best mortar for repointing a chimney

jared123

what is the best mortar to repoint a brick chimney with? can i use FSB fiberglass bonding cement? ive heard if you use the wrong stuff the bricks can crack because of expansion/ contraction. any reccomendations would be helpful, thanks. also i have raked joints on the exterior but theyre not falling apart yet. only a few small holes and gaps. can i just put the mortar right over the old stuff or do i have to scrape it out first?

Bud Cline

You should remove 1/3 to 1/2 the depth of the whole joint. Tuck it with brick mortar. Press it in tight.

Windows

In most cases when repointing, you want to use a mortar that has similar properties to the original mortar. THis is mostly an issue with historic brickwork. And they say that if you really have to work to rake out the old mortar, then you are better off leaving it alone.

Linn

Sorry I may be in the wrong place here but anyway I need help with the right mortar mix. I am re-pointing 100 year old brick have type N mortar and mason sand but keep seeing lime should be added I don't have it will I be ok?

oh'mike

Linn---Please start a new thread---you will get the best attention that way---Mike---

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smax21

Hi Linn,

Be sure to find out what the makeup of your mortar is before you begin repointing. For a home that is 100 years old it will most likely have been built with a lime mortar containing no harmful Portland Cement. Your brick may be too soft for any mortar mix that contains Portland Cement. Get in touch if you have further questions.

Sean