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What is the optimal time delay between installation and nail off? So far on our work, we wait 24 hours before treading on installed tile, but wait only 30 minutes or so before we are walking on the hardibacker (installed on modified thinset) in order to nail it off. Just bothers me not knowing. Found nothing in the literature provided at Homeowner’s Depot…
brian :-)>
Replies
Wait 30 mins? I've walked on cement board after bedding in thinset to "seat" it in the thinset, screw it immediately. After screwing, I give it a day to set. . . that said, I've only done a few tile jobs!
being a condo conversion, we're in production mode. we do walk on it to seat it. the only nailing we do right away is if by chance some edges are not properly seating. then we're on to the next floor. we return to nail off after the thinset has had a chance to set slightly. i dunno... may only be intuitive, but when one observes how a ceramic tile is set after 30 minutes vs. after 1 minute, the tile can still be moved but doesn't "float", and it's more difficult (if not impossible) to displace the thinset underneath vs. watching it ooze out of each side when fresh.
believe me, thatguy. we frequently nail off right after installation, too. but that's the nature of my question - the various approaches employed. i would like to know what Hardi recommends...
brian :-)>
Apply unmodified thinset and nail immediately. Why? There are two reasons. The first deals with why the thinset is there in the first place; the second with its general characteristics.
Thinset is there to cushion the CBU and to prevent gaps over uneven flooring. If there are gaps, the CBU may crack and the tile job may fail. You can not level the CBU when it is cured. High spot on the floor? Nail the edge down a little tighter and smoosh down the thinset. Low spot on the floor? Don't nail it down as much and leave it a bit proud of the floor, using a straight edge or long level to assist you in the installation.
Thinset is not very strong and it crumbles easily. I can only imagine what banging on 1/2 Hardi with a 16 oz framing hammer would do to a thin layer of cured thinset. It would crumble and therefore remove any cushion you would have.
Therefore spread the thinset generously, set the CBU's and nail them off at the same time.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
30 minutes after application, the thinset isn't "crumbly". We use a nailer, not hammers. your point is well taken concerning uneven surfaces. we just press on the gun, more or less depending on high vs. low spots. thanx for your input, comrade.
brian :-)>
Didn't read or notice the 30 minutes part. I stand corrected. Thinset takes about a week to fully cure. With 30 minutes you are fine.Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927