We finished up a exterior tiled deck over a screen porch last winter ( in Vermont, in December , under plastic ) and it looked great until spring, at which time all the epoxy grout pulled away from all four sides of each tile.
The deck framing consists of 2 x 10s on 12″ centers which in turn are laid on top of 12″ diameter ( exposed in porch ceiling below tile deck ) red pine ceiling joists on 39″ centers. The 2×10 cavities have 6″ of high density spray foam insulation, a airspace, and a subfloor of 2 layers 3/4″ CDX plywood, protected , in turn, by a EPDM membrane roof. The subfloor was framed incorpoarating a 1/4″ per foot pitch to the outside perimeter. All this was done with the approval of our structural engineer.
We installed drainage mat, continously across the deck/EPDM surface ( interlocking the dimples to splice adjacent rolls, followed by 5/8 ID rubber tube for radiant heat, with galvanized wire mesh placed on top of the tube. This postioned the mesh in the center of the 2 1/4″ thick slabs of Thickbed mortar & admix. Forms were placed to provide expansion joints, with no panel exceeding 8′ x 12′ in dimensions. The rubber tubing spans the expansion joint, but the wire mesh does not. Air temperature in the tent varied between 50 – 80 degrees while the slabs cured, after which the radiant heat was activated to heat the workzone.
Tiles were set in thinset/admix over waterproofing membrane, and grouted with Spectra lock epoxy grout with Latasil in the expansion joints.
Should also note that myself ( GC ) and the tile sub were both in constant contact with the manufactures technical support department for installation details that are not spelled out on the product packaging ( ie: curing times at low temperatures, for example ).
A company rep visited our job and reported that 1) The tiles and products were properly installed and that 2) he suspects that structural movement was to blame.
I’m taking that with a grain of salt… there a sections of deck that CAN’T move because they are over solid log walls ( framed 4 years ago…the benchmarks the I placed last year have not budged) …and the grout failed there as well.
I’m guessing that the thermal expansion induced by the snowmelt coils may have been more than the grout’s ability to accomodate, but the rep says no.
Bottom line is that we have to grind out the failed grout and replace it … and I’m reluctant to regrout until I know for sure WHY it failed. Knowing the answer may alter the type of grout we use the second time around…possibly a flexible urethane based material might suffice.
Has anyone else run into this problem, found out the cause, found a remedy ? I’ve scratched my head for so long that I’m running out of dandruff.
Slainte’
Jack
Replies
What type of tile? Porcelain? Stone?
I have a deck that's slate and was grouted with cement grout. It worked fairly well but developed more cracks than I like after about 8 months. The tile installer removed the cement grout and installed Spectralock yesterday. I'll keep you posted! This is not a heated deck.
Dave
It's a porcelin tile from Italy (Majico Gres ). Should note that 2/3rd of this deck has snowmelt ( hot tub area ), one thrd does not.
Jack
I have not researched the unique characteristics of epoxy grout vs epoxy paint so this may not be relevant.
A few years ago I purchased some two part epoxy floor paint from Kelly Moore and was told that epoxy did not hold up well under continual exposure to UV light and exterior applications calling for epoxy paints needed to be top coated with polyurethane paints for UV protection.
If I were in your position I would be looking to verify that the epoxy grout you used has been routinely used in exterior applications (UV exposure) with reliable long term performance.
Karl
Karl
we got direct approval from Laticrete to use SpectraLoc in this application. As you noted, though, it is not very UV stable and I can already see the colors fading. We may switch to a urethane based product.
Slainte'
Jack
Here are the technical specs on the tile ... claims it meets ASTM C1026:
http://www.cermagica.it/img_db/prodotti/emilia/download/emilia_imballi.pdf
And SpectraLok is acceptable for exterior locations (according to the manufacturer).
Can you find the appropriate TNCA detail for this configuration and review? Looks like it's referenced here:
View Image
What was the joint width? There are recommnded minimums for expansion joints for exterior tile. See this: http://www.johnbridge.com/vbulletin/showpost.php?p=27985&postcount=1 for more info (and consider posting there too).
