Some volunteers have been working for five years or more.

Today, 30 staff members and 50 volunteers work in the center.

Up to 400 such volunteers may work on a house at different times.

"Most volunteers are working full time and have one or two children," he says.

Instead, individual volunteers work on what they are interested in, or have available.

More than 200 international volunteers have worked at the site, in addition to American researchers and students.

It has become a community event, with volunteers and staff working together each year.

Most volunteers worked a maximum of 10 hours per day.

He noted that volunteers worked throughout the project, doing whatever was needed.

The volunteers work all over the country, a total of 120,000 by one estimate.