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Caulking sealant helps protect the internal wall components from moisture damage and minimizes the risk of mold by keeping water from penetrating the building exterior.
Buildings are designed with expansion joints that expand and contract with varying temperatures. Caulking sealant is designed with elasticity so that it can repeatedly stretch and compress, maintaining a watertight seal.
When sealant fails, it needs to be replaced. Replacing caulking is cost-effective maintenance that helps prevent more serious issues developing.
What caulking cannot do:
-Last forever
-Hold together loose brick
-Be a replacement for failed mortar
-Solve all water infiltration problems
Typical Sealant Manufacturer Life Expectancy
Urethane: 8-12 Years
Silicone: 20 Years
Acrylic: 2 Years
Butyl: 5-10 Years
The owner made the mistake of caulking the window lintel shut, trapping water against the steel, where it festered into pack rust. The force created by this rust cracked the brick.
Using caulking to try to bond together broken brick that need replacement is not only unsightly, but will also need to be continually recaulked to maintain watertightness.
Caulking cannot hold together a loose pile of stone. Water freezing and expanding under these stair treads has heaved them out of place. The caulking has failed because the underlying masonry is water saturated.
When the sealant has separated cleanly from the substrate, it has failed adhesively. This type of failure can be caused by improper sealant installation such as lack of surface grinding, substrate contamination, lack of priming or wrong primer choice.
When a sealant tears within itself, cohesive failure has occured. The joint expansion is beyond the elasticity of the sealant. Cohesive failure may be the result of improper installation such as too thin of joint depth, inadequate joint width or poor sealant choice.
Sealant goes to work every day expanding and contracting with the building. Over time, they lose their performance characteristics. They may harden and dry out, lose elastic qualities or experience UV degradation. This is the end of life for the caulking and it needs replacement.
When the substrate material ruptures below the sealant bond, substrate failure has occured. This can be caused by improperly caulking lintels shut or other severe conditions in the wall weakening the masonry to the point where the sealant bond is stronger than the substrate itself. This may occur alongside adhesive or cohesive failure.
Joint Design is a critical factor in the ultimate success and longevity of the building envelope. Improperly designed joints will not perform. Good design is based on:
Sealant replacement projects include many different materials. Each one has a certain porosity, coefficient of thermal expansion and adhesive characteristics. Some sealant types are not compatible with certain substrates. If the sealant and the underlying material are incompatible, they will fail prematurely.
Sealant joints are either dynamic or static. Joint movement is determined by investigating how each material is anchored and how it will move in relationship to adjacent substrates and thermal movement or through water absorption. This should include all movement that may occur including: extension, compression, shear, etc.
Sealant needs a proper backer rod for consistent depth. Closed cell backer rods are generally best, but more difficult to install. Open cell and dual rod styles are easier to install but introduce potential moisture and hydrolytic stability issues into the sealant repair. Choosing a closed cell backer rod ensures that the repair functions as intended.
Dynamic joints require high performance characteristics in sealant choice to function correctly. Silicone sealants have the most elasticity but some can stain porous substrates like limestone or marble or have a tendancy to attract dirt. Correct sealant choice is critical to successful sealant replacement.
Correct width to depth ratio ensures that a sealant will be able to endure the daily and annual extension and compression cycles. At the center of the joint, the width to depth ratio should be 2:1 unless the joint is less than .5" or greater than 1". Backer rod should be used to control joint depth and prevent three-sided adhesion.
Sealant joints are designed to perform at specific dimensions. Joints need to consider building tolerances so that joints do not become more narrow (and thus less able to accommodate movement) than the joint requires for its span of movement.
The nominal joint size is determined by the substrate temperature during sealant installation. Sealants are designed to both compress and expand, but each type can only expand and contract so far before failure. Installation in moderate temperatures allows the caulk to center the span of movement over its nominal size, maximizing its lifecycle.
Work begins with cutting out the failed caulking and cleaning out all debris from the joint, including all of the old caulking. The surfaces need to be fully cleaned in order to ensure a quality bond between the new caulking and the wall.
Joint surfaces to receive new caulking sealants are ground lightly to remove the old sealant. The joints are then cleaned to remove dust which could interfere with the bonding of the new sealant.
Joints surfaces are treated with a liquid primer matched to the substrate material. Once the primer has been applied, caulk will need to be installed into the joint while the primer is still tacky.
Backer rod is installed in the joint. It allows for proper joint profile and depth-to-width ratio, maximizing the movement capability and life of the new sealant. There is no hurrying a quality repair. The depth of the backer rod needs to be consistent along the entire length of the joint. If the closed cells of the backer rod are poked with the knife blade during installation, the escaping gases will bubble through the new caulking, showing up on the surface.
Joints are then filled completely with new sealant in a color approved by the customer. Factory orders of sealants vary in color slightly from batch to batch and because of this, all of the sealant for the project should be ordered at one time.
Joints are then tooled to a smooth concave profile with a properly sized tooling knife. Each differently sized joint requires its own correctly sized tool. Craftsmen begin by backtooling, removing the excess sealant, followed by finish tooling the new sealant in a smooth, continuous motion to ensure bonding to the substrate.
Completed sealant replacement that blends with the structure. The care used in the replacement process ensures that the sealant will last as long as possible.
"If you're good enough to successfully restore a Cass Gilbert building, you can restore anything. Building Restoration carefully planned out their work and finished ahead of schedule. The craftsmanship that went into the job is truly impressive and the repairs match the building beautifully."
-Larry Hudella, Roselawn Cemetery
"BRC has completed many restoration projects for us over the years and has always done a fantastic job. Our building is registered with the Historic Preservation Commission which provides some unique challenges. Building Restoration handled them with ease, meeting their requirements and providing high quality craftsmanship that matches the original structure."
-Shawn Leko, College of Visual Arts
"Building Restoration Corporation recently completed recaulking our building. The care incorporated into the repair process shows. I would recommend them to anyone."
-Jim Fleischer, Turtle Lake Elementary School
