building shower walls with concrete - DIY Chatroom

canyongirl · 01-25-2009, 01:55 PM

I am considering creating the walls in a new shower with poured concrete. I have seen a building made with wall forms created by wooden boards set side by side and the concrete was poured between 2 forms. Once hardened, the boards were pulled and the boards gave an interesting texture to the concrete. I have a pretty good idea of how to do this but am wondering if anyone out there has done anything like this before. If so, what did you learn? What would you do differently? These walls will attach to the current walls which are ICF blocks. The shower walls will be about 4 inches thick. I plan to use hardware cloth as reinforcement and will have short rebar pieces sticking out of the ICF walls to attach the shower wall to the support walls. Also, I plan to use a small aggregate concrete.
Thanks for any insight you can give me!

II Weeks · 01-25-2009, 04:02 PM

Ive never seen what your trying to do before but the first thought is whats supporting these new walls from below?

canyongirl · 01-25-2009, 05:34 PM

I have built a concrete shower floor that sits on the concrete pad. The walls will sit on this. I plan to line this shower floor with a flexible shower pan and run it up the wall, then build the frames and pour the walls. This way it will be inbedded into the wall, as if behind a tile wall.

II Weeks · 01-25-2009, 05:39 PM

take some pictures during this. i would like to see how it comes out.

concretemasonry · 01-25-2009, 06:16 PM

Pouring a 4" concrete wall is a work different than pourig a floor slab.

You will need a lot of bracing the keep the wood forms is place and reasonably square. Next you will need ties to hold the 2 sides of the 4" wall together and not bulge or blow out. Your form boards would have to be at least 3/4" plywood plus you will ne 2x4's, 2x6's or 2x8's vertically to attache the bracing to.

Keep in mind that concrete is over twice as heavy as water and everyong know how much pressure is created laterally or vertically. - You are fighting Mother Nature and gravity.

block would be more feasible if you can find a suitable surface to apply to the walls.

Tscarborough · 01-25-2009, 06:18 PM

If your only interest is in the look of board-formed concrete, then consider doing vertical stamped concrete. It solves most of the problems with forming and placing a real 4" thick concrete wall.

**thekctermite** · 01-25-2009, 07:01 PM

Forming, reinforcing, and placing concrete aside...How do you intend to sufficiently seal the concrete shower to prevent water from permeating it, especially on the floor? Hopefully you placed an integrated sloped membrane in the shower floor to allow water that penetrates the surface to get to the drain.

canyongirl · 01-26-2009, 11:37 AM

For the floor of the shower I will place a flexible shower pan (its like a big thick sheet of rubber) and the floor slopes to the drain. I will tile on top of this. The walls I will seal with a concrete sealant. This is a bathroom that probably won't be used often and we are in the high desert where things dry quickly. There is a window right next to the shower and an outside door should we need to let more air in. After living most of my life in Florida and living with constant mildew, I am amazed at how slowly it grows here!
But I was wondering if you know if portland cement without aggregate is less pourous and may be a better choice for the walls? And do you recommend a particular sealant? I am very interested in products that don't offgas and are of low toxicity.
Thanks for corresponding!

concretemasonry · 01-26-2009, 12:14 PM

You will need aggregate (sand and pea rock) and reinforcement for strength and crack control. Portland and water is too weak and will crack in addition to being very expensive.

**thekctermite** · 01-26-2009, 12:25 PM

Agreed, you definately need aggregate! There are a myriad of options other than basic gravel limestone stuff...Pulverized granite, etc.

Tscarborough · 01-26-2009, 02:24 PM

Marble dust used as the fines will also assit in the waterpoofing of the concrete.

canyongirl · 01-26-2009, 05:13 PM

Thanks for your imput everyone! It is good to know that this is do-able and not a totally crazy idea. I will write when I complete it to let you all know how it went.
PS--I have a (chocolate) lab too!

yesitsconcrete · 01-27-2009, 08:08 AM

congrats on picking icf system - you'll absolutely LOVE it,,, if you've resolved support issues, it is ' do-able ' however ea wall measuring 3.0 x 6' will weigh 555# - 3 walls = 1,700# + steel reinforcement + floor,,, that's a very serious static load not to mention the difficulty in placing conc,,, vertical thin-stamp makes much more sense to me & we've done both for ourselves & clients,,, form bracing'll be critical so overbrace,,, we lined the forms w/poly & pulled 'em after 24hrs,,, you could use liteweight aggregate but its really not nec in this case since sufficient support's already present,,, plain conc can look good but use a VERY good conc sealer ( solvent based ).