Complete Guide To Mortar Mixing & Ratios

Estimated reading time: 4 minutes

We’ve written a complete guide to get the best mortar mixing ratios for whatever task you you are undertaking. Some of the common reasons that you may require this guide are if you are:

  • Pointing
  • Laying screed
  • Rendering

Although there could be many more reasons that you are working with mortar.

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Types of Mortar Mixes

When you come to mix your mortar there are several different types that you can choose from. Here is a breakdown of each type and an explanation of what they are:

Type N
It’s typically recommended for exterior and above grade walls which are going to be exposed to extreme weather or temperatures. It’s 1 part portland cement, 1 part lime and 6 pars sand as a mix, which makes a medium strength and is the best choice for general application and is the go to for most homeowners.

Type O
This is a mix that is typically used for interiors or non load bearing walls as it’s relatively low strength. It’s not recommended to use this mix when working on anything external and it’s only really suitable for interior work or patching. It’s ideal for repointing or repairs and is generally easy to apply.

Type S
This is a high strength mix and is suitable for many different projects and is often used for masonry foundations, sewers, retaining walls, brick patios & work that requires significant strength.

Type M
This uses a large amount of Portland cement and is recommended for foundations, retaining walls, driveways. It’s quite poor when it comes to adhesion or sealing properties which makes it sometimes unsuitable for anything exposed to the elements, however it’s often the preferred mix to use for natural stone as it has a similar level of strength.

Type K
It’s an extremely low strength mix that is quite soft in comparison to the others and is just primarily used for restorations such as work on historic or older buildings.

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Cement, Concrete & Mortar, What’s The Difference?

People often get confused as builders refer to mortar, concrete & cement differently, so it can be hard to know exactly what means what, it’s all quite confusing so to help you out, here’s a quick definition of each:

Cement – It’s a powder that is grey in colour and you can often mix it with sand which would make mortar or adding crushed rock and gravel to make concrete.

Concrete – A mix of gravel, sand, crushed rock, cement and water and is typically made extremely thick.

Mortar – Mixture of water, sand, cement but is made much thinner than concrete and is used typically for pointing or bricklaying. Making this too thick would cause cracks.

How To Mix Mortar

Mixing mortar is pretty straight forward & easy to do by yourself, here’s a step by step guide on how:

  1. Get the correct sand and mortar – ensure that you use a fine grade of sharp masonry sand & for the bag of mortar use fresh unopened bags from reputable and trusted brands
  2. For a basic mix, measure three parts sand one part masonry cement
  3. Add in the water – A bag of mortar should be mixed with around 13.5 litres of water, although this can vary
  4. Consider adding lime – This is used to strengthen the stonework & increase the bonding, although this makes the mix dry a lot quicker
  5. Mortar of the perfect consistency should be able to hold on a trowel at 90 degrees but not be too thick that it’s not easy to work

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What Mortar Mix To Use

The best mortar mix depends on the task, unfortunately there’s no straight answer so here’s a few examples of a few common jobs and the best mixes to use:

JobCementSand
Bricklaying14
Chimneys15
External rendering23.5
Floor Screed1
Joints for paving13
Pointing13
Retaining Walls13
Roof tiles13

Keep in mind that these obviously all require water as well, but the amount of water is as specified above, typically 13.5 litres per bag, however that can vary based on different factors so ensure you add it slowly.

How To Get The Right Ratio

There’s no one size fits all as explained above, that being said the trick above is a good way of telling if your mortar mix is fit for purpose.

Mortar of the perfect consistency should be able to hold on a trowel at 90 degrees but not be too thick that it’s not easy to work.

Not Confident? Get A Professional Quote

Is it all just a bit too confusing & you just want someone to do the job for you? If you’re looking to get a quote on a job that involves using mortar then we can put you in touch with a tradesman. You can find a list of jobs & quote forms on our quote page.

FAQs

What happens if the mortar is too weak?
If you’re mortar is too weak it may not bind properly, and even if it does, you will find that it will crumble away after a short period of time. It’s important that you use a mortar mix that is strong enough for the job.

What happens if the mortar is too strong?
If you’re mix is too strong then it will dry very quick, but not only that, if you manage to apply it then the chances are it will crack.

What’s the lowest temperature I can use mortar?
The lowest temperature you can lay mortar is 5 degrees, although you can add frost proofing products, they aren’t always ideal.

Mat

A complete novice trying to navigate in the world of DIY. I bought my first home about 2 years ago & ever since I've been trying to research & learn how best to tackle common household problems.

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