# Repointing Brick – The Mason You Hire Can Destroy Your House

- Link: https://www.oldhouseguy.com/repointing-brick/
- Published: 2012-08-15T12:54:00-04:00
- Author: Ken Roginski

Repointing brick or stone is not as simple as it sounds.

It is probable that **masonry repair work performed by professional masons can not
only damage, but destroy old homes.**

You the homeowner and are responsible for protecting your home.

You must therefore be knowledgable on this subject and know what to ask.

Read on – this is extremely important. Let the buyer beware!

I feel like I should write all this in caps and bold, but I will refrain.

[⌊brick needs repointing⌉⌊brick needs repointing⌉[

This brick needs to be repointed. Water can enter and freeze and destroy the entire
wall if not repointed.

Your home may have wood shingles, but don’t forget about chimneys and foundation
walls constructed with brick or stone. As time passes, the masonry on old homes 
eventually needs repair. The mortar holding the bricks or stone deteriorates. Cracks
then form, allowing water to enter. If neglected, the freeze and thaw cycle will
cause the bricks or stone to fall out and hit you on the head. To fix this you need
to have your brick or stone Repointed.

Most of the best and well known masons out there may do a great job building a NEW
brick wall, but you should **use extreme caution when hiring them if you own****
an old home.** When working with new brick, there is no problem, only the old brick
and here’s why.

## What is Considered “Old Brick”?

It is really difficult to know how your brick was fired or if your brick is soft
or hard like brick sold today. In the late 1800’s through WWII some brick was fired
similar to today’s hard brick. It depends on where you live and where the brick 
was made.  Just because you live in a city on the east coast does not mean you have
hard brick. You will be taking a dangerous bet with the odds in favor of the brick
being softer. So – **DO NOT TAKE ANY CHANCES! **

**Wheather your brick was made in 1900 or 1940, treat the brick as if it was from
1890! You cannot go wrong!**

## Repointing the Mortar can Severely Damage Brick & Stone!

Repointing brick or stone is a job that eventually needs to be performed to all 
brick and stone and should never be avoided. Repointing is a process where about
1 inch of old mortar is removed and replaced with new mortar. This is a very common
practice and all masons do this. The problem lies in their knowledge of what type
of mortar to use. **Using the wrong type will cause irreversible damage**.

Mortar used today is very strong and hard because it contains a large amount of 
Portland Cement.** Portland Cement is good for certain applications, but it is not
a fix-all** as masons and building supply stores believe. Portland cement is not
bad, it just must be used in the mortar mixture in a lower percentage when working
with certain materials.

## What Causes Portland Cement to Destroy your Brick and Stone.

 * Moisture within a wall needs to escape and evaporate.
 * This moisture must escape through the mortar.
 * If the mortar that is too hard, that moisture is then forced to escape through
   the softer brick or stone.
 * This will result in permanent damage such as cracking and spalling as in the 
   image below.

[⌊repointing brick with hard mortar⌉⌊repointing brick with hard mortar⌉[

Results of  hard mortar or/and a water sealer. Repointing brick with strong hard
mortar does not make a solid structure. Your brick is damaged beyond repair.

**[Photo courtesy of Old House Journal. Here is a link to their article: “The Lowdown on Historic Mortar” ](https://www.oldhouseguy.com/wp-content/uploads/2012/08/ohj-the-low-down-on-historic-mortar.pdf)**

This is a photo of damage caused to bricks from using the wrong type of mortar. 
Using a Water Sealer creates the same  problem. This can also occur with stone.

### For Houses with Brick or Stone Built Before WWII:

**1.**   The important thing to know is the **mortar MUST be softer (in compression
strength) than the brick or stone it surrounds and have greater vapor permeability**.

**2.**   The new mortar must also be **softer than the mortar it is replacing** 
when repointing brick or stone. **This is accomplished by using less Portland Cement
and more Lime and Sand.**

## Mortar Types for Repointing Brick and Stone. What you need to know:

Mortar comes is types. **Type M, S, N, O, K, and L.**

**Type M is the strongest** and hardest and contains the highest percentage of Portland
Cement while Type L has no Portland Cement and is the softest. **Type S, a hard 
mortar is most commonly used.**

**Type O and Type K are recommended for most historic masonry applications**. However,
masons are not aware of this. When hiring a mason, ask them what type they would
recommend and see what they say – that is the test.  Play dumb at first.

When I worked for the NJ Historic Trust, I worked on state grant funded projects
for historic buildings. In most cases a sample of the old mortar was sent out to
be analyzed to create a receipe in order to duplicate the content of lime and sand
used to obtain a perfect color to match the old mortar. One such place is [Limeworks ](https://www.limeworks.us/).

For the homeowner this analysis is your best option.  Another option for the homeowner
is to **scratch the mortar with a steel key**. Do NOT use a key fob. If the key 
is able to make a scratch in the mortar then you know it is soft. In this case an
NHL product – Natural Hydrolic Lime must be used. This basically means that the 
mortar mixture requires a higher lime content to soften it up. Type “O” is a strength
should be safe to use.

