Adding a basement can be economical way to increase space

Imagine adding 1,000 square feet of unfinished space to your home for only $60,000. Even in this time of deep discounts due to our country's economic problems, $60 per square foot would be dirt cheap for an addition to your home.

But that's all it costs to convert a crawl space under a home to a full basement, according to Nick Miulli of N & M Concrete Construction of Bloomingdale.

That includes the excavation, walls, floors, I-beams, supports, window wells, drain tiles and a sump pit. It does not, however, include any of the necessary plumbing, HVAC or electrical, exterior access doors, finishing touches or even stairs to access the newly created space.

And the transformation doesn't take very long to accomplish, either. Expect to have your life mildly disrupted and your yard torn up for 10 days to two weeks.

You don't even have to move out of your house.

On the other hand, the time involved in then finishing the new space, depending upon how fancy you decide to make it, will probably take months. N & M Construction has a sister company which finishes many of the new basements they construct.

Jon and Twila Radford of Mount Prospect said that they debated for several years about whether they should increase the size of their ranch home by adding a second floor or digging a basement.

"We had been to our friends' houses and discovered that the kids always like to hang out in the basement while the adults were on the first floor," Twila explained. "We have two boys and boys generally don't like to hang out in their bedrooms. They want to be somewhere with more floor space - like a basement."

Besides, when they had gotten several quotes for a second floor addition three or four years before, they ranged from $150,000 to $250,000.

So, after thoroughly checking references on the concrete contractor, the Radfords decided to go the basement route.

"I didn't know anyone who had ever done this and I was nervous about the house falling into the hole or something," Twila admitted. "But we saw two other houses N & M had done and talked to the homeowners who just raved about the great work and lack of problems."

Work on the Radford basement took 11 days in 2007.

"It was noisy but we were able to stay in the house," Jon recalled. "They dug a trench in our yard, cut into the old foundation and had two Bobcats working, digging it out from the middle and slowly working outward, inserting steel jacks to hold up the house."

"I was inside the house with the kids every day, except the first three when we were out of town, and there weren't even any fumes from the Bobcats," Twila said. "It was an amazing process and they had a full crew here 12 hours a day so they could get it all done quickly."

"Adding on a family room eight years ago was much more stressful," she added.

The dirtiest and noisiest part was when the N & M crew had to carefully jackhammer through the slab under the Radfords' old laundry room to make room for the staircase. Since it was attached to the slab under their family room addition, it was a tricky process. But the operation was successful, Jon said.

"We just put up plastic drapes to shield the rest of the house," Twila explained. "You have to realize that no one can do an addition and not expect it to be noisy and dirty. This was very minor."

And before the crew left, they went through the house, making sure all of the windows and doors closed correctly and checking for any cracks caused by settling. The few minor cracks they found, they patched. They also backfilled, graded and sodded the trench they had dug in the yard.

Julie and Jeff Nelson of Arlington Heights had a similar experience when they had their crawl space converted to a basement in 2004.

"We put in the basement and then later did a second floor addition," Julie said.

The Nelsons had looked at buying another house but most of the older homes in Arlington Heights have low basement ceilings that would make actually using the space uncomfortable.

"So we decided to convert our crawl space into a basement so that we could have what we wanted and have it be comfortable to actually use," she explained.

"The whole process of them digging the basement was surreal. It was so fast with that tiny Bobcat and the support structures," Nelson said. "Digging the basement was definitely worth the investment. It absolutely added lots of value to our home. We know that when we go to sell the house we would never get the full worth out of our second floor addition if we didn't also have a basement."

In order to convert a crawl space to a basement, N & M Concrete Construction digs a ramp to the foundation with a Bobcat and then cuts a hole in the existing foundation so that the Bobcat can get under the house, according to Miulli, who is in business with his father, Mike.

The process they use has been perfected during Mike's 50 years in the concrete business and 30 years of converting crawl spaces to basements.

Once they begin digging under the house, Nick said that they insert jack posts every 5 feet under the home's old footings to hold it up. Most of the digging is done by the Bobcats, but some is done by hand.

The posts put up along the perimeter get incorporated into the concrete. Other posts are temporary.

Slightly inside the old footings they sink new, deeper footings for the new basement walls and tie them into the original footings with rebar, or reinforcing bars. An I-beam, supported by posts set on top of concrete pads, is run down the middle of the house to support it over the new basement.

Next they put up the foundation forms, but unlike the forms for a new construction basement, these can only be built from one side. So the concrete is poured against the form on one side and the dirt and original footing on the other side. Wall thicknesses are at least 8 inches, but in some places, due to the shifting of dirt, they may be as thick as 16 inches, Nick said.

Once the foundation forms and braces are removed, they set the drain tiles, dig a sump pit and put a foot of gravel and wire mesh down in preparation for the floor to be poured.

Then the floor is poured and the original ramp is back filled and graded.

"The house will inevitably settle some and we can jack up areas a bit if necessary to level the floors above," Miulli said. "In addition, if we notice any cracks in the original foundation wall when we get there, we call in someone to seal those cracks so the homeowners don't have problems later with water in their new basement."

While this work cannot be done year-round, it can be done from roughly March through late November, according to Miulli.

N & M Concrete Construction can be reached at (630) 936-0416.