TrueDEK® Classic Foundations
TrueDEK® Classic foundations make it easy to build custom, stylish showers with your choice of tile or stone finishing materials. These pre-sloped foundations can be installed and waterproofed in a day, depending on the complexity and framing needs of your project, and ready for tile or stone the following day.
Structural TrueDEK foundations are designed to span 16″ on-center joist systems (spaced 14½″ apart) with help from supplemental blocking to support all edges and the drain hole area. If your joists are farther apart, it’s not a problem; just use blocking to reduce the gaps between joists to an acceptable distance. And forget about the need for expensive joist modifications to make a level-entry shower. You won’t have to notch, lower, or reinforce code compliant joists when using a TrueDEK foundation. If your goal is a zero threshold, level-entry shower, using TrueDEK foundations can save you time and money.
At a mere ⅞″-thick, it’s easy to match a TrueDEK Classic foundation with the surrounding subfloor assembly (when prepped for tile, stone, or vinyl) to create seamless transitions between the shower and the rest of the room. Showers free of a curb are safer and the results are impressively good looking.
You can cut a TrueDEK Classic to most any size or shape you want. Because these foundations are so strong, cuts can be made as close as 6″ from the drain hole—no competitive product comes close. Plus, TrueDEK Classic foundations are structurally complete—the pathway to the drain is continuously sloped and uninterrupted to avoid any possibility of a leak.
Want to be sure you can remodel later? Again, no problem. Simply remove the tile or stone, touch up the waterproofing, and redecorate with the material of your choice.
TrueDEK foundations are fully compliant with applicable codes: International Plumbing Code, Universal Plumbing Code, International Residential Code, and the National Plumbing Code of Canada. Plus, TrueDEK bases comply with IAPMO PS 106-2015e1, Tileable Shower Receptors and Shower Kits standard.
With millions in use, this system has been thoroughly tested and proven in Europe and North America over the past 35 years; it’s considered the modern, sure-fire way to build a shower without leaks, without failures, without risk. And TrueDEK Classic foundations offer the advantages of curbless level-entry with built-in versatility to accommodate any decorative options a person can imagine.
- Structural—designed for installation directly on joist systems
- Precisely pre-sloped for swift, dependable drainage
- Cut to desired size or shape with common tools
- Supports 800 lbs. when installed on 16" o.c. joist systems
- Cover with tile, stone, or commercial grade, weldable vinyl
- ⅞" thick at edges
- Flat perimeter makes leveling easy
- Off-center drain (rotate base to avoid an obstruction at the drain)
- Install on 2× wood joists, truss joists, TJI joists, or concrete
- Limited lifetime warranty
- Made of recyclable materials
Please see product specification sheets for details.
Thickness at edges: ⅞″
Composition: Glass reinforced plastic (GRP)
Slope gradient: Pitch gradients vary, though all gradients exceed ⅛″ per foot (complies with all applicable codes for a pre-fabricated, structural shower plumbing fixtures).
Weight load capacity: 840 lbs. on code compliant, 16″ o.c. joist systems and supplemental blocking; 1,100 lbs. on code compliant, 16″ o.c. joist systems, with ¾″- thick plywood filling all spaces between joists and supported by 2× blocking (call ARC for more information).
Stress capacity: 4,000 pounds-force per square inch.
Support requirements: Installation requires supporting the entire perimeter of the foundation and the drain hole; any cuts or notches made in the foundation must be supported; support can be achieved with joists and supplemental 2× blocking.
Cutting: Foundations can be cut to length and width (keep cuts at least 6″ from perimeter of drain hole); cuts can be straight or curved; for straight cuts, use a carbide blade in a circular saw; for curved cuts, use a hand-held jigsaw equipped with an all purpose blade.
Drilling: Drill anywhere in the foundation; use a twist drill bit, and countersink each hole to bed screw heads slightly below the surface.
