Q: Brick mortar and I don't get along. At my house, the brick and mortar are falling apart. It's happening on the walls and in a brick patio in my rear yard. I desperately need a mortar how-to course so I don't end up with a huge mess. What are some of the important steps in brick mortar repair? Are there special tools that make the job go faster and look more professional?
A: Bricklaying mortar is a fantastic product when you stop and think about it. For all intents and purposes, it's just a glue. You use it to stick two or more things together. You may not know it, but there's an enormous amount of science involved in making mortar for brick. I can't begin to scratch the surface in this column.
There are many different types of brick mortar, many with different strength properties. A standard mortar is a mixture of Portland cement, hydrated lime and some form of clean, washed sand. The sand can have a significant effect on the strength and final color of the weathered mortar joints.
In my opinion, one of the most important tasks is to match the mortar to the job. You don't use the same mortar for your brick walls as you would to patch your brick patio. Patio mortar needs to be far stronger than the wall mortar.
To make a strong mortar for the patio, use pure Portland cement, sand and water. I would make the mixture very rich, meaning that there is lots of cement in the mix. Try a mixture of two parts sand to one part cement.
Get all loose mortar and dust out of the joint. Spritz the joint with water and add the mortar. Make the mortar stand up a little higher than the brick. Wait until it gets a little stiff, then scrape off the excess with a small pointed trowel. If the mortar smears onto the brick, you're not waiting long enough.
To repair the mortar in walls, look at the small, colored grains of sand in the mortar. Initially, when mortar dries it's a uniform gray color because the sand is coated with the mortar-cement paste. Over time, the mortar-cement paste erodes, exposing the pieces of small rock that make up the sand.
Visit a local sand pit and look at the different sands. Note that there can be a difference in both grain size and color. You want to match both as closely as possible. You also want to match the strength of the mortar. The older your home, the weaker the mortar.
Tim Carter is a licensed contractor. To view previous columns or tap into his archive of information and sources of building materials, go to www.askthebuilder.com. You can write to Tim Carter at P.O. Box 36352, Cincinnati, OH 45236-0352.
. TIPS
Mastering mortar
• You don't need too many special tools when working with brick mortar. You'll be able to do most repairs with a medium pointed trowel, a small pointed trowel, a narrow pointed trowel that's only as wide as the width of the mortar joint, and possibly a mortar grouting bag. You may need a mortar chisel to help you remove crumbling mortar from between brick.
• Make sure the brick joints are clean, dust-free and damp before you add new mortar. If the dry brick and old mortar aren't spritzed beforehand, they will suck the water from the new mortar too quickly. If this happens, the new mortar will never get as strong as it could be.
• Take your time to avoid smearing the mortar on the brick face. If you do make mistakes, scrape off as much excess mortar as you can that day. Then wait 30 days before you attempt to clean the mortar paste from the brick. Use a solution of muriatic acid and water, mixing one part acid to 10 parts water. Dampen the brick to be cleaned with water and apply the acid solution. Wear rubber gloves, goggles and old clothes. The acid is very toxic. Allow it to sit and fizzle on the mortar paste for 10 minutes, then scrub the area. Rinse with plenty of water. Repeat if necessary.
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