# Stone wall problem with mortar



## weberus3 (Mar 9, 2009)

Hello to all that answer my question posted here. I put in a pool over the winter and had to do a retaining wall. Its approx. 3 ft. high and cinder block. I wanted to use "real stone" as a veneer style. (the stones are free) I started laying the stones in November the temp were still in the 40's-50's finished around January. I got all of the stones mortared onto the cinderblock wall. My mixture was 2 shovels of sand and one shovel of N type of Mortar. Mixer mixed. This was amount I could use before it started to set. Well we got an ice storm in late Feb. and my top layer started falling off. Understandably water froze behind and popped them loose. But not all of them. So I was removing them and preping the wall to reinstall and more fell off. The temps are in the 60's-70's now. My questions are: 1. Am I not adding something in my mortar mix (sand and N type mortar)?. 2. Was it just too cold if so why are they still falling off and its 70 degrees? I posted some photos of the situation, the numbers on the wall are so I could remount the right stone in the right spots. I'm a homeowner doing it my self. Thanks for the answers and reviewing my problem.


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## DangerMouse (Jul 17, 2008)

i don't see any mortar between the stones... did it fall out, or did you not put any in?
if that's the case, there's your answer. i don't think it's meant to 'glue' the stones to the wall.

DM


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## Bob Mariani (Dec 1, 2008)

Do not use mortar to set real stones, use concrete with concrete sand. 3 sand one to one portand cement. Mortar is used for lighter weight items such as brick or joints like when setting block. Wet the wall slightly so all the moisture in the concrete is not wicked into the block. Clean the stones also. To fix, remove the old mortar completely. Do not mix with any more water than you need. The more water the weaker the cement.


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## weberus3 (Mar 9, 2009)

DangerMouse said:


> i don't see any mortar between the stones... did it fall out, or did you not put any in?
> if that's the case, there's your answer. i don't think it's meant to 'glue' the stones to the wall.
> 
> DM


Yea, there was mortar when I mounted the stones it either came off with the stone or stayed on the wall and I had just finished chipping it the rest of the way off to clear the surface to reattach the stones when I stopped and took the photos.


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## weberus3 (Mar 9, 2009)

Bob Mariani said:


> Do not use mortar to set real stones, use concrete with concrete sand. 3 sand one to one portand cement. Mortar is used for lighter weight items such as brick or joints like when setting block. Wet the wall slightly so all the moisture in the concrete is not wicked into the block. Clean the stones also. To fix, remove the old mortar completely. Do not mix with any more water than you need. The more water the weaker the cement.


Hey Bob,

Do I need a polymer additive you think? Or will the concrete be enough? And the concrete mix, does quickrete carry a mix for this? (kinda a dumb question but I had to ask) Wetting the surface was a thought but it was my first so it was trial and error.


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## Bob Mariani (Dec 1, 2008)

DangerMouse said:


> i don't see any mortar between the stones... did it fall out, or did you not put any in?
> if that's the case, there's your answer. i don't think it's meant to 'glue' the stones to the wall.
> 
> DM


You do not need mortar between the stones.  This is more of a decorative effect. I have more than a thousand linear feet of stone walls and stone veneer over block on my yard as well as others. We do always joint veneer stones, but this is not what is meant to be used to glue these stones down. Mason ties on the other hand, anchored into the block and set into the joints are used for attachment. In your case I would line the block with wire lathe (mason type) which is anchored to the block and allows much more grip for the stones.


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## Bob Mariani (Dec 1, 2008)

no polymer is needed. If cementing concrete to concrete use a bonding agent. You can bag mix, not the best, but good enough if you follow my last post. Use the sand mix not a gravel mix. Follow the directions of how much water to use and mix the whole bag. If you want joints to be a different color (like darker) add a coloring to the mix when you joint the stones. Set the stones and let them set for 24 hours prior to attempting any joints. I normally build the whole wall before jointing. Also be sure to make a jointed cap on the wall to shed water.


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## weberus3 (Mar 9, 2009)

Bob Mariani said:


> no polymer is needed. If cementing concrete to concrete use a bonding agent. You can bag mix, not the best, but good enough if you follow my last post. Use the sand mix not a gravel mix. Follow the directions of how much water to use and mix the whole bag. If you want joints to be a different color (like darker) add a coloring to the mix when you joint the stones. Set the stones and let them set for 24 hours prior to attempting any joints. I normally build the whole wall before jointing. Also be sure to make a jointed cap on the wall to shed water.


Gotcha on all parts and I was going to add the cap over it. I'm just a one man show with a few supervisors watching if you know what I mean. Thanks for the reply


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## Bob Mariani (Dec 1, 2008)

Set up an internet web cam and you can have 1000 more supervisors.


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## NJ Brickie (Mar 4, 2009)

First is there a footing below the stone? If not you might have an issue in the future with the ground heaving up the bottom stones during a hard freeze. Second I would have to disagree with bob on the mix to use. If you were setting a stone wall in the traditional way then yes the mix he described would work. But since you are looking for adhesion to the block wall I would go the route of a type N mortar. Since stone mud has very little adhesion qualities. I would also start from scratch again. Since you already have mortar absorbed into the wall I would wire lath the wall and put on a scratch coat. Use the type N mortar to adhere the stone to the wall then. To point the stones after I would mix 1 part portland cement and 2 parts sand very dry. It should be drier then playdough.


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## scowl (Jan 22, 2009)

weberus3 said:


> My mixture was 2 shovels of sand and one shovel of N type of Mortar.


Is it recommended to add sand to mortar that already has sand in it?


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## Bob Mariani (Dec 1, 2008)

scowl said:


> Is it recommended to add sand to mortar that already has sand in it?


No he is using Type N portland, not a pre-mix bag of mortar mix. You do not modify these mixes..


