If experienced renderers can produce their own mix on site, why would they ever pay for premixed render? The answer isn’t simply convenience. The right premixed product can cut down the variables, give you a more consistent finish and save valuable time, but only if it suits the background, finish and demands of the job.
You’ve still got to think about the background, the finish you’re trying to achieve, how exposed the building is and whether you’re applying by hand or machine. Every part of the system also needs to work together.
Having used plenty of different renders over the years, these are the main things I’d check before putting an order in.
What do we mean by premixed render?
The term ‘premixed render’ can refer to a dry, factory-blended product supplied in bags. The ingredients have already been measured out, but you’ll still need to mix it with clean water on site. This includes plenty of base coats, one-coat renders and monocouche products.
It can also mean wet, ready-to-use render supplied in buckets, such as acrylic, silicone or siloxane thin coat finishes. Both give you more consistency than mixing separate materials on site, but they’re made for different jobs and aren’t interchangeable.
Start with the background
Before you start comparing brands or colours, look at what you’re actually rendering onto. A product that works well over dense concrete might be completely wrong for lightweight blockwork or a high-suction background without the right preparation.
Before choosing a render, I’d check:
- What the wall is built from
- Whether the background is high or low suction
- Whether it’s stable, clean and properly prepared
- Whether any existing coating or render needs removing
- If you need a primer, bonding coat or base coat
- Whether reinforcement mesh needs to be added
- If the job involves render carrier board or external wall insulation
Manufacturers offer different base coats for different backgrounds, so check the technical data sheet before ordering. The right product will help control suction and improve adhesion, cutting down the risk of cracking or failure later.
Choose the right product and finish
Premixed render covers everything from base coats and monocouche to ready-to-use decorative finishes, so make sure you know the full system build-up before you buy.
Bagged products are commonly used for base coats, traditional float finishes and scraped monocouche. Ready-to-use acrylic, silicone and siloxane renders are generally used as decorative topcoats in thin coat systems.
Silicone is often the go-to where water repellence and breathability are important. Acrylic can give you a durable, flexible finish. That doesn’t mean one is always better than the other. It comes down to the wall, the system and the conditions it’ll be dealing with.
The state of the background matters too. If the elevation needs a lot of dubbing out or levelling, you can’t expect a thin coat finish to hide it. Get the surface right with a suitable base coat first.
You also need to know what finish the customer is expecting. Monocouche gives you that familiar scraped appearance, while thin coat renders tend to produce a more uniform texture. Different grain sizes will change both the look and the coverage, so factor that in when working out quantities and pricing the job.
Even with a factory-produced render, I’d order enough from the same batch wherever possible. Try to complete whole elevations without unnecessary breaks and put up a test panel if the customer wants to approve the colour and texture first. It can save a lot of grief later.
Think about hand or spray application
How you’re applying the render can narrow down the choice.
Plenty of bagged renders can be applied by hand or through a suitable spraying machine. Spraying can make a big difference on larger elevations, but the machine, water setting and mix consistency all need to be right.
Some ready-to-use thin coat renders can be sprayed too, while others are normally applied with a stainless-steel trowel and finished with a plastic float. Don’t assume a product is machine compatible just because something else from the same manufacturer can be sprayed. Check the technical sheet.
Think about the size and layout of the elevation as well. If the product has a limited working time, you’ll need enough hands on the job to keep a wet edge and finish it consistently.
Account for weather and exposure
Premixed doesn’t mean weatherproof while you’re applying it. Every product has its own working temperature range and will need protecting from frost, rain, strong wind and direct sunlight.
Bucket renders need the right conditions to dry properly. High humidity, low temperatures and poor airflow can slow things down considerably. Cement-based renders need controlled curing and can cause problems if they lose moisture too quickly.
The building’s location matters as well. A coastal property, an exposed elevation or a wall surrounded by trees may need better water repellence, breathability or resistance to organic growth.
If the forecast looks doubtful, hold off. Losing a day is better than dealing with washed-out render, patchiness or an uneven finish.
Keep the products within one approved system
Trying to save a few quid by mixing and matching products from different manufacturers can cost more in the long run.
Use compatible primers, base coats, reinforcement mesh and finishing renders from an approved system, especially when you’re working with render carrier boards or external wall insulation. Following the manufacturer’s specification protects the warranty and makes it much easier to get to the bottom of any problems.
Check coverage before comparing prices
Don’t judge the cost of a render by the price on the bag or bucket alone.
Coverage changes depending on the product, grain size, application thickness and condition of the background. A cheaper render isn’t really cheaper if you need more of it or have to spend extra time preparing the wall.
I’d cost the whole system, including:
- Primer or bonding coat
- Base coat
- Reinforcement mesh
- Finishing render
- Beads and trims
- Expected coverage
- Labour and application time
- Allowance for waste
Measure carefully and include a sensible bit extra from the start. Running short can hold up the job and leave you trying to match a different colour batch later.
Selecting the right premixed render
The right premixed render should take variables out of the job, not give you a new set of problems.
Rendit supplies bagged base coats and coloured renders, along with ready-to-use acrylic, silicone and siloxane finishes from leading manufacturers. If you’re not sure which product or complete system to order, speak to the Rendit team for practical advice before you buy.