Pre-topped vs. Field-topped — Which option is better for a precast garage?

Pre-topped vs. Field-topped — Which option is better for a precast garage?

May 2, 2018

Originally published on LinkedIn by Sunil Puri, PE, Principal & Senior Project Manager of Walter P Moore's Diagnostics Group in Atlanta

For precast parking structures, there are two types of construction systems for floor surfaces – pre-topped and field-topped. Building code requirements for supporting concentrated loads along with requirements for providing fire resistance, necessitate a 4 in. to 5 in. total flange thickness for precast double-tee members. This thickness can be attained with either a single monolithic placement at the precast plant (identified as pre-topped construction) or by using two-layer construction, with an initial 2-in. thick plant-cast flange overlayed with a 2 in. to 3 in. concrete topping (known as field-topped) after the erection of precast members onsite. MOORE...