May 24, 2019

What types of fences can you build with AB Fence?

Written by Chad Julius

The AB Fence has been used in a wide variety of applications and the literature outlines some basic applications such as screening, containment, beautification and sound barriers. 

But let’s face the facts and realize you are constructing a fence for two reasons.  You either want to keep something out or something in. 😊

The “something” is what makes your application unique.  Examples of keeping something out include traffic noise, curious neighbors, security from vandals and the list can go on.  On the flip side, maybe you are just trying to keep your dogs in the yard or provide a safe place for your kids to play without worrying about them wondering off.  There are many ways to build the AB Fence to satisfy your application and create a beautiful solution. 
I would recommend that you take a look through the photo gallery on at to see some of the applications and projects that are featured. 

May 17, 2019

What are the capping options for AB Fence?

Written by Chad Julius

Capping the AB Fence is like the icing on the cake.  The structural requirements are done so now you are just putting the finishing options together.  Typically, the AB Fence is finished by using the AB Fence Cap Block. This is just glued on top of the panel and post blocks with a high-quality construction adhesive. 

The same cap is used for both the panels and posts to simplify the process. 
The real fun comes by creating by varying the panel and post heights.  We recommend the Castellated Finish for the AB Fence by constructing the posts one block taller than the panels. 

However, you can get created and extend the posts even taller and have iron or steel fencing between them.  Whatever, you decide to do the AB Fence Cap Block is glued in place to finish the top of the panels and posts. For more information on capping and finishing options for your Allan Block Fence, visit our website at

May 10, 2019

Can I use AB Courtyard on top of my existing retaining wall?

Written by Chad Julius

Absolutely.  We have countless projects where Courtyard is used on top of the retaining wall.  You have got to check out some of the pictures we have of raised patios that show the AB Courtyard on top of retaining walls.  However, since it is an existing wall there needs to be some questions answered first.  It will depend on if that existing wall will remain structurally stable when the additional loads are applied.  Let me explain.  The Courtyard itself has weight, but so do all the people that will be standing on the patio that you are building as well.  The existing retaining wall must be able to withstand this additional weight or pressure before moving forward. 

Once the integrity of the existing wall is satisfied then you can simply install the AB Courtyard wall on top of the existing retaining wall.  The AB Courtyard does not require a footing and can installed directly on top of the cap or pavers for the patio. We would suggest adhering them to the cap for some stability, but it is not required since the AB Courtyard Caps are also glued once installed.  Check out the Courtyard Reference material on our website.

May 3, 2019

Getting off the Grid: How to know if your retaining wall needs more reinforcement

Written by: Nate VanBeek

How much geogrid do I need to build my retaining wall? Do I even need geogrid? How tall does my retaining wall need to be for geogrid to be required?

When designing a retaining wall, there are a number of questions that you must ask yourself prior to answering these questions. 

  • How tall is your retaining wall? 
  • What block will you be using to construct your retaining wall? 
  • What type of soil is being retained by your wall? 
  • Are there any additional loads on top of your wall such as a driveway or a slope?
 Once you have answered all of these questions, you may reference the table to the right.

This table as well as all of these design considerations can be found in our Commercial Installation Manual.

Now that you have determined whether or not geogrid is required, what’s next?
If a gravity wall will work for your application you don’t need any geogrid. However, if your wall is outside the parameters in the above table you will need geogrid reinforcement. But, how much? For a quick answer to this question refer to the table to the left.

Once you have determined an appropriate depth of grid and number of grid layers using the table to the left, multiply these numbers by your average wall height to determine how much geogrid is required for your wall.

Would you like a more accurate estimate of the geogrid required for you project? Consider using our AB Estimating Tools. These applications download in just moments and allow you to come up with a material estimate in just a few minutes.

For detailed instructions on building retaining walls using geogrid please refer to the Allan Block Best Practices document which comes from decades of industry experience.

April 26, 2019

The Anatomy of a Retaining Wall

Written by: Danelle DeMartini

A retaining wall is a structure that holds or retains soil behind it. There are many types of materials that can be used to create retaining walls like concrete blocks, poured concrete, treated timbers, rocks or boulders. Some are easy to use, others have a shorter life span, but all can retain soil.

