DELTA®-FL - Vapor Barrier for installation on concrete slabs, provides a warm and dry floor

By: Cosella-dörken  09-12-2011
Keywords: Flooring, Floor, High Density Polyethylene

DELTA®-FL - Vapor Barrier for installation on concrete slabs, provides a warm and dry floor


DELTA®-FL is a uniquely dimpled, heavy-duty grey plastic membrane that keeps your basement floor, or any slab-on-grade concrete floor dry and comfortable. The membrane is installed with its dimples down to create an air space above the slab. It can be covered with laminate floor systems, or with a plywood subfloor topped off with carpet or vinyl flooring.

DELTA®-FL on concrete floors protects sensitive materials by providing a reliable capillary break and vapor barrier. In a conventional basement, dry air in the living space acts as a "magnet" for water vapor migrating up through the concrete. The air-gap created by DELTA®-FL allows the water vapor pressure above and below the concrete slab to equalize, while preventing the moisture to migrate further inwards. Hence, moisture does not affect the flooring material, and your basement area stays dry and comfortable. The membrane also provides a thermal break, which also increases the comfort in your basement.

DELTA®-FL is an inert material. The air-gap membrane is extremely tough and rugged, has an outstanding compressive strength of > 5,200 psf (250 kN/m²) and can therefore withstand heavy loads which allows for any finishing on top of the membrane.

The product is extremely easy and fast to install. Reduction in head room is minimal.


This air-gap membrane is made up of a special high-density polyethylene resin, providing a dimpled surface with outstanding compressive strength, impact resistance and long-term performance.


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.

Technical Data

Product name DELTA®-FL
Color gray
Material High Density Polyethylene (HDPE),
stabilized (oxidation & UV)

Dimple height apprx. 5/16"  (8 mm)
Compressive strength 5,200 psf  (250 kN/m²) ASTM C695-02a

Water vapor transmission

< 20 ng/(Pa s m²)

ASTM E96, Method A                                   

Vapor permeance

< 0.3 perms [grains/h/ft²/in Hg]

ASTM E96, Method A                                   

Air-gap volume between dimples apprx. 5.3 l/m²
Toxicity non-toxic, non-polluting, non-allergenic, odor free

Chemical properties
Excellent resistance to chemicals

Temperature range -22°F to +176°F  (-30°C to +80°C)
Roll dimensions/ Roll weight

4' 9" x 68' 6"  (1.46 m x 20.9 m)  328 sf (30.5 m²)

47 lbs   (21.3 kg) 

3' 6" x 30' (1.07 m x 9.14 m)  105 sf (9.7 m²) 

12.5 lbs (5.7 kg)

Sheet dimensions

Sheet weight

4' x 8'  (1.22 m x 2.45 m)  32 sf (2.98 m²) 

4.4 lbs (2 kg)

Service life expectancy > 25 years (at pH between 4 and 9 and temperature < 25°C). Do not be expose to UV light for longer than 30 days.


Where can I purchase DELTA®-FL?
You can purchase DELTA®-FL at Box Store outlets like RONA, Home Hardware, LOWES, and Building Supplier Outlets.

Can I fit the product in my own car?

Yes, you will be able to fit the 3.5' x 30' rolls into your car without problems. The rolls are light weight and easy to handle.

How does DELTA®-FL work?

DELTA®-FL works as a vapor retarder in two ways:

1. It prevents moisture from migrating into the finish flooring

2. It slows down the migration through the concrete slab once a moisture equilibrium is reached between the DELTA®-FL air cavity and the area below the slab.

What type of subfloor should I use over DELTA®-FL?

We recommend you use min. 7/16” thick OSB or plywood for general purpose floor finishing like carpet. Laminate floor systems can be applied directly over top of DELTA®-FL.

When installing DELTA®-FL should I install the membrane over the entire floor, or should I install my partition walls first before installing DELTA®-FL?

The easiest installation method is to install DELTA®-FL over the entire area to be protected, then install your interior non-load bearing partitions over the prepared flooring system. If your perimeter and partition walls are already installed you would follow the same installation instructions inbound of the walls.

Is it required to secure DELTA®-FL and the subfloor to the concrete slab?

Securing the DELTA®-FL would only be required when installing floor finishing materials that are susceptible to damage from movement of the system. Examples would be nailed hardwood, glued laminates, peel-and-stick tiles and a few others.

Can I install carpet directly over DELTA®-FL without any substrate?

No, carpet should not be installed directly over DELTA®-FL since you will need to attach tack strips along the edges of your room to hold down the carpet. We recommend the use of min. 7/16” thick OSB or plywood over the DELTA®-FL for carpet installations.

When installing DELTA®-FL, should I leave a gap at the perimeter, or should I install the membrane tight to the wall?

Do not leave a gap at the perimeter of the wall. Since DELTA®-FL acts as a vapor barrier it should be installed tightly or “snug” to the wall. The tighter the connection between the membrane and the wall the less vapor can pass by and migrate into the living space. The perimeter (and around penetrations) should be sealed using a low expansion spray foam. There are several brands of low expansion spray foam and one should be available in the same store where you purchase your DELTA®-FL. If you are installing DELTA®-FL to help combat water seepage from the walls, DELTA®-FL should be combined with other components to control this issue, independent of DELTA®-FL as a vapor retarder. DELTA®-FL is not a substitute for proper foundation repair and maintenance. Please contact our Technical Service Department for further assistance.

When installing laminate flooring, do I need to install a substrate, i.e. OSB? If I install the laminate flooring directly over the DELTA®-FL, will this void any warranty with the flooring manufacturer? Does the DELTA®-FL warranty still apply?

DELTA®-FL is a vapor barrier with added benefits that conventional barriers do not offer. Since laminate flooring manufacturers generally require the installation of a vapor barrier over a concrete slab prior to installing their laminate flooring, there should be no reason to void the warranty of the laminate flooring. We recommend you verify this with your supplier. If you are having problems with the use of DELTA®-FL and a particular laminate product, call our Technical Service Department for more information. Cosella-Dörken will honor its own standard DELTA®-FL product warranty for DELTA®-FL installed under laminate flooring.

Can I use DELTA®-FL with a radiant floor heating system in the concrete slab?

Yes, you can use DELTA®-FL with radiant floor heating systems. Ensure that none of the heating elements of the heating system comes into direct contact with the DELTA®-FL membrane. Most systems are designed so that the heating elements are contained within the substrate, i.e. the concrete slab. Please contact our Technical Service Department for further assistance.

I have started the installation of DELTA®-FL and experience a slight curling of the membrane once I unroll it on the floor. Will this affect my floor assembly and cause any problems?

After manufacturing the DELTA®-FL membrane gets rolled, packaged and stored until it is delivered to the customer. During the time of storage the material takes on what is referred to as the “set” of the roll which causes it to slightly curl when first unrolled for installation. This condition will level out over time once the finished flooring is installed and you complete the room décor.

Keywords: Concrete Slab, Density Polyethylene, Floor, Flooring, High Density Polyethylene

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