Big mortar job

[JCC]

I am all set to start to repoint and resurface the field stone walls in my basement. The thing is its a very big job and there is no way I will finish it all in one go. What is the best way to do a big mortar job? Should I lay a thin coat of mortar all around then do the top coat the next day (or days)? Or should I complete one section each day? Is there anything that should be done to ensure good adhesion of each days work to the previous day?

Any tips from the expert masons out there?

 

[smiley]

I'm far from an expert mason but have done it on the outsideof the wall. We cleaned it really well then just wet it down and filled the big holes and cracks one day and re wet and plastered it up the next. Some of it did fall out within a couple years where water got behind and froze. They do make bonding agents you can paint it with first. If your doing it inside, I'd sure consider furring it out, insulating and covering it. A lot easier and more effective.

 

[BHD]

The word "expert" is formed from the conjunction of two roots which phonetically can be represented as "x" and "spurt". Everyone knows that "X" is an unknown quantity. A "spurt" is what one gets from squeezing a drop of water. Therefore, an expert is an unknown drip under pressure.

so I really do not know if I am an expert, I have done some rock and stucco work,

my definition of tuck point is to knock out the loose and then put in new mortar in the joints of the rock leaving the face of the rock exposed,

If the stone is flaky or could pop, one may want to put metal lath on or chicken wire and fasten it in the mortar joints to give the top coat a better grip,

in this I would not worry about starting and stopping, just do what you can do,

on the cover or stucco the surface, I would most likely put on a scratch coat, a coat that would basically level it and make surface to be able to put a nice surface coat on, I would do it two or three stages depending on how uneven the surface is, on the base coats I would "scratch" it so the next coat would key into the first,

picture of scratch coat
Plaster & Lath Code Dialogue

next is the brown coat where more imperfections are worked out and finally the top coat, which is a thin surface coat,

when the under is a good level surface, the top coat can go on fairly fast,

trowel on a masonry mortar, (I use a hawk, and a plaster trowel, one can use a cement trowel if necessary, plaster trowel is usually shorter and wider than a cement trowel), many times I will just sponge the brown coat or the finish coat, after setting it will leave a sand finish and it will help level it and leave a surface that is workable for many instances, in appearance and surface quality, it is nice to be able to to a complete area for the finish but if you can not try to find a natural break (window or doors) to make the splice as minimal as possible as some times the color can change a little do to circumstances, if you use a Pre mixed top coat it has less variation than field mixed, (by Pre mixed the color sand and cement and lime is all mixed in a factory, field mixed the cement lime, or mortar is mixed with sand and color at the job site).

 

[JB4310]

What are you trying to accomplish? Are you trying to make the stone wall look like concrete? all smooth cement finish?

If so then forget about bonding agents just fill the larger holes with a portland cement mortar, get it close to flush and install wire lath over the entire wall. Then parge the wall with a portland cement based mortar.

There are admixtures to help with workability; hard foam block used like a sponge float makes for any easy smooth finish.

I prefer portland cement type 2 for most repair work, it sets up quicker and is higher strength.
You could use masonry type S cement as well, it's a little stickier and may be easier for some to work with.

If the stone is in good condition and doesn't have alot of old cement on it now you could just fill the joints and enjoy the look of the natural stone. Pointing stone work is much easier than brick work.

 

[hr3]

Not a mason but an electrician that see's a lot of old houses and one thing I have been seeing lately is using expanding foam to fill in between the rocks in some old farmhouses in our area,, Supposedly holds the rock together,,insulates ,, and waterproofs ..

Just a thought,,

 

[smstonypoint]

Not a mason but an electrician that see's a lot of old houses and one thing I have been seeing lately is using expanding foam to fill in between the rocks in some old farmhouses in our area,, Supposedly holds the rock together,,insulates ,, and waterproofs ..

Just a thought,,

In a recent episode of "Ask This Old House," Tom Silva used expanding foam to fill large cracks/voids before applying mortar.

