Part 1.  Channel Body Comparison

There are many plastic trench drain manufacturers in the marketplace.  By far, the top two manufacturers are Zurn Industries and National Diversified Sales (NDS). Zurn is a world class plumbing supply manufacturer headquartered in Erie, PA.  One of the four business grouping Zurn has is Drainage Products.  The Perma-Trench products represent the plastic trench drain component of their drainage products offering.  NDS is a manufacturer of plastic components used in storm water management, irrigation, water flow control and landscape water and root management.  They are headquartered in Woodland Hills, CA.

These two very different companies find an overlapping marketplace with their pre-sloped, high density polyethylene product lines.  For NDS, their Dura Slope product line was an outgrowth of their landscape drainage product line development.  This product was meant to be a high performing drainage product used in larger landscape and residential projects.  The Zurn Perma-Trench products (all high density polyethylene) were developed as an economical alternative to polymer concrete trench drain for industrial drainage applications.  The work horse of the Zurn trench drain product line is their 4” wide channel call Z886.  Both, Dura Slope and Z886, have similarities in channel composition and drainage capabilities.  However, each has strengths which should be considered when choosing a product for a particular application.

Dimensional Comparison – Above is a photo comparing the Zurn Z886 and Dura Slope channel bodies as received from our supplier.   At first glance, the main difference you see when comparing two is the length.  The Zurn product is 2 meters (80”) in length while Dura Slope is 4 feet (48”).  Next, you will notice that the Dura Slope has a black plastic cover attached with locking devices.  The Zurn channel has 4 metal “spreading bars” which are used to keep the channel walls from flexing during installation.  Dura Slope’s black cover helps to prevent channel compression during concrete placement, but also works to keep channel free from debris during drain installation.   As a side benefit, the locking devices come free with the Dura Slope channel.

The channel width, slope and colour are relatively similar between these two products.  And likewise, both products can achieve continual slopes of 100 feet (96 in the case of Dura Slope) and have the deepest channel section being 12”.   Look at the close up photo comparing the two below.

Flow Data Comparison – The flow data reported on the Zurn product is 20-25% higher than that reported on similar invert depth Dura Slope channels.  This didn’t seem reasonable since both channels are so similar.  To investigate the disparity, I compared Z886 and Dura Slope channels of similar depth. (See Photo Above)  Flow rate is a function of the cross-sectional area of the channel, the channel slope and the channel material.  As the material in each is HDPE, we can ignore this as a factor of the flow difference seen.  The cross sectional area of each channel seemed to be similar.  Z886 is a full 4” wide with a rounded section at the bottom.  Dura Slope has a top width of 4.5”, but, then goes into a taper to the rounded bottom which has a 4” diameter.  Maybe, Zurn has slightly more area…maybe.  Could the extra 0.05% slope of the Z886 explain the 20% greater flow data?  I don’t think so.

Upon closer analysis, I learned that Zurn’s technical data defines the invert depth of a channel to be the distance between the top of the grate and the lowest point in the channel.  Dura Slope, on the other hand, measures the invert depth as the distance from the bottom of the grate to the lowest channel point.  The resulting 0.75” difference has an effect on the overall cross-sectional area calculation, and in turn, affects the flow calculation.  In essence, Zurn measures flow of the channel without a grate while Dura Slope recognizes that you will have a grate in the trench while it is in full flow.  When each company’s data is compared after adjusting for this depth difference, Zurn shows only an 8% higher flow rate than Dura Slope.

Channel Feature Comparisons – Other channel features worth noting include built in rebar clips and anchors, built-in bottom outlets, channel connections and end outlets.  Both Zurn and Dura Slope products have rebar clips built into the channel body.  (See above.)  Rebar clips are used to help suspend the channel within an excavated trench during installation.  Rebar sections are generally hammered into the ground.  The purpose of the rebar clip is to attach the channel to the embedded rebar.  The rebar clip designs for the Z886 and Dura Slope channels are different but equally functional.   Z886 has a side clipping design while Dura Slope has a clip opening that is perpendicular to the channel.  Both clips have tie wire holes.  The Z886 wire tie hole is in the outer most side of the clip.

Rebar clips are additionally helpful to stabilize and secure the channel after it has been set in concrete.  One complaint I’ve heard about plastic trench drain channels (as opposed to polymer concrete) is that,  over time, there is a tendency for the channels to separate from the hardened concrete, leaving a gap that can fill with debris and pinching the channel opening. In comparison to polymer concrete channels, this is probably a true statement, though maybe a little misleading.  To help secure the channel firmly into the concrete and minimize this separation, Zurn has designed additional anchor posts at each rib point of the channel.  Dura Slope doesn’t have additional anchors at their rib points.  However, the HDPE used to make the Dura Slope product seems to be more rigid, maybe because of added fillers used in the plastic.

