Suggestions on concrete work..

[747mopar]

I've got a renovation project going on at work but ran into an issue, the office floor is 3/4" plywood over a concrete slab then 3/4" oak over it but the bathroom is bad! Evidently the toilet ring leaked but the water went under the oak floor out of sight and destroyed the plywood leaving no support. My plan is to gut all wood and pour concrete on the slab to gain the needed 1" back, suggestions on what to use?

I'm only doing 2 5'×5' bathrooms and will do a ditra membrane over the concrete then tile.

 

[Moms68]

I've got a renovation project going on at work but ran into an issue, the office floor is 3/4" plywood over a concrete slab then 3/4" oak over it but the bathroom is bad! Evidently the toilet ring leaked but the water went under the oak floor out of sight and destroyed the plywood leaving no support. My plan is to gut all wood and pour concrete on the slab to gain the needed 1" back, suggestions on what to use?

I'm only doing 2 5'×5' bathrooms and will do a ditra membrane over the concrete then tile.

 

[Moms68]

I like hardie board. It’s similar to cement board but easier to work with. Comes in 3’x5’ x 1/2” sheets. You could set it in a thinset.

 

[Charles Cook]

Google Ardex self leveler. I use it all the time.

 

[66 Sat]

1" concrete will be too thin and will crack. You need a minimum of 2", and either scabble or apply a bonding agent over the existing concrete.

If you are tiling over the top you can easily make up that height in sand cement screed as a bedding for the tiles, probably the easiest and cheapest way.

 

[kiwigtx]

Google Ardex self leveler. I use it all the time.

Make sure that the self-levelling compound has good ventilation to cure.

 

[bm02tj]

Going with thin concrete like that coat old concrete with white glue and it will bond and not crack

 

[747mopar]

I like hardie board. It’s similar to cement board but easier to work with. Comes in 3’x5’ x 1/2” sheets. You could set it in a thinset.

I've used Hardie board but going over concrete I figured some sort of concrete or grout would make more sense instead of using tapcons to secure a cement board.

Thanks

 

[747mopar]

Going with thin concrete like that coat old concrete with white glue and it will bond and not crack

That's what I was thinking, I've used levelers and the primers before just never had to add a whole 1"over an area. I hated to used the same leveler because they're $34 per 50lb bag and I don't need the self leveling feather edge characteristics this time.

1" concrete will be too thin and will crack. You need a minimum of 2", and either scabble or apply a bonding agent over the existing concrete.

If you are tiling over the top you can easily make up that height in sand cement screed as a bedding for the tiles, probably the easiest and cheapest way.

I saw them doing this on YouTube, what exactly is the mix, just masonry sand and Portland cement?

I plan to use an uncoupling membrane before tiling incase it should happen to crack so it won't transfer to the tile. As far as the 2" minimum goes, I always took that as the minimum thickness when pouring a slab not pouring over top of a structural sound slab?

 

[747mopar]

Google Ardex self leveler. I use it all the time.

I'll look into this, pretty stanky? I've got 2 lovely secretaries in the office that I'd like to not piss off.

 

[66 Sat]

That's what I was thinking, I've used levelers and the primers before just never had to add a whole 1"over an area. I hated to used the same leveler because they're $34 per 50lb bag and I don't need the self leveling feather edge characteristics this time.



I saw them doing this on YouTube, what exactly is the mix, just masonry sand and Portland cement?

I plan to use an uncoupling membrane before tiling incase it should happen to crack so it won't transfer to the tile. As far as the 2" minimum goes, I always took that as the minimum thickness when pouring a slab not pouring over top of a structural sound slab?

The ratio is 4:1 sand / cement. It would need to cure for at least 3 days before tiling on top. It's up to you which method you use, but I've been in construction my whole life and concreting specifically for the last 9 years and I have never seen a 1" topping slab in concrete, but the jobs I'm involved with are large commercial projects with long warranties, so everything is designed to last for 50 years or something. I've occasionally seen 1.5" thick toppings but they are fully bonded (existing surface roughened by scabbling). You'll need a mix with a very small aggregate size too, maybe there is a fibercrete mix that will do the job.

Depending on what tiles you are putting down you might not need to do anything - if you can get a 3/4" thick tile and then use a large notch trowel with plenty of glue you might get your level that way.

 

[747mopar]

The ratio is 4:1 sand / cement. It would need to cure for at least 3 days before tiling on top. It's up to you which method you use, but I've been in construction my whole life and concreting specifically for the last 9 years and I have never seen a 1" topping slab in concrete, but the jobs I'm involved with are large commercial projects with long warranties, so everything is designed to last for 50 years or something. I've occasionally seen 1.5" thick toppings but they are fully bonded (existing surface roughened by scabbling). You'll need a mix with a very small aggregate size too, maybe there is a fibercrete mix that will do the job.

Depending on what tiles you are putting down you might not need to do anything - if you can get a 3/4" thick tile and then use a large notch trowel with plenty of glue you might get your level that way.

That's why I post questions on here, this place is a walking encyclopedia to the minds of professionals from of every trade imaginable. I need to make up about 1 3/4" total, I say 1" because I'm figuring on making up the other 3/4" with the tile and membrane.

The sand and cement method is what I kept finding in my research but nobody specified the mixture.

Thanks

 

[440RUSH]

Might want to add some fibermesh to the mix. That should be available at a nearby ready mix plant. It should be sold in one pound bags. A one pound is about enough to treat one yard. That would help keep it from cracking. It's used a lot in precast products that are thin.

 

[Charles Cook]

I’ve been in the flooring business for 40 years. My cell # is on the card if you would like to call and explain exactly what your doing and what you want to achieve in the end I will be happy to help if I can.

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[Slap Stick]

There are two kinds of concrete. That which has cracked, and that which hasn't...yet.

 

[Moms68]

I've used Hardie board but going over concrete I figured some sort of concrete or grout would make more sense instead of using tapcons to secure a cement board.

Thanks

You can lay it right in a bed of thinset. Use the proper notched trowel.