Principles of Joints & Sealants Chapter 9

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Joint patterns & details

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building Joints result from need to Work with materials that can be easily fabricated, transported and assembled on site Allow for field adjustments Accommodate differing changes in size between different materials Make a secure connection Articulate building surfaces

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Types of joints Static joints provide non-moving connection between building components Dynamic joints (Movement Joints) make connections while allowing for movement of the components

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved.

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building separation joints Continuous joints that completely separate parts of a building from each other Accommodates effects of movements of building as a whole Prevent stresses created in one part of a building from transferring to other parts. Typically1 1/2 inch - 2 inch wide, every 250 ft.

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Typical locations of building separation joints

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Two adjacent columns at separation

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building separation: double columns in concrete frame

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building separation: double columns in steel frame

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building separation at single column

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Building separation at single column

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Seismic Joint Assure that one building segment does not collide with another during an earthquake Accommodate mostly horizontal movement Typically wider than a building separation joint, with width increasing with height

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Typical seismic or separation joint cover

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Factors in sizing movement joints Thermal movement Moisture movement Elastic deformation and creep Construction tolerances Sealant (if used)

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Restrained & unrestrained joints

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thermal movement Occurs in all components Generally most critical type of movement Coefficient of Thermal Expansion (  ), property of a material  t (change in length) =  L (  t)  t is a function of Annual temperature range Temperature at the time of construction

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Approximate value  for selected materials

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Northern US: typical temperature gradient

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Southern US: typical temperature gradient

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Problem: Determine joint width between 100 ft. segments of brick masonry wall  t (minimum joint width) =  L (  t) L = 100 ft = 1,200 in  t = 80ºF  = 4.0 x minimum joint width = (4.0 x )(1,200)80 =.320 in

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Moisture movement Some materials expand on absorption of water or water vapor In some materials (brick), expansion is permanent Some materials return to original shape when dried

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Elastic deformation & creep Creep is incremental deformation of a component caused by sustained loading. Significant in concrete and masonry

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Connection between spandrel beam and non- loadbearing infill wall must account for deflection

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Tolerances Material tolerances are the allowable variation in size from unit to unit Construction tolerances are a function of quality control during construction. Small tolerances require good construction quality and supervision Other tolerances include foundation settlement, story drift, chemical processes and freeze-thaw

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Total joint dimension Width of Joint Width based on temperature, moisture and other movement + Tolerances=

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Joint sealants If a joint sealant is used, its movement ability must also be considered Joint sealants are categorized by movement ability (class 50 has +/- 50% movement ability Width of Sealed Joint Width based on temperature, moisture and other movement + Tolerances= 100 Sealant Class

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Detailing movement joints Expansion joints Control (shrinkage) joints

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Brick expands over time - expansion joint required

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Concrete masonry shrinks over time - Control joint required

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Components of a sealed joint Substrate Primer Improve adhesion of sealant to substrate Sealant back-up (backer rod) control depth and shape of sealant allows for tooling sealant Bond breaker Prevents adhesion where not required

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Untooled and tooled joints

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Effect of bond breaker on sealed joints

Mehta, Scarborough, and Armpriest : Building Construction: Principles, Materials, and Systems © 2008 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Joint sealants Preformed tapes Perform as sealants only when under pressure Caulks First generation sealants, dough-like materials, rarely used Elastomeric sealants Synthetic polymers, most commonly used in construction Vary in performance characteristics Movement ability Water vapor permeability Abrasion resistance Chemical resistance Durability Substrate compatibility Paintability