We had our back porch cement floor painted. The guy said if the cement was poured without a moisture barrier the paint would peel. The cement floor in garage has a barrier and the paint hasn't peeled but the back porch floor peeled in a month. Moisture is in the cement if it has no moisture barrier underneath. We scraped the back porch floor smooth and have to leave it natural cement because of the no barrier. Who pours cement flooring with no moisture barrier? DH asked the previous owner/builder why did he do such a stupid thing. His reply was he saved money because it was just a porch floor.