Support: Frequently Asked Questions

Concrete Pavers | Retaining Walls | GFRC Furnishings | Precast Furnishings

Concrete Pavers

Why do Interlock Concrete Pavers make the ideal pavement?
Our pavers are ideal products for any freeze/thaw environment. Proper installation of the product results in a pavement that is firm, yet flexible. The joints between pavers allow the walkway, driveway, patio, etc. to move without cracking. In addition, they can be easily removed to allow for repairs or access to utilities. Unlike asphalt, concrete pavers are basically maintenance-free and do not need to be regularly sealed or replaced.
Why are the called interlocking concrete pavers?
It is the system that makes them interlocking concrete pavers, not necessarily the shape. When installed properly, the combination of the pavers, bedding sand, edge restraint and joint sand causes them to bind, allowing them to work as a unified, flexible pavement.
How do I determine how much base material and sand I'll need?
As a rule of thumb, use a minimum of 6-8" of base material for walkways and 12-18" for patios and driveways. The sand setting bed should be a maximum of 1" thick. One ton of base material or sand will cover 100 square feet at 2" thick. Using a 10' x 10' (100 sq. ft.) patio as an example, you would need ½ ton of sand for the setting bed (1" thick) and 3 tons of modified stone for the base (6" thick). You'll also need some additional sand (about 5%) for the joints between the pavers.
What can I do if my pavers are stained or damaged?
One of the advantages of pavers is that individual units can be removed and replaced in these situations. Remove the sand around the paver and then use a Paver Puller or flat head screwdriver. Rocking the paver gently in a back and forth motion will loosen it, and eventually it will be loose enough to lift out.
Can Interlock Concrete Pavers be used for my driveway?
Absolutely! 12"-18" of compacted base material is recommended for residential driveways. A standard 2-3/8 thick paver can be used for light vehicular (cars and pickup trucks) applications. A Colonial random pattern is most popular in these situations.
Please tell me about the sand setting bed.
The material for the bedding layer should be course concrete sand. Do not use stone dust or screenings; they do not allow the pavers to set properly and tend to break down over time. The sand should be an even 1" thick layer. Do not compact the sand setting bed. Do not mix cement into the sand used for the setting bed or the joints between pavers, as this decreases the flexibility of the paver system.
How do pavers compare with patterned or stamped concrete?
Patterned concrete pavements are merely slabs of concrete that are embossed with a pattern. This type of pavement is prone to cracking when freezing and thawing occurs. Stamped concrete requires an expansion joint every 10 feet, which may be distracting in the pattern you are creating. As well, repairs to individual units or underground utility problems, can be more difficult and costly.
Is there any advantage to sealing your pavers?
Sealers offer three main advantages: stain resistance, color enhancement, and binding the sand between the pavers, helping to reduce weed growth Sealants must be applied every 3-5 years.
Is snow removal possible on concrete pavers?
Pavers can be plowed or shoveled just like concrete or asphalt flooring. Do not chop or use sharp objects to break away any ice on the surface of your paved surface. Although salt will not damage your pavers, non-corrosive de-icing products are recommended.
My new pavers seem to have a film on them. What do I do to get rid of it?
The film on your pavers is caused by moisture and natural salts settling on the surface of your pavers. The best thing to do is nothing, letting it naturally weather on its own.
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Retaining Walls

What type of base is required for my retaining wall?
A compacted, crushed aggregate base is required for all segmental retaining walls. The thickness will vary depending on the height of the wall and size of the block. A minimum 4" base is recommended.
How high can I build my retaining wall?
Height limitations for walls without geogrid (called gravity walls) will vary, depending on the type of Interlock Retaining Wall system. StackStone® and RomanStack® should not exceed 2' in height. Pisa2®, RomanPisa®, and CornerStone(TM) are not to exceed 4' in height without geogrid reinforcement.
What is geogrid?
Typically made of polypropylene, geogrid stabilizes the soil mass behind the retaining wall and ties the wall face to the earth being retained. Height of the wall, soil conditions, and surcharges (i.e., slopes or traffic above the wall) will effect the type, length, and placement of the geogrid. More information is available from Interlock Concrete Products, Inc.
Can I use dirt to fill in behind my wall?
The first 10 to 12 inches of fill behind the wall should consist of a ¾" clean angular aggregate. This will help reduce water pressure that can build up behind the wall. It is also recommended that a perforated drain tile be placed directly behind the wall at grade level to drain excess water.
How do I make steps in my retaining wall?
Steps are achieved by using the wall block as the risers and the coping or caps as the treads. Step details are available from Interlock Concrete Products, Inc.
How do I make a 90° corner?
All of Interlock's retaining wall systems have manufactured corner blocks for making 90° outside corners. Inside corners are achieved by overlapping alternating rows of wall block. Please see our Installation page for more details.
Do I need to glue the coping or cap block down. If so, what do I use?
It is always recommended that you glue your coping or cap block to the wall block. This will prevent the cap from being pushed off the wall (by children, pets, etc.). Use a high strength, flexible concrete adhesive, available at Interlock Concrete Products, Inc.
Can I build a freestanding wall with your products?
Because StackStone® and RomanStack® are rock-faced on both sides of the block, it is the ideal product for a freestanding wall.
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GFRC Furnishings

What does GFRC stand for?
GFRC is an acronym for Glass Fiber Reinforced Concrete.
Why is GFRC more expensive than precast concrete?
GFRC is more expensive than precast concrete because the glass fiber is rather expensive, increasing raw materials costs. Some of this increased cost is made up for by lower shipping costs because GFRC is about 30% the weight by volume of precast concrete.
Is GFRC suitable for outdoor use in northern climates?
Yes, if installation and planting are done properly, GFRC planters should last for many years.
Should I have drainage holes in the planters?
For exterior applications we recommend drainage holes, whereas for interior plantings drainage holes are not recommended. For applications where drainage holes are needed indoors, GFRC trays are available.
What kinds of finishes are available?
Our 12 standard colors come in either a smooth, glossy finish or a flat, textured finish. Integral coloring with a sandblast finish is available in GFRC with for an additional charge.
Can I get a GFRC planter in a custom color?
Almost any color is available in GFRC for an additional charge.
How do I get a quote?
Simply provide Interlock Concrete Products, Inc. with the item number, quantity needed, and city and zip code for a no obligation quote.
Is there a minimum order?
No, there is not.
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Precast Furnishings

What is Classic Precast?
Classic Precast is a term describing concrete site furnishings that have been formed in a mold under pressure and vibration.
What kinds of finishes are available?
The most common finish is Pebblestone, however charcoal or sandblast finishes are also available for an extra charge.
Are the pebbles only on the surface of the Classic Precast furnishings?
No, they run throughout the thickness of the product.
Is Classic Precast suitable for outdoor use in northern climates?
Yes, if they are installed properly, Classic Precast site furnishings will last for many years.
Should I have bottoms in my planters?
Classic Precast planters come either with or without bottoms. Planters without bottoms can be used over soil, while planters with bottoms and a drain hole should be used over hard surfaces like concrete.
How should a Classic Precast planter be planted?
We recommend that a layer of washed gravel be placed in the bottom of the planter with landscape fabric over it before the planting soil is added.
Can I get a Classic Precast planter in a custom color?
Almost any color is available in GFRC for an additional charge, but custom colors are not available in Classic Precast.
How do I get a quote?
Simply provide Interlock Concrete Products, Inc. with the item number, quantity needed, and city and zip code for a no obligation quote.
Is there a minimum order?
No, there is not.
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