How to render blueboard or fibre cement sheeting
Follow these simple step-by-step instructions to use Cement Australia Render It™ Multisurface to render blueboard or fibre cement sheeting.
Tools you will need:
- Metal trowel
- Plasterers hawk
- Wooden trowel
- Polystyrene float
- Tape measure
- Soft brush
- Measuring jug
- Masking tape
- Access to clean water
Tip: If multiple batches of render are required to complete your job, it is worthwhile considering using a heavy duty drill and stirring attachment to make mixing easier and more consistent across batches.
Materials you will need:
- Bags of Render It™ Multisurface - Grey or use Off White if you'd like to add an oxide colour to your render
- Cement Australia Oxide
(if you are colouring your render)
- Black plastic sheeting
- 50mm fibreglass tape
- Moulded corner beading
- Suitable adhesive
For an easy-to-use, one part render mix we recommend Cement Australia Render It™ Multisurface Grey or Off White.
Use on many surfaces, cure for 7 days before painting with water based paint
Before you get started
- Read the Hints & Tips section
- Plan to complete your rendering project in the early morning before the surface to be rendered is in full sun.
- Coverage: One 20kg bag of Render It™ will cover approximately 2.5 square metres at 5mm thickness.
- Use our simple Calculator to work out how much Render It™ product you will need for your project.
- Render It™ is suitable for both interior and exterior application.
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. You will need a friend to help you handle the 20kg bags and they can assist you in mixing the render and keeping the surface to be coated moist.
How to render a blueboard or fibre cement sheet with Render It™ Multisurface
Step 1: Preparing the surface to be rendered
To protect the area from spilt render, cover paths or driveways with black plastic sheets and mask any other exposed surfaces you wish to keep clean.
Fix the corner beading to the external corners of the surface to be rendered using an approved adhesive ensuring it is straight and plumb to provide a neat rendered finish.
When rendering blueboard surfaces use a 50mm fibreglass self adhesive tape to help prevent cracking and crazing in the joints between the sheets and other abutting structures. The tape is embedded in the joint ensuring that it does not bulge and a thin coating of render is plastered over it to the thickness of the recessed edges. This ensures a flush finish to accommodate subsequent applications of render.
Tip: You can use Render It™ to attach the beading to the external corner if you don't have an approved adhesive available. Apply a small amount of render to the inside of the beading, press it firmly to the corner and clean off the excess render that is squeezed out.
Step 2: Mixing the render
Only mix one bag of Render It™ at a time.
Add 4 litres of clean water to a wheelbarrow and slowly pour one bag of render into the water. Mix thoroughly ensuring that the render is lump free and is stiff so that it will sit on a trowel. Allow the mix to stand for 5 minutes so that the polymer chemicals are activated and then quickly stir the mix again. Render It™ needs to be applied within 30 minutes of final mixing and any spilt render should be discarded.
Tip: A heavy duty drill mixer is recommended for large rendering jobs providing a more consistent mix, where manual mixing in a bucket or wheelbarrow is suitable for smaller projects.
Step 3: Applying the render
Start at the bottom of the surface to be rendered and apply the render with a steel trowel in an upward pushing motion from left to right keeping an even flat finish. Ensure that you use long, even spreads upward and across the surface achieving a consistent and even thickness as you go. Fill any holes or divots with the render as you go. Do not overwork the surface as too much fine material will be brought to the surface increasing the likelihood of crazing (fine cracking). Float the surface in a circular motion ensuring that you do not drag or dig into the surface in achieving the desired finish.
Render It™ can be applied in a thickness ranging from 2mm to 10mm in a single application. If subsequent coats of render are to be applied, the surface should be raked or scratched within 30 minutes of application to provide a rough surface for the next coat to adhere to. A minimum of 3 days must be left between coats to allow the render to develop maximum strength and prevent shrinkage cracks.
Step 4: Finishing the rendered surface
Allow the the final layer of render to become firm and finish off with a wooden trowel or polystyrene float to smooth and finish the surface to the desired texture.
To achieve a different texture a damp sponge can be used to provide a swirl or use a fine brush to provide a swept finish ensuring that not too much pressure is applied to the rendered surface.
Tip: If these techniques are not giving you the definition you want in your finish, wait until the render becomes firmer and finish the surface again.
Step 5: Painting the render
The rendered surfaced can be painted with water based paints after 14 days or after a minimum of 28 days where oil based paints are used.
Hints & tips
- To ensure a professional finish it is recommended to place moulded strips (called beads) on the corners of the surface to be rendered. These strips are available from any leading hardware store.
- In warm conditions when the render begins to stiffen, it is suggested to mist spray the applied render to maintain its finishability.
- Rendering a large surface requires a high level of skill and we recommend that you call in the professionals if you are not an experienced renderer.
- Never wet blueboard prior to the application of Render It™ Multisurface as the coating will not adhere properly.