Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Backerboard over Subfloor

ackof21's Avatar
New Member

Join Date: Jun 2006
Posts: 4

05-05-07, 07:21 PM   #1  
Backerboard over Subfloor

I am putting down cement backerboard (actually Hardiboard) to eventually lay tile. The hardibacker is going over an existing plywood subfloor. The installation instructions for the hardibacker indicate that I need to lay mortar to attach the hardibacker to the subfloor. Additionally, I need to put about 40 screws per sheet into the board to secure to plywood subfloor.

My questiona are 1) Do I really need to cement the backerboard to the subfloor given all of the screws that will be going into the backerboard. 2) If I do need to cement, what is the purpose of cementing and screwing?

Any thoughts would be greatly appreciated.

Sponsored Links
chandler's Avatar
Banned. Rule And/Or Policy Violation

Join Date: Dec 2005
Posts: 39,968

05-06-07, 03:27 AM   #2  
Placing the thinset on the floor prior to the hardibacker will aid in adhesion and will also tend to self level the floor and prevent dead spots. A good part of the hardibacker is they indent the panel everywhere you need to put a screw. Sort of a neat innovation, IMO.

Search this Thread