Mortar/crete for fiberglass shower base?
JohnT8
| Posted in Construction Techniques on
OK, it has been a few years since I’ve put a fiberglass shower stall in, but is it no longer common practice to slather down some mortar or concrete and set the showerstall unit into that? That is the way I’ve done it in the past. Talking with someone yesterday and he says he doesn’t bother. Just slides the unit in and screws it off and is done.
I’ve always thought the mortar or crete gives you a nice solid base to stand on. Without it, a big guy like me can feel the base flex a bit as you walk on it.
jt8
“Worry never robs tomorrow of its sorrow, it only saps today of its joy” –Leo F. Buscaglia
Replies
RTFM!!
;) Our plumber always uses Structolite, a perlited gypsum mortar.
[email protected]
RTFM!!
I take that as the shortened version of: "whether we use mortar depends on the particular fiberglass shower we're going to employ." :)
Our plumber always uses Structolite, a perlited gypsum mortar
K, I'll keep my eyes open for that stuff on the next stall.
jt8
"Worry never robs tomorrow of its sorrow, it only saps today of its joy" --Leo F. Buscaglia
"K, I'll keep my eyes open for that stuff on the next stall."Watching what happens in the next stall can get you into legal trouble..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Concrete no, mortar yes, Eric uses Structolite but I think he's the only one (sorry Eric).
Yes, it's becoming less common practice, but still good practice.
If you believe I am the only one using it, than you are missing alot including the best practices of a multi million $ plumbing outfit with 25 full time employees. And all of the other plumbers I have ever seen or payed to install a non cast iron tub/shower base.
Please be kind enough to convince me as to why portland based mortar which is heavier (something to consider when installing a large two person tub capable of holding 400 lbs or more of water sans occupants) and more difficult to transport, handle and mix is superior in any number of ways than a lightwieght gysum based perlited mortar.
Maybe it is one of those regional things...............[email protected]
John,
just another sign of the times, i.e. no one takes any pride or gives a damm about their work.
I wouldn't use mortar or concrete, I've always bedded fiberglass/acrylic units in plaster.....first I lay a thin sheet (painters poly--1mil. thick) of plastic on the subfloor, then the bedding plaster, then set your tub/shower/whirlpool in place.......try not to step into the unit (or only enough to be sure your setting on the supports) until after the plaster has set up, which is one reason I use plaster, it sets up in about 90 mins. or so.
Geoff
P.S. I have run into a problem since moving to Hartford.......NO ONE does plaster down here!! I have to travel to Springfield, Ma to get plaster!!! Maybe that's a reason to try the structolite.............
We've discussed it here a couple times a year, for as long as we've been here--
I'm sure the Structolite works fine, mortar is what the manufacturers recommend.
I haven't used Structolite much, and not at all for a long time. After it's set, when it gets wet does it break down like joint compound or does it set hard like plaster?
I haven't used Structolite much, and not at all for a long time. After it's set, when it gets wet does it break down like joint compound or does it set hard like plaster?
I'm not sure. I believe it is similiar to plaster in that respect. Certainly not like joint compound though. It is a setting material, not an air dry type.
Not sure why you ask that question though about it getting wet? I would hardly think that there is much possibility of it ever seeing much water beneath a tub or shower pan. At least not of sufficient amount to cause it to disintegrate.
Every plumber around here uses it. In 30 years I have never seen a plumber use portlandt based sand mix.
Of course that doesn't mean it's correct. Maybe it's time to do a little research. I hit a couple of plumbing forums and there seems to be a mix of users as well as here.
They can't all be hacks if that is what you or anyone else is attempting to imply.[email protected]
They can't all be hacks if that is what you or anyone else is attempting to imply.
That is what I was implying but now I'm not so sure. I've never seen it used in Maine or Mass but that doesn't mean it couldn't work.
Concrete no
oops! I know I've used concrete in the past. Hope it didn't damage the unit.jt8
"Worry never robs tomorrow of its sorrow, it only saps today of its joy" --Leo F. Buscaglia
Only problem with concrete is the big aggregate can keep the stall from setting down evenly.
John a couple of reason to do it.
1. Some manufactures will not warranty unless it is imbedded.
2. The feel for the home owner you imbed it and for an hours work you have given them something that has a good rock solid feel. Kind of the difference between closing the door of a, I don't know, KIA and a Benz.
