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Pouring a mortar screed on old ground

On an old tile or old concrete slab, you must pour a mortar screed before placing a tile or other coating. Although ancient soils are often irregular, it is possible to catch up with them and make a screed perfectly flat, even and horizontal.

Necessary material

  • Bubble level
  • Trowel
  • Wooden ruler
  • Wood wedges
  • Float
  • Trowel
  • Cement

Steps

  1. Soil preparation
  2. realization of the mortar screed

Soil preparation

Definition of the level of the screed

Definition of the level of the screed

1. Even if it is not very thick, a screed will involve a slight elevation of the ground level. Trace on the peripheral walls of the room a horizontal line at 1 m from the ground. Use preferably a level with vials (principle is that of communicating vessels). We see this line drawn on the wall on the photo). This line will serve as a reference to define the level of the screed (thickness: 5 cm). Place small piles of mortar on the ground, on which you will place shims of wood. Tamp the small mounds to bring the wedges little by little to the same level.

Wedge adjustment

Wedge adjustment

2. Check the horizontal alignment of the wood blocks with a large metal ruler and a bubble level. Several small piles of mortar supporting the wedges will be placed all around the room to define very precisely the level of the screed. The upper face of the wooden blocks represents the final height of the scre. They are flush with the surface. For safety, check that they are all at the same height.

Checking the start of the screed

Checking the start of the screed

3.Place a small amount of mortar trowel along one of the walls. Spread it with a ruler of wood with well-trained song. Take hold on the holds. Before pouring the screed, you can spread on the ground a thin layer of very liquid mortar for optimal adhesion of the screed.

realization of the mortar screed

Drawing of the screed with wooden ruler

Drawing of the screed with wooden ruler

1. With a large metal ruler, pull the mortar toward you. If necessary, add mortar in places so that the screed is flat. Rake a second time. Remove the shims when the mortar begins to pick up. Fill the gaps with mortar with a trowel and even with the trowel. All stages of the work are done backwards to avoid damaging the newly expanded screed

Smooth from the screed to the trowel

Smooth from the screed to the trowel

2. The finish of the screed is done with a trowel. Smooth the surface of the mortar perfectly.

Trowel Smoothing

Trowel Smoothing

3. Refine the trowel smoothing to remove any imperfections. Protect the screed for one week with a sheet of plastic, to prevent drying too fast.

On the same topic

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    • Preparation and use of mortar in 5 questions
    • How to strengthen a wooden floor in attic to develop?
    • Should a polyane film always be used when pouring a concrete slab?
    • Can we pour a screed on an existing slab?
    • How to insulate an old house?
    • How to turn an area of ​​loose earth into a petanque?
    • What quality of sand for a screed and electric underfloor heating?
    • How to make a cement screed on sand?
    • How to dose a screed on concrete slab?
    • How to pour a floor screed?
  • DIY tips
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    • Insulating concrete slab and screed
    • Doubling a panel floor
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    • Mixing mortar on the floor
    • Mixing mortar: preparing the sand
    • Make a concrete slab and a mortar screed
    • Make a mortar screed on a slab before tiling
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