Hello, I hired a plumber to install shower. As I am watching the shower be built, I noticed he put the rubber pan in. Then he put the mortar over the rubber pan, but strange that he put 2" x 2" wood pieces inside around the parameter of the pan. He then has the mortar going up to those 2x2 wood pieces that are on the inside edges of the shower pan.
I cannot imagine any wood should be inside the shower pan as I am certain the wood will stay wet and rot immediately.
Can anyone tell me if 2x2 wood around the inside edges inside the pan is normal? If not, I need him to stop tomorrow. The wood in the mortar just doesn't seem right. Please advise. Thank you. Lou

Was the wood subfloor, under the membrane sloped towards the drain? The 2x2s are probably screeds(guides), that would be removed and the resulting troughs filled with mortar. The 2x2s should have been removed as soon as the mortar was sloped and then filled. How/why are you having this "plumber" tile your shower?

I think steve is dead on. I used metal from a drop ceiling when I did mine to form the slope, let is sit for a bit, then removed, filled, and finished the surface before it cured. Thinset has good adhesion, so it should work fine to fill in the voids, but it isn't designed to be poured that thick really. The wood should have been removed before the base cured, and the voids filled in, but he may have a different technique that works equally well, or reasoning that we don't know. If you think he doesn't know what he is doing, stop him sooner rather than later and have a talk about his plan of action. Consider replacing him if you don't have confidence. Most plumbers don't take part in the forming of the shower floor. Also, make sure that gravel was placed around the weep holes next to the pan liner around the drain so that they stay open and don't fill with concrete/sand mix/thinset.