I have this flange extender and as you can see it comes with four screws that probably can be used when there is wood floor (main or upper level floor). I am installing this in the basement and the floor is concrete slab. Since I am tiling I will need to install this. How do I use the four screws in this situation or what do I use to functionally replace them

The existing flange is metal in my case enter image description here


here is the existing flange, the holes do not match

enter image description here

  • Can you use a dremel or other type of cutoff tool and cut them to length? That looks like a solid mount much better than some I have used in the past.
    – Ed Beal
    Nov 13, 2021 at 21:24
  • I could probably to that but are them meant to connect the two flange extensions together or they are also meant to attach the extensions to the real flange that is at the bottom.
    – MiniMe
    Nov 14, 2021 at 2:11
  • As I have said I haven’t used that brand it looks like the 4 screws will pull down through the ring and those are the ones I thought need to be trimmed the brass ones attach to the flange or that is what I would guess from the thread pitch’s , I would not suggest tapcons the blue concrete screws in this case and would stick with the oem screws just trimming as necessary.
    – Ed Beal
    Nov 14, 2021 at 15:41
  • Yeah I do not like the tapcon idea that might crack the concrete around the flange and I get into other problems My biggest issue is that I need to go through the metal flange with those screws and I do not have holes for that. Drilling into the metal piece could cause vibrations and cracks which might lead to other issues as well
    – MiniMe
    Nov 14, 2021 at 17:47

2 Answers 2


It seems that the four screws are meant to attach the flange extender to the floor. In this case I seem to need to drill new holes in the flange extender to match the four circular holes in the existing flange. After that flat head screws and nuts under the existing flange should do the trick


You buy flat-head concrete screws in the screw aisle of your local hardware store. They are typically blue or white coated and come in various diameters. Bring your flange with you when u shop to get the right size (diameter and length). The flat head must not sit proud of the flange.

Be prepared to deal with abnormalities of the existing concrete once you pull off the old flange. Flange must be level and on a solid surface. When I pulled up my last flange, there was concrete missing in key places!

  • I am not pulling the old flange out, I am just adding these extenders to get the top of the flange level with the tiles, not sure what you are talking about. To install the screws you are saying you need a hole just below them in the metal flange and maybe that is possible for two of the four screws which happen to align with the slots for the bolds
    – MiniMe
    Nov 14, 2021 at 2:09
  • Please disregard my comments. I misunderstood your post
    – DAS
    Nov 15, 2021 at 19:41
  • It should be noted that these concrete screws typically require pre-drilling, so make sure you also pick up any masonry drill bits in the correct size if you don't have them already. Nov 16, 2021 at 14:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.