A feature of every Dura Slope channel is a built-in bottom outlet. This gives the contractor flexibility in deciding the drainage points of a long run or the convenience of not having to order a separate adapter if a bottom outlet is required.  To use the bottom outlet, a 4” diameter hole bit is used to drill out an opening in the channel within the bottom outlet.  Thereafter, a 4” schedule 40 pipe hub or Sch. 40 hub insert (DS-126) can be attached.

plastic bottom outlet drainage

Zurn’s Z886 bottom outlet design also gives you a degree of flexibility.  The Z886 doesn’t have a built-in bottom outlet with each channel.  However, separate bottom outlets are available in 2”, 3”, 4” and 6” diameters.  These can be installed anywhere along the channel bottom which allow for more complex drainage configurations.

 

channel drain connection

Both Z886 and Dura Slope have tongue and groove joint connections.  They allow for quick and easy installation.  Dura Slope has a trademarked DuraLoc TM design which snaps to lock the channels together once the tongue has been properly inserted into the groove.  I am impressed to see how quickly these go together and how straight the channels remain after connection.

The Zurn tongue and groove joint connection slides together easy enough.  But, it just isn’t as user-friendly as the Dura Slope product.  To secure the joints into place, you are required to place a screw at each side of the joint so you can mechanically connect the channels.

One of the selling points for the Z886 channel in Zurn literature is the fast installation times due to the tongue and groove connection and the 80” channel lengths.  The longer channel lengths are thought to reduce the hassle of connecting channel (which is what takes time in setting drain).  When compared to traditional polymer concrete systems, this may be true.  However, you cannot make the same inference when comparing Dura Slope and Z886.  I feel the quick locking channel design feature of Dura Slope overshadows any installation advantage that the Z886 product may have despite the longer channel size.  Dura Slope is just easier and quicker to assemble.

While I’m on the soap box commenting about channel length, I want to point out that long channel lengths are best when you have larger, longer channel runs.  For smaller projects, you may not have need for a full 80” section.  For common trench drain applications, such as a 12 ft or 16 ft wide driveway drain, a channel with a 4 foot length would be optimal.  If an 80” channel was to be used on this project, a portion of the channel would have to be cut and discarded.  As the project becomes larger in scope, a certain amount of flexibility is inherited.  Lengths can be changed easier in the field to accommodate the channel increment.  And with larger projects, if a channel is to be cut and discarded, it is a much smaller percent of the project cost than it would be in a small residential project.  This is not to infer that smaller length channels shouldn’t be used in larger drainage projects.  Smaller channels can be quicker to install, and they are easier to store.

One feature that aids Z886 in large drainage projects is its extender panels.  These are wall panels that can be added to a channel to allow the drain to be installed at greater depths or with longer continual sloping runs.  Dura Slope doesn’t offer this feature.

A final feature to compare between these two systems are end caps or end outlets.  Both products have caps and outlets made from HDPE, which makes it easy to trim and drill out in the field using standard power tools.  Both have a design that allows the outlet to attach by inserting into a channel groove and the end cap (shallow end) to be attached with screws.   Zurn’s outlets are supplied with screws, while Dura Slope requires you to purchase these separately.  There will be an excess portion of the cap which needs to be removed, with both systems, to make the cap level with grade.  Dura Slope end cap design shows a depth scale that corresponds with the channel you are using as the last channel to make trimming easier.  Zurn’s end cap design has a saddle that rests within the channel to make screw mounting easier during installation.

To recap, below is a quick comparison of the Z886 and Dura Slope with respect to channel features and geometry.

Parting Comments – If we are to look solely at the merits of each channel, I would say that Dura Slope has more to offer both home owners and contractors.  The Dura Slope was designed to be easy to handle, quicker to install, with minimal assembly required.  I personally like the shorter channel lengths because they fit on my shelves and are much easier to ship to my customers.   I feel the plastic used to make the Dura Slope is stiffer than that used in Z886, which leads to straighter channel installations and less channel-concrete separation.

Having said that, I acknowledge that the Z886 channel has advantages over Dura Slope in applications where long, continuous slopes are required.  By using extender panels, runs as long as 300 feet of continual sloping drain are achievable.  In addition, Z886 has a wider variety of outlet diameter options which can help in more complex drainage projects.  This is one of the reasons why you will see Zurn Z886 specified on big jobs more often than you will see Dura Slope.

The channel component of any trench drain is important when considering the engineering properties and installation.  But this is just half of trench drain.  The portion of the drain that people see after installation is the grate.  Increasingly, the channel grating is becoming the focal point of the trench drain selection process.  Aesthetics, ADA compliance, load capability and corrosion resistance are all properties to consider when selecting a trench drain grate.  Part 2 of this report will continue the discussion on Zurn’s Z886 and NDS Dura Slope by focusing on trench drain grate options available from each.

Trench Drain Systems is a company which specializes in providing quick solutions to drainage problems.  For more information about the trench drain products discussed in this article, visit www.trenchdrain.biz or call 610-638-1221 for immediate assistance.

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The Z880 Perma Trench is one of Zurn’s most popular residential trench drain product lines.  Its name may sound intimidating, but there’s nothing to fear from this plastic drain.  It was designed for pools, patios and landscape drainage much like its competitor, the NDS Mini Channel.  Both the NDS Mini Channel and the Z880 are 3” wide at the top, and both systems have similar features that give each other a run for the money.

