type of mortar for tuckpointing


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Old 11-28-06, 07:28 AM
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type of mortar for tuckpointing

need to do some minor tuckpointing on the outside portion of a brick chimney. What type of tool / technique is recommended for removal of loose or cracked mortar and to prep the joints? What type of mortar should I be using to fill the joints? Thanks in advance for your help - as long as I am putting in the labor, I would like to ensure I do the job right.
 
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Old 11-29-06, 06:52 PM
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There are a lot of variables involved. Some questions:

What is the existing mortar (how old, color, hardness, state of deterioration).

Everything else is predicated on that, so give more info, and I will give you more tips on how to fix it. It isn't hard or expensive to do, but it can be tedious.
 
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Old 11-30-06, 11:42 AM
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follow up info

Existing mortar is 30 years old - bricks are red clay. Tuckpointing and some brick replacement was done about 10 years ago, at which time a stainless steel chimney liner was added.

deterioration consists of cracks in mortar joints with some pop-out of related mortar. Cracks less than 1/8" - located at or near joint centerline. Adhesion of mortar to bricks still good.

mortar is solid in areas not cracked.

Chimney masonry cap does not have a decent drip edge - would like to add this as well.

Let me know if I've missed anything - I appreciate the feedback.
 
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Old 11-30-06, 04:44 PM
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Use a Type O mortar, consisting of Portland/Lime/Sand in a 1/2/9 ratio by volume. This is a low compressive, high flexural and bond strength mortar. Be sure to use Type S lime. You can use a 4" angle grinder to remove the old mortar, but in no case should you grind out less than the width of the joint for replacement, and you don't need much more ( a standard 3/8" brick joint should be "dug out" to a depth of 3/8-1/2"). Be sure to remove the dust before you begin repointing the wall and also to tool the joint to match the existing joint profile. If you want the joints to match, you can mix up just the portland/lime into a slurry and rub it into all the joints for an even color, or you can just let them age for a year and they will match just fine.
 
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Old 12-01-06, 12:00 PM
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sweet. Thanks for the info - will do.

Is there a special wheel for the angle grinder that is appropriate for masonry removal? I figure I'll check the supply catalogs and see if any wheels are rated for masonry.

I'll let you all know how it turns out.
 
 

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