Neutralize Graffiti with Our SRW Safe Suggestions

A common question that pops up from time to time, is “What if my Allan Block retaining wall has been graffitied? How can I remove this?” There are a couple of different ways to handle this situation; here is what you can do if you happen to become a target of those pesky vandals –

 

Prepare & Pre-Treat – If you are wary of this becoming a possibility, or have been subjected to this problem in the past, invest in products that will prevent spray paint from adhering to the surface of the wall. We suggest Block Guard & Graffiti Control II, as it is also a weatherproofer and a safe option for Allan Block products. It is also water-based, and will not alter the block’s natural appearance.

Power Wash – If you unfortunately fall victim to graffiti upheaval, the most effective method of removal is power washing. There are several products available you can use to spray the maleficence away, but we recommend applying Defacer Eraser Graffiti Remover, as it is easy to use and has no harsh solvents within its compounds.

 

Keep these options in mind when having to confront a defaced Allan Block retaining wall. You can also reach out to us for additional advice at 800-899-5309, or engineering@allanblock.com.

Can I Build a Fence on Top of a Wall?

If you want a fence on top of a wall, there are some things to consider. Is the wall already built? If it is, then you have to know how the wall was built; did they use geogrid, or is it a gravity wall? If the wall is in the planning stages, you have to decide the placement of the fence and how it will affect the construction of the wall.

There are many ways to build a fence above a wall. One is to have the fence set 3 feet (.9 meters) behind the back of it. This method is preferred because it does not require extra engineering. This requires construction tubes to be placed during the construction of the wall. If the fence is added after the wall is already built, the fence installer could damage the structural integrity of the wall. If the wall was built using geogrid, they could tear it, which will cause the wall to fail. Instead, they will have to dig the post holes by hand. If the wall is constructed using no-fines concrete, the fence installer will not be able to install a fence after the wall is built.  

A second method is to have the fence directly behind the wall. This requires a fence above the wall overturning calculation to be completed to understand how the fence interacts with the wall. This calculation determines the fence’s parameters; how deep do the posts need to be placed? How far apart are the posts? How tall is the fence? These factors impact the wall, which may cause the top to overturn and fail. To have the fence directly behind the wall, you will have to install the construction tubes during the construction just like the first procedure mentioned. A way to do this is with Sleeve-It. Sleeve- it is a product that is installed during the wall construction, but it does not require extra engineering for overturning. If you have any questions regarding this topic feel free to contact us at 800-899-5309, or email us at engineering@allanblock.com.

What is a Gravity Wall?

A gravity wall is a stacked block retaining wall that can stand up by the weight of the stone alone.

Gravity walls are usually shorter in height and consist of block and stone without the use of additional reinforcement.

To determine if your retaining wall can be a gravity wall, check out our Gravity Wall Chart. The chart will let you know how high your wall can reach to still be a gravity wall based on your project parameters.

What are my Choices in Color and Style of an Allan Block Retaining Wall?

Since Allan Block has been in business from the beginning of the modular block industry, there are many options available for you to match the look you want on your project. If you’re seeking an antique appeal such as “Old English”, then AB Europa might be the collection to choose. Maybe you want the split-face block and marbled color that is provided with the AB Collection. If those aren’t suiting what you’re looking for, the natural stone appearance of AB Fieldstone heightens aesthetics and differs greatly from the split-faced façade. Brand new to the AB family is the Aztec Collection, which has a smooth, yet textured face to give the wall many dimensions. The best part about using Allan Block products isn’t just that they have a style just for you, but you can find a color available that will accent your backyard to make your outdoor living space the talk of the town! For exact colors and availability, contact your local AB Dealer in your area!

What Does an Allan Block Retaining Wall Cost, and How Does it Compare with Other Types of Materials?

In comparison to other types of retaining wall material, Allan Block is very competitively priced.

To touch upon a few common choices, let’s first look at Timber. This type of system works, and has been tried and true over the last 50+ years. The problem is, they degrade in time. Although you’d have a low front end cost, the maintenance will cost you more through the years than an Allan Block retaining wall. This also doesn’t include the possible environmental disposal costs that can be associated with timber retaining walls.

Next, let’s discuss a natural stone-type retaining wall. These can be comprised of limestone, boulders, or other natural rock available in your region. Typically, natural stone is one of the most expensive options, as it isn’t always readily available. It doesn’t install as easily, and may require special equipment due to the size and weight of the material. Allan Block is a cost-effective solution with so many collections and finishes that look like natural stone in modular block, offering a cost advantage.

