You’ll hear the terms “above grade” and “below grade.” “Above grade” means it’s installed at or above grade level, and “below grade” describes an area below ground level, such as a basement. Not every kind of hardwood can be used in every location.

Engineered flooring’s cross-ply construction enables installation below, on, or above grade; even over concrete. It resists expansion and contraction caused by temperature and humidity changes. Engineered flooring is typically glued down, stapled down or floated. Some manufacturers offer locking engineered flooring for a floating installation without glue, nails or staples.

Most solid hardwood flooring needs to be nailed to a subfloor and is susceptible to shrinking and expanding from excessive moisture and extreme temperature changes making it unsuitable for installation directly over concrete (the main subfloor in Southern California) and not usually recommended for below grade use. Some manufacturers offer a thin-profile (5/16”) solid that can be glued down over concrete. Hardwood flooring is a great choice for just about any room in your home. However, it is not recommended for full baths where frequent tub and shower spills are likely to occur.

	Solid	Thin-Profile Solid	Engineered
Board Thickness	3/4”	5/16”	1/4” – 5/8”
Board Width	Strips & Planks	Strips & Planks	Strips & Planks
Where Installed	On Grade or Above Grade	On Grade or Above Grade	Below Grade, On Grade or Above Grade
Subfloor	Wood	Wood, Concrete or Existing floor	Wood, Concrete, or Existing Floor
How Installed	Nail	Staple or Glue	Glue, Staple or Float