sloped mortar bed

[Dwight2perfect]

Hoping to save labor on an upcoming shower job, I tried to obtain a laticrete: HYDRO BAN Pre-sloped shower pan. Things are hard to come by here in Hawaii. Local supplier didn't have the 48 x 60 that I needed and would try to air freight one in. Laticrete would not send via air, only by truck and boat. That would take too long, and all involved stated that the chance of getting it here undamaged was a long shot. So I'm stuck doing the traditional sloped mortar bed. Problem, usually takes too long after placing bed before being able to cover with hydroban water proofing or redguard. Can someone help me with the time necessary to wait after placing the mortar bed before I can cover with hydroban. OR is there a mortar product that will set and cure quickly to move the project along. I'm planning on putting down at vinyl liner first, then sloped bed, then hydroban. Thanks

[Kman]

Three days, Dwight. No way of getting around the wait time as far as I know.

[Lou_MA]

Fast setting drypack, says redgard can be applied in 60 minutes:

http://www.custombuildingproducts.co...ng-mortar.aspx


Or - you could use a sheet membrane like hydroban sheet membrane. That can be installed next day using regular drypack.

More importantly, why are you putting down two layers of waterproofing? Either use a liner OR liquid applied / sheet topical waterproofing, but you don't need or want both. In either case, it would have to go over a sloped surface. A liner lying flat, with a slope on top, does nothing.

[Davy]

Yep, I agree. You are wanting to combine systems. Use one or the other.

[Dwight2perfect]

Two scenarios please.
1. I'm going to place the sloped mortar bed, followed by the vinyl liner then, let's say 1 3/4" of dry pack. Is the 1 3/4" sufficient? And how long after placing the dry pack may I proceed with laying tile.

2. If I want to place a drypack sloped mortar bed over the plywood subfloor and use Hydro ban liquid waterproofing anti-fracture membrane over that, then how long after drypack may I apply the hydro ban?

[rmckee84]

1. Usually once you can walk on it you can tile over it

2. 72 hours I believe best to double check the hydro ban spec sheet

[jadnashua]

Most of the sheet membranes allow you to install them after 24-hours. Note, you should wait 24-hours after installation of the membrane before you water test it. If you choose to ignore the flood test, you can tile immediately.

Noble's membrane can be water tested after (I think) a 15-minute wait, but I do not remember how soon you can install it over a fresh mudbed. They use a proprietary sealant verses thinset to make their seams (it's not inexpensive), but offers that extra speed.

[Dwight2perfect]

Ok, for the first time I tried using a mortar bed made of Quikrete Sand Topping mix and Quikrete Play Sand per instructions layed out by John Bridge on this site. Mixed to the proportions noted in the instruction. On day 3 I ran my hand over the surface and it was quite sandy with sand being able to be swept up into dust pan. Some was solid, but some sandy. I cleaned off the sandy part first, then applied Red Guard. Noticed when applying the second coat that some stuck to bottom of my foot. When scraped loose it appeared to be a sandy area. Just a few spots this way. I applied a second coat and the next day was inspecting putting pressure on floor with one hand while testing an area. Red Guard came off and stuck to my had better than to the floor. I didn't trust the application so I scraped the red guard off to mortar bed surface. STill a bit sandy though.
Questions. Was the mix done improperly to have a sandy surface, or could I have troweled to much to bring water to the surface?
Secondly, does the mud need to dry more than 3 days?
I am thinking my issue is the sandy nature of the surface. My thoughts on proceeding would be to apply a skim coat of thinset over the mortar bed and then redguard the next day. What do you think?

[Johnny P]

sorry, what is the project?

[Davy]

Sounds like a shower floor, Johnny. Correct me if I'm wrong, Dwight.

Deck mud, (dry pack) isn't a hard mix and is designed to easily carve and shape. If the mud sucks up with a vacuum then it's usually too weak to hold up and should be removed and done again. If it passes the vacuum test then you can apply a skim coat of thinset over the mud to give it a harder surface for the Redgard to stick to. If you do apply a skim coat of thinset, you might need to knock down any small ridges with a rub stone or sanding block the next day. Vacuum again and then apply the Redgard.

[Dwight2perfect]

Yes it is a shower. The mud bed is hard accept for the sandy surface. After I scraped the RedGuard off along with some of the "sandy" surface it was vacummed. Had no issues with anything other than the sandy part being vacummed up.
If a skim coat of thinset solves it, great. That was my thinking also.
But, more important is for my next shower using a "dry pack". What did I do wrong. I followed the directions per a John Bridge instruction commentary. When I installed the dry pack and sloped it to the drain, some of it troweled out nicely with some water coming to the top. Is dry pack supposed to have enough water in it that when troweled the water comes to the top? Mostly it was packed in because of its consistency, but the finish was troweled to get it sloped nicely and smooth. Help me do it correctly next time.

[Dwight2perfect]

Could moisture in the deck mud be an issue after 3 full days of curing? RedGuard was applied the 4th day, two coats.

[Kman]

If you had standing water that had to be removed or allowed to dry, it was too wet. Probably the reason you had trouble with the Redgard.

One question: Is there a liner of some sort under the mud bed? And if so, is there a sloped bed of mud under the liner? (Okay, that's two questions, but they're both important.)

[Dwight2perfect]

Yes, mud bed in top of liner, on top of sloped bed on top of plywood. I realize this is overkill, but wanted a secondary protection with the red guard being my first defence.
There was no standing water after placing the mud. When I troweled at the end to smooth out, there was a cream on too to smooth out like finishing concrete, but without the water that comes up. Should I not trowel a dry pack?

[Kman]

Yes, I use a wood float to shape it, then a steel trowel to finish it off.

But regardless, I wouldn't use Redgard over it when there is a liner in place. At that point you're not leaving any place for the moisture to evaporate. You've sealed it off from the bottom and sides with the liner, and on top with Redgard. The moisture is still going to escape through the easiest avenue, which will be the top. That's why the Redgard came up so easy.

Trust your liner to work properly and leave it at that.