Lastly, is a traditional, cast-in-place masonry wall. These systems have full reinforced footings with rebar and require formwork typically to complete installation. These walls are expensive, and can drive up the labor cost due to the amount of embedment in northern climates. A ball park cost savings from a cast-in-place retaining wall to an Allan Block system can be roughly 50%. Allan Block provides an avenue to save money and have a wall that looks better.

Now that we know Allan Block is a cost-effective solution for nearly all sites, it really comes down to what collection and color you would like in your backyard. Visit allanblock.com to select a store near you, or call your local dealer for cost and availability.

Stairs Without Being Part of a Retaining Wall

I have a friend that asked me about building a new set of stairs from his cabin’s back patio area down to the lake.  His 20-year-old railroad tie steps were basically gone from deterioration.  The grade is not that steep, which makes his treads quit long relative to the 8 inch (20 cm) riser.  He said he was thinking about using wood again, because he did not think Allan Block products could be used for non-retaining wall applications.

Boy, am I sure glade he asked, because he was totally wrong.  The only limitation Allan Block walls have, is based on the creativity of the installer.  If an installer can think it up, then they can build it with Allan Block, and standalone stairs are downright easy.  In my friend’s case, the installer is simply building a series of one-course walls with cap units, over and over again rising up the grade.  He chose to simply fill in behind the caps with a nice crushed rock. 

Another option could have been to pour concrete or lay pavers for a more solid surface, like this similar project.

For more information on stairs using Allan Block, or any other questions related to Allan Block wall design or construction, contact Allan Block at engineering@allanblock.com.

What makes a Retaining Wall Work?

There are two types of walls to consider when asked the question “what makes a retaining wall work?”  Gravity walls and reinforced walls.  First, let’s look at gravity walls.

Gravity walls require two things to perform well – the Allan Block unit (its weight) and the setback the unit has.  What is “setback?”  Setback is the degree to which a retaining wall “leans” back from vertical as shown in the gravity wall section below.  This setback, coupled with the weight of the block itself, will allow the wall to perform as it should in a “gravity wall” application.  Check out our setback charts for additional information.

Reinforced walls require three things – the Allan Block unit (its weight), setback, and geogrid.  Since we have identified what setback is, the only potential unknown is geogrid.  Geogrid is a woven textile that has been used to strengthen soil for decades.  Reinforced segmental retaining walls utilize geogrid to strengthen soil and create a mass heavy enough to resist the active forces of the soil behind the wall, ultimately allowing us to build taller walls.  A typical reinforced Allan Block section is here:

To learn more about gravity walls or reinforced walls please visit allanblock.com and/or call us today to discuss in more detail. 

Should I be Worried About Water Runoff While Building My Retaining Wall?

Water is enemy #1 for all retaining walls, and must be managed with post construction management details as you will see in our water management section on allanblock.com.  When water is present in soil behind a retaining wall, it will add significant weight and pressure to the wall which may cause concern.  For that reason, routing water away from the wall after—construction and even during construction—is a Best Practice for Segmental Retaining Wall Design and should be done whenever possible. 

As read in Chapter 6 of the Allan Block’s Best Practices for SRW Design manual, backfill should be graded to avoid water accumulation behind the wall, or in the reinforced zone at the conclusion of each day’s construction. This may require a temporary berm at the back of the reinforced zone as outlined in 6-11 on the detail below, indicated by the red arrow.  This is done to help reduce the amount of water that may accumulate behind the wall, which adds weight and pressure that the wall was not designed for.  For more tips on construction, including water management details, visit our Retaining Walls by Allan Block guide or our Design for Water section that outlines post construction recommendations and the potential need to temporarily control water during construction.

How do I Figure Out How High My Retaining Wall Should be?

Retaining walls help us offset grade changes to create usable land on our property.  There are two ways a wall will be constructed, and they are referenced as a “cut” or a “fill” site.  A cut site is one in which you will cut into the hillside to add flat land, and a fill site is one which you will add soil to and raise the land to flatten out the area.

In order to properly size the wall, we will need to have a detailed understanding of site elevations and grade changes to determine wall heights.  Starting at the lowest point on your site, mark your grade changes in 1 ft. (0.3 m) increments on the plan. Mark your elevations on a drawing like the one pictured. 

