- Practical advice
- Terracotta flat tiles
- A protective film
- A newly redrawn lath
- A methodical pose
- Well sealed junctions
- Adapt the roof
- Create skylights and skylights
- Lay an underlay screen
- Fix the counter-battens
- Plot the location of the battens
- Mark junctions
- Nail the first rows of tiles
- Lay the cross-joint tiles
- From bottom to top, by span
- Lay the doublis
- Prevent infiltration
- Check the alignment
- Reposition the tiles
- Lay the window frames
- Renovate the fireplace
- Ensure the junctions
- Seal the joints
- Fix the corner tiles
- Sealing roof and skylights
- Fix the tiles of the banks of the pediment
- Lay the roof tiles
Badly insulated and covered with old concrete tiles, this roof required a complete recovery, in order to regain its aesthetic of yesteryear and facilitate the development of the roof. Lightweight and resistant, the flat tile used to dress it new will ensure waterproofness and aesthetics for many years.
Colorless, anti-cryptogamic treatments prevent the proliferation of mosses and lichens on the roof for about four years. For a good efficiency, it is necessary to use them on a clean and dry support. These different products ("Ot'mousses" by Julien, "Dipcide" by Dip, "Algimouss", "Anti-foams" by Sicof...) are applied by spraying or rolling, with an average yield of 4 to 5 m2 per liter.
The continuous circulation of the air under the roof is essential to ensure the durability of the insulation and limit condensation likely to alter the framework. It is provided by special ventilation tiles that provide air inlets and outlets at the top and bottom of the roof. It should be provided one every 20 m2 of roof approximately, arranged staggered.
Terracotta flat tiles
The gap between the noble stone of the building and the tiles too "industrial" justified the renovation. The new roof was chosen for flat terracotta tiles ("Phalempin" by Imérys Toiture, 37 € / m2). With a size of 16 x 24 cm, their surface is slightly curved and look like a beautiful gray-brown aged. Depending on the spacing between each tile, it takes between seventy-three and eighty-three per square meter. Delivered on pallets, they cross each other on a network of wooden slats thanks to two studs molded on the underside.
A protective film
It is obviously necessary to deposit the original tiles from top to bottom, by span, before tearing the old lattis. Exposed and properly inspected, the framework is treated with a preventive insecticide and fungicide applied to the sprayer. Then, she is dressed with an under-roof screen that prevents the wind from rushing and moving - even taking - tiles. With an air gap between the cover and the insulation, this film also promotes roof ventilation, which minimizes the risk of condensation and rotting of the roof structure. Finally, if tiles are cracked or moved, it channels the infiltrations while waiting for the repair.
Composed of a polypropylene veil, the film (Fel'X from Siplast, in rolls of 1.25 x 40 m) is coated with elastomer bitumen which makes it waterproof. It takes place in parallel stripes on the rafters of the roof beginning in principle by the sewer (edge of the roof where is the gutter), to finish by the ridge (line of separation of the two sides). The strips must overlap by about 10 cm to provide a perfect seal. Similarly, it is necessary to provide at the level of the sewer an overflow of about 3 cm in the gutter.
A newly redrawn lath
The tiles do not rest directly on the frame, but are supported by a wooden frame called "lathing". It consists of treated fir (18 x 27 and 36 x 20 mm) battens, fixed to form a continuous grid. The first slats (referred to as "counter-battens") are nailed lengthwise on the top of the rafters, from their base to the ridge. Their role is essentially to fix the under-roof, while sparing the necessary air space.
Called "battens", the second slats are nailed perpendicular to the first ones. Horizontal lines drawn with chalk mark the location of future battens. The number of lines and their spacing is determined by the width of the roof slope. Raised from the sewer to the ridge, this measurement (690 cm) is divided by the length of the visible part of a tile (here 8 cm), the "pureau". 690: 8 = 86.25 cm, which represents 85 battens spaced 8 cm apart and 1 batten with an interval of 10 cm.
Tracing is done from the bottom up. The first line is marked at the foot of the rafters. The second is plotted 4 cm higher and the following every 8 cm, until ridge.
A methodical pose
A hanging gutter collects rainwater. It is fixed on a wooden sole nailed to the periphery of the cornice. Thickness of 18 mm, this board receives every 25 cm the flat ends of the hooks. So elevated, the gutter can support the first row of tiles on its inner edge. So that the tiles of the first rank display the same inclination as that of the upper rows, a square slat (chanlatte) is nailed on the horizontal plane of the cornice and under the first batten.
