Condos construction remains a hot activity in South Florida, even with perfectly useable units languishing on the side.

Southern Florida, and the many cities that decorate its sunny coast, experienced a landmark building boom at the start of the 21st century, and the Sunny Isle Beach was no exception, with hundreds of new condominium units springing up on a seemingly daily basis.

Those days are gone, now, and quite a few of those condos remain empty, remnants of a past economic time – yet, none of those facts seem to be slowing further condo construction, according to a new report from CondoVultures.

According to the report, three new condo buildings are currently in the works that would add more than 500 additional units to the Sunny Isle area. And they’re not alone — in addition, six more residential projects are at various developmental stages, which will collectively add another 450 condo units and townhouses to Sunny Isles.

It’s all part of a renewed boom in Florida home construction, CondoVultures reports: “Overall, the South Florida condo boom has generated nearly $4.1 billion in developer sales of newly created units in Sunny Isles Beach as of Sept. 30, 2011.”

And Sunny Isles is not the only Florida community with a fixation on new construction. In the tricounty region of Miami-Dade, Broward and Palm Beach, 13 additional towers with nearly 3,500 units are being proposed, according to CondoVulture.

As admirable as building euphoria can be, though, CondoVulture does quote some statistics that should give some pause. Between 2003 and 2011, developers sold nearly 5,700 condos at 9.2 million square feet of space, yet as of Nov. 1, 400 brand new units — in Sunny Isle alone — remain unsold, with some selling for as low as $200 per square foot.