SRW’s (Segmental Retaining Walls) like the Allan Block products, offer concrete masonry blocks that are modular and interlocking for ease of use. Simply stack the mortarless blocks together using our installation information, and create a maintenance-free retaining wall that will add usable land, fix a grading or slope issue, and solve many other site problems. These SRW’s use similar construction techniques as found in the mortarless construction of the Great Wall of China and the Pyramids of Egypt and will stand the test of time. 

The basic parts of a segmental retaining wall, or modular concrete block wall consist of:

Retained Soil:
The area of soil behind a retaining wall that is contained by the wall structure

Infill Soil:
The soil used to backfill behind the wall rock in the reinforced zone. These soils need to be identified and approved by a qualified engineer before they can be used. A granular type of material is best. 

Reinforcement grid:
A manufactured high strength reinforcement grid material that comes in rolls of various sizes and strengths.

Allan Block (segmental retaining wall block - SRW):
Hollow core segmental retaining wall block (SRW) used as the face of the retained soil mass. 

Wall Rock:
Compactible aggregate ranging in size from 0.25 in to 1.5 in. (6 mm to 38 mm) with no more than 10% fines. Used for base material, within block cores and behind the block. 

Drain Pipe:
Used to direct incidental water that makes its way in behind the reinforced mass, and vents it to daylight by creating a channel for the water to flow out from.

Once you build a wall with an SRW – you can be sure it is built to last. For more information on  segmental retaining walls and construction techniques, visit our website at

April 19, 2019

Why the Different AB Courtyard Caps, Allan Block?

Written by:  Nate VanBeek

So you’re building your first AB Courtyard project. You have just finished laying the top course of your first wall panel. Now it’s time to start capping your wall. You start placing the caps atop your wall panel and you quickly realize that some of your wall caps are different. They won’t set right because the groove doesn’t go all the way through the block. Now when you place them on top of the raised ring they’re sitting half an inch higher than surrounding blocks. The reason for this is simple; the AB Courtyard wall caps are manufactured with a standard and an end cap finish. 

These finished end caps are great for capping vertical ended walls or step downs. There is an average of 1 end cap for every 4 standard caps when offered by the local manufacturer (check for availability.) There are two ways to install an end cap when it meets up with the raised ring of the block below. 

Option 1: Flip the block below over
  • Option 1: When the end caps meets up with a raised ring; flip the block below over to create a flat surface. This will allow the cap to be placed with no modification needed. 

Option 2: Remove notch on end cap
  • Option 2: Using a hammer and chisel, break off the notch on the bottom of the cap to allow for proper installation. Once all the caps are installed, secure them in place with a bead of masonry adhesive on both sides of the raised rings.
For more information about how to finish AB Courtyard wall panels with caps take a look at our CappingWall Patios page and for information about all things pertaining to building with AB Courtyard take a look at our AB Courtyard Installation Manual.

April 12, 2019

Segmental Retaining Walls (SRW) or Cast-in Place - Which is Better?

Written by: Kyle Huerd
For decades, commercial site developments have commonly constructed cast-in-place reinforced concrete walls to retain soil. However, since the mid 1980’s, segmental retaining walls (SRW’s) have provided a better solution to these rigid walls. Some of the advantages SRW’s have over cast-in-place walls include the following:

  • Lower installation cost (30-70%)
  • Limited excavation for footing preparation since frost depth is not a factor
  • Faster installation
  • Easier to design
  • Better aesthetics
  • More reinforcement options (e.g. Geogrid, No-Fines concrete, wall anchors, etc.)
  • Flexible vs. rigid system

Aside from all the advantages listed above, what is often missed is the fact that SRW’s can also out-perform rigid walls, particularly in the most aggressive circumstances possible, such as during an earthquake. SRW’s ability to withstand seismic loading conditions has been proven in both the laboratory and the real world.
Allan Block’s full-scale seismic testing documented that SRW’s can withstand large seismic forces. The testing subjected the test walls to forces up to 0.8g and all experienced only minimal deflection and/or settlement. The tests showed the block facing, soil mass and geosynthetic reinforcement all moved together as a unit, in phase with the earthquake induced forces. It was suggested by Dr. Hoe Ling from the Columbia University that these structures, that are both flexible and coherent, are ideal for seismic conditions (ABSeismic Research Summary, Reference Document #R0505, August 2003).
In today's world, with Segmental Retaining Walls being tried and true for more than 30 years, there isn’t much of a market for traditional cast in place walls anymore.  The next time you think you have to use a cast in place wall on a project, just call Allan Block Engineering Department for a second set of eyes to see how we can find the most efficient design.

