How to properly raise and slope over concrete on below grade patio so that we can tile over it?

Submitted by Affectionate_Leg_686 t3_1211u1r in DIY

We have an outside patio with a plan concrete slab floor. In the middle it has a drain for rain/melting snow discharge. One side faces the house and is about 2 1/2" below the inside floor.

The concrete has sagged at some point due to incorrect water drainage. We fixed that by cleaning the drain. What we need to do now is add a layer on top with some slope so that water goes to the drain from all sides if possible. On top of that we would like to add tiles.

We are in Toronto, Canada, so whatever approach we take the poation will have to withstand temperatures well below freezing and also warn and humid summers.

How would you approach this?

https://preview.redd.it/lxjhhc6borpa1.png?width=560&format=png&auto=webp&v=enabled&s=4871237e12fec05cd99d89648fc954fff8485e4a

Thanks!

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Comments

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CogitoErgoScum t1_jdk4i6m wrote

The right way is to cut out all the concrete. Then you drill holes into the slab, hammer in rebar, and repour it.

If I was going to half ass it, I would just clean it up and tile it with a super thick mortar bed so you can grade it as you lay the tile.

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Affectionate_Leg_686 OP t1_jdk7y0v wrote

Thank you for the suggestions.

I hope these are appropriate questions to ask (still trying to learn how to abide by the forum's rules ):

Mortar wise, what do you think about reinforcing it with wire mesh? Any mortar will do or would you recommend some particular mix (not looking for a brand here -- the type),. Structurally strong concrete mixes seem to need 5" to 7" thickness which we cannot do here (I see your point about redoing the whole thing is the right approach).

Would adding a cement board on top of the mortar be a good idea? I am thinking this would reduce how thick the mortar needs to be and maybe it can help avoid crumbling in the long run. Or this is half assing it to the square :)

Thanks!

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bartonlong t1_jdkjkgl wrote

An easy way to fix this (kinda) is to put in rubber pavers. Just google that and find some that are available near you. You put down a heavy duty plastic frame than some heavy duty stiff rubber composite pavers go into that frame. When you are done the patio will look like (kinda) like regular pavers but will have a hollow spac eunderneath in the plastic frame that will allow the water to filter into the drain and keep the pavers dry. It isn't the perfrect long term soluation but way easier and cheaper than busting out the concrete and will allow you to enjoy your patio faster.

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Affectionate_Leg_686 OP t1_jdkl39k wrote

thank you. I understand and agree that would be a quicker fix with immediate results. I'm looking for a more permanent solution. Already committed to tiles (bought them). let's see if this turns out to a major mistake at the end where I "fix" it, and then have to pay for someone to remove the mess I create, and really fix it :)

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PrestigiousTrouble48 t1_jdl8hb8 wrote

You can either add an additional layer of concrete with bonding agent and scree to create the correct level, then tile. Or use a thick bed of tile glue (I’d guess some type of mastic for cold temps ?!? Sorry from Australia) start at drain and work outward using a level to keep the correct slope.

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Affectionate_Leg_686 OP t1_jdm1752 wrote

Bonding agent is a good idea. I was also thinking of cutting some grooves into the slab for added adhesion too. Thanks! I've been toi Australia once. Loved it despite being reminded that everything there can kill you :) We were around Cairns.

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