# Thinset drying too fast when tiling floor



## dalepres (Mar 20, 2011)

I am laying tile directly on plywood in my kitchen - Yes, I know the pros and cons but I only need this to last for a year or two because we're building a new house.

I've never laid tile before so I'm not very fast. I've been only getting two rows of tile across the floor (16 rows needed in total) in each tile laying session - I've done two of what looks like will be 8 sessions. The first time, I gave out before my thin set gave out. But the second time, the thin set was hardening in only 30 minutes and unusable by 45 minutes. At that point I added a bit more water - about half a pint, mixed for 4 or 5 minutes and got the same consistency I had started with but this time it was so hard within 10 minutes that I couldn't use it. Luckily, the 3 tiles I laid before it got hard the second time do appear to be solidly glued.

So what caused my mortar to harden the first time so quickly? It says 2 hour working time on the bag but I only got 30 to 45 minutes at the very outside. Could it be the hot weather? Maybe 78 inside the house but the mortar was in my truck in 100 degree weather - probably 140 inside the truck - until I brought it inside to mix. Was it heat? too little water? Any suggestions on how I can extend the working life of my mortar so I'm not throwing out so much?

Thanks,

Dale


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## JazMan (Feb 17, 2007)

Hi Dale,

Tiling on plywood huh? You need it to last only a year or so. Then what happens to this house? Is it being razed? :whistling2:

Why was the mortar or any materials outside in 100 + temps? You might have not used enough water, I don't know. Why mix the mortar 4-5 minutes? Did you let the original batch slake then remix before using it. Sounds like several errors here. What mortar did you use and type of tiles?

Jaz


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## dalepres (Mar 20, 2011)

It's an old mobile home and will be trashed when the house is finished.

The mortar is mapei ultraset 1. It calls for 5 to 6 quarts of water mixed in. Following the directions I put 5 1/2 quarts of water in the bucket, added the mortar, mixed with a heavy drill for 5 minutes. I let it rest for 10, mixed again for 2. It then sat for a couple more minutes while I cleaned the mixer tool before starting to lay tile. The tile is the cheapest ceramic tile Lowes sells - 69 cents a square foot.

As for why it was in the heat - well, not sure what else to do with it. I could have not left it inside the even hotter truck interior; I didn't think it would hurt it but now I am questioning. I have a construction shed I could have put it in until I was ready to start. It would have still been 100+ degrees but not as hot as the truck interior.


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## Bonzai (Oct 29, 2010)

So basically what you are saying is that the thinset has been sitting for a total of 20mins by the time you start using it, you are not fast at installing the tile and it's going down on plywood in 100+ temps. 
The combination is essentially a guarantee for any moisture in the thinset to evaporate pretty fast. The working times for the product will be based on certain working temps and that will almost guaranteed not be in the 100-140F range. Also installing on plywood will suck up a lot of the moisture too. You probably should just have installed sheet vinyl as the cheapest form of flooring if you will only need it to last one year.

Also do not add water to an existing batch of thinset ... You can't keep remixing as it will already have started the curing process.


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## oh'mike (Sep 18, 2009)

It's hot---make small batches--trowel down only two squares at a time (about 8 square feet)

No need to trowel a whole row--keep that mortar fresh.


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## Blondesense (Sep 23, 2008)

From what I understand the temp of the water can make a difference too. Use cool, not hot.


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## JazMan (Feb 17, 2007)

Do no tiling when the work area temp and/or materials are anywhere near 90 degrees. So, keep materials inside a conditioned space or in the shade, use fresh cool water. Do not mix a 50 lb. bag, that's too much even in cool weather. You mix with heavy-duty 1/2" drill motor at slow speeds, below 300 rpm. And mix for no more than 2 minutes, let slake as directed, then re-mix for 30 seconds or max 1 minute. Mix by hand occasionally while tiling. Do not add more water or admix after initial mix.

Mixing longer will "burn" the mortar which will make a good anchor for your fishing boat, which is where you should be when it's close to 100. :thumbup:

Jaz


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## dalepres (Mar 20, 2011)

JazMan said:


> Do no tiling when the work area temp and/or materials are anywhere near 90 degrees. So, keep materials inside a conditioned space or in the shade, use fresh cool water. Do not mix a 50 lb. bag, that's too much even in cool weather. You mix with heavy-duty 1/2" drill motor at slow speeds, below 300 rpm. And mix for no more than 2 minutes, let slake as directed, then re-mix for 30 seconds or max 1 minute. Mix by hand occasionally while tiling. Do not add more water or admix after initial mix.
> 
> Mixing longer will "burn" the mortar which will make a good anchor for your fishing boat, which is where you should be when it's close to 100. :thumbup:
> 
> Jaz


I've been away from the PC so I just got this. Thanks for the helpful information. I'm positive it's exactly the answer.

Regards,

Dale


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## dalepres (Mar 20, 2011)

Bonzai said:


> So basically what you are saying is that the thinset has been sitting for a total of 20mins by the time you start using it, you are not fast at installing the tile and it's going down on plywood in 100+ temps.
> The combination is essentially a guarantee for any moisture in the thinset to evaporate pretty fast. The working times for the product will be based on certain working temps and that will almost guaranteed not be in the 100-140F range. Also installing on plywood will suck up a lot of the moisture too. You probably should just have installed sheet vinyl as the cheapest form of flooring if you will only need it to last one year.
> 
> Also do not add water to an existing batch of thinset ... You can't keep remixing as it will already have started the curing process.


Thanks. I actually bought sheet vinyl for it. It was about twice the cost of the tile - for the cheapest vinyl I could get. Plus, in my particular circumstance, it would have been harder to install than the tile. I know now why most remodelers won't remodel a kitchen when the family is still living in the home. I just can't empty the kitchen completely to get that whole role of vinyl in and laid out.


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## bob22 (May 28, 2008)

Perhaps dampening the plywood a bit (not soaked, just dampish) to keep it from sucking all the moisture out of your mix?


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