A semi-dry stone wall is an excellent choice for a retaining wall. It is more expensive than timbers but less expensive than brick. These walls have some cement in the joints but porous enough to allow for drainage and freezing. For this reason, and the fact that the wall is slightly wider at the base, a much smaller footing is needed for a semi-dry wall. A stone wall can be capped with flagstone or a natural cap can be constructed of the same wall stone. In a solid stone wall, each stone is encased entirely in cement. There is no allowance for freezing, and a concrete footing is necessary, making this method much more expensive than semi-dry wall.