Protection Of External Walls From Moisture

2023 Author: Douglas Hoggarth | [email protected]. Last modified: 2023-05-24 11:23

A brick wall looks like an insurmountable obstacle to dampness, but this impression is deceiving. The fact is that the brick has pores through which moisture can penetrate. Damp can also pass through the not very tight connection between the individual bricks and onto the inner wall surface. Thus, the penetration of water into the dwelling is possible even in cases where dense bricks, concrete blocks or stone were used in the construction of the house.

Moisture that has penetrated the walls destroys floors and other wooden parts. Moreover, the heat loss with damp walls is 50% higher than the loss with dry ones. Thus, external waterproofing of a dwelling seems to be a very urgent task. The best protection can be a layer of cement-based plaster or a special protective coating. The first method is more difficult to implement, but much cheaper.

The plaster is applied in two or three layers, its external surface can be given a different appearance from flat to bumpy structure. The appearance of the wall is largely determined by the tastes of the owner of the house, but the number of layers depends on the rate of moisture absorption. If the adhesion of the coating to the wall is good, then it is enough to apply two layers; in the case of poor adhesion, another thin layer with a rough surface should be applied, which will serve as a base for laying other layers. This layer is also applied if the wall has an increased ability to absorb moisture. A simple test is recommended: spray water on the wall and see how the wall absorbs moisture. If the water flows down in the form of drops, then the wall repels moisture; otherwise, water is absorbed into the wall almost instantly. Having determined the number of layers that will be applied to the wall,prepare the surface for work. The wall should be cleaned of dust, mold and everything else that will interfere with tight adhesion to the coating; the same applies to mortar between bricks.

If you doubt that you can do the plastering on your own, then you can simplify the task and limit yourself only to painting the walls outside. The cheapest is the so-called cement paint, which is sold in powder form and mixed with water before use. You can also apply an emulsion to the wall, which has the advantages of being easy to apply and drying quickly. The emulsion is water-repellent and can further act as a base for subsequent layers. It should be borne in mind that paint and emulsion are applied to a dense and thoroughly cleaned surface. If, when carrying out work on waterproofing walls, it is undesirable to change the appearance of the structure, then it is recommended to use colorless seals. These seals are applied by brush or spray;blocking the pores of the brick, they prevent moisture penetration. If the manufacturer's instructions are strictly followed, the specified coating will last for 10 years; if the wall has pores of too large a diameter, then a second layer of sealant should be applied. Do not forget to seal all cracks and potholes before using these products.

Renovation of masonry joints

1. Cleaning. Remove old mortar and crumbs; lightly wet the inside of the seams. Prepare a mortar: 1 part Portland cement, 3 parts fine sand and enough water to obtain an elastic mixture.

2. How to put the solution. Using a falcon and a trowel, put the solution in the cracks; press it down. After the solution dries a little, press it into the seam with a 15 mm tube.

Applying a protective layer

Preparation for painting. Using a stiff brush, remove dust and solution particles from the surface. If there is mold or any kind of vegetation on the wall, treat it with a fungicide, and only then remove it with a brush and scraper. Apply a second coat of fungicide and let it dry. Finally, seal all cracks and gouges with fresh mortar. If the surface to be coated is smooth, then it can be painted with a regular brush or roller. An uneven surface requires a special coarse brush as shown in the illustration. After dipping your brush or roller into the paint, make steady, slow strokes, while the paint penetrates cracks and potholes.

Choice of coverage. A typical coating is board cladding. The planks are nailed to a batten frame, with each plank partially overlapping the underlying plank. Architraves are made around windows and doors, which cover the ends of the boards. It is more difficult to join the edges of the boards in a quarter. In this case, the boards do not just overlap each other, but are connected by inserting part of one board into the groove on the other. This connection is more durable and prolongs the life of the nails used. However, the use of wood also requires appropriate care - painting or impregnation with linseed oil. The picture shows a different coating that uses plastic or aluminum sections; it does not require much maintenance. When applying the coating of your choice, it may be necessary to simultaneously install thermal insulation;in this case, it is recommended to get advice from a specialist, as this job is not so easy.

