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-   -   Mortar bed uneveness help (https://www.johnbridge.com/vbulletin/showthread.php?t=126926)

laostirch 02-09-2019 01:11 PM

Mortar bed uneveness help
1 Attachment(s)
Hi everyone,

Before I begin, I’d like to thank you everyone for taking your valuable time and knowledge to help others.

My tile contractor is working on tiny powder room, 5x3, the house is about 100 years old, when he ripped out the plywood, the diagonal tong and groove hardwood subfloor under neath was so rotten, he suggested to replace the subfloor, so we did with 3/4” acx exterior 1 grade subfloor. After subfloor, he suggested floating motar bed with metal lath, since I read somewhere that this is great method for uneven floor, I took his suggestion, now I’m checking the floor and the floor is not even with some towel mark, you tube video that I found has really smooth even surface where mine is very bumpy and from 4ft leveler, there is some hollow space in between about 3/8”. He’s coming back tomorrow to set tile, is this okay? He’s nice guy and I trust him to do the right thing but I want to ask everyone here what is acceptable and not. Please help!!

Tool Guy - Kg 02-09-2019 01:17 PM

Welcome to the forum, Renee! :wave:

If the floor is sound, you can knock off the high spots with a "rub brick", fill in the low spots with mortar, or a combination of the two. The rub brick works like really rough sandpaper on steroids....it's much, much faster at grinding material away than you might initially think. You can find them at any box store.


cx 02-09-2019 01:28 PM

Welcome, Renee. :)

A mud bed should be much flatter than that, 'specially in such a small area.

Do you know just what was used to create the mud bed?

How thick was the mud bed?

laostirch 02-09-2019 01:31 PM

Thank you Kg, I’m relieved that it doesn’t require complete do over. My contractor told me the bed is about 3/4” thick, based on what I researched, any size smaller than 100 sqft, 3/4” is okay,
So would you agree that this motar bed needs free of bumps needs total level, right? The room will get 1x1” hexagon porcelain mosaic tile.

laostirch 02-09-2019 01:37 PM

2 Attachment(s)
Hi CX!

Your advise steered me from keeping existing non flanged tub to getting a integral tile flange bathtub! Which will get to it after small powder rooms are done.

He told me he used Portland cement board and mixed with not sure what, I can find it through him, when he comes back tomorrow. Also should the motar bed have been gap for expansion by the wall?

cx 02-09-2019 01:44 PM


Originally Posted by Renee
He told me he used Portland cement board and mixed with not sure what

Shouldn't be any CBU ("cement board") involved if he intended to make a mortar bed for the tiling substrate, Renee. And the surface of that floor looks to me as though whatever he used was a good bit too wet for a proper mud be, which could certainly be part of the cause of it not being nearly as flat as it should have been.

Have you any in-progress photos of the floor?

My opinion; worth price charged.

laostirch 02-09-2019 02:01 PM

Hi CX,

This is what he’s done so far, he couldn’t come today but he is scheduled to be back tomorrow. My understanding is this motar bed is replacing any cement board. It had a wet look with no water when I came home last night. Urghhh. What should I do? He will work on the other powder room tomorrow and he make make more thick consistent ( like peanut butter?) currently just subfloor installed on the other powder room.

What needs to be on current situation? I’ll definitely check out what KG suggested, my understanding was any add on motarbed to fill the low spot wouldn’t adhere well on existing dried motar bed, is it?

laostirch 02-09-2019 02:02 PM

My bad, cement powder, not board, my typo!

Topspin 02-09-2019 02:28 PM

Floor patch to fill low spots. 15-30 min to cure. Some options

Custom Building Products https://www.custombuildingproducts.c...compounds.aspx
Mapei Planipatch
Laticrete NXT patch
Henry Universal patch
Uzin 888

laostirch 02-09-2019 02:48 PM

Thank you Kevin, I’ll check it out, I’m make a trip to Home Depot really early tomorrow morning before my contractor come in, so if anyone else can suggest, please let me know! Thank you so much everyone!!

cx 02-09-2019 03:57 PM

Renee, go to our Liberry and find the Shower Construction thread. In there find the article titled Making Deck Mud. That's the material he should be using to make the tiling substrate and it should be an absolute minimum of 3/4" thick over a cleavage membrane (polyethylene sheeting or roofing felt) and expanded metal lath and it should be dead flat.

One of the reasons for using deck mud is because you can make the surface nearly perfectly flat. You can also make it level if you want. But you should certainly not need to flatten the surface when it's finished. He should remove what is there and do another mud bed correctly.

My opinion; worth price charged.

laostirch 02-09-2019 04:33 PM

Ok, looks like some reading to do, I’m at work now but definitely will done reading by 6pm pacific time, I’ll post any questions if you can swing by tomorrow 9:00am in pacific time, I feel little better at least you guys are here to shed some lights unlike last time when I did some house related work, felt complete left in dark. Thank you! talk to you soon!

speed51133 02-09-2019 04:38 PM

Could that be SLC on the entire bathroom floor?

laostirch 02-09-2019 08:00 PM

I read through under deck mud section, I know my contractor used metal lath, not sure about roofing felt, he mentioned it when we were still at planning installing cement board. He did tell me that he made it mud pack pretty thick but not sure if the thickness was close to what mr. John bridge instructed.

My contractor is really descent guy and he reinforced the floor by blocking without me asking him, and he always leave clean site and he’s late 40’s and has a license since 1990’s. So it really puzzles me why he left the floor like that. I did text him a deck mud link and told him to let’s discuss it tomorrow.

My questions are below

1. Say mud mix was bit watery than how it should have been, what can be done to remedy, I’m willing to do over, ——- my contract left my home around 4-ish and I got home 7:30 and you can tell the mud was soft to touch, was too scare to press any hard, it felt like if I gave it a press then it will dent. By reading deck mud, John mentions that the mix shouldn’t be workable after 45mnts, this tells me the mix was definitely watery than said recommendation.

2.if The current mix is okay/passable, I’ll just need to make sure the floor will get even. Can anyone confirm that what Kevin recoomened ( for little hollow area to fill here and there) can be used on top of DRIED mud? Is self leveling same thing?

3. Subfloor plywood has expansion but mud bed pretty much covered all gaps between floor and wall, please let me know if this is okay..

I can only find a YouTube video on shower floor, if anyone can post a link for deck mud on regualar powderromm floor.
Thanks everyone....

Just In Tile LLC 02-09-2019 09:26 PM

Hi Renee,
I'll answer the first two questions, for a typical dry pack what I see there is not close. That look like it was mixed to a flowable consistency, not damp beach sand so I'd confirm too much water was used for sure. It's mixed and tooled dry for the exact reason you are showing, too wet and it sticks to your tools and is very difficult to leave a flat bed. Is it a do-over...?, well I do find it ironic that "flattening of the floor prep" is not to any degree what most would call acceptable. It was done to get the floor ready and flat for tile so a red flag for me on the finish work. Nice guy or not.

It can be saved if it's a good install like Kevin has mentioned, but to me if the whole purpose of the mud job was to prep for the tile, why in the world create an obstacle that large to fight in the tile job, 3/8ths off!? Doesn't make sense to me.

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