If your fingernail can make a scratch mortar you would then need a softer mixture.
This is all quite different from the usual S-Type used for hard brick or stone.

I recommend doing more reading or contacting [Limeworks ](https://www.limeworks.us/).

## Fake shopping

Forget about [Home Depot ](https://doityourselves.com/the-hidden-truth-about-home-depot/)
type stores.  I wanted to ask the pros in the concrete, block, and sand business
that specialize in masonry work.

I recently contacted Clayton Concrete Block & Sand ([www.claytonco.com ](http://www.claytonco.com/))
a very large company in NJ, and told them I had 150 year old brick that needed repointing.
They recommended Type S. I played dumb and asked if it may be too hard for the old
brick and asked if they carry Type O or K. I was told they are not familiar with
those types!!!

I then phoned a different office and Type N was recommended and again this sales
person was not aware of the softer mortar types. **If I depended on the pro’s in
the business for information, and repointed my basement foundation, 10 years later
I may not have a foundation**.   Let the Buyer Beware!

[⌊repointing brick with hard portland cement⌉⌊repointing brick with hard portland
cement⌉[

Repointing brick with mortar harder than the brick. Moisture will escape through
the softer brick damaging it while allowing only the mortar to remain.

## The words of an honest mason

The following was posted in a LinkedIn forum discussion. Too bad those discussion
groups are now gone.

> **How do we make all Masons aware that using Portland cement is ruining our historical
> Masonry! This is as big of a problem as one can possibly be.**
> We see all these historical society groups raising Hell about all different types
> of issues but nothing is said about the masons who go out into our cities everyday
> and open up a bag of Portland Mortar and start packing joints and ruining work
> that is over 100 years old. The question is how do we educate the Masons who don’t
> know anything about Restoration Masonry but call themselves Restoration Masons?
> Forum Reply:
> _“I consider myself to be a Great Mason and I have 28 years of laying Brick and
> just up to 3 weeks ago i had no idea about the damage that i could do to historical
> Masonry if I used Mortar that we use today on masonry that was done before 1933.
> If I would not be the type of person that reads up and researches things before
> i do something’ I could have done the same as all the Masons I see do and been
> using Portland Mortar also._
> _THANK GOD FOR THIS SITE IT SAVED ME FROM POSSIBLY RUINING A PIECE OF HISTORY.”_

I would love to take the credit but the site he references is the LinkedIn forum.

## Painting Brick?

Many people believe that painting brick or applying a water sealant will protect
it. In reality, painting a brick wall can actually cause serious damage. Modern 
paints are engineered to be waterproof and flexible, designed to keep water out 
at all costs. Bricks, however, behave like sponges—they absorb moisture and then
release it as they dry.

When a layer of paint or waterproofing sealant is applied, any water that penetrates
behind that coating becomes trapped within the porous brick. Since the brick can
no longer “breathe” and release moisture, the trapped water eventually forces off
the outer surface of the brick, a process known as spalling. Unlike mortar joints,
which can be repaired by repointing, once the face of a brick has spalled, the entire
unit must be replaced.

If you decide to coat brick, only use a vapor-permeable finish that allows moisture
to escape. A lime wash is a traditional and safe option, especially suitable for
historic homes.

![](/wp-content/uploads/2014/12/icon1.jpg)

**Lime versus Portland Cement** – The Craftsman Blog by Scott Sidler

See what to do based on the age of your house.

[https://thecraftsmanblog.com/lime-mortar-vs-portland-cement/ ](https://thecraftsmanblog.com/lime-mortar-vs-portland-cement/)

![](/wp-content/uploads/2014/12/icon1.jpg)

**Lime versus Portland Cement** This article is from Lime Works

[https://www.limeworks.us/limemortarvsportlandcement/ ](https://www.limeworks.us/limemortarvsportlandcement/)

![](/wp-content/uploads/2014/12/icon1.jpg)

**For much more detailed information and a chart of types of mortar to use for different
applications go to:**

**[Preservation Brief #2 – Repointing Mortar Joints in Historic Masonry Buildings ](http://www.nps.gov/tps/how-to-preserve/briefs/2-repoint-mortar-joints.htm)**

[Preservation Brief #1 – Assessing, Cleaning, & Water-Repellent Treatments for Historic Masonry Buildings. ](https://www.nps.gov/orgs/1739/upload/preservation-brief-01-cleaning-masonry.pdf)

[Preservation Brief #6 – Dangers of Abrasive Cleaning to Historic Buildings. ](https://www.nps.gov/orgs/1739/upload/preservation-brief-06-abrasive-cleaning.pdf)

![](/wp-content/uploads/2014/12/icon1.jpg)

Video of The History of Concrete by The History Guy

[The History of Concrete ](https://youtu.be/rwb8S1SiGCA?si=o4egsSC5aEsuRcPX)

![](/wp-content/uploads/2014/12/icon1.jpg)

**Need Help?**

Contact: [https://www.limeworks.us ](https://limeworks.us/)

These guys are qualified by the state of NJ to work on grant funded projects. You
really can’t get much better than that.

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