“fight”:Great Stuff under fiberglass tub
MrSQL
| Posted in Construction Techniques on
I saw an article in FHB a while back where the author was using great stuff foam insulation under his fiberglass tub installs.
We’ll I have two fiberglass tubs to install in my own house and DW is afraid that when the great stuff expands it will lift or distort the tub [she saw how it bowed the window frames].
The installation manual for the tubs calls for using construction adhesive or a 2″ moarter bed. I’m ok with the construction adhesive, but I think the great stuff would give great support to the tub bottom (it does flex a bit when you stand on it).
Well who is right:
- me with my umpteen years experience (and having read an article …) 🙂 or
- DW with her observation of bowed window frames
or is there another way to get the same support effect short of the 2″ mud base?
thanks,
Roger <><
aka Mr. SQL
Replies
Your wife is going to love me... she is right. Use the mortar base.
Your Wife is right.
The Wife is ALWAYS right.
(-:
Hands-down the easiest stuff to put under a tub/shower or pan is Structolite plaster. It mixes up to the consistency of cottage cheese and hardens like rock. Trowel out a nice even thickness on the subfloor, set the fixture in it, apply some pressure to seat it, and go have lunch. I'd never use mason's mix or spray foam or anything else. It's a USG product, and you can set most fixtures with less than one bag.
http://www.usg.com
Go with the Structolite!!, as stated it will provide the extra support for the floor of the tub/shower to prevent cracking or hazing down the road from flexing that would take place during daily use, IN ADDITION, I use a sheet of poly on the floor, then pour your plaster bed on the poly, if you ever need to remove the unit, this will make that process enormously easier and it will help to keep the structolite from setting up to quickly and cracking (due to the plywood sucking out the moisture from the plaster). Also be sure to seat the tub on the supports that are intended to be the bearing points, Don't do this by stepping into the tub,but instead apply downword pressure at the corners, which is where the support blocks are usually located.
Geoff
Sorry Dave, this should have been to the OP
Edited 2/7/2007 7:04 pm ET by Geoffrey
David, I have always used mortar, simply because I always have some around.....but I like the idea of the Structo- Lite better. Where do you usually buy it? I can't say as I've ever seen it stocked around here. Do they usually have it at big box stores??
My local lumberyard has it by a different manufacturer, they call it 'gypsolite'._______________________________________________________________
"But this august dignity I treat of, is not the dignity of kings and robes, but that abounding dignity which has no robed investiture. Thou shalt see it shining in the arm that wields a pick or drives a spike; that democratic dignity which, on all hands, radiates without end from God; Himself! The great God absolute! The centre and circumference of all democracy! His omnipresence, our divine equality!" - Chapter 26, Knights and Squires, MOBY DICK
I used to get it at a mason's/plasterer's supply when I lived near one, now I have it ordered in at my lumberyard, which stocks a lot of other USG products.
Thanks guys...I'm definitely going to give that a try next time.
i used the plaster once and must have overmixed it or something. dumped it on the floor ,spread it out a little,tipped the shower stall in place and it had set up. i was in there like a mad man hammering and busting it up before it got hard. now i use mason mix and don't worry about set time. larryhand me the chainsaw, i need to trim the casing just a hair.
It takes less than 10 minutes to mix a sack of Structolite in a wheelbarrow, dump it on the floor, trowel it more-or-less level, and then drop the unit in place. I much prefer it to cement mortar because you don't have to be careful at all with the thickness--it squishes down nicely and when dry the bottom surface of the unit is absolutely solid.
UNCLE!
All 'Yall Win. and so does DW. been married 21 years so far, I wanna keep it that way.
Strucco lite or moarter.
Thanks a million. I hate making dumb mistakes! Thanks again.
Roger <><
I can tell that you didn't manage 21 yrs. by being stupid!! ;-)
Ok, prove you're married ... let DW type a few words praising us for our knowledge.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Like I said, I always use Structolite but I think you should know that I "think" Structolite voids the warrentee on a lot of tubs so if that bothers you........I just seem to remember on one of the first tubs I put in (was in my own house) it said no something or other can be in the product that goes under the tub...I forget what that something or other was but it was in Structolite...I remember even calling the tub company which I think was Kohler and they verified that...I used it anyway with no problem. Mannnnnn...aren't I helpful...something or other : )~
Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"! From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~ by Isaiah Berlin
http://WWW.CLIFFORDRENOVATIONS.COM
Andy and David,
The only time I've ever used Structolite--it was a bitch to find around here--I used it in a solid masonry wall repair. I had taken the rotten old plaster down to the bricks--spread the the Structolite on the bricks before finishing with DW compound. I didn't like the way the Structolite cracked and shrank--even when I sprayed the bricks with water to keep them moist. I ended up using Durabond in other places. I don't understand why the Structolite under your tub doesn't crack and shrink.