You may find it easiest to use string lines and line levels to create the elevations on your site. Determine the elevation (height) you want to “fill to” or the elevation point you want to place your wall and “cut” into.  This point, or elevation, will be your standard/benchmark.  From the point you just created, run a string line away from it towards the low spot on your property and/or to the point that will be the low part of your wall.  Keep the string level by using a “line level” and pull the string all the way to the low spot on your site.  Use a stake to hold the string in place and ensure it is pulled tight.  Now, mark the elevations in 1 ft. (0.3 m) increments up to the standard/benchmark identified at the beginning.  Using this technique will help you understand how tall of a retaining wall you will need to build. 

How Much of the Base Course Should I Bury?

One of the great things about segmental retaining walls (SRWs), is the fact that the installer does not need to excavate to frost depth and/or pour a concrete footing below the structures. This helps reduce cost and speed up the installation of the systems.  SRWs are flexible in nature, and only require minimal burial below grade.  So, how much block do I need to bury on my first course?  The industry recommends that your first course be buried a minimum of 1ft (2.5cm) for every foot (.3m) in wall height, or 6ft (15cm) (whichever is greater) if the ground in front of your wall is flat.  

For unique applications where a slope is running away from the face of the wall (pictured below), the industry has a different recommendation of 5ft (1.5m). This means that though you have a slope downward, the soil against the block is still 5ft (1.5cm) deep. the burial outlined in both situations helps reduce the likelihood of erosion at the front face of the wall.

What Would you Suggest for Hiding the End of the Wall?

There are many ways you can hide the side of Allan Block units when finishing your wall.  While it is not necessary to do for structural reasons, one may decide to hide the side to avoid seeing an “unfinished” end.  There are two ways we want to address today:

First, you could incorporate AB Corner Blocks from any of our collections that are finished on two sides to help hide the end of the wall units.  Simply use a corner block as shown below to return the wall into the retained soil and then miter cut caps to finish the wall as shown here:

Second, you could incorporate AB Lite/AB Barcelona/AB Aztec Lite units to step the wall down in 4” (10 cm) increments to hide the side of the block.  If your AB manufacturer makes AB Lite/Barcelona units, this may be the easiest and more economical method to hide the end of the wall, but check on availability before a decision is made.  This is seen below:

Finishing the wall and “hiding” the side of visible units may prove to be just the finishing touch you need for your project.  Don’t hesitate to call us or check out our Retaining Walls by Allan Block brochure for additional installation tips.

How do I Calculate the Quantity for a Circular Seating Wall Around a Fire Pit?

So you’ve already designed an Allan Block firepit using our step-by-step guide, and you’re looking for your next project? If you want to design a seating wall and don’t know where to start, then grab your smartphone or tablet!  Allan Block has a free app that lets you design and estimate your perfect seating wall.  Customize the size and style with the flexible AB Courtyard Collection™. 

First, determine the length of your seating wall.  If you would like the wall to curve around parallel with your fire pit, then you can select the XL curve style in the element selection screen.  Decide on the heights of the walls and posts, and you are done!

Get a rough estimate right on the screen, or submit your project and receive a full estimate report with detailed drawings for free in your inbox.  The report also includes a list of your local dealers where you can go and get your materials.

 Don’t be afraid to add your own unique touch by adding posts, inlaid lighting, or anything you can dream up. The possibilities are endless!

For a better understanding of how to install courtyard walls, and also a visual of parallel curved walls, visit our courtyard reference guide. 

Top 3 Ways to End your Wall

Here at Allan Block, we love retaining walls. However, every great wall needs to come to an end at some point, and we’re here to share our favorite ways of doing so. The look and feel of the wall can change completely depending on how you decide to approach the endings. Luckily, the versatility of Allan Block allows for several different finishing options, each with its own unique style. While there are countless ways to finish off a wall, these three methods are some of our favorites:

1.  The Step Down

            A step down is probably the most common way to end your wall. A step down is exactly what it sounds like; the top of your wall gradually steps down until it is even with the grade. This is a great option because it provides a subtle way for your wall to slowly shrink until it’s completely gone. A step down can be made even more smooth by using our AB Lite Stones, AB Aztec Lite, or AB Barcelona blocks as a way to transition from one course down to the next.

