Energy Efficiency Solutions Starts At The Top -- the Attic.
As a top-notch mechanical contractor, H&H Plumbing & Heating are always looking out for information that will help homeowners in the Greenville, Rockford and Grand Rapids Area improve the value, efficiency and comfort in their home. Adding insulation or new replacement windows are common areas people look to improve but they may not be the best money spent. Reducing air leakage is one of the biggest improvements you can make. You see blowing more insulation or rolling out more fiberglass batts won't fix your air-leakage problems. Air can pass through them.
The goal is to dramatically slow the loss of heated air during the heating season, and reduce drafts throughout your house. Heated air tends to rise and leak out in an unfinished attic, which draws in outdoor(cold) air is drawn into the lower levels of the house. In technical terms it's called the “stack effect”; which is a principal cause of air leakage.
The Attic Floor: The best time to seal an attic is prior to installation of the insulation, but for purposes of retrofit air sealing, the following locations should be addressed. Large openings (flue, duct, and plumbing chases). These should be sealed with rigid material (sheetrock, plywood, foam board, etc.) caulked or foamed at the edges. Note: Always maintain required clearances between flues/chimneys and combustible materials. For sealing around flues, use sheet metal or foil-faced fiberglass ductboard and high-temperature caulk.
Plumbing chase: Vent stacks are those pipes that go through the attic floor right up to the roof. Seal around vent stacks at the level of the attic floor with expanding foam or caulk. Caulk hose bibs where they pass through the band joist or exterior wall.
Plumbing vents passing through top plates into the attic should be sealed with caulk or one-part foam. Larger chases and plumbing walls lacking top plates should be sealed with foam board and one-part foam.
Attic hatch: Doors to walk-up attics and kneewall cavities can be weatherstripped. Small lift-up ceiling hatches (“scuttle holes”) are often relatively airtight, provided that the scuttle board makes good contact with the trim boards holding it in place. A thick layer of foam board insulates and gives weight to the scuttle, and prevents rattling in windy conditions. Hook and eye securing mechanisms can have a significant impact to minimize air leakage. Pull-down attic stairs are usually quite leaky. The plywood “door” itself is often warped, and the springs do not provide tight closure. The best approach is to build or purchase a lightweight removable insulated cover (typically made of foam board) that fits over the stairs in the attic. To work well, this should make good contact with the attic floor; the gap between the ceiling sheetrock and the plywood floor should be blocked with wood or other material.
Do you have a whole house fan? They are typically located in the main hallway in the upper level. The louvered covers of whole-house fans are usually very leaky. These are typically sealed from the attic by building a plywood or foam board box around the fan assembly. The box must be tightly sealed at the attic floor; Remember: the fan cover must be removed each summer and put back in place each winter.
Do you have recessed lights? Here's the problem they can present. When we talk about having a window open in your house all year around….most homes today are like this. Richard Rue, who has engineered over 40,000 Ultra Energy-Efficient homes, says, "recessed lights that penetrate into the attic space can be the “kiss of death,” unless you’ve insulated the attic with sprayed foam. One of these seemingly innocuous little lights represents 1 square foot of uninsulated attic space, and 20 of them is equivalent to having a door open in the attic at all times".
The way to fix this situation may be a little more challenging. Recessed light fixtures should be replaced with sealed fixtures whenever possible. Otherwise, only IC (“insulation contact”) rated fixtures should be sealed. The best way to seal these is by building sealed boxes from fire-rated materials such as sheetrock or ductboard and covering the fixtures in the attic floor. Recessed can lighting – each one leaks 3-10 cfm into the attic. If you have 20 that leak 10cfm, that is equal to ½ ton of air. A home of 2500 sq. ft has about 3-5 tons. Which is about 12% of your HVAC System. Caulk inside the can to seal and use low heat bulbs. Most are not IC rated –
Chimney Chase Flue and chimney chases should be sealed at the attic plane(floor)
with rigid, non-combustible material such as sheet metal or foil-faced fiberglass ductboard. Use high-temperature caulk to seal the ductboard or metal to the flue pipe or chimney. If insulating the attic with cellulose, wrap the flue pipe in unfaced fiberglass batting, secured with wires, to prevent cellulose from coming in contact with the chimney.
Hope this helps.
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