Stone chimney repair specialists for Plymouth homes

What the code says about adhered stone veneer

Section R703.12 of the residential code covers adhered masonry veneer, the category manufactured stone falls into. It accepts the manufacturer's instructions as one installation route, and on framed walls it pairs the veneer with a water-resistive barrier plus a screed or flashing that resists corrosion at the foundation line.

In practice, that makes the maker's installation guide the working document for repairs too. We follow the guide for the stone on your chimney when one is known, and the general standard practice when the product cannot be identified.

The weep screed at the bottom of the stone

On framed walls, a corrosion-resistant weep screed at the base of the veneer gives water behind the stone a way out. The same maker notes that most building codes require one in framed applications and that the barrier laps over its flange.

A screed that is buried, painted over, mortared shut or missing traps water inside the wall. We check the base of every veneer chimney and describe what we find, since loose stones near the bottom of a chase often trace back to this detail.

Handling mortar smears on the stone

Accidental smears and droppings on the face of manufactured stone should be removed only after the mortar has become crumbly, using a whisk broom or dry bristle brush, according to the maker. A wet brush or wire brush is never used, since it can cause staining that may be impossible to remove.

We protect finished stone below the work area and brush smears at the right moment. It is slower than wiping them away wet, and it keeps the face of your stone clean.

How deep to rake out stone joints

The National Park Service's Preservation Brief 2 sets the raking depth at 2 to 2 and a half times the joint width as a minimum, so new mortar bonds and stays put. For stone masonry with wide joints, that can mean several inches.

Loose or crumbling mortar beyond that depth also comes out. The brief shows new mortar falling out of a joint that was not prepared deeply enough. We rake to a sound depth and show you the prepared joints before filling.

• At least 2 to 2 and a half times the joint width
• Deeper where mortar is loose
• Square back so new mortar locks in

Tooling timing and joint color

When the last layer is thumbprint hard, the joint is tooled to match the existing profile. According to the brief, early tooling dries paler and risks fine cracks, and late tooling marks the joint with dark tool burning and fails to seal tight to the stone.

Our masons check joints by hand as they go, so each area is tooled at the right moment. Consistent timing is how the joint color stays even across a repair.