How to Fix Crumbling Chimney Mortar

By eHow Home & Garden Editor

Rate: (14 Ratings)

Avoid extensive, costly damage to a masonry chimney. Maintain the mortar joints by tuck-pointing (repointing) them, and make sure the chimney crown remains sealed against water.

Instructions

Difficulty: Challenging

Things You’ll Need:

  • Crown Repair And Sealing Material
  • Jointing Tool
  • Brick Trowel
  • Mortar Mix
  • Soft Brush
  • Cement-mixing Container And Hoe
  • Grinder With Tuck-pointing Attachment And Blades
  • High-temperature Caulk And Caulking Gun
  • Ladders Or Scaffolding
  • Mason's Hammer And Chisel
  • Pointing Trowel
  • Scraper
  • Square Mason's Trowel Or Board

Tuck-pointing masonry joints

Step1
Work from the bottom up to remove loose mortar a few feet (a meter or so) at a time. Set up ladders or scaffolding if necessary. Use a mason's hammer and chisel, a scraper and similar hand tools for difficult-to-reach areas. For extensive tuck-pointing, rent an electric grinder with a tuck-pointing attachment and blades.
Step2
Mix water into a packaged mortar mix as directed on the label, using a cement-mixing container and hoe.
Step3
Apply the mortar by first loading the bottom side of a square mason's trowel (or a board) with mortar (see A). Then, holding the trowel against the chimney just below the joint you're filling, slice off a portion of the mortar with a pointing trowel and pack it into the joint.
Step4
When the joints in an area are all full, strike off the excess by slicing through the mortar with a brick trowel held flat against the bricks.
Step5
Compress, shape and smooth the joint. Run a jointing tool across the joints for concave and V joints (see B). Or use the tip of a pointing trowel to create a 30-degree bevel from the underside of the upper course to the edge of the lower course. Knock off any excess and move up to the next section.
Step6
When the joints have set up, clean the face of the brick with a soft brush.

Repairing a chimney crown

Step1
If a traditional crown made of portland cement and sand is badly eroded or cracked, replace it with a modern (crown-sealer) system. These coatings, which you can apply with a trowel (following the manufacturer's instructions), remain flexible and provide a far superior water seal. If the crown has some cracks and is beginning to show wear, or even if a masonry crown is in good condition, consider using this material as part of an overall chimney repair.
Step2
Seal joints between the clay flue's liner and the crown with high-temperature caulk.

Tips & Warnings

  • For very minor tuck-pointing repairs, use mortar-patching material in caulking-gun cartridges.
  • Exercise caution and follow proper safety procedures when working on a ladder or scaffolding.

Comments

| View All Comments
flashover

flashover said

Flag This Comment

on 5/11/2008 I have a severely deteriorated chimney crown. I need to know how to recover the open void area between the chimney liner and the brick

Mehdi

Mehdi said

Flag This Comment

on 2/12/2007 very helpful thanks

View All

Post a Comment

POST A COMMENT

Request a New How-To Article

Looking for more How To information? Chances are there’s an eHow member who knows how to do what you’re looking to do. Submit an article request now!

eHow Article: How to Fix Crumbling Chimney Mortar

eHow Home & Garden Editor

eHow Home & Garden Editor

Category: Home & Garden

Articles: See my other articles

Related Ads

Home & Garden

Willi
Meet Willi Galloway eHow’s Home & Garden Expert.