A zero-pad can be used with orthogonal frequency division multiplexing (OFDM) for low-complexity robustness against multipath interference. In this paper, we use adaptive overlap-add (OLA) equalization for improvements of up to 0.6 dB improvement when used with multi-band OFDM (MB-OFDM) ultra-wideband in multipath channels. A theoretical model that relates the size of OLA window to post-equalizer signal-to-noise ratio is derived. An approximating algorithm is then developed that is suitable for low-complexity implementation, with Monte Carlo simulations used to quantify the performance improvements. We conclude that adaptive OLA equalization is computationally simple and can be implemented while remaining fully compliant with the MB-OFDM standard.