Palm Beach County Contractors

Designed to Move

Precast panels expand and contract with temperature. Watch the sealant stretch and compress as you change the temperature. Learn why joint design matters in Florida's extreme heat.

Calculate Wind Loads Joint Size Calculator

Temperature: 80°F

Joint Width Calculator

Find the right joint width based on panel size and temperature range.

Thermal Movement Calculator

Panel Length 30 ft

Temperature Range 120°F

Sealant Movement Rating +/-50%

Expected Movement

0.24

inches

Minimum Joint Width

0.48

inches

Recommended Width

3/4"

with safety factor

Proper Joint Cross-Section

Sealant Types for Florida

Choose the right sealant for Palm Beach's heat and UV exposure.

Silicone

Best UV resistance and longest life. Excellent for Florida sun exposure. Can handle +/-50% movement. Doesn't shrink over time.

Best for Florida +/-50%

High-Performance Polyurethane

Good movement capability (+/-35% to +/-50%). More paintable than silicone. Costs less but may need replacement sooner in Florida UV.

Good Choice +/-35-50%

Standard Polyurethane

Only +/-25% movement. Not recommended for precast joints in Florida. Will fail when panels move more than expected.

Not Recommended +/-25%

Acrylic Latex

Only +/-12.5% movement. Never use for precast joints. These are for interior non-moving joints only.

Never Use +/-12.5%

Common Questions

Real answers about precast panel joints.

Concrete panels in Palm Beach can experience surface temperatures from 40 degrees F in winter mornings to 160 degrees F on summer afternoons. A 30-foot panel can move almost 1/4 inch from this 120 degree F temperature swing. Joints must accommodate this movement plus building drift.

Use silicone or high-performance polyurethane sealants rated for +/-50% movement capability. Standard sealants rated for +/-25% will fail. In Florida's UV exposure, silicone performs best long-term. The sealant must also bond to concrete without primer if possible.

Joint width depends on panel size and expected movement. Typical joints are 3/4 inch to 1 inch wide. The rule: joint width should be at least twice the expected movement, divided by the sealant's movement capability. A 1/4 inch movement needs at least a 1 inch joint with +/-25% sealant.

Joints fail when: 1) The joint is too narrow for the movement, 2) Wrong sealant type is used, 3) Sealant depth is wrong (should be half the width), 4) Backer rod is missing or wrong size, 5) Surfaces weren't cleaned before application. Any of these causes sealant failure.