Article From HouseLogic.com
By: Rich Binsacca
Published: December 11, 2009
Converting your basement into living space requires being aware of building codes and understanding special requirements.
Finishing your basement into a family room, game room, or spare bedroom is a financially sound decision. In addition to increasing the usable (and enjoyable) living space of your home, a finished basement pays back a high percentage of your investment at resale. According to Remodeling Magazine’s annual Cost vs. Value Report, a basement remodeling project (http://www.remodeling.hw.net/2009/costvsvalue/article/basementremodel.aspx) returns more than 75% of its original cost.
The cost of finishing your basement into usable living space is about $100 per square foot-generally less expensive than building up or out from your existing footprint. That’s because the basic structure-your home’s foundation-is already in place. Placing occasional-use areas, such as a laundry room, a spare bedroom, or a home theater below grade means that square footage above can remain dedicated to daily uses.
The first step is to determine if your existing basement meets building codes (http://www2.iccsafe.org/states/2009ICodes/Building/Building_Frameset.html) for habitable space. As defined by the International Residential Code (IRC), a basement living space must have a clear, floor-to-ceiling height of at least 7 feet (6 feet for bathrooms). There are some exceptions for the presence of exposed structural beams, girders, or mechanical system components along the ceiling, but only if they’re spaced at least 4 feet apart and extend no more than 6 inches from the ceiling. Note that local and regional building codes may vary–always check the specific codes in your area.
If your existing basement ceiling height doesn’t meet those specifications, you have two options: The first is to raise your house and build up the foundation around it to gain the ceiling height you need. The other is to lower the floor, which entails removing the existing concrete slab floor, excavating to the desired level, and pouring new concrete footings and a floor slab. Both options require professional and precise engineering, excavation, and structural work that will cost at least $20,000.
Assuming, though, that your existing basement meets the IRC definition of “full height,” your next code challenge is to accommodate egress. The IRC dictates that at least one of a habitable basement’s windows or doors to the outside must be large enough to serve as an emergency point of egress (or exit, as well as an emergency rescue access) in addition to the staircase to and from the home’s main level.
If you’re planning a basement retreat to include a bedroom (what code calls a “sleeping” room), that room and all other sleeping rooms also must have their own point of egress, in addition to the one required for a general “living” space, such as a rec room or home office.
Each egress opening (http://www.houselogic.com/articles/add-egress-window-your-remodeled-basement/) must be at least 5.7 sq. ft. with the windowsill no more than 44 inches above the floor, among other requirements that allow safe passage to the outside in the case of an emergency.
If you have a walkout basement, egress shouldn’t be an issue. Otherwise, you’ll have to build an egress. Most basement walls are built using poured concrete or masonry blocks, which can be cut (although not as easily as wood-framed walls) to create openings for egress windows or doors.
A proper staircase
In addition, the IRC regulates the specifications of the staircase from your home’s main level to the basement. Requirements include a handrail and stairs with proper width, tread, and riser dimensions. Also, there must be at least 6 ft. 8 inches of headroom at every point along the staircase.
It may be that you simply need to add a handrail–perhaps with a balustrade if the staircase is open to the basement instead of encased in a wall structure. If the stairway isn’t wide enough (at least 36 inches) or the steps aren’t to code, you may have to rebuild them, an extra cost of about $2,000.
Make sure your contractor confirms or considers code compliance for ceiling height, egress, and the staircase in your project budget to avoid potential conflicts, delays, and additional costs.
Checking for moisture problems
Arguably the biggest problem with basements is moisture and water infiltration. If you have seen water or moisture on your basement walls or floor, or signs of efflorescence or mold as a result of long-term dampness, you’ll need to solve that problem before you go any further. In addition to damaging finishes and eroding your home’s structure, unchecked moisture and water may cause mold and mildew growth (http://www.houselogic.com/articles/how-eliminate-mold-your-home/) that can adversely affect your health.
Depending on the severity of the water infiltration, and your available budget for a basement retreat, you have several options for addressing moisture problems. The best solution is to determine and solve the root cause, which is usually hydrostatic pressure from water in the surrounding soil pushing moisture through the basement (http://www.houselogic.com/articles/8-solutions-to-common-wet-basement-problems/) walls or floor.
