Green Building Library
Advanced Air Sealing:
Air Sealing Materials
| Materials | Applications | Pros and Cons |
| Caulks | ||
| Siliconized Acrylic Latex | seal cracks and holes up to 1/2 in. wide seal sole plates to subfloor, rough openings to window frames, drywall to framing or masonry, and drywall to electrical boxes high volume users consider a professional grade refillable caulking gun |
adheres well to clean, dry surfaces of wood, metal, drywall and masonry readily available inexpensive paintable may not adhere in cold or damp conditions clean up with soap and water |
| One-Part Polyurethane | same as above, plus seal concrete expansion joints can be applied to joints up to 2 in. wide if done properly. |
extremely good adhesion to almost all surfaces applies in temperatures down to 0° F if caulk is kept at 60° F or above applies to damp, but not saturated or ice-covered, surfaces very elastic and flexible -- will stay in joints even with substantial movement poor adhesion to glass more expensive than siliconized acrylics clean up with chemical solvents |
| Silicone | most silicones are "acetoxy" cure. They release acetic acid as they cure, which can weaken the surface of concrete and corrode galvanized metal. Acetoxy cure products have a characteristic vinegar smell. "Neutral" cure silicones are more expensive, but are also more flexible and work on concrete and metal substrates. | very elastic and flexible good adhesion to glass clean up with chemical solvents most can't be painted |
| Adhesives | ||
| Construction Adhesive | seal subfloor sheathing to joists seal tongue-and-groove edges of subflooring |
on job site during floor construction not flexible |
| Drywall Adhesive | seals drywall to plates and studs if applied in a continuous bead |
already on the job site adds little to drywaller time method has not been blower door-tested not flexible |
| Foams | ||
| High-Expansion Urethane | seal cracks or holes up to 3 inches wide seal odd-shaped holes seal rough openings to windows and doors, seal plumbing and electrical penetrations |
large canisters with adjustable nozzles are convenient and allow adjustment of foam bead for 1/4 in. up adheres well to any material except slick plastic, such as polyethylene foam expands to fill hole shape avoid getting foam on metal window frames avoid overfilling around windows and doors -- may warp frames |
| Low-Expansion Urethane | same as high-expansion | low expansion allows better control reduces potential to overfill cavities eliminates stress on window and door frames reduces cleanup from overfilling |
| Gaskets | ||
| Polyethylene Backer Rod | seal cracks from 1/4 in. to 2 in. wide seal at rough openings to windows and doors, especially for wood or vinyl windows use 1/4 in. diameter between drywall and framing use in deep cracks (greater than 1/2 in.) to back caulk |
can be applied in any temperature can be applied to wet surfaces (staples on) inexpensive clean -- no gunk on tools or tapes once fully compressed, may not recover -- avoid using where joint will move |
| Polyethylene Sill Sealer | use between mudsill and basement foundation wall |
prevents water wicking up from concrete avoid using under wall bottom plates |
| Foam, Neoprene, EPDM and Other Building Gaskets |
use between drywall and framing use between nailing flanges of metal or vinyl windows and rough openings use on attic and crawl space hatches use between all major framing members |
staples on -- can apply in any weather or on wet surfaces rolls easily requires care to apply drywall highly elastic -- recovers well when compressed clean |
| Sheets | ||
| Rubber or Neoprene Sheet Membranes | seals plumbing stacks and pipes to wall plates adjacent to unheated spaces (attics, crawlspaces, etc.) |
seals plumbing stacks and pipes to wall plates adjacent to unheated spaces (attics, crawlspaces, etc.) |
| Housewrap | can be used for sealing complicated leakage sites, such as stairs on outside walls, soffits and dropped ceilings fully-wrapped walls can connect to the air barrier on inside ceilings and floors |
durable vapor permeable, so it can be used on the outside surface of walls |
| Polyethylene Sheets | can be used for sealing complicated leakage sites, such as stairs and tub enclosures on outside walls |
not vapor permeable, so it must be used on the warm side of the exterior barrier |