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## scowl (Jan 22, 2009)

Are we're absolutely sure he mixed his sand into cement and not premixed mortar? Because if he *had* mixed sand into premixed mortar, I would expect a very weak bond and results just like this and he did say "type N Mortar" twice.


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## chicojones (Mar 8, 2009)

*Hate jack the thread...*

Hey guys i have a kinda related question (has to due with natural stone).

i have a old time rumble foundation with some lose rocks. i want to parge it with a lime mortar ( 1 part lime, 3 part sand, 1/2 part portland) on the inside and outside of the walls. i planned on using a mason bag to inject the mud into the holes in the wall and re mortar the lose rocks, then parge over the whole basement wall.

my question is (any mason guys out there?) do i have to use wire lathe before i parge with a rumble foundation? if so how do i anchor the wire lathe to the stone? 

i would appreciate any help. thanks


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## concretemasonry (Oct 10, 2006)

bob -

I assume he was using a Type N masonry cement (that you add cement to to make mortar meeting the ASTM C270 spec for mortar) and not a "Type N Portland cement" that does not exist. You may be confused with a pre-proportioned bagged Type N mortar mix that you do not add sand to.

If that is the case, he slightly under-sanded the mix according to the specs.

Just a guess and a clarification on terms -

Without knowing the location and climate, it is easy to make the mistake of looking at air temperature instead of the temperature of the materials that really controls what happens.

Dick


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## Tscarborough (Mar 31, 2006)

You can't adhere those stone, they have to be stacked.


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## weberus3 (Mar 9, 2009)

Follow-up,
I am using Portland Type N masonry cement purchased at Lowes. 80 lb bag. My sand mix was masonry sand. My mix is half of the recomended for the hole bag because I could only work that much before it started to set up. 1 shovel of mortar 3 shovels of sand, machine mix about pancake consisty. When I was setting the stones it was always dry weather and I covered the area for 1-2 days to keep the elements off the wall. I'm doing the job at home in West TN. area. Thanks for continuing to discuss my situation.



concretemasonry said:


> bob -
> 
> I assume he was using a Type N masonry cement (that you add cement to to make mortar meeting the ASTM C270 spec for mortar) and not a "Type N Portland cement" that does not exist. You may be confused with a pre-proportioned bagged Type N mortar mix that you do not add sand to.
> 
> ...


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## Tscarborough (Mar 31, 2006)

Webrus, it doesn't matter what you are using, although Type N is the correct mortar. You have to set those stones in a mortar bed and tie them to the wall with metal ties, not attempt to stick them to the wall like faux stone.

Edit-There is no such thing as Type N Portland Cement. There is Type N Masonry Cement, and there is Portland Cement Type I, II, III, or H (and a few other specialized ones). You may have a portland cement/lime MORTAR blended to Type N, though.


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## hardhatnheels4 (Mar 13, 2009)

*finishing up where the mason left off*

I have contemplated on finishing up a stack stone project where my Mason has left off...I have never mixed mortar and have never laid stone, but am a very quick study usually and quick learner....1st question tho is the mortar mix...I have the beach sand, have the portland cement, and have the water for sure...As I am reading and as I understand it...you mix 3 parts sand (meaning 3 shovels?) to 1 part cement(1 94lb bag) and mix in water (2-3 gallons?)...as I have watched this mason set the rock for the past 8 weeks now he built a box to manually mix this concoction instead of using the wheel barrel for this project....I'm not at all worried about breaking the stones for the completed arrangement....I just want to be sure it STAYS once I am done....any suggestions and/or comments are welcomed...Thanks


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## Tscarborough (Mar 31, 2006)

The proportion is by volume: 1 five gallon bucket of cement, 3 - 5 gallon buckets of sand, for example.


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## NJ Brickie (Mar 4, 2009)

Tscar is correct sticking the natural stone to a wall is not a good idea. I did see someone do it before. I am not sure how long it lasted though. The guy was sticking shims in between the stone as he went then went back and pointed it all in.


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## CAFrye (Mar 16, 2009)

You had several problems make your job go awry. 

First, the temperature probably did play a role, if it gets too cold before your mud sets, then it weakens. If it gets cold enough to freeze, then your mortar will get really dark and will crumble. 

Second, you cannot adhere river rock to a wall, they are too smooth and heavy for this. You have to lay them in a bed, and stack them, using mortar between and behind every stone along the way. Thy are not cultured stone, so you can't simply adhere them and grout the joints later. 

Third, wall ties! You can buy them for a penny a piece at any harware store, and use alot of them! 

Fourth, check the lime content of the mortar your using. 

Fifth, use alot of mortar. Although finished jobs don't look it, natural stone requires alot of mortar, properly cleaned up ("struck" and brushed) afterward. 

Sixth, you can only stack so high in one session. Because of the weight of the stone, after four or five courses, you have to stop for a while to allow your mortar to set a bit. Then come back when the mortar is more set (but still workable) and clean the joints of what you just laid. Then wait a bit longer, and you can go back and start laying more courses on top of that. 

You shouldn't have a problem if all this is done properly.


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## weberus3 (Mar 9, 2009)

*Follow up*

I wanted to follow up on my problem with the stones not holding to the wall. I ended up getting them on and they have worked out. Now granted I'm not a mason but I did get them to work. The stones that did fall off I took some F26 and put them back on. It did take a few day to put them all back but it did work. I filled in the mortar around them and they worked good. It didn't turn out exactly like I wanted but the wife said she was happy. I was wanting tighter joints. I should have went with the Faux stone. But 300 feet of wall 3 ft high, minus the cinder block cost. Cost me under $200 and a lot of time. The stones were all free. So here are a few finished photos I took last night. Almost a year later.:thumbsup:


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