Mini Channel, Z880, plastic trench drains, residential drain

NDS Mini Channel drain compared alongside Zurn Z880 residential trench drain

 

Channel Body Differences

The difference between the two systems really starts with the channel bodies.  Take a look at the photo above.

The Mini Channel (shown left) has a gray, honeycombed channel design meant to distribute load stress and prevent the system from collapsing.  This design extends to the grate supports, which hang out from the channel walls in an upside down flying buttress.

You can see that the Zurn Z880 (shown right) has a thicker, solid channel body. It is composed of high density polyethylene (HDPE), the same material as the Zurn Z886 or NDS Dura Slope commercial-grade trench drain systems.  The inherent durability of the channel body gives some “street cred” to this little patio drain.

The Z880 channel body also has “ribs” extending from the outer walls that give the channel extra surface area at vital contact points to the surrounding concrete.  The ribs help “grab” the concrete, anchoring the system in place and providing additional strength.  The channel will not separate from the concrete once installed.  The ribs also add flexibility to the design of the system because they serve as cutoff points in the drain that can still connect to other modular channels or outlets.  I’d estimate the cutoffs are every foot.

plastic trench drain, residential drain system, Zurn, patio drain

Zurn Z880 plastic drain features include ribs and support legs

The walls of the Mini Channel are made of smooth PVC.  The absence of ribbing is advantageous when installing in a paver patio but poses a problem in the long run if you want to install it in concrete.  Without ribbing to act as anchoring points, the drain body can begin to separate from the concrete years after installation.  In addition, water and dirt may begin to flow between the concrete-channel interface, causing the channel to pinch.  To prevent this pinching effect and the subsequent weakening of the channel wall, make certain that the Mini channel grates are always securely fastened down.

Grating Option Comparison

While Mini Channel grates come in a standard slotted pattern, the Z880 grates (shown below) have a more decorative pattern that gives them a classier appearance.  The thicker grate also holds more weight, providing more structural integrity than thinner Mini Channel grates, but ultimately has less open area for water to drain.

plastic drain grates, decorative grating, trench drain grates

Color options for the Z880 plastic trench drain system

The Z880 and Mini Channel systems each offer six color options which are the same with one exception.  The Z880 offers a sky blue grate while the Mini Channel offers a forest green grate.

If you choose the Z880 system, you’ll be surprised to see that the channel matches the grates’ color.  Unlike pool drains by other suppliers, the Zurn Z880 eliminates this “edge line of a different color” that borders the grating.  This gives the system an overall nicer appearance.

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Z880 grating matches the trench channel body

Grates for the Z880 system clip into place.  Each grate has several “tongues” on its sides that snap into the channel grooves.  It’s easier than buying grate screws and lockdowns, won’t create weak points in the channel structure and can be popped out of place easier for cleaning.

Iron Age Grating Options – Cast iron decorative grating is available for both drainage systems.  Created by Iron Age Designs, the grates are both beautiful and efficient.

The Mini Channel has three decorative patterns that fit the system:  the Minnione, Carbochon and Interlaken, respectively (see photo below).  Each grate is slightly different in terms of thickness and how it sits inside the channel.   Iron Age cast iron grates make NO accommodations for screws needed to lock down the grate.

decorative grates, iron grating, Iron Age Designs, residential drains

The Minnione, Carbochon and Interlaken decorative iron grates by Iron Age Designs

So far there is only one cast iron grate option offered by Iron Age for the Zurn Z880 pool drain.  What amazes me about the pattern is that it’s a Regular Joe.  No, really, it is.  I’ve never found out who was behind it, but somewhere along the lines the decorative option for the Z880 drain became a cast iron slotted grate.  Of course, it looks entirely more sophisticated than a standard slotted grate, but it’s something I’ve never stopped being amused about.

Zurn plastic drains, cast iron grates, decorative grating, residential drains

Zurn Z880 plastic grate compared to Regular Joe by Iron Age Designs

One thing that is not amusing about the Regular Joe grate for the Z880 is the placement of its “tongues.”  In the picture above, you can see the inconsistency between the plastic Zurn grate and the Iron Age Designs option.  The lockdown tongue on the cast iron grate is placed too high, which means that it won’t secure into the channel properly.

I don’t want to sell the Z880 drain short, though.  Zurn does offer four other decorative options, including a bronze decorative grate, for homeowners who want to upgrade from plastic without buying the Iron Age grate.

Whereas, the Mini channel may wear and tear more quickly (especially in regions of freeze-thaw) because of the cellular channel design, the Z880’s solid body design and anchoring points makes it a more rugged product over the long haul.  The Mini Channel is a sleeker, less expensive channel drain system that works well when used with pavers. The Z880 is a sturdier system designed for concrete installation. These two systems are so similar, yet they are worlds apart.

For design assistance and pricing on any of these products, contact Trench Drain Systems at 610-638-1221 or email us at sales@trenchdrain.biz.

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