What should i use to secure the shower base to the subfloor [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


View Full Version : What should i use to secure the shower base to the subfloor

02-21-2005, 10:46 AM
I installed a new 3/4 inch plywood over the existing 1/2 plywood subfloor. Now when i lay the new shower base (Swanstone) down what should i use. Someone suggusted thin-set mortar mix another suggested Structo-lite?? Another person even suggested liquid nails for that application. The base is reinforced underneath with lines that look like a spiderweb. Please respond with any advise. Thanks in advanced

- Confused Lou

Sponsored Links

02-21-2005, 10:53 AM
All you need is a little extra support, gravity will do a fine job of holding your pan to the floor. Get a bag of sand topping mix and make a lump in the middle of the floor (you'll have to eye-ball the size of the lump) that will be big enough to fill the void spaces under the pan. Ste the pan into the lump of mix and mash it down until the base sits on the floor. Attach the nailing flange to the studs like the instructions say. When the sand mix sures, you'll have a solid feeling pan.

02-21-2005, 10:55 AM
Here's a link to Swanstone's shower floor installations instructions. They suggest bedding the receptor in quickrete mortar.


02-21-2005, 11:03 AM
Thanks, that helps. I will use quikrete. It doesnt say how to apply it. SHould i do as stated above and put it in the middle around drain, or can i spread it out evenly all over the sub floor and then drop the base in on top. If i should do the later one how thick would you recommend? 1/2 inch of it or 3/4 inch and sould i leave it smooth or use the trowel to make groves?

Thanks again

02-21-2005, 11:05 AM
Just make it into a lump or donut that is slightly thicker than the space between the underside of the pan (not counting the webbing) and the plywood. You want to be able to squish the mortar so there is no gap between the pan and the floor. You do not need 100% coverage, just support the middle most areas.

I suggested sand mix because of the webs, use what the instructions say and you'll be fine

02-21-2005, 11:18 AM
Have you ever used Structo-Lite. A plumber told to use that because it goes on gooey? What that be better than quikrete? WHat quikcrete do i look for at HD? Sand based mortar quikrete?

John Bridge
02-21-2005, 06:20 PM
Hi Lou,

I use brick mortar mixed fairly loose. At Home Depot it's called "Mason's Mix," and it's sold in the green back -- 80 lbs. :) Just make a few small mounds under the base, push the base down all the way and make sure it's level.

02-26-2005, 04:32 PM
When it says to use a mortar mix (quikrete) what do they mean? cement mortar? Or thinset mortar such as versabond or flexbond?

02-26-2005, 05:04 PM
Mortar mix is also called mason's mix. Quikrete is a brand. It contains portland cement, lime and sand. It also may say masonry cement and sand, since masonry cement contains (you guessed it) portland cement and lime.

The purpose of the mortar is just to fill the space under the shower floor to stop it from flexing. It does not "glue" the base to the subfloor.

02-26-2005, 07:16 PM
Thanks, SHould i screw the base to the studs on the flange. The Swanstone website doesnt say anything about it.

But when i was looking at the Jacuzzi website for the installation guide. They say to screw the base to the studs.


I think i am going to screw the swanstone base to the studs. What do you think?


02-26-2005, 09:25 PM
I took a look at the Swanston instructions. They're pretty skimpy. I especially like the cross-section drawing of a tile installation that recommends installing the tile over drywall. In a shower. Not too swift.

I naidid notice that the drawings show that a 3/16" space is recommended been the receptor flange and the studs. So in order to naill it, I suppose you shoud use spacers. You might try to call the folks at Swanstone on Monday.

I installed a Kohler acrylic receptor in my own house several years ago. If I remember correctly, I screwed it to the studs after notching the studs to recess the flange (so that I could bring the CBU to 1/4" above the receptor, and predrilling the flange to avoid splitting.

02-27-2005, 09:47 AM
The mortar should hold up on its own, but be squished by the weight of the pan. Caution should be taken here though. if your mortar is too stiff, the weight of the pan won't squish it. While seating the pan into it's bed, don't over push it as the fiberglass has a tiny bit of flex to it. mortar will press too deep, and the pan will spring up just a bit leaving a minimal gap.

Best of luck

05-04-2007, 10:30 AM

I love this thread. It's answering a lot of my questions. I'll be doing a project similar to your in a few weeks. I'm about to order my base, but before I do, I'd like to hear what you think of the product, how you've found working with it, anything else you think would be helpful.

Thanks in advance.


Brian in San Diego
05-04-2007, 10:36 AM

Welcome! I just checked Lou702's activity since that thread and there hasn't been any. If you want his opinions, you may have to try to PM him or send him an email.