What is a sand and cement render with a waterproofing additive?

The article aims to answer the question, “What is a sand and cement render with a waterproofing additive?”. It will also discuss what a renderproof is. Read on to know more:

What is a sand and cement render with a waterproofing additive?

Continue reading the article to know sand and cement renderings with a waterproofing additive.

Plaster replacement after rising damp treatment necessitates the addition of a waterproofing agent to the sand and cement render mixture. At least 14 days after installing a new damp proof course, combine 1 part Brunopel Waterproof Additive with 30 parts water, and use the resulting pink, turbid liquid as the backing coat in a sand/cement ratio of 3:1.

Render mixes should consist of two or three parts clean, sharp sand to one part Portland type A or type GP cement, with one component Bondall Silasec to five parts water added to provide a workable consistency. Cement tends to settle in the water, so you should stir the paint mixture often.

What is rendering?

The rendering process applies a cement mixture to walls (exterior and interior) to alter their appearance (texture or smoothness). It’s a lot like putting up drywall. It is fireproof and waterproof, and it also looks rather lovely. 

The Mediterranean area of Europe is rich in examples, with numerous structures sporting this style. Sand, water, cement, and lime are the common ingredients in most renders. The typical formula for this mixture is six parts sand, one part cement, and one component lime (6:1:1). 

Any cement will suffice; there is no need to use a special kind. It is essential, however, that the sand is of very fine grain and completely pure. Rendering or plaster sand is ideal for this purpose. Typically, coarse sand is utilised for the bottom layer, while somewhat more delicate sand is used for the top. As a result, you may use construction sand as either the first or last layer.

Adding lime helps the mixture retain flexibility and resists breaking as it dries. Hydrated lime is the best kind of lime to utilise while rendering. Pigments that change the colour or adhesives that speed up the drying process are only two examples of what may be used in the rendering mixture.

What is the basic rule for making the ideal renderings?

The basic rule for making the ideal renderings is never to use a rendering mix that is more powerful than the material being produced. For making a concrete block with a strength of 3.6kN, a potent mixture is not necessary. 

Cracking the render is the apparent reason that the wall will shift due to inevitable contraction and expansion. Too much cement may also ruin a render by causing it to dry out too quickly and crumble.

The 6:1:1 ratio is the optimal proportion of ingredients. This ratio should not be exceeded under any circumstances. Since lime can’t be set without the help of cement, the ratio of lime to cement must be kept at precisely 1:1. 

Just the appropriate quantity of lime juice gives the mixture a velvety texture and supple consistency. The use of lime allows the render to self-render and self-cure. So even if the building shifts slightly due to temperature changes, the render will shift somewhat with it, keeping it from cracking. 

The lime may re-calcify somewhat in the cracks where failure has occurred. Many renderers erroneously assume that lime is unnecessary, yet its absence is a common flaw in their work. They often resort to plasticisers, which introduce many air bubbles into the mixture. 

Lime is superior to plasticisers, which are still helpful. Render mix ingredients should be put in a cement mixer to guarantee uniform mixing. It’s best to use a trowel to spread the mixture in even, thin layers. 

Lightly applying a finishing wash or topcoat with a sponge, trowel, or brush may provide an excellent aesthetic result. You can buy ready-mixed goods instead of making your render mix. Acrylic materials make the render very durable and impervious to moisture. 

Its complexity allows it to be utilised on expanded polystyrene and other similarly challenging surfaces. These acrylic renderings cure in a day or two at most. However, conventional renders might take up to a month to dry.

Silicone-enhanced rendering is a contemporary render that combines the benefits of both conventional and acrylic rendering. Like acrylic render, it is water resistant, but unlike acrylic render, it allows air to circulate through the structure. 

This makes it more resistant to breaking than average. Typically, the silicone-enhanced render will last for more than 25 years. Colour options aside, its characteristics make it the de facto standard in the rendering industry.

What is renderproof?

Renderproof is an alkaline soap formulated with fatty acids; Renderproof is an ingredient used in sand/cement and exterior render coatings after a chemical DPC has been inserted. After a chemical DPC, efflorescent salts are often left behind in the wall, damaging the plaster surface and giving the impression of wet areas. 

This means that a salt inhibiting and waterproofing solution like NO MORE DAMP Renderproof should be employed as part of the replastering specification. One way is to reduce the amount of liquid water that may penetrate cement, rendering’ its porous nature.

RenderProof helps keep salts from being deposited on the top. Whenever feasible, the drywall should be allowed to cure to the touch before re-plastering begins. A drying interval of at least 14 days should be provided between installation and re-plastering. 

After installing a damp proofing course like Ultracure or Siliconate K, you may then use Renderproof in your exterior render coatings.

What is sand and cement rendering?

Sand and cement renders are typically made by combining sand, cement, and hydrated lime at a 6 to 1. Lime is added to the mix to give it flexibility and avoid cracking and breaking once it dries (or is cured). 

A mixture that is too moist will flow, while one that is too dry will be difficult to deal with. Small additions of water brought the mixture to the perfect consistency. Some arguments claim it doesn’t matter much what kind of cement or sand you use in the mixture. 

This, however, will change the overall appearance and feel of the combination and its durability and efficacy. In most cases, building sand is inappropriate since it shrinks and cracks. Use sharp sand, rendering or plastering sand, in its place. 

It’s possible that, at this point, a waterproofing agent might be helpful. This is important for rendering big areas since it boosts the protection offered by the dry render and increases the render mix’s working duration. Lime may be substituted with a mortar plasticiser. However, this is a matter of taste. 

Both help the mixture perform better, but lime is often preferred since it breathes with the structure, moves with the building, and fills in any little gaps that may develop. Concerning cement, it is generally acknowledged that any general-purpose brand sold by construction supply stores may be utilized. Obviously, the higher the quality, the better the outcome.

Conclusion

Always include lime in your rendering mixture. In addition to lime, it may include goods capable of the same or similar tasks.

Ensure the ratio of your render mix is appropriate for the material being produced. It’s essential to remember that even after a wall has been rendered, it may need some upkeep.

Frequently asked questions (FAQS): What is a sand and cement render with a waterproofing additive?

What is a sand and cement render with a waterproofing additive?

Plaster replacement after rising damp treatment necessitates the addition of a waterproofing agent to the sand and cement render mixture. At least 14 days after installing a new damp proof course, combine 1 part Brunopel Waterproof Additive with 30 parts water, and use the resulting pink, turbid liquid as the backing coat in a sand/cement ratio of 3:1.

What is renderproof?

Renderproof is an alkaline soap formulated with fatty acids; Renderproof is an ingredient used in sand/cement and exterior render coatings after a chemical DPC has been inserted. After a chemical DPC, efflorescent salts are often left behind in the wall, damaging the plaster surface and giving the impression of wet areas. 

This means that a salt inhibiting and waterproofing solution like NO MORE DAMP Renderproof should be employed as part of the replastering specification. One way is to reduce the amount of liquid water that may penetrate cement, rendering’ its porous nature.

Bibliography

Waterproofing additive for use in sand and cement renders. Retrieved from: https://www.twistfix.co.uk/water-proofing-additive#:~:text=A%20waterproof%20additive%20for%20use,the%20new%20damp%20proof%20course.

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