- A precise calculation
- Construction choices
- Prevent stains
- Slab support: concrete on hedge of rubble
- Planters: cinderblock
- Paving finishing: laying on sand bed
With some tips and few resources, Francis Pelletier has managed to expand his terrace without investing in expensive equipment. He has thus transformed it into a convivial space.
Cost: about 45 Euros / m2 including 40 euros / m2 for slabs.
Time: 1 week
Supplies: breeze blocks (10 and 20 cm thick), quarry sand, cement, lime, corner sticks, shuttering boards, slabs (50 x 50 x 2.4 cm), blades (68 x 15 x 3) cm), waterproofing.
Tools: wheelbarrow, concrete mixer, grinder, drill, sieve, ruler of 3 m, measuring equipment (meter, cord, level), masonry tools (trough, trowel, trowel).
See the plan of this realization (in pdf): Terrace easy to live: the plan
Originally, the family house Pelletier was bordered by a terrace of only 2.30 m wide and 9 m long. This provided a transition from home to the garden, but significantly limited the use of this space. The project consisted in creating a real living space of 5.70m long and 3.50m wide so that the whole family can eat (see diagram). Rather than being confined to a rectangular layout, the creation of a large bench seat and two planters (one with cutaway and the other with the rounded end) has broken the strict geometry of the existing scheduling. Not to mention, the installation of two screens that came to bring the vertical structure that was lacking perspective.
● To achieve this result, no mystery: imagination and work! An issue all the more easy to note that, on the last point, Francis Pelletier was able to benefit from the active support of his granddaughter and his two sons-in-law. It counts!
A precise calculation
Everyone knows that rationalization is a basic principle of the modern economy. Once the general dimensions of the development decided, the establishment of the plans passes by an optimization of the constraints. In the case of this terrace, the dimensions of the extension correspond for example to a whole number of slabs, in length as in width. The only binding point is the connection between the cladding and the foot of the facade. This approach has made it possible to reduce the cuts and the difficulties of laying. The same minutia is applied here for the drawing of planters and the bench. Remember: to master the measures, it is always easier to play the eraser on a drawing than to correct it on the spot when the construction started. Good preparation can sometimes take longer than the site itself. But what a pleasure and what a yield when it advances without delay.
All you need to do is take a tour of a large DIY store or a retail store open to individuals to appreciate the wealth of outdoor offerings. These products have the advantage of being quickly bought and quickly put... but have the disadvantage of being often expensive.
● In this context, our reader's concern for economy led him to use the classic cinder block for planters and the bench. Admittedly, it's more technical and longer to build. On the other hand, it is cheaper than a ready-to-use solution and the choice of
forms belongs to you. For the flooring, the concrete slabs selected by our reader combine the aesthetic character of the wood appearance with the proven longevity of the material, for a cost price comparable to a wooden grating in an exotic essence.
● Reflecting on the construction choices is finally about not neglecting the quality of the work. The concrete slab of the extension is the example. It is based on a hedgehog made of crushed construction waste. To even out, a thin layer of earth replaces the lean concrete. But, planted in the nose of the existing slab, irons Ø 8 mm stitch mesh square mesh. Under these conditions, the whole, even if it is done inexpensively, has little risk of deforming.
Francis Pelletier chose to lay the slabs on a sand setting layer. Given the good planimetry of the concrete slab that supports its terrace, he could fix them permanently to the adhesive mortar. This choice limits the risks of infiltration under the slabs and the nesting of the ants which adore the sand, easy to dig...
But this solution could turn into a disadvantage if he wishes, one day, to change the floor covering: he would have to unseal all the slabs, one by one!
The application of a waterproofing agent, specially formulated for outdoor application, preserves the appearance of slabs and delays a few years their fouling.
After having dusted the slabs by a jet rinse (followed by a day of drying), the product is applied by brush until refusal.
Slab support: concrete on hedge of rubble
1. The search is dug with a spade on a depth of 20 cm.
Then filled with crushed rubble to the ground to tamp and equalize the layer. There is no plaster, this material is too sensitive to water.
2. A layer of fine soil is spread on the hedgehog. Wedged between stakes, wooden planks act as lost formwork. The soil is groomed flush with the existing slab with a grass roller.
3. The square mesh is attached to irons of Ø 8 mm and 70 cm long, planted in the nose of the existing slab (previously pierced) and in the hedgehog.
4. Poured into place, the concrete is spread on a rake. It is dosed at 350 kg cement per cubic meter and wasted on the concrete mixer. removable, a new formwork overcomes the previous one up to the level of the existing slab.
5. The planter is made with two rows of blocks of 10 x 20 x 50 cm. Their spacing provides a 30 cm wide tray. For finishing, the blocks were cut to the grinder.
6. The bench of 30 cm seat has two layers of block, 10 + 20 cm.
A space of 5 cm is created with the next gardener in order to integrate a screen.
7. Corner sticks are glued to putty on all edges of masonry. They ensure a perfect finish and act as a peg to adjust the thickness of the coating applied in two layers.
Paving finishing: laying on sand bed
8. The sand, which has the same origin as that used for slab concrete and masonry mortar, is sieved more finely to be used as a bedding layer for slabs.
9. The leveling of the slabs is carried out thanks to a thin layer (3 cm) of sand compacted and trowelled... a technique usually used for the free installation of pavements on ground-full.
10. All slabs are installed before cutting near planters and bench. To adjust the horizontality of the set, each slab is checked on the spirit level.
11. The connection between the slabs and the foot of the facade is ensured by cut-outs made to measure. The joints are then blocked by sweeping a layer of fine sand, copiously watered.
12. The planters are filled with half rubble and then leveled with a mixture of soil and potting soil. The banks of the slab are dressed with concrete slats co-ordinated with the covering of the terrace.