- A partially preserved roof
- Take advantage of the offset to insert an insulation
- 1 REMOVAL AND VOLIGAGE
- 2 UPGRADE AND INSTALLATION OF THE INSULATION
- 3 SETTING UP THE SCREEN
- 4 INSTALLING SLATS
To renovate and level two roofs, the solution was to elevate one while laying a thin multilayer insulation between rafters. Covered with slates, they show a second youth!
Cost: 120 € / m2 on average
Time: 5 days
Equipment: meter, walking foot, cord, hammer, bubble level, trowel, bucket, cutter, grinder, screwdriver, drill, hammer, freight elevator, chainsaw and roofer ladder...
Before being partially destroyed by a fire, this house included two buildings with offset roofs. Fortunately the incident saved some of the slate roofs and their roofs, and the owners quickly made the choice to limit both the cost and the duration of the reconstruction, preserving the existing building as much as possible.
A partially preserved roof
But this disaster is also an opportunity to rebuild a roof in one piece, much easier to cover and much more durable... For this, it was enough to dismantle a cover (the highest) and keep the other with some repairs... This stage ended, it was then necessary to connect the two roofs without touching the original frame. The two original roofs (one of which is already insulated from the inside) had in some places up to 15 cm difference in level.
Take advantage of the offset to insert an insulation
The idea of the building site: take advantage of this "gap" to isolate, develop a blade of air and recreate a liteaunage up to the level of the slats of the highest roof part. For this purpose, horizontally laid rafters (70 x 50 mm) are leveled and attached to the existing rafters. They receive rafters going from the ridge to the gutter. Part of the insulation is provided externally by a reflective multilayer product sandwiched between the two "layers" of rafters. The work is then ready to receive under-roof screen, slats and slates cut in fish scales, laid on the hook. Result: the two roofs now seem to be more than one...
1 REMOVAL AND VOLIGAGE
After completely removing the slate and inspecting the condition of the roof support, the damaged elements are removed.
To correct the deflection of the rafters, cleats are cut to size and nailed on the top... A line helps to check the alignment of these new pieces of framework.
The planks are nailed starting at the bottom. Measuring 2 m in length, they are fixed without being cut beforehand to the desired length
Once the row is finished, the logs are cut to size with the chainsaw. The cut is made on the axis of the chevron to provide support for the next row.
2 UPGRADE AND INSTALLATION OF THE INSULATION
On the other roof, the preserved logging requires an upgrade. This one is realized with two thicknesses of rafters (one bed horizontally, another vertical). To be sure of the future alignment of the future roof, a reference chevron is nailed to the top of the highest roof...
Before laying the second rafters bed, a thin insulation is unwound, ensuring that the strips overlap by at least 10 cm.
The insulation is stretched and permanently held in place by the rafters... Nailed to a distance of 50 cm maximum to ensure the strength of the network of battens to come.
At the ridge, the connection with the other roof is pre-drawn. The rafters are then cut with a chainsaw.
In the absence of a sand pit fault and to guarantee the tightness between the roof and the front wall, the spaces at the bottom of the rafters are filled with lime mortar.
After drying the mortar, the overflow part is covered with nail nails so that the underside of the two roofs are identical...
3 SETTING UP THE SCREEN
The under-roof screen is unrolled and stapled to the rafters. Each side overlaps the previous one, starting from the bottom towards the ridge. The width of the cover is indicated by a red line printed on the screen.
Depending on the desired slate coverage, locate the location of the battens with the chalk line.
Then nail them on the rafters. The tracing is done as and when the installation.
In the lower part of the roof, the gutter supports are fixed before putting in place the first row of slates.
4 INSTALLING SLATS
The implantation of the slates and hooks is materialized with chalk line. The slates are laid in full caliper (half-width offset from the previous rank).
The first row of unrounded slates protrudes from the cleat on which it rests. It is held by hooks and nails.
The hooks of the 2e and 3e ranks are planted in the roofing hammer. They are then attached to the battens on one roof and to the eaves on the other roof.
Each row covers half of the lower row, from the sewer to the ridge. This doubling is necessary in order to fill the gaps and to avoid leaks.
And the insulation?
A roof well insulated, it is the comfort assured in winter as in summer. The choice of a thin reflective multilayer insulation is here linked to the configuration of the site (adaptation to existing) and is an effective complement to an insulation that will be achieved from the inside.
• Stiles of 18 x 200 mm
• Chevrons 70 x 50 mm
• Plates of 47 x 25 mm
• Roof underlay screen
• Thin multilayer reflective insulation in roll
• Fish slates and hooks
• Gutter, ridge strip, flashing and zinc vents