Jump to content

What causes the chimney crown to float?


Recommended Posts

I've seen this and repaired one with mortar once. The masonry flue is supporting the concrete crown.

The chimney is straight and on a concrete footing. Bit of a creek behind the house, but a dry crawl. This is an extreme case, and I would like to understand better what has happened.

Built in '88.

Click to Enlarge
tn_20153182129_Image1.jpg

87.77 KB

Click to Enlarge
tn_201531821228_image2.jpg

75.77 KB

Click to Enlarge
tn_201531821243_Dscn9931.jpg

69.5 KB

Click to Enlarge
tn_201531821259_Dscn9952.jpg

50.82 KB

Click to Enlarge
tn_201531821331_Dscn9930.jpg

62.23 KB

Link to post
Share on other sites

Fired clay products like brick and flue liners expand as they absorb water. Concrete based products like block shrink as they cure. If the crown is bonded to the flue liner movement cannot occur so a mortar joint gives way. I have seen this even on chimneys that were never used.

Link to post
Share on other sites

What is required and what the mason actually did are usually two different things. Like Mark wrote, the crown was sealed to the clay flue which lifted up due to expansion while the block of the chimney did not lift. I like how it actually broke the one block loose and lifted that block also. Good pics.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...