Do they usually have it at big box stores?? <<<<<<<<HD by me carries it and keeps it by the cement...sometimes by the spackle.
Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"! From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~ by Isaiah Berlin
http://WWW.CLIFFORDRENOVATIONS.COM
Durabond!
Well, it COULD be done your way and avoid bulging if you fill the tub with water - or bags of sand - or her, but if you are asking about the best way - ( how much were you offering to pay me to say you are right?) she is the one who gets to say so
and say so
and say so....
How long did you say you've been married?
;)
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Use mortar to set tub.
But the foam may work as a sound dampener after the tub is set.
J. D. Reynolds
Home Improvements
I would not consider using construction adhesive.
DW is right about the Great Stuff, but if you used the low-expansion flexible type sold for use around windows it would probably not deform the tub.
A mortar base would be the best solution.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
The low-E stuff won't provide much support either.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Two different issues:
Most tubs will have fins or feet that need to be on a solid surface. These provide the primary support, and need to be on solid (non-flexing) plywood, concrete, or something of similar firmness. No sort of foam is strong enough for this task.
In addition, many folks realize that it would be nice to provide additional support between these fins/feet, to help keep the floor from flexing (both because this creates an unpleasant sensation and because it can eventually lead to cracking and failure). For this purpose foam is probably a good choice, though it's not clear that "Great Stuff" is dense/hard enough to provide much support, as compared to a purpose-made foam product.
I can imagine some concern that the foam would cause the floor to bulge as it expands. Whether this is a real problem would depend on the stiffness of the floor -- ironically, the more the floor needs the support, the less well it will stand up to the foam expanding against it.
Gotta agree with david m., structolite. It's easy, solid, and permanent.
Plus it provides a little thermal mass to hold in heat during a bath.
Use the structolite, you'll never regret it...buic
Man ,
I just hope his wife isn't the vindictive, lording it over you , "See I told you so " type.
;-)
I did the foam stuff under my tub. Thank bog it was my tub and not a clients tub.
The foam put it out of level, that was filled with water first.
Not enough that I had to remove it and reset it, but enough that I had to cheat the tile work around it to make it appear level.
I can only imagine what would have happened if I had not filled it with water.
Take it from a guy who made the mistake. Go get the crow and cook it up just right and chow down. Do the cement.
I've seen a tub that got great stuffed...the expansion was not really an issue, because there is a lot of unrestricted space for the stuff to go...the problem was after repeated uses, the foam "crunched" up, leaving voids that flexed...it was a bear to clean it out...
So your wife is right and wrong...but don't tell her I said so<G>
As others have pointed out, the tub does not need a bed for structural support. But it certainly is nice to have a sturdy, non-flexing tub bottom.
I had a similar situation, but I used my old, partially used, partially set up bags of concrete and mortar to fill under the tub. To put it in was easy because this was new construction--I simply pushed it in from the room next door after the tub was set into place. Has worked fine for years.
Mortar bed.
Easy.
No worries.
Used it ONCE also, put the tub out of level so much so that not all the water would drain. Heck of a mess with a long old crosscut saw getting it out from under enough to restore the correct slope.
DW is right yet again.
I too have always used Structolite but I put a sheet of thin plastic over it so it doesn't stick to the bottom of the tub in case you ever wanna get it out again.
Greek poet Archilochus said: "The fox knows many things, but the hedgehog knows one big thing"! From The Hedgehog & The Fox ~~~~ An essay on Tolstoy's view of history ~~ by Isaiah Berlin
http://WWW.CLIFFORDRENOVATIONS.COM
Well i'm going to go with you on the great stuff under the tub. Easy, fast, insulating, never had a problem after a few tubs. I tried it on mine first, a fiberglass jacousie unit, did the hook ups, tested for leaks, filled it with water and foamed away. No problems and the tub never budged. So now I use it on all my other installs; no problems. Just to say that also have used structolite with good results, but the foam is easier the more I get older and more lazy.
I do it the same way...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
The wife is always right.
Simply add water to the tub and leave it for a few hours after putting the foam there. After the curing drain the water and your good forever.
Stu