Gainesville's planning department has a new way to plant trees around town.

The city's code requires developers to plant a certain number of trees per acre, and planning staff realized those who don't meet the minimum requirement could contribute trees that can be planted around the city where needed.

Staff will soon propose the idea to the planning and appeals board to establish the City of Gainesville Tree Replacement Fund.

"There are rare occasions when the developer can't accommodate the required number of trees, and this will allow them to put money in a fund to plant trees on public property," said planning director Rusty Ligon. "We've seen the issue come up in the past and thought it could be a potential issue in the future. This is our solution, and it's a good idea to put it in the code to formalize it."

Currently, developers must plant 18 tree units per acre in commercial and industrial zones and 20 tree units in residential areas. A tree unit corresponds to the diameter of the tree, where trees 1 to 4 inches wide count as 0.3 of a tree unit and an 8-inch tree counts as one full unit.

"The idea is to weigh the value of preserving existing trees than go back and replace them all," Ligon said. "Typically developers go back with 2-inch caliper trees. With that diameter, four trees count as one unit."

Under the current code, developers who can't meet the tree unit requirement must make the development site larger or remove parking spaces in the lot to create planting islands.

The developer can also plant trees along public street rights-of-way or easements if the planning department approves it.

The new code will allow developers to contribute money for up to 50 percent of the number of trees they can't plant on the site.

Ligon and staff members are thinking of priority places around the city that could benefit from tree planting.

"We plan to work with Parks and Recreation for the areas in parks that can use some trees, and the greenway at Midtown could also benefit," he said. "We're immediately looking at possibilities for these trees."

Planning officials will also update the Unified Land Development Code to include new building definitions passed by state legislators in the spring.

Industrialized and residential industrialized buildings, which are structures designed and constructed in manufacturing facilities for installation on a building site, can now be constructed in more industrial and residential areas than previously allowed.

"These changes and updates happen periodically, and the legislature passed this to make the code modern," Ligon said. "By allowing these buildings in new areas, the change likely reflects what's happening in the economy."

Under new requirements for single-family and two-family detached dwellings, homes must have exterior siding that extends the full height of the exterior walls, be attached to a permanent foundation and have a minimum width of 20 feet.

Each exterior entrance must have a porch or hard-surfaced landing that is at least 36 inches wide and 36 inches long. Minimum roof overhang must be 12 inches, and each home must be connected to an approved water supply and sewage disposal system.