Tag Archives: cement

Repointing mortar or External Wall Insulation: Which do I need?

Mortar refers to the substance that ‘glues’ bricks together and helps to protect walls from water ingress and heat loss. It has a long and successful history, with the earliest record from Israel which is thought to date back as far as 10,000 years, and many other examples of age-old mortar still exist today. For instance, if your house was built pre-1930, it’s likely that it was built with lime mortar; alternatively, if your house is a new build, it was probably built with Portland cement. Needless to say, mortar can eventually begin to crack, meaning it needs to be either ‘repointed’ – that is, filled in or repaired – or you should have external wall insulation installed on your home.

Here at EWI Store, we’re often asked lots of questions about mortar, with the most common being “what is mortar made of?”, “is mortar the same as cement?” and “is mortar waterproof?”. In today’s blog, we’re going to answer all these questions by explaining how mortar is made, the main types of mortar and how to tell whether it’s time to repoint your property or have external wall insulation installed.

What is mortar made of?

Mortar is comprised of materials such as cement, sand and water, and sometimes lime, to create a high-quality substance to seal bricks together. It is either mixed on-site using a concrete mixer or manufactured in a factory off-site by expert suppliers.

What’s the difference between lime mortar and Portland cement?

Lime mortar is generally produced by burning calcium-based raw materials; in the UK and Ireland, chalk and limestone are most commonly used. When these materials are heated to about 850oC, the heat removes the carbon dioxide, leaving calcium oxide or ‘quicklime’. The quicklime is then submerged into the water for weeks or months to create a lime putty, or ‘slaked lime’, which is then mixed with sand and water to create the lime mortar.

Portland cement was invented around the 1820s by heating limestone with clay, mixing it to create a slurry, then heating it again. This formula achieved quick drying times, which helped it gain its commercial recognition and become the favoured additive to residential and commercial lime mortars.

Is mortar the same as cement?

Understandably, the name “Portland cement” can cause confusion in that it sounds like… well, cement. However, cement is a binding powder that is never used alone; it is a component of both concrete and mortar, as well as tile grout and thin-set adhesive. Therefore, cement is an element of mortar, so mortar and cement are not synonymous with one another. To break it down even further, here are the differences between cement, concrete and mortar:

Cement:

  • Binding component of both concrete and mortar
  • Comprises limestone, clay, shells and silica sand
  • Hardens and gains strength when mixed with water

Concrete:

  • Used for building foundations, slabs and masonry
  • Comprises cement, sand and gravel
  • Forms into a flexible mould

Mortar:

  • Substance that ‘glues’ bricks and blocks together
  • Comprises sand, cement, water and sometimes limestone
  • Not used as a sole building material

Is mortar waterproof?

When rain comes into contact with exposed walls, the water can freeze in the bricks and the surrounding mortar which expands the mortar, thereby causing damage. Not only does this freeze-thaw weathering look unappealing but, the longer it’s ignored, the more likely it’ll lead to a cold and damp house. Therefore, if you can see cracks in your mortar, you might want to consider repointing your property.

How much does repointing mortar cost?

Repointing generally costs between £20-£40 per metre squared depending on the condition of the brickwork. In addition, scaffolding may add to the cost. Working out the square meterage of your external walls is easy: you just need to go outside and measure the length and height of the wall, then multiply the two numbers together.

The alternative to repointing mortar: External wall insulation

If you’re considering investing in repointing, it would be extremely worthwhile to go that bit further and consider having external wall insulation installed onto your home. Both external wall insulation and thin-coat renders will provide a weather-tight seal on your external walls, as well as enhance their appearance, increase thermal qualities and reduce energy costs. It might be more expensive but think of all the long-term benefits! If your property is a cavity wall property, learn more about why you should have external wall insulation installed on your cavity walls here.

Is mortar needed in External Wall Insulation?

If your property has uneven substrates and you’re considering having external wall insulation installed, Levelling Mortar is the perfect product for preparing an even substrate before applying an external wall insulation system. Levelling Mortar is a polymer-modified sand and cement mixture which can be used for repairing and filling cavities and walls, making for an easy installation and application of external wall insulation and render. Read more about the stages of an external wall insulation system here.

We hope this blog was useful in clarifying the purpose of mortar, the difference between lime mortar and Portland cement, the permeability of mortar and whether you need to repoint your mortar or go for external wall insulation. If you have any questions, do not hesitate to comment below or ask our lovely Sales Associates!

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Installing External Wall Insulation

Want to spruce up the look of your property? Fed up with the temperature fluctuating in your home? Looking for a way to cut those energy bills? Then, look no further than external wall insulation. The EWI Store team are here to answer all your unanswered questions about external wall insulation and render solutions; find our contact details here to get in touch.

