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

[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.