The steps you should follow to repair racked-down corners are as follows:
1. First remove all the bricks inside the V, including any bricks that have been broken (fig. 7-5). This forms irregular sides and helps to hold or key the brick in place.
2. After the bricks are removed, clean the sound bricks and obtain as many new matching ones needed to fill the opening. Relay the bricks in mortar up to and even with the horizontal crack running along the side and end of the building. If all joints are made the same width as the original joints and the mortar tends to match the old mortar, a very presentable job will result. As the bricks are built up, coat the backup bricks with mortar so that the newly laid bricks will be bonded to them.
3. Partly fill the top joint with mortar that is on line with the horizontal crack. This can be done by pushing the mortar into the joint with a narrow pointing trowel. When about half the depth of the joint is filled, fill the remainder with sealing compound. This system of mortaring only half the joint supports the brick above but forms a weak plane along the top of the racked-down areas. If movement takes place, the mortar joint breaks, but the relaid bricks remain in place. The sealing compound keeps the joint watertight.
Interior walls are usually made up of gypsum and plaster materials - the most common material being drywall. Other materials used are plywood, wood paneling, ceramic tile, or glazed-faced masonry. Partitions may be of plywood, drywall, hard-pressed fiberboard (particle board), structural clay tile, gypsum block, metal, and glass. Ceilings are usually
Figure 7-5. - Damaged brick removal.
made up of either drywall or acoustical materials. Another material commonly used to cover ceilings is plaster. Some of the major defects to look for when inspecting the more common types of interior walls, partitions, and ceilings are given in the following sections.
Cracks, holes, and looseness in plastered surfaces are signs of excessive internal or external stresses. They may be caused by poor workmanship, such as improper proportions or application of the plaster, imperfect lathing, and poor atmospheric conditions during plastering; by moisture infiltration or an excess of moist air generated inside a building; or by the settling or other movement of some part of the building frame. External stresses that cause plaster damage should be investigated and corrected before repairs are made to the plastered surfaces themselves.
STRUCTURAL CRACKS are easily identified because they are usually large and well-defined, extending across the surface and entirely through the plaster. They generally develop during the first year after completion of construction and, in most cases, can be successfully and permanently repaired. However, before repairs are initiated, the cause of the failure should be determined from an engineering standpoint and necessary precautions taken to prevent recurrence of the failure. Structural cracks may extend diagonally from the corners of door and window openings, run vertically in corners where walls join, run horizontally along the junction of walls and ceilings, or occur in walls where two unlike materials join.
To repair a structural crack, use a linoleum knife or chisel to cut out and remove loose material. The crack must be formed to a V-shape to provide adequate keying action by making the surface opening narrower than the bottom of the crack. Care should be exercised to widen the crack only enough to ensure a good bond between patching plaster, old plaster, and lath. Expanded metal or wire lath should be cleaned and the mesh opened, so when patching plaster is forced into the opening, a good key is formed. Break out the key between wood lath so that a new key can be formed when patching material is forced into place. Thoroughly wet wood lath before applying patching plaster. Brush out all loose material, remove all grease or dirt from surrounding surface areas, and wet the edges of the groove. Press the first coat of patching plaster firmly into place, filling the groove nearly toContinue Reading