Plastering works

1. Installation of rails. Begin by installing 10mm battens spaced 1.5m apart. The slats are nailed down and inserted into the gaps between the bricks. The nail heads should be above the surface of the laths so that they can be easily removed. A 15 mm thick strip should be nailed along the upper edge of the waterproofing layer; the thickness of the plaster should be the same. Finally, nail slats around doors and windows.

2. Preparation of the solution. Spread sand on a hard, horizontal surface (such as a sheet of plywood). Add lime and stir it all with a scoop until the mixture is evenly colored. Make a hole in the middle of the mixture and add cement; mix the components of the mixture thoroughly again. After making the second hole, add water; the amount of water should be approximately half the volume of the dry mixture. While stirring the solution, add water until you get an oily mass. Make sure that no lumps remain in the solution. Transfer the solution to a special board mounted on a trestle or stool. Holding the falcon almost perpendicular to the surface of the board, take about 1 liter of mortar.

A typical mortar recipe for masonry is as follows: 1 part Portland cement, 1 part hydrated lime and 5 parts dry sand. You can also add 1 part regular cement mixed with lime to 4 parts sand. For very dense walls (for example, concrete blocks or solid bricks), the proportions are 1: 1/2: 4 and 1: 21/2, respectively. If you do not have the desire to deal with the calculations of all these proportions, then buy a dry solution in the store, to which you just have to add water. If you decide to do the work of preparing the solution yourself, then start with a ten-liter bucket of cement, adding the appropriate amount of sand and lime. If you can estimate the amount of mortar that you manage to put in one hour (that is, the time after which the mortar begins to set), then you can easily determinehow much solution to prepare.

3. Application of the solution. Holding the falcon in one hand almost horizontally, use a trowel to separate the layer of mortar. Tilt the falcon as shown in the picture and throw some of the mortar onto the wall with a sharp upward motion of the trowel. After that, distribute the solution along the wall, moving from one rail to another. Repeating this operation, fill in all the space between the slats. After each movement, rotate the falcon about a quarter: this will maintain centering and it will be easier for you to hold the falcon in your hand.

4. How to level the solution. After filling the space between the slats, the mortar should be leveled with a trowel. Make sure that no air bubbles remain in the solution and that the coating is firmly attached to the wall.

5. Leveling the mortar layer. The coating must be of the same thickness. Take a bricklayer's trowel (this is a flat board with a handle) and flatten the surface, flush with the surface of the planks. If the grater pulls the mortar with it, then do the indicated work after the mortar has set a little.

6. Filling the grooves. After covering the entire wall with the mortar, let it dry for three hours and then remove the wood slats. Fill the grooves remaining from the rails with mortar and level these places.

7. Why scratch the surface of the first layer. When the mortar has hardened slightly, cover the surface of the wall with wavy scratches. This is done to ensure that the second layer is firmly hooked on the first. The lines are drawn using the special comb shown in the figure. You can make such a comb yourself by hammering a few nails into a block of wood. After removing the strips around the windows and doors, lay the mortar 10 mm thick. After scratching, install the battens so that they overlap the quarters of the windows and doors by 5 mm. After completing all the indicated work, leave the wall to harden for about a week. In warm, dry weather, spray moisture onto the wall surface to help the curing process.

8. Application of the second layer. Prepare enough mortar to cover the second 5 mm layer. Apply this layer in the same way as the first, moving from one side of the wall to the other. Now you should not install vertical slats, because they can damage the first layer. The second layer should contain less cement than the first. The mortar should be prepared according to the following recipe: 1 part cement, 2 parts lime, 8 parts sand (or 1 part ordinary cement mixed with lime and 51/2 part sand). After the mortar has hardened (after about 24 hours), remove the horizontal batten that is at the GIS level and the battens around windows and doors.

9. Recent transactions. Level the coating using a trowel and trowel in sequence. Do this effortlessly, otherwise water will come out of the solution. If you want, you can roughen the surface by using a trowel, comb or steel brush. For added strength, you can cover the wall with pebbles; this is done immediately after applying the second coat. The technology for this process is extremely simple: scatter the pebbles onto the damp wall with your hand or a shovel.