline and can cause burns to exposed skin or eyes.
  • When working outdoors, be SunSmart - Slip on some sun-protective clothing – Slop on sunscreen - Slap on a hat - Seek shade - Slide on some sunglasses.
  • All 20kg bags of cement products require 2 people to lift them safely. Always follow safe lifting procedures to avoid injury.  So you will need a friend to help you handle the 20kg bags and to assist with holding the letterbox post whilst you add the Rapid Set Concrete.

How to set a post in the ground to hold a letterbox

STEP 1: DIG THE HOLE(S)
Replacing an existing letterbox?  Dig out the current letterbox post and dispose of correctly.

If you’re putting your letterbox in a new location, use a post hole digger or long handled shovel to dig your post hole(s) adding 10cm depth to allow for gravel to be placed under the post for drainage.  Aim for the letterbox opening to be between 900 mm and 1200 mm above the ground.

Refer to our simple Calculator to work out how much concrete product you will need.

STEP 2: SOAK THE HOLE(S)
Pre-soak the hole thoroughly with clean water and allow the water to drain into the soil.

STEP 3: POSITION THE LETTERBOX POST
Place 10cm of gravel in the hole for drainage. Position your letterbox post in the centre of the hole, ensuring that it is vertical using a spirit level.  Ask your friend to hold the letterbox post steady in position.

STEP 4: ADD WATER & HALF THE RAPID SET CONCRETE
Accurately measure 2.5 litres of clean water per 20kg bag and add the water to the hole. Immediately pour in half the bag of Rapid Set Concrete making sure that it is evenly distributed around the post.

Watch this video to see how it’s done.

STEP 5: TAMP WELL & ADD THE REST
Tamp the product around the post using a rod to remove any air pockets. Add the remaining half bag of product and tamp again.  Add small amounts of water only if required to ensure that the mix is completely moistened.  Should you need more concrete for the hole, immediately repeat the process with another bag.

Tip: Tamping is essential to remove air pockets and achieves a solidly set letterbox every time.

STEP 6: SLOPE THE SURFACE
Heap the surface of the concrete to create a rounded crown around the letterbox post so any surface water flows away from the post.  Cover the concrete surface with earth or a decorative gravel for a tidy finish.

STEP 7: ATTACH THE LETTERBOX
Wait for 24 hours for the concrete to harden before attaching the letterbox to the post.

 

Hints & tips

  • If the post is made of aluminium or steel, make sure that it has been properly sealed before setting it into the ground using any concrete product.  Concrete contains cement which is an alkaline substance and can cause corrosion to uncoated metals.