Cotto terracotta laying costs, products and methods

07/11/2012 - 09:43

Can anyone tell me their experiences of having handmade cotto laid by Italian builders please? We are in Lazio. I was under the impression that our floor was going to cost €22 m2 cost of cotto and around €25 to lay. Now, at the last minute, the builder is saying our chosen cotto tiles from the village builders merchants that he chose with us months ago will cost more to lay because they are approx 15x30 rectangles so a bit smaller than some cotto plus they need treating with 'acido' before laying which will be an extra €7 m2 plus impregnator plus sealing plus grouting as an extra cost and is coming up with a figure into the 70m2. Is this normal? I just spoke to a Uk terracotta company who said they can simply be impregnated twice once laid but before grouting and then waxed and sealed after grouting. I am going to do this myself if the prices get stupid but can anyone advise the best products available in Italy? We definitely want to go over the wax with an easy clean soft sheen seal as the place will eventually be let from time to time. Thanks



Well - in my opinion cotto is most frequently 15x30, so suggesting that he can up a price book charge for the format is absurd. (I bet if you gave him 30x30 he'd up the price because the cutting is more difficult!) I'd expect the E25/m² to cover laying and grouting but that is all. In other words it wouldn't include anything but the roughest cleaning, and certainly not finishing or polishing. I have no idea why he would want to use acid before laying, and I've no idea why anybody would want to impregnate the clay before grouting. Has he ever laid a floor before? (IMO using any sort of impregnation before grouting would make it most probable that the grout would fail very quickly because it would not adhere adequately to the sides of the floor bricks.) Using a grout gun on a cotto floor is gilding the lily IMO. What you do, in my experience, is you lay the floor bricks (which you have avoided getting saturated by any rain, but you do wet them superficially before laying). You then grout them - either with a pre-mixed mortar such as a rinzaffo storico (for joints above 5mm), a bagged large grain tile grout (Keracolor or similar) for joints between 3 and 4mm, or a fine grained tile grout for 2mm joints. The grout is very wet, and forced into the joints with a sponge grouter (for the wider joints), sometimes for very narrow joints a metal tool is necessary. You can use any colour you want, but it costs least for dark grey, and I like dark grey for 2mm joints - anything light looks a bit contrived to me. For wider joints the rinzaffo just looks like lime mortar, but it is too coarse for narrow joints. It then looks a mess, so at this point you apply acid to get all the excess cementitious film off the clay - it should only be a 'film' if the grouting has been done properly. That's as far as the builder will go, and he might even have the cheek to ask to be paid for the acid wash. Wash with water a few times and then get on with the finishing and polishing. I'm sure I (and someone else on this forum) have sung the praises of Geal products (they have a website). You can get protective finishing and polishing done by professionals, but they do charge rather a lot in my opinion. You can buy perfectly adequate domestic polishing machines for about E100, and the materials will cost less than E8/m².

I recently chose 15 x 30 plain, untreated terracotta floor tiles from one of the long-established Tuscan manufacturers (they aren't what I would like, but the choice was dictated by cost and they'll suffice). I asked their man what finishing treatment he would recommend and he said to clean them with Geal acid wash, then apply two coats of Base or Barrier, followed by two finishing coats of Woplus which comes in a low sheen or a matt finish. I was pleased to hear this because it is exactly the technique I have used in the past with success and I like Geal products and all the info on their site. I have applied various combinations of the products to several sample tiles and I'm about to try out their stain and water resistance before deciding exactly how to proceed. I'm thinking of washing the tiles and applying one coat of sealant before they are laid (because, Fillide, anything I can do at a comfortable working height rather than on my knees or from the top of a ladder, sounds good to me). I'll only be treating the top surface so I don't think it should case problems with the grout failing to adhere - in any case, many tiles are sold pre-finished. Of course the tiles will still need to be cleaned after they have been laid and grouted, but it should be an easier job thanks to the sealant. Fillide - what is your view on laying tiles with glue rather than cement? If it's relevant, my tiles are only 1.6cm thick. I'll have them laid by a tradesman and just do the cleaning/sealing/finishing myself so it's not the technique I'm interested in, just the pros and cons of the two methods.

I'd always go for a tile adhesive (though I have seen one super-expert pavimentista with his own dedicated crew use sand and cement, blindingly fast, so if your tiler wants to use it, let him). You should ask the tile manufacturer whether they recommend a particular tile adhesive, and especially with a thinner clay tile (as with anything stone) it is essential to have an absolutely solid bed of adhesive (colla) below the tiles or a patchy effect can occur, even after some years.  Mapei make a wide range of tile adhesives, here is the page for Keraflex which I have often used, though it is probably unnecessarily expensive, and a more basic compound is probably just as good for internal use. Have a play around with their site, but take the advice of the tile manufacturers and your tiler above all. For the protection tests, water is generally okay on cotto with just a polish surface, even wine tea coffee won't get through polish and Woplus. It's a good idea to test Base and Barrier (I've never used Barrier - Protect seems to do the same thing) against any other stains. Hand cream is something to test against, and of course olive oil and any other greases, together with animal urine (if you have any to hand!) Acids (within reason) don't seem to be a problem with cotto, but they are a nightmare on polished stone - the liquid from mozzarella packaging is one of the nastiest common acids around if you want to test for acid.

Most helpful, thanks, Fillide. I'll have to report back on my stain testing results. I wouldn't have thought of using hand cream - I rarely remember to put it on my hands, let alone the floor - and I had no idea mozzarella juice was acid. In fact, as I write this I'm realising that when I accused my partner of marking a travertine counter top with lemon juice last week, which he hotly denied, he must in fact have done the damage with mozzarella liquid, it being the season for caprese salad. Barrier is much more expensive than Base so I'm assuming that it provides better water and stain resistance. Thanks for the suggestion of asking the tile makers about adhesive and for the site links. I'm considering it because it will reduce the amount of moisture in the house that will need to dry out, and will perhaps leave the tiles cleaner after laying. The floors have been completely rebuilt so they are a good, level surface and the tiles, being new, are of uniform thickness so I think adhesive should be a suitable laying method.

Nothing's happened's a year later nearly and only now I'm mid treating my cotto floor!I'm scrubbing the small rooms with acid by hand with a decking brush but wondered about hiring a machine scrubber for the two bigger rooms? Any advice? Also will I be able to remove wax drips from unsealed cotto and odd bits of oil from food dropped by my four year old? Last cry for help is that despite using Fila's highly rated water based range and applying HP98 water repellent and HP68 oil and water repellent followed by Filajet and then a liquid wax seal I feel my tiles are still quite porous....could it be poor quality tiles as much as anything perhaps? Thanks