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Sand and Cement, Monocouche and Silicone Render: Which is best?

Of the 28 million properties in the UK, a large proportion are rendered, or at least coated, with some form of protection like pebbledash. However, while pebbledash was vastly popular pre-1930, this aesthetic is now largely considered outdated, making render the go-to for creating a clean, modern look. In this blog, we investigate why render is so popular and the best products to create an incredible finish on your property or home.

 

Originally, UK properties were built with either brick or block. Over time, however, the mortar fusing the bricks together would break down due to natural weathering. Replacing the damaged mortar – known as re-pointing – is incredibly time consuming and, as such, very expensive. Therefore, a feasible alternative to re-pointing a property is to apply render. Render acts as a protective layer for a property; not only does it disguise the existing damaged mortar, but it provides a new facade for the brickwork, offering a clean, modern finish.

 

Traditionally, sand and cement render – typically six parts sand, one part cement and one part lime – was applied to the surface of a property. This render would be applied at a thickness of about 20mm and be coated with paint to complete the aesthetic. As with mortar however, the issue with these traditional renders was that, over time, they would crack due to the natural movements of the buildings by season, expanding in the summer months and shrinking in the winter months. While the addition of lime was intended to provide flexibility to adapt to such movements, the render was still not flexible enough to withstand these movements, causing hairline cracks. Such cracks cause further issues as they would provide an entry point for water to travel behind the render system and, as such, cause it to come away from the wall.

 

In the 90s, several manufacturers introduced a render known as “monocouche”, French meaning “one coat”. Monocouche render is easier to use than sand and cement render as it is premixed, typically four parts sand and one part cement with various other additives; all you need to do is add water. It is applied at a similar thickness to sand and cement render however, once applied, it is scraped to provide a chalkier finish. Monocouche render always uses white Portland cement as the binder; the white base allows for the manufacturer to add a coloured pigment to the render, meaning it does not require paint on top. As such, monocouche became increasingly popular in the 2000s, becoming the go-to product for those looking to render their properties.

 

Again, monocouche render ultimately comes with its downfalls. Firstly, as with sand and cement render, the thickness of monocouche render means that it cannot withstand the seasonal structural movements of the building, therefore causing cracks which again create an entry point for water. Secondly, while monocouche looks fantastic on application, it becomes a hot bed for algae growth as it encounters water. The biological growth on the monocouche can quickly lead to discolouring so, while it initially looks great, it quickly starts to look messy and requires a lick of paint to keep it looking fresh.

Then, in early 2000 came silicone renders – sometimes referred to as thin-coat renders – from Eastern Europe. Silicone render fundamentally differed from sand and cement render and ultimately replaced monocouche render. As opposed to a 20mm-thick render, the silicone render maxed out at 7mm and consisted of two main layers: a 4-6mm cementitious basecoat with embedded fibreglass mesh, and a silicone render topcoat typically at 1.5mm thick, although 0.5mm, 1mm, 2mm and 3mm grain sizes are also available. The fibreglass mesh in the basecoat is vital; it provides the render system the ability to flex with and absorb a building’s natural movements, making it crack-resistant – the defining factor and main benefit of silicone render.

 

Much like paint, silicone renders can also be tinted to any colour, providing infinite design options to apply to your property or home. Monocouche renders do come in various colours however, since pigments need to be added in the factory, they are very limited. So, if you need to match a specific colour – for instance, RAL-7016 anthracite grey – then silicone render is the obvious choice as it can quickly be tinted to match the required colour.

 

What’s more, silicone renders are hydrophobic, meaning that they possess self-cleaning properties which repel water. This means that, whenever it rains, the rain carries away any dirt particles from the render system, so the facade stays cleaner for longer. The EWI Pro Premium Bio Silicone render also has added slow-release biocides within the render, helping to prevent biological growth, which is especially useful if the render is being applied in areas of high vegetation.

 

Finally, unlike sand and cement and monocouche renders, silicone renders are lightweight, meaning that they are ideal to use in conjunction with external wall insulation systems. The weight of sand and cement and monocouche renders can pull the face of the insulation away and are therefore not recommended to be applied on top of insulation materials.

 

As this blog has established, render technology has changed significantly over the last 30 years. Whether you have a property that has existing damaged render that needs an upgrade, or even a new build like an ICF or a timeframe building on which you desire an advanced render system, then look no further than silicone render. With a silicone render system, you can rest assured that the facade will not crack over time and will likely stay much cleaner than either sand and cement or monocouche render, therefore providing a render system that will last for years to come.