Jeff
Edited 9/7/2008 10:44 pm ET by Jeff_Clarke
Hi Jeff
Yep, I found the tile specs on the net too....fowarded them to Laticrete's technical advisors who basically said that they don't handle this type of stuff....it's the architect's domain. I also emailed Majico Gres in Italy ( in both languages !...no reply )
The whole tile/deck system was built to conform with Laticrete's Plaza and Deck system ( DS - 290.0 - 0707 ) , also referencing Laticrete's drawings ES EJ10 and ES F314.
The decoupling/waterproofing system used was Laticrete's 9235 membrane, not the Schluter system. I will check with my tile guy, but I'm pretty sure that we used Laticrete's 254 Platnum thinset to set the tiles, and that had a week plus to set up on top of a warm slab before grouting. I'll ask him if any additives were used in addition to the water.
The expansion joints between the slabs was 1/2 - 5/8 ", about 1/4 between the tiles. I plan to open up the tile joints to a full 1/2 inch as well since the Latasil was being force up and out of the expansion joints. We were using the TNCA guideline sheet , but I will definitely check out johnbridge.com as well
Thanks
Slainte'
Jack
One possibility is the Spectralock failed and the other is that there was structural movement. Usually I would say it is structural movement that caused this but your construction approach sounds pretty good. Direct sunlight on your deck can cause expansion issues but I don't think that's the problem. I doubt the porcelain tile is an issue -- it should be fine outdoors.
By the way, I would think there is lots of seasonal movement in solid log walls -- much more than in traditionally framed walls because wood moves more across the grain, as you know.
You say there is a waterproofing membrane directly under the tiles -- be specific about what type membrane this is and whether it is designed for this application. A better choice would have been to use a decoupling membrane such as Ditra which both waterproofs and helps isolate the tiles from substrate movement.
The best thing to do now is get yourself over to John Bridge's pro tile hangout and post pictures together with your description. They will help you get to the bottom of this.
http://www.johnbridge.com/vbulletin/forumdisplay.php?f=4
Billy
Edited 9/7/2008 11:44 am ET by Billy
Edited 9/7/2008 11:46 am ET by Billy
I think you may have stated your problem.
You said the porcelain tiles were set with thinset/admix over a waterproofing membrane. How long did you let this cure before grouting? Hopefully it was more than a week.
Modified thinset (made with liquid admix or an included admix in the powder) sets by drying to the air. Because modified thinset is sandwiched between the waterproofing membrane and the impermeable porcelain tiles, it takes a long time to dry and might not ever dry if the grout lines are prematurely filled with epoxy grout. This is especially true for large format tiles. This could cause the tiles to shift slightly when walked on or the uncured modified thinset to freeze/thaw under the tiles and grout which could crack the grout.
For this reason Schluter recommends the use of UNMODIFIED thinset when setting tiles over Ditra, because unmodified thinset cures by a chemical reaction -- unmodified thinset it is essentially like cement which can cure under water by chemical reaction.
In Jeff Clarke's post the Schluter figure states that unmodified thinset should be used directly under the tile.
Maybe using modified thinset caused your problem?
Did any of the porcelain tiles crack? If not, then perhaps the problem is not a substrate movement problem but a thinset/grout problem.
Billy
Edited 9/7/2008 11:43 am ET by Billy
Edited 9/7/2008 11:47 am ET by Billy
Billy
We didn't use the Schluter system, rather the Laticrete 9235 membrane and Platinum 254 thinset.....which had about 10 days cure time on a warm slab before grouting. I'll check my job notes to confirm the time factor. I never considered the possibility of trapped moisture though....The grout ( applied in late December ) started to visibly fail in April after the radiant heat hadbeen turned off for the season. Do you think there would be that long of a delay before visible grout failure ?
I probably mispoke about the admix being used with the thinset....the Platinum only needs water. Again, I'll double check.
We don't have any cracked tiles anywhere.
Slainte'
Jack
Sounds like a real PITA, but as far as I'm concerned it's just further proof that no mater how well engineered, some ideas, like tiled outdoor decks, are just plain bad ideas.
It's obvious from your description that a lot of thought went into the detailing, and perhaps your grout failure is a fluke......