3. It gives the ability to get it level with out shims less chance of a stress crack.
4. Along the same line as 3 the caulk at the bottom (if any, given it is not a caulkless unit) has less chance of opening up and always cracking,
5. My favorite, gives the next guy who comes along something to B---- about (don't know can I spell out the B word) when he is in there trying to pull the thing out and complaining " that thing was never coming out, I could not believe how much mortar he had under the thing." about the time we will be sitting in our condo in Hawaii retired.
I was surprised, put in two Swanstones a few months back those things are heavy, they called for mortar. I don't care what is used just know most manufactures call for mortar in the fine print some say not to use drywall compound, don't know if that extends to plaster?
Wallyo
You're singing to the choir. I like having a solid feeling floor in a stall. As a big dude, I don't want it to feel like the dang thing is flexing and possible about the crack as I'm walking on it.
The guy I was talking with is probably 5'9" or so and average build. He might not notice the difference, but I sure do.
jt8
"Worry never robs tomorrow of its sorrow, it only saps today of its joy" --Leo F. Buscaglia
+1 on the Structolite
The awful thing is that beauty is mysterious as well as terrible. God and the devil are fighting there, and the battlefield is the heart of man.
- Fyodor Dostoyevski
We bed all of ours in mortar (showers and tubs) except if we install an American Standard Americast which specifically says not to. On showers it is a really good idea as in time (with guys our size) the base will move up and down and often lose the seal of the drain which starts leaking. We repair a few of these each year.
I know there is a company where Eric lives the uses structolite, they are wildly successful company with many plumbers, but no one else I every heard of uses it. :-) Anyway we always use it and have never had a problem or complaint associated with it. DanT
Maybe it's a regional thing... in my experience(NYC), the better plumbers even Structolite the CI tubs.
The awful thing is that beauty is mysterious as well as terrible. God and the devil are fighting there, and the battlefield is the heart of man.- Fyodor Dostoyevski
I was reading some tech sheets on the Structolite earlier.
Apparently it has decent thermal isulation properties. My guess due to the perlite?[email protected]
I dunno about the insulation properties of Structolite but it can't hurt. The last CI tub we had set was on a concrete floor after shimming, the plumbers packed about 3/4 of a bag under the tub. With a 200lb slab of Carrera on top of the tub it's nice to know it'll never move.JimPS You going to JLC?
The awful thing is that beauty is mysterious as well as terrible. God and the devil are fighting there, and the battlefield is the heart of man.- Fyodor Dostoyevski
PS You going to JLC?
Classes Wed and Thurs, Expo Friday.
Meet at Angelos noon on Friday.
[email protected]
The builder I worked fo early on when I was learning the trade, would stuff FG insulation in, under and around the CI tubs. Said it helped keep them warmer and helped keep the hot h2o warmer longer if you were soaking in a bath.[email protected]
All the fiberglass tub and shower units we get come with "feet" on them. The feet often don't touch the floor so we shim under them. I like using those plastic composite shims - seems to make sense in a possibly damp location. Probably the mortar bed is better though...
Some people here have talked about using Great Stuff Poly foam. I've never tried it though. I wonder if you have to be careful that the Great Stuff foam doesn't over expand and bow the fiberglass?
I have also found this to be practiced less and less. I recently asked a plumber about this very question. He told me that if it is a high quality tub/shower where the fiberglass is extra thick it is not necessary. I’m not sure I agree with him. On a side note I have also seen Grate Stuff used after the unit is installed - assuming you have access to the unit.
He is wrong because as I said Swanstone requires it and it is high quality. Depending where you measure it it is close to a 1/4 inch probably closer to 3/16. It is ribbed and cross ribbed on the bottom and is expensive.Walllyo
That's basically what the dude I talked with said too. But I still think it is an inexpensive way to make a super solid base and level the unit all in one stroke. jt8
"Worry never robs tomorrow of its sorrow, it only saps today of its joy" --Leo F. Buscaglia
Why does americast not specify a mortar bed? We cut up our americast tub for a weird installation and had to set it in a mortar bed (like a drop in - we had an extra americast tub so we cut the sides off the tub and built the custom frame).
If it set in nicely (which it did) what is the mode of failure? And when?
Eric
I don't know. We install them occasionally. Usually when you have someone that wants a bath tub but wants it shallow so they don't (or can't) have to step over high sides since the off the rack unit only has 14" sides.
But it says it right in the direction sheets so we follow that. Just in case there is an issue you don't want the manufacture telling the client you installed it against their directions. Bad karma from that one. DanT
+1 more on the Structo. Important to read the manufacturer's instructions for the unit you are installing, as some do not want mortar. Last tub I installed wanted construction adhesive under it.