When installing new wood flooring parallel to an existing solid nail down floor add a minimum of 3 8 plywood underlayment over the existing floor to increase stability.
How to install new hardwood floors over old hardwood floors.
The surface of the old floor needs to be cleaned.
Or if the thickness of the floor will allow it staple to the existing floor.
They are available in 3 4 inch thickness as well as low profile styles that are 5 16 to 5 8 inch thick which are a good or installing over existing flooring.
For instance i will look at much older floors that were nailed into floor joists before the widespread use of subfloors.
If you will install on top the old floor boards have to be securely fastened try to avoid any loose floorboards.
Typically it is sheets of plastic laid on the slab and taped at the seams with waterproof tape.
To save money and effort the best choice is to sand the old hardwood floor and to avoid installing the new one over the old floor.
Check with the flooring manufacturer for recommendations.
Installing engineered hardwood over existing flooring is a great option for people who have hard to remove floors such as glued down hardwood or glued down vinyl.
Like unfinished hardwood floors the prefinished types typically have tongue and groove edges on all sides.
Solid wood floors should not be installed in basements or below grade.
When installing a floor over your existing floor you will want to choose an engineered wood floor that is at least 1 2 thick and over 4 3 4 wide.
If your subfloor is already hardwood but you want to improve the look of your home with new material it is possible to lay engineered hardwood over the existing floor with proper preparation and traditional installation techniques.
It will extend up the wall for about 2 to 3 inches creating a bowl where your wood floor stays dry and protected.
To keep the new wood flooring level with other transitioning floors in your home consider using inch thick.