Mortar Types

Interpreting the Differences in Types of Mortar for Home Improvements

There are four main types of mortar that you might consider when making home repairs.  The central mistake that those who don’t have a great deal of experience in construction make is to think that it’s best to get the most durable type of mortar—the kind that can withstand the greatest amount of abuse.  This actually can be a little bit confusing since some weaker types of mortar allow structures to withstand more force because they are not as firm.  Such “weaker” mortars are like rubber bands that bend but don’t break.

Before we go on to consider the types of mortar and their pros and cons, you should know a little bit about exactly what mortar is.  Mortar is a mix of cement and sand.  When you mix in H2O, a chemical process begins which leads the mortar to harden.  Generally speaking, the harder the mortar the more difficult it is to apply properly.

Heat-Resistant Mortar

Also called refractory mortar, contractors employ heat resistant mortar when they have a project that requires the mortar to withstand strong temperatures without melting.  Heat-resistant mortar is the choice when you are rebuilding the wall of a fireplace, for example.  Typically, the mortar incorporates an aluminum substance that makes it able to remain strong even at harsh temperatures.  The main drawback is that it is substantially more expensive than regular mortar.

The Hercules of Mortars: Type M

The strongest of all the types of mortar is Type M.  Contractors opt to use this “Hercules of Mortars” on projects that require the mortar to dry as strong as the stone it is generally used with for added support.  Retaining walls, for example, since they must deal with an even greater share of force than most other constructions, will typically use this kind of mortar.

The main drawback of this type of mortar is that it is difficult to work with, especially for beginners.

Common Mortar

If Type M is the “Hercules of Mortars,” than Type N is the “Average Joe of Mortars.”  It is the most common type of mortar because it scores right down the middle when it comes to its abilities.  It’s not the strongest mortar, but it can hold its own for most projects.  It doesn’t withstand heat but it sets well.  It is much easier to work with than Type M, but not the very easiest.

This is the kind of mortar that most beginners use either because they don’t know the differences between types of mortar.

Outdoor Mortar

Type S is the kind of mortar that contractors use when working on outdoor projects.  Type S is able to resist the damage that rain can cause.  Although it is not as difficult to use as Type M, Type S can cause beginners some problems.  If you are planning an outdoor project, you should probably get someone with some experience doing this sort of thing rather than trying it yourself.


There is a second type of mortar that is used specifically when the builder wants to use glass brick.  This kind of mortar can be painted so that it will closely match the shading of the glass block, thus making it ideal for projects using this kind material.

If you are embarking on a project involving mortar, you will want to be sure to look for help when you need it.  Ask the knowledgeable workers at your hardware store or get your mechanically inclined friends to consult with you.  Construction is best conducted as part of a small group of trusted friends, because this allows you to pick the brains of multiple others before making a foolish decision.  It is always a good idea to have a back up team to help you think things through.