Attic Sealing Los Angeles

Insulation and How it Effects Attic Sealing

Most every attic has at least some insulation in it, and that's fine. Insulation helps prohibit heat loss. It doesn't stop airflow, however, and that's a problem. The insulation lying on attic floors often conceals a very large problem -- cracks, gaps, and holes through which pressurized air from the house below is driven into the attic.

These fissures take many forms: holes drilled into the wood framing where wiring runs from a room below up into the attic; lighting fixtures and electrical boxes; areas where the tops of partition walls in the room below intersect with the attic-floor framing; bulkheads over kitchen and bathroom cabinets; exhaust vent fans; and fireplace and heating equipment chimneys and flues. It's a long list, and it's likely you can find fissures in your own attic that aren't even mentioned.

Every one of these holes represents an opportunity for warm air to escape the rooms below -- and that escaping air represents your energy dollars flying up and away as well. So, although digging through insulation in the attic to find and seal up these trouble spots is probably not anyone's idea of fun, it is time well spent.

The materials used for sealing most attic floor penetrations are caulk and spray foam. The application does not have to be neat; no one is going to come along and grade you on tidy performance. Once you foam or caulk, you'll just cover the area with insulation again. But it will behoove you to do a thorough job. Remember, any gap left unfilled will leak air.

Sealing Leaks in Your Home

In an attic filled with unfaced fiberglass insulation, it's relatively easy to find spots where air is leaking upward from the rooms below. You'll often see gray, brown, or black smudges or staining in the insulation. Those discolored spots are dirt that was borne on the air leaking from below. Fiberglass insulation strains contaminants out of the air and leaves them there as telltale indicators of air leakage. Lift up the fiberglass batting at one of these spots, and you'll find an opening into the rooms below, maybe an electrical box or wire chase.

Attics insulated with cellulose fiber don't show air-leak smudges. The material is as dark as most airborne dirt, and it doesn't act as a filter. So you'll need to use your sleuthing skills to come up with places likely to contain room ceiling/attic floor penetrations. Examine rooms below before you enter the attic. Take note of where light fixtures and interior walls are located. You may even want to draw a map.

Once you locate a hole that needs to be filled, use a brush to sweep the insulation back, squirt caulk or spray foam to seal the hole or gap, replace the insulation, and move on to the next spot.

Be especially aware that many interior walls have wires running up into the attic. Foam around the wires to fill the holes in the framing. Electrical boxes should have the power switched off before you work around them. Caulking around the box where it penetrates the drywall or plaster and around the wires that run into the box will seal things as well as possible. Vent fan housings can be sealed in a similar manner.

Chimneys require a different approach. Building codes now mandate at least a two-inch gap between any flammable material (usually wood framing) and the masonry or metal. In newer homes this gap is sometimes left unfilled, leaving a hole that goes directly from the basement to the attic. A lot of warm air can rush up a hole that size. Older homes may not have as sizable a gap, but the solution for either is to close the hole with a nonflammable material and fireproof caulk. Sheet metal nailed to the framing and shoved against the chimney works well, and it can be sealed with the caulk to eliminate any of the remaining small gaps.