I've tried looking for info but no go...maybe didn't use the correct keywords. Anyway, a little background info: I'm renovating a bathroom where the cabinets were removed (didn't like them) but the heat vent was in the centre of the room, underneath the cabinets. Since I'm replacing the cabinets with a couple of pedestal sinks, I've decided to move the heat vent closer to the wall on the left. I've removed some 1x6 planks (of unknown type) as they were mangled by a previous reno of past owner. So, my question is: How do I repair the subfloor as shown in the pictures below? What I've done: Since the planks (near the wall on the left) isn't secured, I've screwed in a 5" wide 3/4" plywood underneath the planks. In the picture below, the yellow dots represents 3" screws while the black dots represents 1 1/2" screws. I've stepped on this little piece and didn't notice any problems. [Edit#2: the 5" wide plywood piece underneath the planks on the left is flush with the planks above because the floor register will be right next to it. Immediately right of the floor register will either be a 2x4 or 2x6 cross-member/brace/whachamacallit anchored using joist hangers as shown in the pictures below.] What I plan to do (see pix below): 1. Screw in a 2x6 between the two joists using joist hangers as shown in dotted red line. 2. Screw in another 2x6 along the joist (dotted red line). 3. Replace the mangled 1x6 planks. NOTE: I've found 1x6 planks from a different Home Depot (what a PITA ). Returned the 1x6 Cedar planks for fencing. I wasn't comfortable with using those fencing planks as it was slightly thinner than the original planks and a bit soft as well. Edit: I'll leave this question in case if someone can't find replacement for their original planks and end up in a similar situation. Would 3/4" plywood be sufficient as a replacement to 1x6 planks? I plan on installing exterior grade 3/4" plywood then 1/2" Hardiebacker secured by modified thinset and cement board screws (Buildex Rock-On 1 5/8") for 12x12 porcelain tiles. The joists are 2x10 and 16" apart. The bathroom is approx. 30 sq. ft. Let me know if my plan is OK or not. Thanks.