Drain capacity: A 2″ dia. waste line connection will handle a water flow rate of approximately 6 to 7 gallons per minute (consult a qualified plumber to properly calculate water flow and drainage requirements for a project); shower heads typically generate a flow rate of 1.5 to 2.5 gallons per minute.
Adhesive: Always use polyurethane construction adhesive (product must bond to plastic and wood) to install a TrueDEK foundation on wood. For installations on concrete, use modified thinset mortar.
Tile or stone adhesive: After waterproofing has dried completely, use modified thinset mortar to bond tile or stone to the waterproofing membrane.
What You'll Need
- TrueDEK Classic foundation
- drain assembly
- 2″ drain connector
- waterproofing kit (extra waterproofing supplies may be required depending on the size and complexity of a project)
- circular saw
- flush-cutting saw or reciprocating saw
- power drill
- belt sander or orbital sander
- pry bar
- caulking gun
- speed square
- measuring tape
- scissors or utility knife
- 3″ or 4″ paint brush (throw-away type)
- paint roller and cover
- polyurethane construction adhesive (five 10 oz. tubes)—make sure adhesive bonds to plastic and wood
- acrylic paintable caulk (one 10 oz. tube)
- #9 x 2″ ceramic-coated or stainless steel screws
- 2× lumber for blocking
What do I use to bond tile to the shower foundation?
Use a quality brand of modified thinset mortar mix. Before installing tile, TrueDEK foundations must be coated with Tank/10 waterproofing compound, which improves the bond between the foundation and the modified thinset mortar, and provides an anti-fracture membrane to protect grout and tile from minor movement in the underlayment that may otherwise cause a crack or fissure in the tile layer. Waterproofing must be completely dry before applying modified thinset mortar.
Can I get a TrueDEK Classic foundation with a centered drain hole?
You can trim the edges of a TrueDEK foundation so that the drain hole ends up in the center, but in their original format, all TrueDEK Classic foundations have an off-center drain hole. An off-center drain hole allows an installer to rotate the foundation so the drain hole misses a joist or some other obstacle.
Why is my TrueDEK Classic flexing when I lay it on the joists?
Chances are, the blocking you installed to support the drain hole is too close to the hole, so that the reinforcement ring on the underside of the foundation is preventing the foundation from sitting on the joists properly. If you look at the underside of the foundation you’ll see there is a strengthening ring and a squarish-shaped reinforcement area around the drain hole. If the ring or reinforcement area rests on blocking or a joist or some other support, it can prevent the shower foundation from seating properly. As screws are driven around the perimeter of the base, the area around the drain hole will remain raised, resulting in flex when a person steps on the base. This error must be corrected before tiling the shower; if not corrected, grout is likely to crack, tile may pop loose, and water may run away from the drain.
If joists or blocking are uneven, or there are high or low spots on the top edges of joists or blocking, this can also cause flex. You want to achieve even support along every joist, and from joist to joist, while assuring that the foundation is level.
A Classic foundation that is seated evenly on joists and blocking may flex a little, but once it’s fastened and bonded to the framing structure it becomes very rigid, just like plywood subfloor does when it’s installed on joists.
Do I need to support all edges of the TrueDEK Classic foundation?
Yes, all edges of a TrueDEK Classic must be supported, as well as the adjacent subfloor edges. Additionally, the drain area requires support. We recommend 2x stock for all support blocking, and make sure the blocking supports the edges by 1″ or more.
How level does a TrueDEK Classic foundation have to be when it’s installed?
The simple answer is, it must be level. The bubble has to be centered on a spirit level, and you want to check for level all around the perimeter and across the base from end to end and side to side. TrueDEK foundations offer plenty of pitch to speed water to the drain, but every degree that’s lost to an out-of-level installation diminishes drainage performance.
Do I have to use ARC waterproofing supplies, or can I use different products?
Some waterproofing products will not bond well to the plastic foundation. The waterproofing products ARC carries have proven to work over thousands of installations, and we stand behind them. Using other products may work, but you’ll have to experiment to build the confidence you’ll want to have before laying the tile. Whatever you use has to do the job for the long haul.