Re-roofing

Retechado  Now that the clay barrel tiles and mortar had been pried up, chipped off and taken off the roof, we were left with a structural surface of very rough (about 1:4 slope) reinforced concrete slabs about 10cm (4") thick.  It was immediately apparent why we had leaks into the master bedroom.  Above this room there were areas where the concrete covering the reinforcing was very thin, so water had entered into cracks and rusted the rebar, causing the concrete to spall.  I had the guys chip out the weakened concrete, wirebrush  the steel and apply new concrete to patch the holes.  At this point we could have started re-tiling the roof.

The roof itself is composed of three slopes facing east, north and west, with diagonal hips at the two outer corners.  A short ridge line running north-south abuts a small open-to-the-sky "room" above the bathroom. The walls to this space are about 2.4m (8') high, and hide the location of the tinaco (water storage tank) and house plumbing from view.  These walls are the highest point in the house, except for the chimney which comes up the north wall of the building and thru the roof there, several inches higher.

Not wanting to have to ever revisit the roof slab surface again, removing tiles, patching etc, we decided to put a bit more money and effort at insuring the roof was water-tight.  After doing some research, we purchased some Impercem, a cement formulation used for watertight applications (water tanks, pools, etc) and had the guys apply a smooth thin coat of waterproof stucco over the entire roof surface.  After this was cured, a coat of Fester Acriton, a fast drying impermeabilizante (sealer), was painted on top.

There was much discussion about how best to finish the roof.  Many homes here have smooth slabs just painted with sealer, usually red like we used, so we could have been finished at this point.  But, we would have to repaint the roof every seven years or so.  And we would have changed the appearance of the house significantly by removing the arching tiles that gave it the "colonial" look we liked.

In Cordoba one day, I took a tile taken from our roof to a tile and block store, to ask what replacement tiles like these would cost. Seems they would be a special order, as the only ones now made in that old style are a bit smaller. The new tiles would cost MX$8 a piece, and we'd need about 2000 tiles.  Another option would be to use a formed sheet material (steel, composite, asphalt) with a large corrugated aspect so from a distance it would be in keeping the with tiled lower roofs.  The problem with these materials is that it is difficult to attach them to a slab and prevent them from lifting off in a strong wind. We settled on using concrete "California" tiles from a local company, Pretensur, which quoted a price just about what the weaker clay tiles would have cost.  The concrete tiles from a distance are in keeping with the spanish look we wanted to maintain, are harder/tougher and safer to walk on for roof maintenance, and don't lift off in hurricanes.  The tiles would be delivered in a week.

While we waited the guys shifted focus to building the structure for our future roof top deck and mirador (overlook), and to sealing and waterproofing the space where the tinaco sat (topics for another post).  Our new concrete roof tiles were delivered late one morning.  Our guys unloaded the 1000 tiles by hand, stacking them in the backyard on three sheets of plywood laid on the ground, two rows high. As they were needed, they are carried on shoulders up two ladders to the roof top, three tiles at a time. Each tile weighs about 11¼ pounds.

Luis made the calculations to figure out how much overlap each row of tiles would require, to avoid having to the trim the final upper row at the ridge. Chalk-lining done, the first row, overhanging the roof edge by an amount sufficient to allow water to run off and not seep back to the fascia was mortared into place.  The mortar, of course, mixed by hand on the street outside the backyard gate, and brought up to the roof by the bucketful.  The only cutting we had to do was for the angles along the hips.  I brought down an esmeriladora angular (angle grinder) when we moved here, and it saw plenty of duty cutting these tiles (and later cutting, block, brick, floor and wall tiles, cutting channels in masonry walls, and with a steel abrasives disk installed, cutting rebar).

The job of re-roofing took about two weeks, as laying the tiles accurately, adhering each one with mortar, is not as quick as nailing down shingles.  After getting into the swing of things, two of the guys moved over to filling in mortar along and under tile eave edges (eg bird-blocking) along the now-finished east side of roof. They also tiled (with tiles cut in half) the top of the 18' high perimeter wall off the southeast house corner.  This put them on a stepladder on top of the lower porch roof, using the special slanted plywood platforms I had made for painting the windows there.  To do the north and west roof edges, straight drops to the ground, the guys attached wood studs to the top sides of the extension ladder so it could reach up under the eaves. These two were the gophers carrying mortar and tiles up to the roof for the guys laying the tiles down.

The final touches to the roof was the application of red sealer on all of the bare mortar surfaces.  Before we finished with our crew, they also pressure washed all of the older clay-tiled roofs, and waterproofed them a bit with a clear coat of Comex sealer.  Later I came up to the roof to fill in the few corrugations in the tiles upslope of the chimney with stucco (where in the states we'd build a cricket) that I had noticed sitting filled with water after rainstorms.

Next:  Skirt-roofs & Overhangs