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DIY Ideas — How to install a letterbox

This month’s featured DIY idea focuses on the perfect addition to a front wall or front fence; the humble letterbox! Read on to find out how to install a letterbox  into your very own modular wall.

Customise Your Wall | ModularWalls

Choosing the right letterbox

Our wall systems accept a large range of letterboxes; you have the choice of ordering a ModularWalls letterbox (pictured above), or sourcing one on your own.

The ModularWalls letterbox includes a front finish of brushed stainless steel, while the back is galvanised and powder-coated to withstand whatever the elements throw at it.

However, if sourcing your own letterbox, just be certain that you’re buying one with durable, high quality materials; as an outdoor product, it needs to stand the test of time. Basically, you get what you pay for!

DIY Ideas — How To Install a Letterbox | ModularWalls

How to install a letterbox into the post

If you’re installing an EstateWall or VogueWall, these wall styles can easily accept a letterbox within their robust post dimensions.

 

Tools you’ll need:

  • Tape measure
  • Builder’s square
  • Pencil
  • Masking tape
  • Angle grinder with 1mm metal cutting blade
  • Caulking gun with polyurethane sealant (i.e. FLEXIT or Sikaflex PRO)
  • Broom/mop (optional: drying prop)

DIY Ideas — How To Install a Letterbox | ModularWalls

Step 1: Mark out position of letterbox on post

Measure the height you wish your letterbox to be and mark out the size of the hole to be cut. Always allow your hole to be a few millimetres larger than the letterbox; being too tight will only cause alignment issues and possible paint-scuffing when you slip the letterbox into place later on.

If you’re unsure of the correct height your letterbox needs to be, you can either call your local post office for their regulations or walk up your street and measure your fellow neighbours!

 

Step 2: Cutting the hole

Using use appropriate guards and personal protective equipment, take an angle grinder with a 1mm metal cutting blade and cut out the hole for the letterbox.

Next, you must test fit the letterbox. Firstly, remove all sharp edges made by cutting. If the rear housing of your letterbox is painted or powder- coated, further protect it from possible scratching with masking tape (or similar). When test fitting, you should be able to get it in with minimal resistance. If it doesn’t fit, don’t push it!

DIY Ideas — How To Install a Letterbox | ModularWalls

Step 3: Securing the letterbox in place

Most letterboxes will have a larger ‘face’ flange at the front. Apply a bead of polyurethane sealant (i.e. FLEXIT or Sikaflex PRO) around this front internal flange of the letterbox and slip it into place, removing any excess immediately.

The letterbox will need to be held in position while the sealant is drying. We recommend either using masking tape or a ‘prop’ between the letterbox and the ground; a broom or mop makes an ideal prop.

Once installed, apply a bead (very neatly) around the rear edges; this will act as a waterproof seal, as well as an adhesive. Note that the sealant you apply around the rear of the letterbox will be visible; if you haven’t painted your post yet, be sure that the sealant you are applying is ‘paintable’. If this is not the case with your sealant, apply it sparingly after you have painted.

DIY Ideas — How To Install a Letterbox | ModularWalls

Installing a letterbox into the fence panel

If you’re installing a SlimWall or TrendWall, you are still able to incorporate a letterbox into the design!

 

Tools you’ll need:

  • Tape measure
  • Builder’s square
  • Pencil
  • Masking tape
  • Angle grinder with diamond tip blade
  • Knife or hack saw blade
  • Shim
  • Caulking gun with polyurethane sealant (i.e. FLEXIT or Sikaflex PRO)
  • Broom/mop (optional: drying prop)

Step 1: Mark out position of letterbox on panel

Mark out the letterbox position on the panel. It is usual for the letterbox to be thicker than the wall panel; it will simply need flashing around or sealing on the back side of the panel.

DIY Ideas — How To Install a Letterbox | ModularWalls

Step 2: Cutting the panel

Using a drill, drill through the four corners of the hole, so it goes right through the panel; it should leave four holes on the uncut side of the panel, too. This will give you a perfect template for cutting your hole on the other side of the panel.

Now, using an angle grinder with a diamond tip blade, cut through the fibre cement sheeting on both sides of the panel.

Finally, using a knife or a hack saw blade, cut the core of the panel away and push it out. Test fit the letterbox and adjust the hole size until you are happy with the fit.

 

Step 3: Securing the letterbox in place

As above, secure the letterbox in place by applying a bead of polyurethane sealant (i.e. FLEXIT or Sikaflex PRO) around the front flange of the letterbox, removing any excess immediately after slipping it into place.

On the back side of the letterbox (if required), shim the letterbox under or on top of the panel to get it level and further seal around the outside (between the letterbox and the panel).

Using a prop, allow the sealant to dry. If you are installing a large letterbox, you may need to install additional support on the back side of the letterbox; this will be your call!

DIY Ideas — How To Install a Letterbox | ModularWalls

Download & print our Letterbox Installation Guide

If you’d like to print these instructions off for your install day, you can download the PDF version of out Letterbox Installation Guide here.

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Written by Evelyn Kandris

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