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I cant find anything in the D1 manual about leveling, and they recommend you to the delaer for everything. It does of course say in the warranty that they are not responsible for a tub on an unstable foundation or incorrect installation.... the dealer's service/install guy who leveled it said it wouldnt cause a problem would be the same one to service it if there was a problem. I just dont want to get screwed if something happens and they determine it wasnt installed correctly.
If the dealer is confident that it won't affect your warranty, have them put it in writing, and see if D1 will acknowledge it as well. Stuart is a D1 dealer who may be able to give you a second opinion. Pictures and a more thorough description of the situation would help.A quite awhile ago, perhaps a year or more, someone posted pics of a concrete shim they constructed by laying poly on the existing patio, building a frame that leveled the tub area, and pouring concrete. The poly should make it easy to remove the shim if they ever decide to move the tub. That may be a better solution.