Slipform Stone Building

by Chuck Hall

Nothing says ‘stately elegance’ like a home made of stone. Stone has been used as a building material for thousands of years, but traditionally homes of stone have been built by highly-trained masons with years of experience. But in recent years, a technique called ‘slipform building’ is regaining interest, making it possible for people with little or no stoneworking talent to build their own stone homes.

Traditional stone masonry involves a laborious practice of selecting and fitting stones by hand using mortar. Each stone is carefully cemented into place individually. Slipform stone masonry uses a much easier approach. Forms about two feet tall are placed directly on the foundation, then about three or four inches of concrete is poured into the form. Stones are then put into the form, more concrete is added, and so on until the top of the form is reached. The walls are allowed to dry, then the forms are removed and ‘slipped’ up another two feet, where the process is repeated.

One major advantage that slipform stone building has over other do-it-yourself green building techniques is that most building inspectors will accept it as a form of masonry. Masonry is covered by all building codes, so you may not have to obtain the services of an architect or engineer to get your plans passed. Another advantage is that if you have a lot of suitable stone on your property, and don’t mind a little sweat equity, you can build your own home very inexpensively.

While stone is a poor insulator, it has a lot of thermal mass. The denser the stone, the more heat-storing properties it possesses. It stores heat when it’s not needed, and radiates it back into the building when it is needed. When this property is used in conjunction with passive solar techniques, it can greatly reduce your heating and cooling costs if you live in a temperate zone.

Now for the bad news…while stone homes have a lot of thermal mass, are durable, attractive and insect-proof, building such a home is not for the impatient or the frail. Moving stones all day is a labor-intensive process. Some stones approach a weight of 100 pounds per square foot, so it helps to have a strong back. The most you can hope for is about two feet of wall height per day, since the walls have to set before you can move the forms up to the next level. But if you have patience and endurance, a beautiful home of stone can be yours.

A good site on slipform building, with lots of pictures, is Heartbeat Nursery’s site in New Zealand at: www.heartbeatnursery.co.nz/stonehouse/index.html. I would also recommend Tomm Stanley’s book, Stone House: A Guide to Self-building with Slipforms.