|Many homes already have the capacity to heat and cool a finished basement. If that's the case, simply add whatever ducting and fans are necessary following the Air Conditioner Contractors of America's Standards.|
Full-service remodelers can have their time nickel-and-dimed with a flurry of little projects. That makes it important to take advantage of the big projects that come along such as a basement remodel.
Well-constructed basements have characteristics that make them suitable for daily living space. They are quiet, naturally cool and inherently private. And because the plumbing, heating, and air conditioning equipment is usually already located there, they are easily able to support an upgrade.
Before you commit to a basement remodel, though, you'll want to assess six elements: radon; moisture; insulation; HVAC; walls and ceilings; and lighting.
Your first concern is safety, and radon heads the list. Radon is a colorless, odorless gas and known carcinogen that can seep into a home from the soil and rock below. Because it comes from the ground, radon levels are usually highest in basements.
The Centers for Disease Control, the Surgeon General, the American Lung Association and the American Medical Association all agree that you need to reduce the radon level if it is 4 pCi/L (picocuries per liter) or more. Do-it-yourself radon test kits are available in retail stores. If radon levels are high, contact a local remediation contractor. Generally, some type of venting is added to reduce radon to safe levels.
|Poor installation of insulation increases the likelihood of condensation inside the basement walls and within the insulation itself. Install insulation behind framing or with furring strips placed against the foundation wall.|
To be a useable living space, the basement has to remain dry, even during heavy rain. Possible mold growth also must be addressed before and during construction because most basements are naturally humid. Your goal is to control water penetration and prevent condensation on walls.
Proper drainage outside the home is one of the best ways to control moisture. "Preventing water penetration is a big part of [any finished basement]," says John Piazza Jr., president of Piazza Construction in Mount Vernon, Wash. "We use black tar sealer on the outside of the home, install drain footings that lead water away from the foundation and make sure we have effective downspouts."
Also make sure the yard is graded away from the foundation and gutters work properly. If you can, install a capillary break, such as waterproofing or rigid insulation, to separate the foundation from the soil. This will minimize wetting the foundation wall.
Basement walls will probably get wet sooner or later from internal moisture caused by condensation, spills, leaks, pipe bursts or external moisture caused by leaking or damp foundation walls. This is where properly installed insulation comes into play.
Basements don't naturally feel like a warm and cozy living space, but a well-educated remodeler can change that with proper insulation, which separates cool foundation walls from the mild interior. Insulation is also a key element in managing moisture. Here are some basic guidelines:
- Any accumulated moisture must be able to dry to the basement's interior.
- The warm interior air should not come in contact with the cool foundation wall because the moisture in the air will condense on the wall.
- Materials in contact with the basement floor and the foundation wall must not promote mold growth or deteriorate if they become wet.
Vapor barriers can actually cause mold growth or even building failures if installed where they shouldn't be. Inside basements, vapor barriers are only appropriate on fully exposed walls, and they should never be used in hot and humid climates. In those climates, a misplaced vapor barrier can trap condensed vapor within a wall assembly and prevent the wall from drying.
The best basement insulation is usually some type of rigid polystyrene glued to the foundation walls. Seal the joints with mastic and mesh tape. This will prevent warm, moist air from coming into contact with the walls leading to mold.
|An increasingly popular option to basement daylighting is tubular skylights, roof-mounted light collectors that guide sunlight to a lens in the basement that spreads light evenly throughout the room.|
Conventional batt insulation is usually not a good choice for a basement because it can hold the moisture from leaking or sweating walls. Other types of insulation — such as blown cellulose or fiberglass — can be just as troublesome if poorly installed. Poor installation increases the likelihood of condensation accumulating inside the basement walls and within the insulation itself. Wet insulation dries slowly, which can result in mold and water damage. Damp insulation also doesn't insulate as well.
Install insulation behind interior framing or with furring strips placed against the foundation wall. Seal joints and penetrations through the drywall, and leave at least a ½-inch gap between the bottom of the insulation and the floor.
Don't forget to market that insulation to your client, who will likely enjoy some major savings. According to the U.S. Department of Energy, typical annual energy savings achieved by properly insulating a 1,500-square-foot basement range from $250 a year in Washington, D.C., to $400 a year in Minneapolis.
Many homes already have enough excess capacity to heat and cool the unfinished basement, especially if it's insulated. If that's the case, simply add whatever ducts and fans are necessary to condition the finished basement rooms evenly. Always use Air Conditioning Contractors of America Manual J and Manual S to properly size HVAC equipment and Manual D to size the ducts.
If the existing HVAC system can't handle the load, you may not need to replace the equipment. Instead, consider adding a separate self-contained heat pump/air handler, which provides heating and cooling in a single, compact unit. This option may be more energy efficient and require less maintenance, and it avoids additional penetrations through the outside walls.
If the system is 15 years or older, have your HVAC contractor evaluate it. It may be more cost effective in the end just to replace the entire system. Here are two essential guidelines: look for an ENERGY STAR qualified system, which will operate more efficiently than non-qualified equipment, and use Manuals J and S to be sure the equipment is properly sized. Oversized systems cost more up front, raise monthly bills and are often louder than necessary. And oversized air conditioning systems can actually leave the air feeling damp and clammy.
To control humidity, start by sizing the system properly and sealing all air leaks. Hot air from the furnace should handle the humidity in the winter, but it does this most effectively if the ducts are positioned near the floor. As long as the air conditioner takes some return air from the basement, the unit should control humidity during the summer as well. If this doesn't do it, install an ENERGY STAR qualified dehumidifier. Draining the unit to an exiting sump will relieve the homeowner from having to empty it manually every day.
When framing the basement walls, set the furring strips against the rigid foam insulation that covers the wall. The strips should not touch the foundation or they may absorb moisture.
Mold-resistant, paperless gypsum drywall is ideal for moisture-prone interior walls. This is an exceptionally good choice in areas prone to flooding. The interior panels have a noncombustible gypsum core that resists warping, rippling and buckling and is flame-resistant. However, you may need the client to sign off on the extra expense, because paperless drywall panels cost 10–20 percent more.
A suspended ceiling is ideal, because it will keep the plumbing and electrical wiring accessible. Also, water-damaged ceiling panels can be easily replaced.
Often what makes a basement feel unappealing is the lighting. To make the basement inviting, maximize natural light and plan electric light carefully.
Unless the basement is a walkout, window wells may be the only way to provide daylighting. These are often located high in the basement walls to produce less glare. Another increasingly popular option to enhance daylighting is tubular skylights, roof-mounted light collectors that guide sunlight to a lens in the basement that spreads light evenly throughout the room.
For the electrical lights, specify ENERGY STAR fluorescent fixtures, which offer substantial energy savings. Installing these products for the five most used fixtures will save homeowners about $60 per year.
Any objections to the glow cast by fluorescent lamps can be overcome by specifying a lamp with a higher Color Rendering Index (CRI). The CRI scale ranges from 0–100, with natural daylight representing the top of the scale. Newer fluorescent and compact fluorescent bulbs can be purchased with CRIs in the 70–90 range. Lighting experts target a CRI of 80 and above for visualizing true color.
The Northwest Energy Alliance lists fluorescent fixture alternatives to incandescents based on fixture wattage. Information on ENERGY STAR's Advanced Lighting Package and Seattle City Light's efficient home lighting packages can help choose the right process.
This will put the finishing touches on a potentially amazing transformation: changing a merely serviceable space into a comfortable living space.