Building a brick wall is involved enough that you will benefit by having had some experience handling the material before-hand, even if you have done no more than lay bricks in sand. Still, there is no substitute for working with mortar and brick. No matter how much you read about handling a trowel you will never quite appreciate the degree of skill involved until you try it yourself. Therefore, it is wise to restrict your first efforts to the building of a low wall (no more than 3 feet high).
WALL THICKNESS A CONSIDERATION
You can build a wall that is 4 inches thick (the width of one brick), providing it is no higher than 2 feet -a higher wall must be wider to withstand lateral pressures. One exception is a curved wall, which forms its own support. (Since each curve is an arc of a circle, in laying out such a wall you merely set up a stake or pole to serve as a center point for a string to form what-ever diameter you wish.)
The width of a brick wall higher than 2 feet, or of a high retaining wall, should be 8 inches, and steel reinforcing rods should be used at frequent intervals. If a wall is also of con-siderable length, it should be reinforced about every 12 feet with a pilaster or brick pier.
The size and type of foundation needed for a brick wall varies with the underlying soil structure, the weight of the wall, and (if a retaining wall) the ground water pressure behind it. If there is any question in your mind about the stability of the wall you plan, it is best to get professional advice before you begin.
For walls up to 2 feet in height the first course of bricks can act as a foundation. Simply dig down to solid ground and set the first course on a bed of mortar. Make this first course twice the width of the wall. Walls that are higher than 2 feet should be set on a concrete foundation.
MIXING THE MORTAR
Everyone has his own favorite mortar mix for brick work. Opinion varies about the proper proportions of cement, lime, and sand, but the following considerations seem to be univer-sally recognized. The more lime in the mix, the easier it is to work; it is more plastic, holds water better, sticks to the trowel better, but has less strength. The more cement in the mix, the harder it is to work; it may be granular and lumpy, and won’t stick to the trowel, but it’s stronger. A good all-around mortar mix is 1 part cement, 1 to 1 VA parts hydrated lime or lime putty (lime in a plastic state), and 5 or 6 parts loose, damp sand.
For very small jobs, you can buy ready-to-mix mortar to which you just add water, or sand and water.
For the actual mixing, you will need a flat surface such as a square of plywood, a wooden box, or an old wheelbarrow. Mix all the dry ingredients thoroughly with a short-handled, square-edged shovel or a garden hoe. Then add water slowly. The mortar should be just wet enough to slide cleanly off the mixing tool or a trowel but it should not be runny. Mix mortar in small batches so it won’t dry out.
TOOLS AND EQUIPMENT
The most important tools for brick laying are the pointed trowel with a 10-inch blade, for spreading the mortar, and a broad-bladed cold chisel called a ‘brick set,’ for cutting bricks. Other tools that you are likely to need are a hammer, a carpenter’s square, a length of fishing line, a piece of straight wood about 5 feet long and a level.
SETTING THE BRICKS IN MORTAR
Before applying any mortar to the bricks, lay an unmortared test row on the foundation to check the fit, leaving a ½ inch opening between each brick for the mortar joint. Space the openings until the bricks fill the guide lines properly, then you can set them in place with mortar.
Pick up some mortar on the trowel and spread it on the base about ½ inch thick, working from left to right. Turn the trowel over and use a zigzag motion (called furrowing) to work the mortar out to the edge. Pick up a brick in your free hand, ‘butter’ one end with mortar, and set it in place. Push it down into the mortar bed until the mortar squeezes out the sides. Scrape off this excess mortar and use it to butter the next brick. When the first course of bricks is in place, build up the ends or corners of the wall . Attach a guide line to these corners (such as a good quality fishing line), using nails in the mortar joints. Use a length of straight wood to check that the end bricks are plumb. Then complete laying each course moving the guide line up as you work.
STRIKING THE MORTAR JOINTS
For a professional-looking finish, trim off any loose mortar and smooth off the joints before the mortar completely sets up. Smooth the vertical joints first, then the horizontal. The most popular method is to use a short piece of steel pipe with a diameter slightly larger than the joint. By drawing the pipe along the mortar joint, you produce a smooth, concave surface. Some other methods for striking mortar joints are with the edge of a board; with the handle of the trowel held down; with the handle of the trowel held up; with the tip of the trowel; with a professional striking tool. The joint made with the trowel handle held down is preferred by many because of its water-shedding ability and because each course of bricks will throw a pleasing shadow effect that runs horizontally along the wall.
CLEAN WITH MURIATIC ACID
For the first two or three days after completing your brick wall, it is a good idea to keep it wet with an occasional fine spray from a hose. This helps speed the setting-up action. Wait a period of two to three weeks to see if any white efflorescence (excess water rising to the surface of the brick) appears over the brickwork. Efflorescence and any smears of mortar can be removed with a mild solution of muriatic acid. This chemical is extremely potent and should be handled with care.
HOW TO BUILD A BRICK WALL
Wet the bricks with fine spray until they are damp but not soaked through; do this about four hours before you plan to use them.
Dig trench for concrete foundation deep enough that first course of bricks can be mortared in place below frost level.
Lay dry bricks on foundation for first course to check fit, leaving about % inch space for mortar Joints. Then secure with mortar.
Build corners first using step method. Attach guide line to keep courses straight: check for plumb at each corner.
Use steel pipe to give joints a smooth, concave finish while mortar Is fresh. Smooth vertical joints, then horizontal.
Brush wall with stiff brush dipped in solution of muriatic acid to remove mortar smears and any coating of efflorescence.