Retaining wall contractorin Woburn, MA

When you need a wall, how to pick block, fieldstone or granite, what goes behind it, and what to do about a wall that is already leaning.

When a yard needs a retaining wall

A retaining wall holds soil at two different levels. Around Woburn and the towns north of Boston, plenty of yards were graded for the house and nothing else, which leaves a slope that is too steep to mow, a patio with nowhere flat to go, or a bank that sends mud onto the driveway every spring. You probably need a wall if:

• Soil or mulch washes down a slope after heavy rain
• You want a flat patio, pool deck or lawn on a sloped lot
• A driveway or walkway is cut into a bank that keeps sliding
• An existing wall is leaning, bulging or has stones falling out

Low walls that only edge a garden bed are a smaller job. Walls that hold back a real slope, a driveway or a pool deck are structural, and how they are built matters far more than how they look on day one.

Block, fieldstone or granite

We build retaining walls in three main materials, and each one has a place.

• Segmental block. Interlocking concrete wall block from Unilock and Techo-Bloc, which we install, along with Belgard. The units lock together course by course, and taller walls tie back into the soil with geogrid. Block handles height and load well and comes in colors and textures that range from smooth to a split stone face. The raised, block-faced side of the pool deck we built in Billerica is a good example.
• Natural fieldstone. Rounded New England fieldstone is the classic stone wall look around here. Each stone is picked and fitted by hand, so it takes more labor than block. The North Reading pool area is wrapped in round-fieldstone retaining walls we built, with granite steps set through the wall.
• Granite. Granite blocks, caps and steps are about as durable as wall material gets. Granite steps are often the best way to get through a wall to the level above.

Brick and stone veneer suit low garden and planter walls next to an older home. Timber sleeper walls are common in garden books, but wood that sits in wet ground eventually rots. The walls on our jobs are block and stone.

What is behind the wall matters most

Most retaining walls that fail don't fail because of the block or stone. They fail because water builds up behind them. Wet soil is heavy, and in winter it freezes and pushes. A wall built without a way to let that water out will lean, bulge or crack no matter what it is made of. Here is what goes into a wall built to last:

• A compacted base. The wall sits on a leveled, compacted crushed-stone pad, and the first course is buried below grade so the bottom can't kick out.
• Drainage stone and pipe. Clean crushed stone fills the space directly behind the wall, with a perforated pipe at the base that carries water out to daylight or a drain.
• Setback. Each course steps back slightly into the hill, so the wall leans into the soil it holds.
• Geogrid on taller walls. Past a certain height the block manufacturer's design calls for layers of geogrid that reach back into compacted soil and tie the wall to the hill.
• Caps. A well-built wall has its cap stones glued down, which finishes the top and keeps the upper course from shifting.

Leaning or failing retaining walls

If you have a wall that is tipping forward, bulging in the middle or dropping stones, the cause is almost always water, a missing base or a wall that was too tall for how it was built. Some walls can be taken down in sections and reset with proper drainage. Others need to come down and be rebuilt from the base. We will look at it, tell you which one it is and why, and give you a price for the fix. A failing wall next to a driveway, walkway or house shouldn't wait, because it usually gets worse each winter.

Permits, engineering and Dig Safe

Short garden walls usually don't need a permit. Taller walls, and walls that hold up a driveway, a slope or a structure above them, often need a building permit and a stamped design from an engineer. Your town's building department makes that call, and work near wetlands can also need conservation commission approval. We'll tell you at the estimate where your wall is likely to land.

Because every wall starts with a trench, buried utility lines are marked through Dig Safe before excavation, as Massachusetts law requires.

Walls as part of a bigger project

Many of the walls we build are there to make something else possible. A wall levels the ground for a patio, gives a pool deck a flat place to sit, turns a bank into terraced garden beds, or adds a seat wall along the edge of a fire pit area. In Lynnfield, a wall-block raised planting bed with granite steps frames the edge of a pool patio. When a wall is part of a patio or pool job, we plan the levels for both together so the drainage works across the whole yard. See more on our hardscaping and pool deck pages, or browse our landscape wall photos.

How the price of a retaining wall is decided

For a deeper look at each factor, see our retaining wall cost guide.

We price walls after seeing the site, because the cost depends on things you can't measure from a photo:

• The height and length of the wall, and whether it needs geogrid or an engineered design
• The material: block, fieldstone or granite
• How much digging, soil removal and backfill the site needs, and whether equipment can reach it
• Drainage, including where the pipe can drain to
• Steps, curves, corners and caps
• Taking down an old wall first

The visit is free, and you get a price before any work starts.

How to choose a retaining wall contractor

• Ask what goes behind the wall: what drainage stone, where the pipe drains, and how deep the base is.
• Ask when they use geogrid and when they bring in an engineer.
• Look at walls they built several years ago, not only new ones. A badly built wall looks fine for the first season.
• Get the price in writing and check that they are insured. Gerrior is family-owned, fully insured, and our work is guaranteed.