Is the brickwork on the outside of your house looking tatty? Rendering might be the solution - we take a look at the steps you need to take to get a professional finish when applying a render to external brickwork.
The first thing to do is prepare the brickwork by brushing off any loose material. Then coat it with PVA. Mix the PVA up with water in a bucket or paint kettle and liberally apply all over the brickwork. Use the brush to flick it into all the nooks and crannies.
As for your render, the mix should really take into account the atmospheric conditions, the type and condition of the background, and the finish you want to achieve. If it's freezing outside, this can have a detrimental effect on the bonding process. The cement packaging should provide a guide proportion of cement, sand and water to use. Before you add the water, add a blob of plasticiser and a drop of water retarder to it and mix well. Don't add too much and make sure it is well mixed into the water. If you don't have a cement mixer, it might be worth renting one from a tool hire company - the work it saves will pay for itself.
Put the sand into the mixer first, then add the cement. If the mixer has a cover, great, otherwise you might want to use something like a dustbin lid or piece of board to cover the front of the mixer to stop dust spilling out as the drum spins. Once the cement and sand are well mixed, start adding the water/plasticiser/retarder a little at a time. Easy does it as you don't want it to come spilling back out everywhere due to the motion of the mixer.
The number of coats required depends on the final thickness of render required. Each coat should be half an inch or maybe three quarters thick.
Don't try and get too much on in one coat, as it will fall right back off the wall. Second and subsequent coats should never be thicker than the preceding coat. If you do need multiple coats, you need to score a key in the surface so the later coats will hold easier. Once the render is beginning to dry, scratch parallel diagonal lines about an inch apart from each other over the surface using your trowel. You can get a fork from your DIY store to make this quicker.
Once the undercoat is dry, coat with PVA as you did for the brickwork before adding the next layer of render. When you are on your final coat, trowel it as smooth as possible, then use a float to smooth the surface over. You may wish to use a slightly finer grain of sand for the finishing coat. One point to bear in mind is that with finer sands there is more danger of shrinkage due to fine sand's higher water absorption. Use a wooden float to carefully smooth the surface. As the render begins to dry if you see any shrinkage cracks, spray with a fine water mist and smooth them back.
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