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DELTA®-FL Plastic Sub-Floor

Cosella Dorken DELTA FL Subfloor for basements

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No Open Seams • No Moisture • No Mold!

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For a warm and comfortable basement, choose the Dorken DELTA®-FL Subfloor. Its dimpled, rugged gray plastic membrane provides a seamless mold and moisture barrier for any concrete, slab-on-grade floor in your home. With the right moisture protection, you can turn a damp, moldy basement into a safe and livable family room or workshop. This subfloor moisture-management system helps concrete basement floors dry out so the finished floor above doesn't absorb the water. You'll have a lower level worth spending time in when it has this Delta-FL underlayment for sale at Spycor Building Products.

High-Quality Subflooring

Every roll of DELTA-FL plastic subfloor is made of high-density polyethylene (HDPE) that has dimples added to each side. By using dimpled polyethylene, homeowners create an air cavity to equalize water pressure and improve ventilation. While small amounts of moisture are allowed into the basement so the air won't be completely dry, you'll avoid excess humidity that can lead to warped floors, rotted beams and mold. As an added bonus, your finished floor is isolated from the concrete so it doesn't absorb the cold from being below ground level. This means it will be much warmer downstairs.

Affordable Basement Moisture Control

We have low prices on this premium subflooring system that can be used with many different coverings. Install it underneath hardwood floors, floating laminate floors, carpeting and anything else you want in the basement. If you want to learn more about the DELTA-FL system, watch our product and installation videos below or scroll down for a full overview of its features. You can also visit ourProduct Questions page for even more information.

*Delivered Rates Apply to the contiguous 48 U.S. states. For freight charges outside this region, please e-mail support@spycor.com.

(DELTA®-FL products usually ship within 24 hours)

**Buy One Roll of Tuck Tape per Roll of Delta-FL

Delta-FL is easy to install!
Great for Basements!
Item# Item Name Delivered Price Qty Add
DLFL-ROLL DELTA®-FL Subfloor ROLL 4' 9" x 68' 6" (328 sqft) $ .60 PSF
DLFL-SKID DELTA-FL Subfloor SKID 4' 9" x 68' 6" (11-Rolls/3608 sqft) $ .58 PSF
4XT526 Tuck Tape Red Sheathing Tape 2.36" X 216'
Check the items you wish to purchase, then click

The Science Behind Superior Design

DELTA-FL uses the science behind vapor pressure, which is that the vapor moves from high pressure to low pressures areas to equalize its pressure. In a standard basement, the dry air in the room is a magnet for water vapor that seeps through the concrete. However, this subfloor system works differently, since the space within the material's dimples equalizes the water pressure both above and below the concrete. Although the air in the room is isolated from the system, the DELTA-FL subfloor allows small amounts of water vapor into the room. This helps to maintain optimal humidity for greater comfort, while sensitive flooring materials are protected.

DELTA-FL Advanced Materials and Design

The DELTA-FL subfloor is constructed from high-density, impact-resistant polyethylene (HDPE) material, featuring an air-gap membrane. It is an inert material that is extremely rugged, withstanding heavy loads and suitable for any floor finishing. The unique design provides an effective capillary break and vapor barrier, for a drier basement. This thermal break makes the basement floor warmer, with whatever floor covering you use. This lightweight material has exceptional compressive strength of greater than 5,200 psf (250 kN/m2). Even with this added layer of projection, there's minimal head room reduction — just 8 millimeters.

DELTA-FL Subfloor System - Easy Application

This advanced, high performance subfloor comes in easy-to-use sheets and in two roll sizes. Installation of DELTA-FL is fast and simple and can be done by the average homeowner. It is installed with the dimple side down, which creates a 5/16-inch ventilated air space above the slab. Use DELTA-MOISTURE PROOF TAPE for taping the seams, to keep moisture from moving into the joint areas. After laying down DELTA-FL and plywood sheets on top of the concrete floor, you can put down the flooring surface of your choice:

  • Laminate floors (directly on top of the DELTA-FL)
  • Carpeting with rubber underlay, vinyl flooring or hardwood floors (on top of plywood boards)
  • Linoleum (on top of multiply board)

DELTA-FL subfloor comes with a 20-year product warranty.

*Delivered Rates Apply to the US contiguous 48; For freight charges outside this region, please e-mail support@spycor.com.

DELTA®-FL products usually ship within 24 hours.

Technical Specs:
Product name
High Density Polyethylene (HDPE)
Dimple height
apprx. 5/16" (8 mm)
Compressive strength
apprx. 5,200 psf (250 kN/m˛)
Air-gap volume between dimples
apprx. 7,9 l/m˛
Temperature range
-22°F to +176°F (-30°C to +80°C)
Roll size
4' 9" x 68' 6" (1.46 m x 20.9 m) 328 sf (30.5 m˛) (1.52 m x 20.0 m)
47 lbs
Sheet size
Sheets No Longer Available
non-toxic, non-polluting
Water permeability (EN ISO 11058)
8 · 10-˛ m/s
Service life expectancy
Ř25 years (at pH between 4 and 0 and temperature < 25°C).
ŘThe membrane should not be exposed to UV light for more than 30 days.
DELTA®-FL functions as an effective vapor barrier in conjunction with wood laminate floors and many other common floor coverings, and is a simple new solution to create a beautiful, high-performance basement floor.

The leight-weight product comes in two different roll sizes, as well as easy-to-handle sheets. It is fast and easy enough for the average homeowner to install.

Once DELTA®-FL and plywood sheets are laid out, a variety of floor coverings can be installed:
- laminate floors (floating directly on top of DELTA®-FL)
- carpeting with underlay (on top of plywood board)
- vinyl flooring (on top of plywood board)
- hardwood flooring (on top of plywood board)

Seams are simply taped with DELTA®-MOISTUREPROOF TAPE to ensure that moisture cannot migrate inwards through the joint areas.

Average Customer Review: Average Customer Review: 5 of 5 5 of 5 Total Reviews: 96 Write a review.

  0 of 0 people found the following review helpful:
5 of 5 May 26, 2021
Reviewer: Gregory Gates from Annandale, VA United States  
did not expect delivery so quickly.

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  0 of 0 people found the following review helpful:
5 of 5 DELTA-FL Plastic Sub-floor January 25, 2021
Reviewer: Anonymous Person from Scarborough, ME United States  
Our shipment was so quick and the product was wonderful!!   So glad we ordered from your company!!!

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  0 of 0 people found the following review helpful:
5 of 5 January 14, 2021
Reviewer: Steven Ricker from Derry, NH United States  

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  0 of 0 people found the following review helpful:
5 of 5 Easy install January 14, 2021
Reviewer: Mustardchips from Indianapolis  
I have yet to finish the basement project, but the Delta FL is down with 22/32 OSB on top, fastened with 1 3/4” flathead tapcons.

Install is very easy using Blue Tuck Tape with a layer of landscape fabric beneath.  Product cuts very easily

Shipping was slower than originally advertised due to Covid, but not problematic for me.

Would purchase again and would recommend.

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  0 of 0 people found the following review helpful:
5 of 5 January 14, 2021
Reviewer: david helmkamp from Maplewood, NJ United States  
easy, pain-free order and delivery.  thanks.

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