it will NOT add 3 oz, my Gladiator, the 720 sq in version, has one foam brushed coat and one sprayed coat totally 2 oz. Had I only sprayed I think is would have been 1 or just a tad over 1 oz. Mike is right, thinning much more that the instructions say is necessary. the only caution I put out there is when you spray, be extremely careful, even though this stuff kicks pretty fast, (the higher the humidity the faster) it also flows readily until the cure starts and it will run and sag.