April 5, 2019

More Circles! Building tips for AB Courtyard projects

Written by: Nate VanBeek

Everybody loves building circles with AB Courtyard! But, what is the smallest circle that I can build with AB Courtyard? If you build a circle using AB York blocks with the long edge oriented to the outside of the circle it will take twenty-eight blocks to complete a circle.

The circumference of a circle made with AB York blocks exclusively is roughly 81 in. (2.0 m).  to the outside edge. That is the smallest diameter circle that can be built using AB Courtyard without modifying blocks. Our AB Courtyard Fire Pit page has videos, pictures, and step-by-step instructions on how to build this circle.
For more information about building with AB Courtyard refer to our AB Courtyard Walls by Allan Block publication. For more specific guidance building curves check out this page: Howto Build Patio Walls with Curves. We also a page dedicated to building larger curves: How to Build a Large Curved Patio Wall Panel.

The fun doesn’t stop there

With AB Courtyard you can build all sorts of circles. By alternating AB York blocks with the short edge towards the inside of the circle and AB Dublin center split blocks with the long edge oriented towards the inside of the circle, a slightly larger radius is obtained (roughly 96 inches).

Another option for a slightly larger radius (roughly 112 inches) is using one AB York with two AB Dublin center splits. Orient the AB Dublin center splits so that their tapered edges face one another. Follow this with an AB York with its short edge oriented toward the inside of the circle. Repeat this pattern to complete the circle.
 For an even larger radius (roughly 184 inches) use two AB York blocks side-by-side (or one AB Dublin) followed by a AB Dublin center split with its long edge oriented toward the inside of the circle. This pattern is then repeated until the circle is completed. All of these radii are shown in our AB Courtyard Reference Guide.

March 29, 2019

What is Geogrid Reinforcement?

Written by: Rich Lovdal

Geogrid reinforcement is really amazing stuff.  Since its North American introduction in the early 1980’s, geogrid can be commonly found in many different types of construction projects, not just Segmental Retaining Walls (SRW).  Geogrid has revolutionized the soil stabilization industry which includes substructure design for roadways and building foundations and slope stability design among many others. The most common geogrids are made from polyester fibers that are coated in polyethylene.  The coating makes them resistant to degradation and the polyester fibers are very strong and resists tension/shear force in soil similar to how a reinforcing steel bar will do when cast into concrete.

Geogrid typically has woven strands of fibers in two directions; transverse and longitudinal (or in the roll direction or sometimes called the machine direction).  Geogrid rolls are typically manufactured in 6 or 12 ft wide rolls and have as much as 250 ft on each roll.  Lightweight geogrids are very commonly Bi-Axial, meaning that their transverse and longitudinal strands are the same strength and these grids are more common in residential applications.  Commercial strength geogrids are Uni-Axial meaning their longitudinal strands are stronger than the transverse strands.  Using these Uni-Axial geogrids in a retaining wall means that you must roll the grid layers out perpendicular to the wall so the strong members are running perpendicular to the wall providing the most shear strength to the wall structure.

The weaker transverse strands play a very important role in the grids function as well.  They are woven to the longitudinal strands to keep them aligned and they add lateral soil pullout resistance when embedded in the soil mass.

For more information on what Geogrid is and how it works please see our website at

March 22, 2019

Can Allan Block be Used in Water?

Written by: Ryan Miller

Rendering #1
Can Allan Block be used in water?  Absolutely!!  Many of the site challenges Allan Block products are used to solve include “water applications.”  What is a water application?  A true water application includes water being present all the time (such as a pond) or in some cases only periodically such as detention pond (water levels rise with rain events).  No matter the reason for the water application Allan Block can be used to solve your problem! 

Design and construction of a water application is virtually the same as a traditional Allan Block retaining wall project.  However, we do recommend the following when building a water application:
Detail #1
  • Removal of all clay and use of free draining aggregate known as wall rock within the wall system.
  • The four-inch drain pipe should be placed above the low water level.
  • Embankment protection fabric should be used behind and under the reinforced zone to protect fines from migrating into the mass.
  • Rip-rap should be used at the front of the wall to protect from erosion (specifically when the water is going to be moving).

*Check out Detail #1 and Rendering #1 for more information on recommendations.

For more information on building with Allan Block in water, check out our SRW WaterApplications Technical Newsletter or