Your Common Masonry Questions Answered

Contractors and masonry workers often run into problems during the course of their work. Here we have listed eight common problems one might encounter when doing masonry work and their possible solutions.

Why isn’t the rock sticking on the wall?

There are several things that could be causing this. First, it’s possible that the rocks are dirty. If that is the case, be sure to wash them well. Or perhaps the rocks are too wet, in which case you must wait until they are dry to resume working with them. If the mortar is too wet or too dry, use more water or more sand and cement to adjust your mix. Or you may have to add more cement or bonding agent if there is not enough in the mix already. Finally, it is possible that the stones are of poor quality, and are too shaley.

Why isn’t the mortar sticking to the masonry wall?

Did you use bonding agent to coat the wall? If not do so, or if you haven’t roughed the surface up, that might also be the problem. If you are working on a dirty or greasy wall, clean it and coat it with bonding agent. It is possible that the mortar is too wet or too dry, in which case you should add more water or more sand and cement to adjust your mix. Add more cement in the mortar if you think there might not be enough already, and if the wall is too wet, take a break from it until it is dry.

Why doesn't the mortar stick to a wood wall?

If the mortar will not stick to a wood wall, it is possible that it is the mortar is too wet or too dry and you may need to use more water or more sand and cement to adjust your mix. Another common cause of this is if there is not enough cement in the mortar; add more cement. And finally, did you remember to put on metal lath?

How do I deal with mortar joints?

Mortar joints make all the difference between professional and unprofessional looking stonework. The most important thing is to keep your work neat and clean. It is easy to clean the mortar off the stone while the mortar is still weak. It is extremely difficult, if not impossible, to get mortar off after it has set up.

How do I repair a loose stone?

If the mortar is still solid in the hole, remove the stone and clean it well. Put a good adhesive on the back of the stone as well as in the hole it came out of and re set the stone. You may have to brace it until the adhesive sets.

What should I do if the mortar is crumbling or broken up?

Remove any loose stone and mortar, clean the stone well, re-mortar it into place and redo your mortar joints. Use bonding agent in your mortar.

Why is rock falling off the wall after the job is finished?

The cause could be that stones were disturbed before they had set up. Or perhaps stones were not tapped into the mortar to create suction. Still another reason would be if not enough mortar was put behind the rocks or it was poor mortar. Did you use a bonding agent? In not, that is why the rocks are falling off. It is imperative that you use quality, clean rocks, otherwise, rocks might fall off. It is possible that the building settled and cracked the stonework, or that the footings were not adequate or that they settled too much (or perhaps a frost heave caused it). Still other reasons would be if the metal lath was not secured well enough, or if the mortar froze.

Why is the mortar starting to crumble and fall out?

There could be several reasons for this, many of which we’ve already discussed. You may not have used enough cement in your mortar. If you used bad cement, or if there was dirt in your sand, or you used poor sand this could also happen. The sand must be sharp and clean. If your sand contained salt it would also cause the mortar to crumble and fall out as well. It is possible that the moisture was sucked out of your mortar too fast and it dried too quickly and did not have a chance to cure properly. Bonding agent helps to prevent this.

Did you use mortar that should have been thrown out? Do not add water to drying out mortar unless you really know what you are doing. Once the chemical reaction has taken place, the mortar could be destroyed. Another reason is that your mortar may have frozen.

Construction Book Express has many guides to working with cement and stone. Check out our huge selection of masonry and concrete products for further tips and instruction.