Natural Stone Floors: Flagstone

Flagstone walkway and decks have become increasingly popular as more homeowners want their backyards to become lush, intimate spaces. But creating a natural look takes attention to detail. Installing flagstone in a yard might seem a daunting and expensive task, but the project can be rewarding -- and affordable -- if homeowners do their homework and don't mind getting dirty.

Flagstone is defined as thin slabs of stone used for paving walks, driveways, patios, garden sitting areas, etc. Flagstone is a natural rock that is sold in irregular shapes and various thicknesses and colors. The rock is mined in all parts of the world. It is generally fine-grained sandstone, bluestone, quartzite, or slate, but thin slabs of other stones may be used. Real flagstone is the result of sand that has been compressed over thousands of years. It has a rough, porous texture that feels like sandpaper, and it comes in shades of pink and red. Quartzite is sandstone that has, over time, been converted into a solid quartz rock. Because it is not porous, it has a smoother surface than flagstone. Quartzite usually is gray, green or white. Slate is a fine-grained rock made from clay. It usually is black, purple, blue, green or a mixture of dark colors. The stone may be irregularly shaped as it was quarried, varying in size from 1 to 4 square feet, or the edges may be sawed to give a more formal appearance. Thickness may vary from ½ to 4 inches; therefore the flagstone must be set in a thick mortar base in order to produce a level surface.

The trickiest part of installing flagstone is deciding which piece to place first. The irregular shapes make this a daunting task. A flagstone deck consists of hundreds of pieces, fitting together like a jigsaw puzzle. Craftspeople must take these stones of various colors, shapes and sizes, and compose a finished product that looks balanced and natural. The stones also must be fit together so they leave the right joint sizes.

Another point to remember with flagstone is that the surface is usually slightly uneven because it comes from naturally cleaved rock; therefore, flagstone is not suitable for use under tables and chairs as the legs will rock. An entrance hall of flagstone is very durable but needs to be protected from grease.

When the flagstone deck is finished, acid wash the surface to eliminate concrete residue and drippings. Use a sprayer to apply the acid solution evenly. You can seal the deck for more durability. This especially helps with softer stones, such as Arizona flagstone, which tend to get crumbly over time. There are sealing compounds on the market that make flagstone impervious to any staining and wear. These compounds are available in gloss and matte finishes and protect the treated surface against the deteriorating effects of weathering, salts, acids, alkalizes, oil, grease. The finish does seem to give a rather unnatural shiny appearance to the stone but where the impervious quality rather than the aesthetic quality is of prime importance, these sealers many be used. Vacuuming will remove dust and siliceous material from the surface and a damp mop will remove any other soil from the sealed surface.

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