Knock down is a sprayed on product that is applied over drywall typically.  It is called Knock Down because after the walls are sprayed the installer takes a trowel and smooths over the surface to "knockdown" the stucco effect.  You are left with a very noticeable, but more flat "nibs" vs. a full stucco or plaster wall.   Here are some photos and video of what this might look like on your wall.

Video of Knock Down being installed

This type of wall surface is very typical in certain parts of the country - such as Florida for example.  Due to the uneven and textured surface created by this technique, you will need to do the following in order to successfully apply a wallcovering product like our Dreamscape.  

In order to install wallcoverings or wallpaper over this type of surface,  you will need to create a smooth surface and then install a special liner so that your wallcovering will adhere properly.  

1.  Skim coat the wall, at least one coat

2. Sand the wall.  If you want it smoother you can repeat step 1.

3. Prime the wall.

4. Hang a "liner" or "bridging" liner

5.  Now that you have created a sufficiently smooth and receptive surface, you should follow the wallpaper manufacturers normal installation instructions.