Horizontal wires add strength. If you don't use them, the extract with care and keep the comb warm. You can get away without any foundation at all, if you want. I experimented, and continue to do so, with waxed-wire frames. The technique is to put two or three (3 is better) coat-hanger guage wires horizontally in each frame and to coat them with bees' wax. The bees will build comb hanging down from the strip of bees' wax on the underside of the top-bar and from each of the wires. As the combs grow downwards, they coalesce into a complete frame of comb. The resulting combs are strong enough to run through both tangential and radial extractors. The main problem is that you must keep the hives exactly horizontal accross (along doesn't matter) the frames so that the combs hang exactly vertically as the bees build them. If the combs hang askew to the end bars, then the comb isn't flat and you may get a mess. I do warn you, that bees, as perverse as they are, may not follow your waxed-wire instructions. But, it has worked for me, most of the time! I learned this trick from a beekeeper near LaBufa, Chihuahua, Mexico.