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  1. #1
    Join Date
    Dec 2012
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    2

    Default Repointing for 1890 historic home after Superstorm Sandy

    We have an 1890 historic Victorian that has a red brick foundation. Many mortar joints were loosened by the flooding from Hurricane Sandy. I hired a mason who has raked and cleaned the mortar and it is prepped for repointing. The question is what to use?

    From what I have researched it seems that type N would be the best fit. The home is located 3 blocks from the ocean and has about a 3 ft crawl space. It doesn't appear that the brick has ever been repointed before and it is in generally good condition. They are structural walls and the exterior is covered by a wrap around porch. I also read that type O would be a good fit but it doesn't seem right for structural walls.

    I have read varying opinions with regard to the type of mortar that may currently exist. Some say that homes between 1890 to 1930 would likely contain a mix of lime, sand and Portland concrete. Others have said that Portland may not have been readily used until later. Evidence suggests the home was built between 1885 to 1895. The fact that much of the mortar is still in great shape and is still relatively hard makes me think that it was not just a lime/sand mortar and that there was Portland added to the sand and lime. Is there any way of knowing without extensive testing as to mortar type?

    The foundation is not visible from the outside so I am not concerned about the appearance as much as the structural integrity. Thanks for any input.

  2. #2
    Join Date
    Jun 2009
    Posts
    254

    Default Re: Repointing for 1890 historic home after Superstorm Sandy

    The mortar in your area could have contained Portland cement in 1890 being portland was inducted in about 1864 and in your area it may have been before that.
    As for a repair mortar a type " O " should work ok given the age of existing.
    See if you can research this site MC2 Estimators Reference it will give you all the ASTM Test status for the mortar mixes.
    Keep in mind that the ASTM Test are based on MINIMUM STANDARDS and a type " N " mix is 750 PSI min but may reach 2400 PSI.
    Type " O " is 350 PSI Min. but may reach 1800 PSI.
    MY guess is all the current mixes will exceed the Minimum reaching the max.PSI.
    Your problem in the long run is going to be the SALT content that will remain in the brick substrate.
    I have not found a means of stopping the salt migration after repairs are made. Salts and moisture will cause all mortars to fail after many years.
    You can also get the Historical Type O premix it is sold as 1-2-9
    and 9-2-1 these numbers stand for 1 part cement 2 parts Lime & 9 sand.

  3. #3
    Join Date
    Dec 2012
    Posts
    2

    Default Re: Repointing for 1890 historic home after Superstorm Sandy

    Thanks Clarence. I read that type O is great for repointing but is not to be used on load bearing walls just above grade, non load bearing. Opinions seem to vary greatly from article to article and blog to blog. I read on one blog that type O is pretty much the same as type N. .I gather that when the home was built in 1890 it had a ratio very similar to O and has been standing strongly for 120 years so the psi factor comes less into play?

    I have no masonry background and am doing the research as we go so bear with me. It seems to be what I am hearing and reading is that the most important part is to try to match the mortar type.

  4. #4
    Join Date
    Jun 2009
    Posts
    254

    Default Re: Repointing for 1890 historic home after Superstorm Sandy

    I am working on a building along the coast and not more than 100 ft. from the harbor it is interior and below grade.
    The Engeneer has specified the following mixture to be used.
    1 cement " White cement "
    1 lime " Type S "
    7 to 9 sand
    I had this mixture premixed just outside of Atlanta , GA.
    The company was A. W. Cook
    I used the following 1-1-8 this makes the sand fall in the middle of the required amount.
    This mixture has not been tested under ASTM standards but my guesss is that it will reach 1800 PSI and higher.
    The brick on this job are in the range of 5000 PSI & up.
    Question did the Mason rake the joints to a depth of about 1 1/2 inch ?.
    Also this Engeneer will not allow GROUT BAGS OR GROUT GUNS TO BE USED IT IS ALL HAND FILLED AND PACKED WITH POINTING TOOLS.
    IF you find a mixture that you like A. W. Cook will blend it for you using this proceedure will require that you purchase the complete hopper which is 112 bags weight of 50 lbs ea.
    cost should not exceed $1600.00.

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