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Keeping stone in place

Repairing mortar is not dificult, but experts say it's not as easy as it seems

Repairing mortar is not dificult, but experts say it's not as easy as it seems

May 23, 2004|by ANDREA ROWLAND

andrear@herald-mail.com

Over time, homes and walls constructed of brick and stone can develop cracks, holes, crumbling mortar, or uneven areas of mortar from settling or foundation problems. A process called tuck-pointing to repair cracked mortar is needed to keep air and water from leaking through gaps between brick and mortar, according to the DoItYourself.com Web site.

Tuck-pointing is typically needed when 25 to 30 years worth of exposure causes mortar joints to crack, flake or disintegrate. While homeowners with the right materials and know-how might be able to do the repair work themselves, it usually takes the skill of experienced professionals to use the proper mortar mix and tools to match existing mortar, said Paul Creek, masonry instructor at James Rumsey Technical Institute in Martinsburg, W.Va.

"It's very difficult for someone without some experience in mortar and mortar mixing," he said.

Mortar is a tricky material. There are different kinds of mortars and cements, and it's common for amateur masons to purchase the wrong type for the job at hand, Creek said. Mixed mortar also must be used before it hardens - generally within about a half-hour - but rushing through the job usually yields sloppy results, he said.

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"You really have to take the time to prepare for what you're going to do," Creek said.

That means first taking a beginning masonry class, attending a do-it-yourself masonry workshop, such as those sometimes offered through large home improvement retailers, reading books about masonry or watching a masonry repair videotape, Creek said.

And mixing mortar takes practice. It often isn't enough to simply follow the instructions on the mortar bag, he said. For example, mortar sets much faster in warmer weather, and can only be re-mixed with water twice before it loses its strength, Creek said. He said it's a good idea for beginners to mix smaller batches of mortar so less is wasted.

"Mixing mortar is the hardest element because there are different variables involved," Creek said. "If you get that down pretty good, a homeowner could do it a pretty decent job - if you're not in a hurry."

Proper preparation of the surface to be repaired is essential. The old mortar must be raked out to a depth of at least one inch, "or there's a good chance the new work won't hold for long," Creek said. The raked-out joints must then be swept clean before applying new mortar, he said. Creek added that brick walls must be dampened before new mortar is added so the brick doesn't suck the moisture out of the mortar.

"If it dries out too fast, it just won't stick," he said.

Professional masons should be contacted for difficult or unusual jobs, Creek said. Professionals should just about always be called upon to tackle masonry repairs in historical buildings to avoid irreparable damage during re-pointing and in the future. Modern hard cement mortar often cannot be used in older buildings because applying modern mortar over old lime mortar can result in serious damage to the original building materials and may not last, according to information from the National Park Service's Technical Preservation Services at www2.cr.nps.gov/tps on the Web.

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