Tips

Renovation and painting of a facade

Renovation and painting of a facade

Diagnostic

In addition to the succession of rain, sun radiation and frost, the difference between the coefficients of expansion of the materials is at the origin of cracks, large or narrow, in the facades of buildings. It is first necessary to assess the extent of the problems and to carry out a first cleaning - because an old coating can hide more important degradations.

The right products

When you have identified the nature of the cracks as well as the repairs to be carried out on the shell and, possibly, on the gutters, buy suitable products: sealants, plasters and mortars intended for facades.

Saltpetre diagnosis

The presence of saltpetre on an interior wall (or even outside) is always synonymous with humidity inside the masonry, and requires exterior and interior treatment (and even, often, injections). However, do not confuse saltpetre (whitish efflorescence due to the action of bacteria in the presence of moisture, when the soil is rich in nitrous organic matter) and hard white patches, which even form on perfectly healthy and dry, and which come from building materials: these crystals are eliminated by simple scraping.

Tools & materials

• Trowel
Corner trowel
Float
Coating knife
Painter's knife
Mason's chisel
Painter's chisel
Mallet
Triangular scraper
Wire brush
Quackgrass brush
Extruder gun
Trough to spoil
Protective glasses
Pressure washer
Angle grinder
Concrete disc
Stool
Ladder
Masonry putty
Building putty
One-component repair mortar
Two-component mortar
Roof sealant
Gutter sealing tape
Trichlorethylene
Facade painting
Facade cladding (resins)

On the trowel

Mix the mortar in a trough, respecting the proportion of water recommended by the manufacturer of the product. You must obtain a product that is neither too liquid nor too thick, which holds without running on the trowel. To transport it on the job, use a mason's trowel.

Special mortars

Two-component mortars, based on emulsion resin, cement and fibers, are available for filling cracks on facades as well as for repairing outgoing corners of openings. These "thixotropic" mortars are remarkable for their adhesion to the support, for their very low shrinkage and for their mechanical resistance after drying. They are applied in the same way as a conventional mortar.

Recessed pipe

The renovation of a traditional facade, coated with a mortar coating, can be an opportunity to embed a pipeline, for example for conductors of exterior lighting or a doorbell. It is enough to open a bleeding using a grinder or a mason's chisel and a mallet, before filling with cement mortar or putty for masonry. It is of course necessary to comply with the standards for the installation of external electrical pipes.

Elastomeric sealant

This product can act both as a sealant to seal cracks and joints, and as an adhesive for repairing broken construction elements. It remains elastic after drying and does not show any shrinkage. It is very resistant to weathering and chemical agents. It is dust-free in 1 hour and dries in the mass in 12 hours. One cartridge can process 12 linear meters of 5 x 5 mm joint. Clean tools immediately with methylated spirits. Know-how © La maison rustique - éditions Flammarion, 2005