Loose stones reset and joints repointed on Oakland chimneys

The top of a solid stone chimney

Section R1003.9.1 of the residential code tops a masonry chimney with concrete, metal or stone, edged with a drip, and seals a bond break with caulk at every flue liner per ASTM C1283. A stone chimney is covered by that rule.

A cracked cap, a missing drip edge or a failed bond break lets water into the top courses, where it works down behind the stone. We inspect the top every time and quote cap or crown work separately from the stone.

Matching the sand in the old mortar

Sand is the largest ingredient in mortar by volume, and the brief notes that the color and texture of new mortar will usually fall into place if the sand is matched successfully.

We look at the old joints closely, sometimes breaking off a sample to see the sand grains. Then we compare sands and test batches until the match is close. That extra care at the start keeps the repair from reading as a patch for years afterward.

Removing caulk and sealant from joints

Caulk pressed into stone joints is a common quick fix for a leak. It seals the joint face while water still moves behind it, it stains stone as it ages and it leaves a surface that new mortar will not bond to.

We cut caulk out completely, scrape the residue off the stone edges and rake the joint to sound mortar before repointing. If the caulk was hiding a leak, the leak goes into the findings with its source.

What a stone chimney estimate lists

A clear stone estimate separates the work so you can see and approve each part. Ours list the stones to reset or replace, the joints to repoint and how deep, the mortar type and how it will be matched, and any access equipment.

Cap, crown, flashing, drainage and flue items sit on their own lines beside the stone work. Each has its own price, and the total does not change later without your approval.

• Stones to reset or replace
• Joints to repoint and depth
• Mortar type and color match
• Access and site protection
• Related items on their own lines

Drainage gaps behind stone veneer

Some wall systems add a small drainage gap, a rainscreen, behind the veneer. The maker's instructions we follow describe it as optional in general and required by some building codes, with a space of 3/16 inch to 3/4 inch and materials that resist corrosion and rot.

Where a chase is being re-clad, we discuss whether a drainage gap makes sense for your chimney and what it adds, and we follow the local requirement for your address.