Few things are as inviting as a garden retaining wall in Mount Desert, Maine. You may be surprised to learn that stone is less expensive than you thought.

In some parts of the country, stone may cost slightly more than brick, but in other areas, brick is quite a bit more expensive. To choose the right stone, find out what's indigenous to your area of the country. (Shipping stone in from elsewhere is expensive.) Depending on your project, you can use softer, porous stones or stronger, hard ones.

Need to extend a retaining wall? Want to put an addition on your stone-faced home? It may be hard to match what you have. Ideally, remove some of the old stone so you can mix and match with the new.

For fireplace surrounds, home exteriors, front porches and similar applications, mortar holds the stones in place. When using bigger, heavier stones for walkways and retaining walls, mortar isn't necessary. Instead, the standard method is to drystack using sand or sandy loam.

Maintenance isn't a big issue with stone. Properly applied, mortar should last as long as the stone, at least 40 or 50 years. But if it's falling out, it needs to be repointed. Afterward, use a sealer. In the past, sealers were taboo for stone because they didn't allow stones to breathe. But the new generation of sealers aren't acrylic- or urethane-based. Instead, they shrink the pores of the stone to keep water and oil out but still allow air to move through.

A sealed stone wall can still stain, but it's far easier to clean. Water and a scrub brush should do fine. If you need more help, turn to a mild dish washing detergent. Be sure to rinse thoroughly, though, or the soap residue will attract more dirt. If that doesn't work, click on the Find a Contractor link on the Reply! home page for contractors in your area who clean stone.