2. The Turn-In

            The turn-in is a popular finishing option that is great for steeper grade changes and a quick end to the wall. With a turn-in, the wall turns directly into the hillside and gets built “into” the hill. This is also one of the easiest methods to end a wall since you won’t need any corner blocks, and instead of the wall slowly stepping down, you can end it almost immediately.  For a more bold, sharp transition into the face of your hill, you can use a 90° corner rather than a curve.

3. The Planter

            A planter is the perfect choice for making the most of your space. With a planter finishing option, you would finish off your wall at different courses, leaving gaps between wall endings to use as a planting space. The planter endings can be designed as either of the options listed above. Also, you can choose whether you want your planter segments to subtly break away from your wall with curves, or create a more pronounced planter by using 90 degree turns at each step-down.

While there is no “best” way to end your wall, each finishing option achieves a different look and feel to it. Maybe you want a bold look and decide to go with a 90° corner turn-in. Or maybe you are going for more of a soft discrete feel and use a step down with caps for an even smoother transition between courses. Regardless, all finishing options can look amazing.

Measure Twice - Cut Once (Using the Estimating Tools)

Allan Block has created estimating tools that will help you design and estimate your projects.   These tools are a great recourse to help you estimate your building materials.  Retaining wall materials are not convenient to run to the store to return or get more.  Ordering the correct amount the first time is important. 

Allan Block has tools that can help you determine just what is needed to complete the project.  Each of our estimating tools have been customized to help specific customer groups.

Homeowners:

AB Retaining Wall Design and Estimating App (Windows, Mac, iPhone and iPad)

Courtyard Patio Walls Design & Estimating App (Windows, Mac, iPhone and iPad)

Contractors / Builders:

AB Estimating Tool for Retaining Walls, Patio Walls and Fence (Windows and Mac)

Engineers and Architects:

AB Walls (Windows only)

Contact Allan Block for information about AB Walls - engineering@allanblock.com

By using our apps or software, you can receive a 3D image of your project, along with the estimate, to have a visual before it’s built.

How Long Will the Wall Last?

The approximate life of a concrete retaining wall could be between 50 – 100 years, though the National Concrete Association estimates it at 75. This will greatly depend on the quality of installation and the condition of the site.  The soil it is built in and the materials used to construct the project, are key to ensure a proper foundation is beneath the wall and water has been addressed. The next factor is how water is being directed away from the wall.  Water that pools above or within the wall adds pressure to the project and over time may, at a minimum, wash out the base materials which will weaken the wall and limit its lifespan.   But by following the Allan Block installation guidelines, any project should perform for many years.

How Does a Retaining Wall Work?

A retaining wall retains soil similar to how a dam retains water.  A dam’s mass must be large enough to withstand the pressure of the lake that it’s holding back. A retaining wall’s engineering principles are similar.  Even though earth doesn’t move as fast as water, it still applies pressure to a retaining wall just as water does to a dam.  

Dams and retaining walls are also similar in how they are designed.  Many dams are created using compacted soil that is protected with concrete or rocks.  Retaining walls use a similar design where engineers combine compacted soil with geogrid.  Geogrid is a structural building material that helps consolidate the soil into a stronger mass.  It’s a similar concept as putting rebar into concrete.  The combination of soil and geogrid makes a perfect structural reinforcement for retaining it all.  The concrete retaining blocks are the finishing material that adds beauty and provides protection to the soil mass.

A properly designed retaining wall will last a lifetime as long as the compacted mass is protected from water saturation and erosion.  Engineers design many features into their designs to protect it from these situations.  Properly designed retaining wall structures provide pathways to remove excess water from the base and also behind the wall facing.

How long will Allan Block last (life expectancy)?

This is a subject that comes up quite often, but is truly a hard question to answer. Allan Block is manufactured by dozens of different companies around the world, which all have different aggregate and testing on their blocks.  Each block will act differently due to the type of aggregate and manufacturers output product.  With that being said, there is a set of standards that each block manufacturer must meet.  By achieving those minimum requirements, a life expectancy can be calculated.  Since the dry cast block industry looks to the National Concrete Masonry Association (NCMA) for guidance, that is where we can extrapolate a true life expectancy.  The NCMA puts a life expectancy of upwards of 100 years when the product is not exposed to chemicals that increase the breakdown of the concrete.  Since most retaining walls incorporate geogrid reinforcement, we have to look at the life expectancy of that material as well which the NCMA provides guidance of 75 to 100 years.  Since geogrid is the limiting factor in this case, the industry then can use a 75-year life expectancy of a retaining wall block.  With all this information, we have given a long answer to such a simple question!

