View Full Version : Setting wall cap block

Stephen Tashiro
03-07-2010, 11:45 AM
The wall cap blocks for concrete block walls are often the first part of the wall to deteriorate, especially if people sit or walk on the walls. I think a wall cap block will hold better if it is mortared to a bigger surface that the topside of a concrete block. Is there a good way to fill-in the top part of the cells in a standard block with mortar? I've seen block that have old cement bags or pieces of broken block stuck in them, with mortar put on top of that. I'd like to know a more systematic procedure and one that doesn't leave anything in the wall that might get moldy.

Lee Schierer
03-07-2010, 4:18 PM
Cut pieces of styrafoam and plug the holes before you place the block in the course below your top cap. Or fill the openings with canned foam spray and top that off with cement or mortar.

Jim Becker
03-07-2010, 8:38 PM
What Lee said with the added advise to consider using the flexible adhesive that's available for this function, rather than mortar. It sticks them tight, but has some give with seasonal changes.

Jim Mattheiss
03-07-2010, 8:58 PM
Jim Becker is correct on the adhesive.

PL makes a Concrete Paver Adhesive thats used for attaching cap stones on the stackable concrete block walls. I don't have any more here to get the official name. I've seen it at Home Depot occasionally.

I've used plenty of it and it's good stuff.

The challenge is still to find a simple way to allow you to fill the top row of cores with mortar for more bonding area. Rigid foam and spray foam topped by mortar seems the easiest.

Good luck.


Brian Effinger
03-07-2010, 11:36 PM
Stephen, your top course of block should be a bond beam, grouted solid with a pair of horizontal rebar running continuously. That will give you more than enough area for bonding the cap.

Stephen Tashiro
03-08-2010, 12:27 AM
Is this the PL block adhesive?: http://www.amazon.com/Henkel-828488-Landscape-Adhesive-28-Ounce/dp/B000DZBH5E

Jim Mattheiss
03-08-2010, 7:17 PM
That's the stuff!

Not to change direction at this point but I was watching Holmes on Homes last night and his landscaper used a version of adhesive is sold in rolls like weatherstripping. It's a bead you roll out on top of one course set the cap block into. You have some wiggle room till you pound it down with a mallet.

I just searched around his website and no mention of it - that I see.

They are serious when they say the adjoining surfaces should be dry and dust free. DAMHIKT.