In that case, it’s best to excavate around the perimeter of your home’s foundation and install a drainage system and waterproofing membrane to relieve hydrostatic pressure against the structure and effectively block water from getting through the walls–a professional job that can cost $5,000 or more.
If that’s too far out of your budget, and the moisture issue is relatively minor, you can cover all cracks and joints with a 100% acrylic elastomeric sealant and apply brush-on coatings to the inside poured concrete or masonry walls and floor surfaces, a DIY project that might cost about $1,700 for a full-size basement.
If there’s a potential for flooding in your basement, think twice about turning the space into a living area. Even a minor flood can ruin flooring and finishes, leading to expensive repairs.
Your best defense against minor flooding is a sump pump. A sump pump automatically engages in the event of a flood and is about a $1,400 investment with professional installation. Because sump pumps run on a dedicate electrical circuit from the service panel, you might also consider a battery-operated backup pump (around $300) to engage in the event of a power outage, such as during a severe storm.
Heating and cooling your remodeled basement
Your next task is to extend or supplement your home’s heating, cooling, and ventilation systems to serve the below-grade spaces. Those systems also requires code compliance for occupant health and safety (such as adequate venting of furnace combustion gasses), though typically nothing out of the ordinary or restricted by most jurisdictions.
With your contractor, make sure that your existing HVAC system can adequately keep your additional living space comfortable and properly ventilated. Sizing a furnace and air conditioner is a calculation generally based on square footage per ton of capacity. However, contractors should consider the home’s insulation values and other high-performance building practices to “right-size” the equipment and balance its performance and cost.
If your existing HVAC setup is not up to the task, you may have to add a secondary system dedicated to your finished basement or replace your existing system with larger-capacity equipment. Installing a vented room air conditioner and heater may add a few thousand dollars to your budget, while a complete HVAC system upgrade can run $10,000 or more.
A usable basement will also need electricity for lighting and other fixtures or finishes, such as an entertainment system or small appliances. Most homes will have adequate capacity in their existing electrical service box for basic needs; if not, a subpanel may be required to bring power to your retreat at a cost of a few hundred dollars.
Adding a bathroom
The last big (and also potentially expensive) consideration is whether to add a bathroom to your basement retreat. The main issue here is draining wastewater to the existing city sewer or on-site septic system, and venting sewer gasses directly to the outside–just as your other bathrooms do–in compliance with building codes. That’s why a bathroom alone might be a $10,000 line item in your basement retreat budget.
Wastewater drainage typically relies on gravity, so you have to make sure that the waste pipes from your basement bathroom sink, shower or tub, and toilet are designed with enough of a slope (or “fall”) to drain properly and effectively. Achieving proper fall will require the removal and rebuilding of a small section of the basement slab and excavation of the ground underneath. The process involves digging a trench for the drainage pipe to connect the new bathroom to your home’s existing drainage system.
For the toilet, you might also consider a pressure-assisted toilet (http://www.wisegeek.com/what-is-a-pressure-assisted-toilet.htm). A toilet equipped with a pressure valve forces waste through the pipes, rather than relying only on gravity to do the job. Such a unit may allow you to avoid digging into the foundation-consult with a licensed plumber about the feasibility. Expect to pay $150-$800 for a pressurized toilet.
If possible, locate the toilet (and any water-using appliance, such as a clothes washer) against an outside wall. This location will reduce the costs required to drain away waste and vent sewer gasses. Vents typically are required to extend up the wall (either through the structure or along the outside) to a height of at least 8 feet and at least 4 feet from any operable windows.
Converting your basement into finished living area calls for a contractor familiar with the special requirements of basement remodeling. When looking for a contractor, be sure to find one who has experience as a basement remodeler.
Rich Binsacca has been writing about housing and home improvement since 1987. He’s the author of 12 books on various home-related topics, is currently a contributing editor for Builder and EcoHome magazines, and has written articles for such magazines as Remodeling, Home, and Architectural Record. He still has the plans and cost estimate for the addition of a finished basement to a previous house, which required digging out the crawl space to create a full-height room.
Reprinted from HouseLogic (houselogic.com) with permission of the NATIONAL ASSOCIATION OF REALTORS®
Copyright 2009. All rights reserved.