Can You Have a Driveway or Parking Lot Above Your Wall?

Allan Block segmental retaining walls (SRW) can be designed for virtually any site condition, including all sorts of surcharges.  Surcharges are defined as any external loading condition that is above the wall.  Common surcharges are slopes, driveways, parking lots, roadways, sidewalks, buildings, patios, etc.  Driveways and parking lot loading come from vehicles, of course, and from an engineering standpoint, are considered Live Loads.  Live Loads, like vehicles, are not always there.  They come and go with high loads, and then no loads.  This type of load is perfectly handled by an SRW because they are designed to flex and move.  The geogrid reinforcement interacts with the soils and the block facing to handle these surcharges easily.

The AB Walls Design Software has many versatile surcharge functions built into the programing.  Engineers can put combinations of live and dead load surcharges that are either continuous or line loads.  These combinations provide engineers the flexibility to model virtually any surcharge they will encounter on any project site.

Things to consider with surcharges above your wall, are lengthening the top layer(s) of grid to provide additional strength to the pavement structure above, fences, pedestrian guardrails, and traffic bumpers.  These external conditions all apply a top-of-wall overturning force that the engineer can easily design for.

For more information on AB Walls modeling, surcharges, top of wall overturning, or any other questions related to Allan Block wall design or construction, contact Allan Block at engineering@allanblock.com.

Do I need a permit?

It is always a good idea to contact your local city or county building department for their requirements.  These can typically be found on the city’s website or by giving them a call.  Typically, we have found that any wall over 4 ft (1.2 m) in height will require a permit per the International Building Code (IBC).  Some may also have requirements on length or the location to a property line.

When a permit is required, generally you may need to provide a set of drawings showing the retaining wall location and size.  Depending on the scope of the project, stamped engineering drawings may also be needed.  Allan Block has a pre-engineered manual that can be provided to the city with information and specifications for the product for walls up to 6 ft (1.8 m) in height.  If your city does not already have a copy on file, or if your wall is over 6 ft (1.8 m), contact your local AB Distributor or AB Sales rep for this information.

Checking with your city is always recommended when starting any retaining wall project. To assist in this, visit our website to create a custom residential submittal package.

What is the AB Europa Collection?

For a rustic, antique look, the product of choice would be the AB Europa Collection™. This product offers a tumbled look to give an old-world style to the landscape. When retaining walls are needed, they tend to be highly visible, and using the right look and color will create a beautiful finished landscape. This collection offers 4 block shapes in sizes that not only work great on their own, but can be used together to create patterns with the modular blocks. When matching the natural stone on a building or home, the AB Europa Collection™ with its range of blended colors is sure to please.

As with any of the AB retaining wall blocks, this system can build any size project from small garden walls, to large engineered walls. Easily create curves, corners, and stairs; the options are open to your design. With the pleasing aesthetics to offer an old-world c harm, your project will create unbelievable results.

Better Than the Day We Built it

In the spring of 2007, my wife and I decided this would be the summer we were going to transform our backyard. It had been an unusable narrow dirt strip, with a steep slope covered with more than 75 old trees and buckthorn bushes.  Allan Block’s Abbey Blend, from their Europa Collection, was the easy choice for us since it has that great tumbled natural stone look, and that incredible four block pattern that sets it apart from everything else.  I did the entire project by myself, and with a lot of help from friends and family, it turned out great.  It truly transformed our backyard into a usable, enjoyable place to just hang out or to entertain our well deserving assistants.

Well, here we are 10 years later, and I can tell you that it looks better than the day we finished it. The wall has performed perfectly and shows no signs of settlement or movement at all.  It is truly the structural wall I was hoping it would be to take care of our unusable steep slope. 

So why is it better?  The landscaping!

The wall is the picture frame that enhances the beautiful landscaping.  Like a painting in an art gallery hanging without a frame, the picture is not complete; but with the right frame, the picture comes to life.  Because my wife and I love to be in the yard, over the years we continue to change around and enhance our flowers and shrub.  Each time we make changes, the wall changes with it to add its fluctuation and beauty.  The wall is always there, tirelessly doing its job of supporting our hillside, but it is more than that to us; it is the foundation of our transformed backyard.