The Inside Outside Guys: Finishing a lower level – getting it right

Ken Calverley and Chuck Breidenstein
Special to The Detroit News

Years ago The Guys heard a story about the owner of a new home looking for a contractor to “finish his basement” only to be repeatedly told by the building firms, “We don’t do basements”. It turns out this fellow was finishing 5000 square feet of a two-sided walkout on a piece of very expensive real estate. He spent $500,000 on his “basement”!

In the Midwest, the space in the basement is treasured by owners who pour untold amounts of money into them. Finishing a basement can range in cost from $30 per square foot to $70 or even more. But when you compare that to the $150-400 per square foot for main floor living area, it is a real bargain!

What issues should concern an owner anticipating a lower level finish?

Refinishing a basement takes a good plan.

Good floor planning is important. What functions will the space provide? Perhaps you want a party room, theater space, work space, additional bedrooms or a bathroom. Use blue painter’s tape to “map” out the plan on the basement floor including all doorways. Does the plan allow for furniture movement? Based on the plan, where will your mechanicals be located? Consider ease of access for future servicing.

Potential for active water is a big concern. Make sure you have a good system in place to take care of potential ground water, surface water or sewer back-ups. Good footing drain tiles and good surface water control above are critical. Rod holes or cracks in walls and floors should be sealed. Additionally, a backflow preventer in the main sanitary and storm sewer should be installed.

Moisture also needs to be considered. It can wick up through the floor or through the foundation sidewalls and potentially create the conditions for mold growth. Sealers should be applied to these surfaces to minimize this.

Egress is another issue. A habitable space must have at least two points of egress. The stairs coming down from above account for one of those but an additional, qualifying, means of egress like a window or door to the outside would also be needed. Also, every “sleeping room” must have a direct means of egress as described in the building code. SPC Glass Block is an excellent resource for egress windows.

Minimize organic materials that, when combined with moisture, oxygen and warmth, may contribute to the growth of molds. Untreated wood products used for framing should never come into direct contact with a masonry or concrete wall or floor. Construct exterior perimeter walls as free-standing, an inch or so away from the foundation walls and resting on a good capillary break such as PL400 or other construction adhesives. This will also create a “truer” wall that does not conform to the imperfections of the basement walls. Bottom plates on walls should be treated material or you could opt to have all metal (steel stud) framing.

Do not put visqueen on sidewalls. If any moisture should wick through the walls, you want it to dissipate, not be trapped behind plastic where it may condense and create issues.

An excellent thermal insulation is rigid foam glued directly to the foundation walls.

Drywall finishes should be installed just off the concrete floor, as should wood trims. MDF trim materials are a great substitute for wood, are easy to cut and accept paints really well.

Suspended ceilings should be your first choice to allow for design variability, sound deadening, and future access to mechanicals above the ceiling.

Mechanicals like plumbing, electrical and HVAC need to be well thought out in advance and installed by professionals to assure safety, function and comfort.

There are all kinds of non-organic finish flooring choices, from carpeting to vinyl plank flooring systems. You might also consider a custom floor finish like those installed by Motor City Floors and Coatings which will also seal the floor from moisture and potential contaminants.

“Finishing the basement” can provide great living value. But only if it is done correctly!

For more Home Improvement advice listen to the Inside Outside Guys every Saturday and Sunday on News/Talk 760, WJR-AM, from 10 a.m. - noon  or contact us at with your questions.