"Dry mix" vs. concrete screed and which is stronger and price differences?

[Ronin63]

Good morning everyone!

I am a contractor for interiors and have an inquiry about ceramic tile fixation. I have a contractor, that has quoted for concrete screed , for the tile fixation. On site, he did a dry fix, now,,i'm not a mason, and i did some youtube searches, and ,,please clarify this....youtube vids, seem to show the dry fix method, to be a sand/cement , with a sprinkling of water, and level the mixture up to required levels. then they let it dry??or i got that wrong..because my contractor, simply mixed the sand/cement mixture, got the required levels, then through down the ceramic tiles after splashing a whitish cement(glue)?? on top of the sand/cement mixture.
Now i paid for screed, because in my opinion pouring a concrete screed and letting it dry, will give me a solid foundation to lay my tiles down on, with an appropriate tile adhesive.
Is my understanding of the dry mix method misunderstood?? and shouldn't the dry mix method be significantly less in price for installation,,since i am paying for screed??

Thank you.

 

[Dumbo]

Why would think that when there is the same amount of material going in . Why is he doing it this way do you have time constraints .

 

[Ronin63]

No, there is plenty of time. I have seen plenty of contractors doing this method and i feel it is far inferior of an installation method. I realize that they are doing this, to save time, because they can throw down the sand/cement, then install the ceramic tiles immediately. No waiting for a proper screed to dry.

 

[One Day]

Are you in the US?

 

[Ronin63]

DubDu

 

[Ronin63]

Dubai

 

[Bill]

Before adhesive - fixing in sand and cement was the only way to have a solid bed.

If I have the chance to lay tiles into my own screed on jobs, I do. It is quicker for the client even if it costs more to hire the tiler, the tiler is saving money on not having a floor screeder/concreter. (is that a made up word?)

 

[Spud]

It is also called monolithic tile fixing it is a reliable method if done correctly

 

[Blunt Tool]

I would think that over in Dubai the sand and cement fix method is still the most popular and what the tiler is used to, as long as he makes a good job why have him change what he is used to?

 

[Ronin63]

Please clarify my concerns. Firstly, what they have been doing for years, doesn't mean its the best way to fix/install things, that's why they hire westerners like me to come and run their construction works.
So, firstly, this "dry fix" method, as they do it here( dumping a load of sand/cement, mix it with a hand shovel, throw it down, level up, then splash a whiteish concrete liquid on top, then throw down the ceramic floor tiles,...exactly as i described it, is it correct? strong? or, is it better,stronger, more durable/reliable, as i prefer, to mix up a wet concrete screed bed, make my levels, let it dry for a few days, and then install the ceramic floor tiles with a tile adhesive.
Also, shouldn't the installation costs be higher for concrete bed? and if so, what percentage higher cost should concrete screed bed be? since they quoted me and i issued my lpo for screed and they installed dry mix?
Finally, even if i considered dry mix,,and i don't, is there a minimum thickness of dry mix?

 

[Dumbo]

Why are they hiring you if you don't understand these things . If you have paid a for a certain method and it's in the contract and you want it done that way make them do it that way or isn't it clear in the contract .

 

[WetSaw]

If someone told me they were going to screed a floor I would expect a "dry" mix to be used unless a liquid screed was specified. What they would call it in Dubai I have no idea. Just because you're not used to seeing that it doesn't mean it's not the correct method.

 

[Dumbo]

Just re read your post. I wouldn't do it your way wet concrete bed left to dry for a few days then use tile adhesive will fail . Left for a few weeks should be .

 

[One Day]

Perhaps dry screed in a hot country has less tendency to stress fractures?
Minimum depth I believe should be 50mm. Sand and cement well tamped down.
I'd echo the above comment (although maybe not quite so bluntly!)
You're the contractor so you should know these things. Me? I'm just a domestic tiler here!

