LAST

Proper Masonry Restoration

— many modern-day masonry contractors don't have a clue

 

A stately old brick facade horribly defaced by modern-day masonry "restoration":

Chances are, if you live in Ghent, particularly its oldest section in the vicinity of The Hague, you live in a vintage house that's a hundred years old or so. There's also a good chance your house has old brickwork. And there's a good chance that some, if not all, of that brickwork could stand some much needed maintenance.

 

How your mason can destroy your house

A particularly egregious example of what can go wrong

 

Right Technique

The technique of repointing — removing an outer layer of old mortar from the joints and replacing it with new mortar — remains much the same as always. The main difference is that nowadays most masons use powered grinding wheels to remove the mortar rather than hand chisels. And therein lies much of the problem, because much more aggressive grinding wheels in the hands of inexperienced, careless, or unscrupulous masons more interested in finishing quickly and getting paid than in doing quality work can remove the edges of soft old bricks along with the mortar. This irreparable damage to the bricks (short of replacing those bricks) leaves extra wide joints that ruin the appearance of the brickwork by making the repaired areas stand out like sore thumbs.

Also, old mortar should be removed to the proper depth, and new mortar should be installed in layers for proper curing. Temperature and curing time are very important. Finally, the mortar should be properly tooled to match to match the historic tooling.

Here's an example of bad tooling. The original joints (upper half of photo) were raked (indented), which gives the joints added definition and character, but the repointed joints (lower half of photo) were not similarly raked:

 

Right Mortar Type

The thing is, there's a big difference between old bricks and mortar and new bricks and mortar. Old bricks are much softer and more porous than modern bricks. The same is true of mortars: old lime rich mortars are softer and more porous than modern mortars rich in Portland cement.

A mason may tell you, "Sure, I can fix your problem. I'll just grind out that crumbling old mortar and replace it with some modern, strong, water-tight type N mortar." The mason may then raise a confidently clenched fist to suggest how strong and water-tight that new mortar will be. DO NOT HIRE THIS GUY — unless he first learns a thing or two about proper restoration of old masonry.

Mason apparently using type N mortar on old brickwork of turn-of-the-20th-century house:

Mortar Types

Use the Right Mortar!

Type "O" Mortar for Repointing

A Good Repointing Mortar Consultant and Source

If your mason doesn't use the right type of mortar, don't be surprised if your bricks crack or someday their faces even start breaking off (which is called "spallng" in the masonry trade), thanks to what happens to soft, old, porous bricks during freezing and thawing spells when such bricks are mixed with hard, more water-tight modern mortar.

Examples of spalled bricks:

 

 

Right Color Mortar

The right color mortar for repairs is also essential. If your mason doesn't even bother to match the color of the replacement mortar with the color of the old mortar, tell him to get lost for that reason alone, because mismatched mortar colors also make for a real eyesore. You'll be left with brickwork that looks like it has been badly patched — because that is exactly what you will have. Wrong color mortar joints can even make the color of the bricks they surround look differenct from the other bricks.

Example of mismatched mortar color:

 

Proper Brick Cleaning

Even cleaning up after themselves, masons can damage and/or discolor old brickwork if they use the wrong cleaning agents, tools, and/or technique.

Recommendation for cleaning historic masonry buildings

 

Tip for the Homeowners of Ghent

Before giving a mason the go-ahead to work on your house, have that mason demonstrate his/her technique on a small, out-of-the-way sample of our house's brickwork. Compare how that sample looks with the rest of your brickwork.


So where's the City in all this?

Masonry restoration is the very kind of important architectural consideraton that the Architectural Review Board should concern itself with. Yet, to date, it seems unconcerned. The folks down at the building permits office don't seem able to care less either.

Since most homeowners are completely ignorant about proper masonry restoration, and evgen most modern-day masons seem to be, shouldn't someone in authority finally start looking out for the welfare of our old houses?

In fact, the City of Norfolk Historic District Design Guidelines says the following about masonry (pages 47-48):

Historic masonry materials include brick, stone, terra cotta, cast stone, concrete, and stucco. These materials are some of the most durable building materials, though they can suffer damage from improper maintenance, repair or harsh cleaning techniques. The following are guidelines for masonry:

  1. Preserve and retain the historic masonry material and detailing. Repair materials whenever possible by removing damaged areas and patching them with a material similar in texture, color, composition and strength.

  2. Match infill brick or stone to replicate the adjacent historic material as closely as possible.

  3. The most common work to be done on brick or stone walls is repointing. This should be done with a mortar similar to the original in texture, color, composition and strength. Execution of mortar joints in width, style and profile should match the existing. Caulk or Portland cement (unless it is the original mortar material) are not appropriate for use on historic masonry walls because they are stronger than the historic brick and can cause the brick to crack or spall.

  1. Use the gentlest means possible when cleaning or attempting to remove paint from masonry structures to avoid damaging the masonry. Sandblasting should never be used on historic masonry.

  2. Avoid covering or concealing historic masonry with new materials. In some cases, parging brick foundations is acceptable.

  3. Avoid painting previously unpainted masonry, including brick.

  4. Avoid repairing or replacing historic stucco with a stronger, modern material.

  5. Substitute materials, such as pre-cast concrete as a substitute for concrete, may be appropriate as a replacement material as long as it matches the original stone in color, texture and detail.

  6. It is not appropriate to alter or remove masonry elements from a historic building, such as removing stucco from historic brick, because it alters the appearance and the brick may not be made to withstand the elements.

  7. It is not appropriate to introduce, recreate or alter masonry features that would create a false historical appearance. Sufficient historical documentation, such as photographs or physical evidence, is required to introduce, recreate or alter such features.

 

Great Vintage Masonry Restoration References

An excellent resource website for all things brick

National Park Service Advice

US Heritage Group

(this place also analyzes old mortar for content and color,

and can provide custom replacement mortar)

 

 

Photo examples of bad brick repointing

Unfortunately, if you walk around Ghent, you can spot many more such examples.

 

Bad mortar color match, sloppy tooling, sloppy clean up:

 

The original joints are uniformly narrow. The repointed joints have been ground too wide and are sloppily tooled. Arrows indicate spots where grinding wheel was carelessly allowed to gouge adjacent bricks:

 

Again, poor tooling, no raking, and bad color match:

 

Wrong color mortar and sloppy workmanship for a "standout" job:

 

Need we say more?

 

Horrors! Does it get any worse?

 

This chimney needed repointing — and it never looked the same:

 

The Moses Myers House

Bad masonry repair by the City of Norfolk

The point of historical preservation is to keep historical places looking the way they did.

The Moses Myers house was built in 1792, one of the first brick buildings to be built in the town of Norfolk after its destruction during the Revolutionary War. In other words, the old house is a historic treasure. But the modern-day City of Norfolk doesn't seem to have taken nearly as good care of the place as Moses and the missus did:

 

A small example of bad repointing:

 

A larger example:

 

And another:

 

And another:

 

And mjuch more:

 

 

MowbrayArch.com

 

 

 

 

Last Up Next