An ablation apparatus for ablating an inner layer in an organ or lumen of a body, or any desired thin layer, includes an expandable member made of a material with a porous exterior surface. An electrolytic solution, housed in an interior of the expandable member, releases electrolytic solution through the porous exterior surface. A conforming member, which can be an open cell foam material, has an RF conductive surface, and a back side in a surrounding relationship to an exterior surface of the expandable member. Further, the conforming member includes non-zone areas that have a first porosity rate for delivering electrolytic solution to the inner layer. The conforming member also includes a zone for housing each RF electrode and electrolytic solution. Zones have a second porosity rate that is less than the first porosity rate, thus permitting electrolytic solution to pass through the non-zone areas at a faster rate than in the zones. The zones provide an area where electrolytic solution is heated to a higher temperature, due to the differences in porosity with the non-zones. With the combination of the electrode and the heated electrolytic solution in each zone, a larger electrode is created, and there is a more effective, and even application of both RF and thermal energy to the tissue site, such as the endometrium.