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How to patch a limestone flag?

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Posted 2013-08-22T15:21:17+0000  by john_bellerose john_bellerose

Hi john_bellerose,


Thank you for your question and welcome to our community.  Were you trying to patch a limestone or a flagstone?  Either one will require the same amount of care when breaking up the mortar and damaged stone. 




Here are some tools you will need:



Cold Chisel


Grout bag



Shop Vacuum

Replacement flagstone



Step one:

Break up the mortar that is around the damaged stone with your chisel.  I like to use a 3 lb. hammer as well as a heavy framing hammer.  Be sure to position your chisel so that you are toward the damaged section of stone.  This way you will minimize any damaged to the surrounding stones.


Step two:

Once the damaged mortar & stone have been broken up, remove it.  If the stone has been broken up into smaller pieces, it will be much easier to remove.  Remember that you are doing surgery here, not demolition!


Step Three:

Once the damaged stone and mortar have been removed, clean any leftover pieces of stone and mortar from the area you are going to repair.  Take the piece of stone you are going to use as a replacement and shape the stone to fit the area to be repaired.  Use you hammer and chisel to shape the stone into the approximate shape of the old stone.  You will want the stone to be the same depth as the old stone so that it will be level with the rest of the stones. 


Step four:

Dampen the inside of the hole using a spray bottle.  Prepare you mortar and spread it along the bottom of the hole.  The mortar should be thick enough to allow you to press he stone into the mortar and make the stone level with the surrounding stones.  Take the flagstone you just shaped and press I firmly into the hole.  Use you straight edge to make sure that he replacement stone is level with the surrounding stones.   If the stone is level, allow the mortar in the hole to dry for 24 hours. 


Step Five:

Mix another batch of mortar to use in your grout bag.  Make sure that your mortar is thin enough to flow thru your grout bag.  Take your spray bottle and dampen the area around the flagstone.  With your mortar bag, fill the joints around the flagstone.  Use your trowel to smooth the mortar our around the joints.   Let the mortar dry overnight. 


Be sure to take pictures of your project from start to finish and share them with the rest of our community in our Project Library under "I Did This".


Please let us know if you have any further questions.


This has been another of;


Posted 2013-08-31T00:05:44+0000  by Rick_HD_OC
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