Proper cement used for chimney repair?

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Henry G

New Member
Aug 25, 2008
28
Washington Coast
I've gotten some conflicting advice on which cement to use on an old chimney. I was told that I cannot use just any motar mix for chimney repair because I have an older chimney. In my current house I'd like to redo some of the exterior parts of the chimney above the roof, but in the house I'll be moving into at the end of the summer I have some repairs I'd like to do on the chimney that is inside the house (attic, etc). I have cement needed to repair anything in the firebox, but it didn't say anything about exterior use, or outside the firebox area.

This is what I bought, but have yet to use...

cement.jpg


Type S Mortar Mix

Any thoughts?
 
I used type S to build a chimney, but they might be referring to a lime mix of cement. I really don't know when they moved away from those mixes. How old is the chimney?

Matt
 
The mix you have should be fine for an exterior repair, you only need special cement in the firebox/smoke chamber area of a fireplace.
 
Generally you want to use a cement that is "softer" than what you are laying. Type "s" is used mainly for block and sometimes stone. Type"n" is better suited for brick. For soft clay brick, lime mortar is best. When laying the old soft clay brick, it is necessary to soak the brick in pails of water before they are laid. Even better to work on an overcast/drizzle type day....
 
EatenByLimestone said:
I used type S to build a chimney, but they might be referring to a lime mix of cement. I really don't know when they moved away from those mixes. How old is the chimney?

Matt
Click to expand...

I would assume the brick is as old as the house.. so 1915-1920 era.

Does it matter if this repair will be exposed to the elements or not?
 
I wouldn't think it would matter inside or outside. I think it has to do with the brick type more than internal or external application. I'm not a mason so I really couldn't tell you for sure.

Hopefully the mason from above comes back.

Matt
 
Well if this Type S is the wrong kind, and I can't bring it back, is there anyway to turn this into type N?
 
Why can't you bring it back? It's only a few dollars, use it to fill a crack in the basement.

Matt
 
Yeah, go ahead and use it. It's not life or death. I've been stuck more than once and as long as you are not sloppy it'll be a fine job. If it is sloppy, let it set up for a day or two, soak the hell outta the area and brush some muriatic/hydrochloric acid on it( wear a mask and rubber gloves and boots and stuff...) scrub and rinse. Repeat if necessary...RINSE WELL....rinse some more.

Kev
 
The acid is really effective in removing mortar stains.
 
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