How to repoint masonry joints?
Repointing Mortar Joints in Historic Masonry Buildings
- Historical Background
- Identifying the Problem Before Repointing
- Finding an Appropriate Mortar Match
- Properties of Mortar
- Mortar Analysis
- Components of Mortar
- Mortar Type and Mix
- Budgeting and Scheduling
- Contractor Selection
- Execution of the Work
What is spacing for control joints for retaining wall?
CONTROL JOINT SPACING. Space joints (in feet) no more than 2-3 times the slab thickness (in inches). A 4" slab should have joints 8-12 feet apart. When arranging joints, skilled contractors will often use them to create an attractive diamond pattern. If your concrete will be stamped, ask about the best ways to avoid interrupting the pattern ...
How to cut control joints in concrete slab?
Tips for Making Control Joints
- Do not twist the saw blade.
- Do not let the blade spin in the cut as this will increase wear on the bond.
- When cutting concrete with heavy rebar, use blades with soft metal segment bonds.
- Always use the required PPE (personal protection equipment).
What is a concrete wall control joint?
Control joints in walls, for example, are intended for defined crack control by engineered concrete cross-section weakening and formation of a controlled point of cracking through the concrete. This relieves stresses due to temperature and shrinkage, which thereby prevents uncontrolled cracking in the wall.
Where should masonry control joints be placed?
The National Concrete Masonry Association (NCMA TEK 10-2C) recommends that control joints be spaced at 25 feet or 1.5 times the height of the wall, whichever is less.
Are control joints required in masonry walls?
Control joints are typically required in exposed above grade concrete masonry walls, where net aesthetic shrinkage cracking may detract from the appearance of the wall, and to limit moisture or air infiltration. Shrinkage cracks in concrete masonry are not a structural concern.
Where are expansion joints located in a masonry wall?
The joints are formed by leaving a continuous unobstructed opening through the brick wythe that may be filled with a highly compressible material. This allows the joints to partially close as the brickwork expands. Expansion joints must be located so that the structural integrity of the brickwork is not compromised.
How far apart should brick control joints be?
20 to 25 ft.The normal “rule of thumb” is to place either one joint at the corner or to place two joints spaced no more than 20 to 25 ft. (6 - 8m) apart around the corner. For example, the distance on one corner wall from the control joint to the corner may be 8 ft.
How far apart should control joints be in concrete?
Concrete control joints should be no less than ¼ of the total thickness of the slab (1” deep for a 4” thick pour) and placed no less than 2-3 times (in feet) the thickness (in inches) of the slab (8-12 feet apart for a 4” thick pour).
What is a control joint in masonry?
Control joints in masonry are vertical weak planes intentionally built or cut into masonry to control where cracking occurs. Control joints should be installed in any masonry assembly that expected to experience net shrinkage over time. Usually, we think of control joints in concrete masonry (CMU).
What's the difference between control joints and expansion joints?
In building materials, a control joint is used to control cracking while an expansion joint is designed to handle structural movement.
Are control and expansion joints the same?
Control joints provide a place for shrinkage cracks to occur so they do not randomly creep across the concrete's surface. Expansion joints permit the concrete to expand and contract without causing damage and also allow it to move freely and independently of other portions of a structure.
How far apart should expansion joints be in Blockwork?
– 12 metresThe general thinking in the construction sector is that your expansion joint will be spaced at approximately 10 – 12 metres. This joint will be continuous for the full height of the brickwork or blockwork, from floor to roof of a house, for instance.
How often do you put expansion joints in brickwork?
As a general rule, the spacing of vertical movement joints in clay brickwork should be between 10m and 12m apart.
How long can a brick wall be without an expansion joint?
Movement joints in internal walls are not normally necessary for single dwellings unless the walls are straight and unbroken and over 6m long, in which case the block manufacturer's recommendations should be adopted.
What types of movement joints are required in masonry wall systems?
Movement joints are used to allow dimensional changes in masonry and to minimize random wall cracks and other distress. There are various types of movement joints in buildings: expansion joints, control joints, building expansion joints and construction joints.
Are control joints needed with adhered concrete masonry veneer?
A control joint is the separation designed into the outer layer or facade of the wall. There are no code or industry requirements for control joints for adhered stone veneer.
How long can a block wall be without an expansion joint?
Movement joints in internal walls are not normally necessary for single dwellings unless the walls are straight and unbroken and over 6m long, in which case the block manufacturer's recommendations should be adopted.
How often do you need expansion joints in brickwork?
With respect to horizontal expansion joints for vertical movement the outer leaf should be supported at intervals of not more than every third storey or every 9 metres whichever is less.
What is a control joint in a wall?
A control joint is a continuous vertical joint filled with mortar, but with a bond breaker on one side so that tensile stress cannot develop across the joint. If control joints are not provided, a concrete masonry wall may crack as it shrinks over time.
Why are control joints stopped short of the bottom of a wall?
Often, control joints are stopped short of the bottoms of walls due to below-grade waterproofing concerns. However, if the portion of the wall below the joint cracks anyway, the waterproofing conditions are worse than continuing the joint below grade.
What is a control joint?
Control joints in masonry are vertical weak planes intentionally built or cut into masonry to control where cracking occurs. Control joints should be installed in any masonry assembly that expected to experience net shrinkage over time.
What is the primary number for expansion joints?
Like expansion joints, the primary number to remember is 25 feet (Figure 1).
Where to install waterstop?
A better approach is to install waterstop (and joint sealant) at the joint below grade and continue the joint to the base of the wall. Joints are often stopped short at soldier courses above windows and doors since the head (vertical) joints do not align. Better practice is to continue the control joint, even if it must include a horizontal jog. Bed (horizontal) joints cannot be left free of mortar, but the mortar in bed joints can be raked back from the surface to permit joint sealant (caulk) installation.
Do control joints have weak planes?
If adequate control joints do not provide an intentional weak plane to control where cracks occur, shrinkage cracks will generally find their own weak points in the wall. This typically occurs adjacent to window and door openings since the amount of masonry is reduced at these openings (Figure 2). Windows and doors serve almost like perforations in a sheet of paper being ripped apart. Therefore, it make sense to locate control joints at these locations where cracks would naturally tend to form.
Do you need control joints in masonry?
Control joints should be installed in any masonry assembly that expected to experience net shrinkage over time. Usually, we think of control joints in concrete masonry (CMU). However, other masonry products that are portland cement based also shrink over time and should have control joints. For example, precast concrete ...
Do bond beams have to be continuous?
All joint reinforcing and non-structural bond beams (such as bond beams used for temporary wind bracing or shrinkage control only) should be discontinuous at every control joint (Figure 3). Structural bond beams, such as diaphragm chords at the roof line should be continuous across control joints. If you don’t know whether or not a bond beam should be continuous across a control joint, be sure to get clarification from the Design Engineer in writing.
Why use a control joint in masonry?
The purpose of a masonry control joint is to allow free movement while maintaining the weathertightness of the construction.
What is the purpose of a control joint anchor?
Also, control joint anchors are often utilized at the control joint to help keep the wall from expanding and to maintain it’s purpose as a control joint only. Movement joints are commonly spaced 100-125′ along unbroken masonry walls and as follows:
