What is the standard width of a control joint in a CMU wall?
The control joint is a continuous space where the brickwork does not touch. The width of the joint, typically 3/8” to 1/2” (10-12mm), is dependent on the building movements and is kept water tight by a backer rod and a commercial sealant that can withstand the calculated movements.
What is the maximum spacing between control joints?
The spacing of Control Joints is related to the thickness of the concrete or mortar slab. It is generally 20 – 25 times the thickness of the slab. Ardex generally state that 4.5m is the maximum allowable spacing. Once the joint is cut or tooled into place, it is ready to do its job.
What is the distance between control joints in a 10 high CMU wall?
Thus, for a 10-foot-high wall, control joints should be placed 20 feet on center. If joint reinforcing is used, the spacing can be increased as shown in the table.
What is the maximum distance of control joints from corners in masonry walls?
It is typical to recommend the control joint be located at the change in the wall height and no more than two or three brick lengths from the corner of a building.
How often do you need a control joint in CMU?
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.
Should concrete control joints be caulked?
Even expansion joints in your concrete driveway should be caulked. They can be the biggest culprit of water under your slabs. Notice how the caulking is slightly lower than the concrete slab around it. This protects the caulk from wear and tear of people walking and driving over it.
What is the difference between an expansion joint and a control joint?
In building materials, a control joint is used to control cracking while an expansion joint is designed to handle structural movement. A control joint can be formed during placement of the building material or cut after the material is placed.
What is the spacing of concrete slab control joints?
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.
What does CMU stand for in masonry?
CMU stands for concrete masonry unit, which is the 8x8x16-inch concrete block that makes up CMU concrete block walls. CMUs have been improving in materials and mixtures since 1882, but their general size and purpose remains the same.
What is a CMU wall in construction?
An interior wall of painted CMUs. A concrete masonry unit (CMU) is a standard size rectangular block used in building construction.
What is spacing for control joints for retaining wall?
The joint between the base and the wall is continuous, and extending along the length of the wall and the base. Distance between joints in a retaining wall. Vertical construction joints are no standards for retaining walls unless discharges are required separately. Contraction joints or control are placed vertically at regular intervals to control cracking of the expansion and contraction of soil movement. Generally, the spacing of the control joint is specified for a minimum of 20 feet (609