Frequently Asked Questions (FAQ)

Browse Frequently Asked Questions (FAQ)-accepted answers from construction contractors and architects. Each FAQ pair includes a link to a related product category, for more information.

What is backer rod?

Backer rod is a polyethylene foam rod used for a variety of construction purposes. When applying liquid sealant, backer rod is used to maintain proper joint design. There are different types of backer rod, including a bi-cellular soft-rod, closed cell backer rod, high temperature and open cell rods, all used for different sealant applications. Soft rod is non-gassing and most commonly used to prevent sealant from bubbling. Backer rod is extremely flexible; it is available in a variety of different diameters and custom shapes.

Product Category: Expansion Joint Systems, Joint Fillers

How do I choose the best sealant for my application?

Many different types of sealant exist, and no sealant can do it all. All are engineered differently for movement and intended bonding materials. Here are five criteria to help you choose the best sealant:

  1. Life Expectancy: Warranty required
  2. Substrates: Is a primer needed? Are the sealant and substrates compatible?
  3. Movement Requirements: +/-50%, +/-12.5%, +/-25%, +100/-50%
  4. Paintability
  5. Color Options: Least important.

Product Category: Sealants & Adhesives

What is the standard, minimum recommended application temperature for applying urethane sealant?

Most sealant manufacturers recommend 40 degrees Fahrenheit and rising for application of urethane sealant.

Product Category: Sealants & Adhesives

How do I recoat my deck?

Deck recoats vary by manufacturer, so it is important to consult the manufacturer’s maintenance manual.

Product Category: Coatings, Sealers & Corrosion Inhibitors

What is the difference between Fireproofing and Firestopping?

Fireproofing is typically cementitious material, sprayed onto the underside of metal fluted decks and structural beams. Trained contractors typically install fireproofing products.

Through wall (a.k.a. thru-wall) firestopping is used where wall penetrations create a breach in the hourly rating of the wall system. Firestopping products return the wall to its correct fire rating. Materials that can penetrate a wall include: plastic pipe, conduit or HVAC systems.

Product Category: Fire Protection

What does intumescent mean?

Intumescent material expands in the presence of high heat to fill a void.

Product Category: Fire Protection

What sealant has a USDA approval?

DOWSIL™ (formerly Dow Corning) has no USDA rated sealant. USDA has discontinued certifying sealant. Most end users will accept FDA (DOWSIL 732 has FDA approval).

Product Category: Sealants & Adhesives

What is the difference between organic and inorganic sealant?

Both types of sealant can be good depending on the application. Organic sealant is susceptible to degradation over time to UV light, weather and other elements of the atmosphere. Inorganic sealant chemistry has been designed to eliminate breakdown when exposed to the elements. Both organic and inorganic sealant have their pros and cons. Contact an Atlas Supply sealant representative to discuss your options.

Product Category: Sealants & Adhesives

What happens to DOWSIL (formerly Dow Corning) 790 when you use alcohol or solvent tooling aids?

Any application or contact of DOWSIL 790 Silicone Building Sealant and Contractors Concrete Sealant with alcohol, solvents or other uncured sealant may result in cure inhibition.

Product Category: Sealants & Adhesives

Last Modified: February 16, 2018