L4: Building Joints

Question 1

Why are materials constantly in motion?

Answer 1

Environment - temperature, moisture, freeze/thaw cycles
Structural movements - deflecting under loads, lateral loads
Curing - concrete and stucco shrinks; gypsum and plaster expands

Question 2

How is motion accommodated?

Answer 2

Strengthening

Movement joints

Question 3

What are non-movement joints?

Answer 3

Connections between different building elements not meant to move eg. nails in wood, bolted steel

Question 4

What are movement joints?

Answer 4

Connections designed to adjust to anticipated movements

Question 5

What are the types of movement joints?

Answer 5

Working construction joints
Structure/enclosure joints
Surface divider joints
Building separation joints

Question 6

What are working construction joints?

Answer 6

Joints part of the normal assembly process eg. shingle roof, sealant joints

Question 7

What are structure/enclosure joints?

Answer 7

Prevents loads being transferred to non-structural elements eg. soft joints between shelf angle and brick veneer

Question 8

What are surface divider joints?

Answer 8

Abutment joints - separates new and old construction (settlement)

Control joints - directs cracking to specific locations to avoid random cracking

Expansion joints - open seams that close to allow expansion

Question 9

What are building separation joints?

Answer 9

Volume-change joints - divides large masses into smaller pieces to allow for independent movement

Settlement joints - divides building sections likely to have differential settlement (eg. on different soils, different foundation types)

Seismic separation joints - divides large buildings into smaller symmetrical shapes to allow segments to sway and avoid collision

Question 10

What type of joint is commonly confused as a name for all building joints?

Answer 10

Expansion joints