Steve

 

[JB4310]

I don't like the idea of the foam, not just cause I'm old fashioned, but for one thing the foam offers no structural integrity, it is a foundation. Second I would be worried about critters getting in there and and hollowing out a nice little protected, undetected nest.

I don't see any advantage except maybe to speed up the production of the shows episode, or to make a quick temporary repair. Also if you weren't using wire lath then I don't think the mortar would stick to foam very well.

I mix all my own repair mortars from scratch, but Home Depot sells 80 LB bags of type S masonry mortar mix. Takes the guess work out for the less experianced, easy to handle etc.
Type S is a higher strength cement for structural work, required on Govt. jobs for example, nothing new but until recently was not available in premix.

JB.

 

[hr3]

I don't like the idea of the foam, not just cause I'm old fashioned, but for one thing the foam offers no structural integrity, it is a foundation. Second I would be worried about critters getting in there and and hollowing out a nice little protected, undetected nest.

If the rocks aren't falling out there is no need for "structural integrity" motor adds none when the frost moves a rock.. At least with the foam you can have a little movement and still have adhesion to the rocks.. Rodents don't like the stuff..

 

[JB4310]

If the rocks aren't falling out there is no need for "structural integrity" motor adds none when the frost moves a rock.. At least with the foam you can have a little movement and still have adhesion to the rocks.. Rodents don't like the stuff..

I respectfully disagree, though I'm probably thinking worse case, the mortar in a stone foundation is definitly structural.

As far as the foams adhesion to the stone, yeah if the stone was perfectly clean the foam would stick better. But that benefit is negated by it's minimal compression strength compared to cured cement, the stones would move the least when properly bedded and joined in cement mortar, when exposed to frost/ ground movement effects.

Like I said I may be blowing it out of proportion, and OP may be just talking about cosmetic repairs. Also I'm a little biased since I make a good part of my living patching things up with cement

JB.

 

[JCC]

Like I said I may be blowing it out of proportion, and OP may be just talking about cosmetic repairs.
JB.

For the most part existing pointing is in good condition except for a few stones where it has completely crumbled. The "Stucco" veneer on the wall is crumbling and that is causing the pointing to deteriorate quickly. So I figured I should take care of it before it gets much worst.

One thing, the old mortar is really soft, sort of like chalk, even has little white bits in it. Anyone know whats up with that?

 

[hr3]

I respectfully disagree, though I'm probably thinking worse case, the mortar in a stone foundation is definitly structural.

As far as the foams adhesion to the stone, yeah if the stone was perfectly clean the foam would stick better. But that benefit is negated by it's minimal compression strength compared to cured cement, the stones would move the least when properly bedded and joined in cement mortar, when exposed to frost/ ground movement effects.

Like I said I may be blowing it out of proportion, and OP may be just talking about cosmetic repairs. Also I'm a little biased since I make a good part of my living patching things up with cement

I respectfully bow to your opinion,,

 

[tcartwri]

I respectfully disagree, though I'm probably thinking worse case, the mortar in a stone foundation is definitly structural.

As far as the foams adhesion to the stone, yeah if the stone was perfectly clean the foam would stick better. But that benefit is negated by it's minimal compression strength compared to cured cement, the stones would move the least when properly bedded and joined in cement mortar, when exposed to frost/ ground movement effects.

Like I said I may be blowing it out of proportion, and OP may be just talking about cosmetic repairs. Also I'm a little biased since I make a good part of my living patching things up with cement

JB.

Foaming the inside of rubble or field stone foundations is pretty much the standard OP these days. It will make a damp dusty unuseable space into a nice warm, dry and mold free basement. It will also significantly cut your heating and maintenance costs in the floors above. A good friend of mine had his century home done, and it really transformed the house.

 

[B8FISH]

the white bits are likely bits of Lime from the original mix (typically just sand and lime), nothing to worry about.

 

[Dogballs]

Around here old stone foundations are tuck pointed and then covered with closed cell urethane foam. If it were my house I would spray the rubberized foundation coating after it was tuck pointed, making sure it overlapped the footing. Then foam over the coating.

If it's done right the foam will transform a damp cold basement into a warm useable area with no drafts.