The laying of the tiles is carried out from bottom to top by successive bays of one to two meters in width. Nailed on the first row of battens, the first row is cut to the grinder to be completely covered by the second row. Called "doublis", this double thickness rests on the rim of the gutter and on the chanlatte. To prevent the alignment of the vertical joints from one row to another, the end elements are cut in half. This splitting makes it possible to lay them with crossed joints and to adjust their width to the slope of the roof, which is narrowing.
Well sealed junctions
Largely provided with chimney stacks, dormers and ridge, the roof is interrupted in several places. To make it waterproof, it is necessary to connect certain tiles between them or to connect them with the masonry works.
The junction in projecting angle formed by the meeting of two slopes of roof is made with special tiles shaped truncated pyramid. Sealed with bastard mortar (1 volume of hydraulic lime, 1/2 volume of white cement and 4 volumes of sand), they are placed from bottom to top between the end tiles of the two faces.
The connection between the two main slopes of the roof is made with roof tiles, kind of half-cylinders of terracotta. They are placed on a bastard mortar rod and then secured by ridges that prevent the infiltration of water.
The tightness between the main roof and the roofs of the dormers (or "hats") is provided by zinc plates folded in V (called "noquets"). For each row, the two corner tiles are cut obliquely along the length. As for the ridge of the main roof, the slopes of the dormer roofs are joined by ridge tiles sealed with mortar, then secured with masonry crests.
The gap between the tiles and each chimney stump is filled with four flashings of bastard mortar, so as to make a sealed peripheral junction.
Adapt the roof
The roof of origin covered with its old concrete tiles. These, first generation, swore cruelly with the style of the building, which deserved a return to compliance.
Create skylights and skylights
After tearing the slats, four trimmers are made to create two roof windows and two skylights. They register between the sand pit and the intermediate failure, after sawing the rafters.
Lay an underlay screen
The strips of the under-roof screen are unrolled and held with nails. They overlap about 10 cm in the direction of drainage (the upper one overlaps the previous one).
Fix the counter-battens
From the sewer to the ridge, the counter-battens are fixed with stainless steel toothed points on the top of the rafters, in their length. They firmly hold the underlay screen.
Plot the location of the battens
The location of the battens is traced on the contrelattes. The first line, consisting of a plaice, is nailed at the foot of the rafters, the second at 4 cm and the following every 8 cm.
The junctions between the roof and the sides of the dormers are marked by joined planks. Here, fir-tree fences on which are nailed the ends of the battens.
Nail the first rows of tiles
Starting from the sewer and one of the banks, the tiles of the first two rows are nailed with short points made of galvanized steel. For this purpose, pilot holes are provided in the terracotta.
Lay the cross-joint tiles
The cross-joint installation requires to start every other row with half-tiles cut with the grinder.
From bottom to top, by span
The work is carried out from bottom to top by successive bays. The tiles must be joined.
Lay the doublis
The first row is cut to the grinder to be completely covered by the second row. Called "doublis", this double thickness rests on the rim of the gutter and on the chanlatte.
L-shaped zinc pieces are placed between the cheeks of the dormers and the tiles to prevent any infiltration. This done, a metal flap is attached to reject the water to the roof.
Check the alignment
Approximately every 5 linear meters, the vertical alignment of the tiles is controlled using a cleat pressed against the joints to locate the overflowing tiles. These are adjusted gently.
Reposition the tiles
To visualize the alignment over the entire height of the roof, a chalk line is drawn. Tiles outside the line are repositioned by slightly shifting the row they end.
Lay the window frames
The frames of the roof windows are nailed to the rafter rafters. To ensure the watertightness of their sides, nozzles are placed making sure to overlap them on 3 to 4 cm.
Renovate the fireplace
Taking advantage of the renovation of the roof, chimney stumps are swept and their joints staked. They are tightened with hydraulic lime bastard mortar with white cement.
Ensure the junctions
The presence of skylights, chimney stumps and pediment surmounting the facade requires specific connections between the tiles and these structures.
Seal the joints
The junction of the ends of the battens is sealed by square zinc plates folded in V and nailed with a covering of 3 to 4 cm.
Fix the corner tiles
The corner tiles are laid blank on the valleys to draw the cuts, and resized diagonally to the grinder to form a slicing trench. They are nailed alternately with whole tiles.
Sealing roof and skylights
The hats of the dormers are covered with an under-roof screen, on which is nailed the lathing. He will later receive the tiles laid as before with crossed joints.
Fix the tiles of the banks of the pediment
The tiles on the banks of the pediment are aligned with a string stretched from the sewer to the ridge, then sealed with bastard mortar. The joint is smoothed with the cat tongue trowel.
Lay the roof tiles
The roof tiles are laid on two mortar beds and joined by crests. In dry weather, the mortar is moistened so that the terracotta does not absorb its water prematurely.