Block wall with no mortar in vertical joints

[Stephen Tashiro]

Does laying a concrete block garden wall with no mortar in the vertical joints make the wall more durable?

Many concrete block walls around yards in a friend's neighborhood were laid (many years ago) with no mortar in the vertical joints and painted with a flat paint that now looks more like a stain than a painted surface. These walls have aged well. They are as attractive as any of the other concrete block walls around town. I wonder if omitting the mortar in vertical joints keeps water from washing out the mortar in the other joints.

[John K Jordan]

Does laying a concrete block garden wall with no mortar in the vertical joints make the wall more durable?

Many concrete block walls around yards in a friend's neighborhood were laid (many years ago) with no mortar in the vertical joints and painted with a flat paint that now looks more like a stain than a painted surface. These walls have aged well. They are as attractive as any of the other concrete block walls around town. I wonder if omitting the mortar in vertical joints keeps water from washing out the mortar in the other joints.

Is it a retaining wall, holding back dirt/rock? There are several important things to consider when building a retaining wall that will last including a way to manage the water. Much depends on the site and the height of the wall. You can google "retaining wall design" for some examples.

JKJ

[Matt Day]

Simple answer (mind you I'm no mason), is no. Mortar is like glue, more surface area to glue the stronger. I've never seen anyone not do vertical mortar joints and never seen specs say not to do it. Doesn't make sense, unless the installer didn't know how to Lay block properly. Are the blocks filled with concrete, rebar, wire?

[Michael Dye]

Many, many years ago, as one of my engineering projects in school, we were tasked with building a containment (5'X5') using standard mortar construction methods. Then, we built another identical containment, this time using what was, at the time, a brand new product known as polyurethane construction adhesive. That product is now known as PL Construction Adhesive and is one of the finest adhesives on the planet. Once the vessels were finished, the first thing that caught your eye was how smooth and finished looking the PL built unit looked. Not that the other unit looked bad, it just didn't look as good.

We attached strain gauges to both vessels and hooked up the monitoring equipment. Although the tubs only stood 5' tall, it was amazing to see how much wall deflection took place, especially on the mortared one. The vessel assembled with polyurethane adhesive barely moved. Both vessels were emptied and allowed to sit for a few days. We then dropped rebar into each of the voids, filled them with quick set, and let them cure for a few days.

We then filled the tubs again, with the strain gauges still attached, and took new readings. The strength of the mortared tub doubled, as I recall, where the PL tub still showed almost no signs of movement. But the best part came with the amount of water staying in the tubs after filling the voids. Although our collective thought was that we weakened the joints when filling the non-rebared, mortared tub with water, both tubs retained a majority of the water initially put in them.

If you haven't figured it out yet, I am a big fan of polyurethane adhesives like PL. Just don't get any of the stuff on clothes or skin. It is impossible to get off, especially skin. Good luck with your project.

[Bill George]

Years ago, perhaps 30 or more my Mom purchased a new house. Basement No mortar, stacked blocks like you would normally lay and a fibered cement coating of some type. She died a few years later and the house is still there, don't know how the basement wall made it. She never had water come in those walls.

Mortar has been around for thousands of years, glue how long?

[Stephen Tashiro]

. Are the blocks filled with concrete, rebar, wire?

I don't know. The walls aren't retaining walls, they are just "privacy" walls serving as dog and people barriers.

Even strong mortar is weak building material and it is designed to be so. If some stress cracks a masonry wall, we want it to crack at the mortar joints, not across the blocks or bricks.

[Wayne Lomman]

If it was a retaining wall, I would say it is to allow drainage. Since it is not, I would say cost cutting. Cheers

[Bruce Wrenn]

If it was a retaining wall, I would say it is to allow drainage. Since it is not, I would say cost cutting. Cheers

Could be that installer didn't know how to load a trowel. and butter head joints. It's an art, that takes practice. Usually easier to butter them when standing on end.

[Art Mann]

I think it is conceivable that the mortar on the vertical joints was left off to provide weep holes although I have not personally seen it done that way.

[Mike Cutler]

Stephen

I would take a guess that it was some type off personal design aesthetic. Especially since there is more than one built this way.
I grew up in the land of mudslides, So. Calif, during the 60's and 70's, and saw hundreds and hundreds of retaining walls built. None had any gaps to let water through. Run off was controlled by the design of the drainage system behind the walls.

Is the wall "weaker" without that mortar? I'd say yes. It's a free standing wall though and doesn't need that much strength. If the walls are straight and plumb, and rows are even, logic says that builder wasn't being lazy, they knew how to build a wall. They chose to build it that way.
The dry blocks by them selves would stay in place for centuries without any mortar, as long as they weren't disturbed. There are freestanding houses and barns in New England on top of dry stacked stone walls that have lasted for hundreds and hundreds of years. Mine was built this way in 1921. ( I since added mortar between the stones. )

[Larry Frank]

Another consideration is the location and climate. Maybe that type of wall works OK in that location but in my area with more rain and much colder weather and ground heave would not work.

[Jim Becker]

I also think this was a design thing; done properly, those empty vertical joints can add a sense of depth. I've seen this done a few times here and there.

[David Helm]

How about a photo. Are all the vertical joints unmortared or just the lower levels?

[Stephen Tashiro]

How about a photo. Are all the vertical joints unmortared or just the lower levels?

The top vertical joints have mortar.


JohnsWall1.jpgJohnsWall2.jpg

[Karl Andersson]

Bill,
what you're describing was most likely "surface bonding cement"; you just stack the bock dry and then trowel this like stucco over them. I have used it for garden walls, interesting that it can be used for a foundation.
Karl