 

[Ronin63]

Let me expand on that a bit. I do huge fitoutsF on large hotel and commercial projects. All large scale projects give me an allowance of 100mm from slab to top of finish. All projects have always been concrete screed. A nice hard finish, that used glue adhesive for my final finish, weather that is marble, granite or ceramic/porcelain tiles. That is from 15 years of fitout works on multi-millio dollar projects. In my opinion i am well qualified to instruct and install floors. My ignorance and uncertainty, came from having to do a small project, and this small time contractor was awarded the work, as concrete screed, and proceeded with dry fix. That was my sticking point, since, I have little experience with this method of fixation, anda from a logical prospective, it seems far inferior, since it is not highly compressed, say, like when you tamp down soil before placing concrete. These guys just threw the dry mix down, levelled it off with their straight edge, splashed down some white liquid glue, and proceeded to lay the tiles. Without hard compaction, logic, and for the good of the client, tells me, i am correct in rejecting this.

What about my other queiry, shouldn't the installation cost of a dry fix be less?

 

[Bill]

Dry fix should cost more because you are having your 100mm of top up from the base added as the tiler fixes his tiles so you are saving on the concrete screed, the labour of the concrete screed and then the waiting time for the concrete screed to dry.

Personally, I think you are not explaining everything to us and you most certainly don't understand what different methods work.

 

[Ronin63]

The LPO was signed and issued to the ceramic tile contractor, so cost and time savings is not the issue. LPO was issued for concrete screed. This one i believe in, since a concrete surface is reliable against earth shifting and causing movement in the soil, and it is just plain stronger.
I was simply inquiring on others' professional opinion, on the strength of this method of dry fix, and if you felt i was able to reduce the payment for less, since the dry fix, in my opinion, isn't stronger, and takes far less time to install.
Also, logic tells me, that this method would only be believable, if i saw the installer doing a concentrated effort at compacting the soil, and, based upon the situation of the install, and please correct me, but it seems there should be a minimum of 75 mm of dry mix sand/cement material, to have something to compact, because i'm sure it must be difficult to compact material that is any less in thickness.
After all, as i said earlier, typical scenario, is that i'm given 100mm from concrete slab to top of finish material, and i've got my 20mm conduit to cover, which is secured to the concrete slab.

 

[WetSaw]

 

[Ajax123]

I' not quite clear here. Are you saying that ggdvtiles were fixed to a sand cement screed laid direct to soil?

 

[Ronin63]

Not sure what "ggdvtiles" are, but they were porcelain, 600mm2 tiles, laid on 75mm of dry mix, white cement type liquid splashed down, then the tiles laid/installed immediately.

 

[Ajax123]

But what was the 75mm dry mix laid on?

 

[Dumbo]

The LPO was signed and issued to the ceramic tile contractor, so cost and time savings is not the issue. LPO was issued for concrete screed. This one i believe in, since a concrete surface is reliable against earth shifting and causing movement in the soil, and it is just plain stronger.
I was simply inquiring on others' professional opinion, on the strength of this method of dry fix, and if you felt i was able to reduce the payment for less, since the dry fix, in my opinion, isn't stronger, and takes far less time to install.
Also, logic tells me, that this method would only be believable, if i saw the installer doing a concentrated effort at compacting the soil, and, based upon the situation of the install, and please correct me, but it seems there should be a minimum of 75 mm of dry mix sand/cement material, to have something to compact, because i'm sure it must be difficult to compact material that is any less in thickness.
After all, as i said earlier, typical scenario, is that i'm given 100mm from concrete slab to top of finish material, and i've got my 20mm conduit to cover, which is secured to the concrete slab.

There it is . You are not happy with the method he is using because you believe it isn't as strong but if you can get some money all of a sudden it's ok .

 

[Simon Dale]

Did A drive Monolithic, still there rock hard. You don't see that word often Gary .

 

[Julian 'Farmer' Bonsall]

Ronin - I will start by saying I am not a professional tiler (and you can tell this by the questions I ask here). I am an experienced and well qualified engineer. Anyway I used to have an apartment in Dubai as I had some work there and the way in which our bathroom floor was fitted was like this. I remember saying it was similar to how I heard my father said our kitchen floor was done (marble onto sand/cement screed circa 50/55 years ago). I hadnt seen it before and your post caught my eye.