Tag Archives: Brickwork

How to do Rendering Over the Brickwork

The Rendering over the brickwork of a house wall (on solid walls) prevents rainwater reaching the bricks of the outer face of the wall and thereafter crossing to the inner walls to cause damp patches which ruin decorations. Should a damp patch appear, check the outside wall to see if the rendering is cracked or damaged. Sometimes defects are not immediately apparent; gentle tapping along a suspect area with a hammer will find defective patches – they will sound hollow and could fall out even under a light tap. For repairs, use a mortar mix of 1 part Portland cement to 6 parts sand. The sand should be a mixture of soft and sharp sand. For smaller cracks use a proprietary mix, available form d-i-y shops in small bags.

Brickwork How to do Rendering Over the Brickwork

  • Use a sharp cold chisel and club hammer to widen the crack.
  • Undercut the edges with a scrape so that the new mortar can be pressed behind the crack. Remove all loose material using a wire brush. Brush a pva bonding agent, proprietary type, into the crack.
  • Press the mortar well into the crack using a scraper. Remove excess mortar immediately, using an old damp brush.
  • Allow the mortar to dry partially before damping down smoothing off with a trowel or a block of wood.

How to Look After Walls, Brickwork

Efflorescence – a white powdery substance that forms on brickwork – is caused by water drawing the soluble salts in the bricks to the surface.

Since water caused the trouble, do not attempt to wash away the substance; this will add to the problem. Using an old distemper brush, apply a fluid called ‘Efforless’ which will neutralize the soluble salts. Usually three coats are needed and this type of fluid is readily available at most builders’ merchants. Should difficulty be experienced in obtaining a supply, contact any leading paint manufacturer to find a local stockist.

Damp wall may give rise to vegetation or fungus growth. Here, use a stiff broom (not a wire brush) to clean down the wall before brushing on a coat of fungicide. The cause of the damp must be cured or the trouble will reoccur. Efflorescence and fungus growth can appear on interior walls and spoil wallpaper. In this case, there is no alternative but to strip off the paper, complete the remedial work and then redecorate. As an added precaution use a wallpaper paste containing a fungicide. Often solid brick walls which face the prevailing winds can be saturated by driving rain, which can cause efflorescence. A liberal application of silicone solution to the brickwork in dry summer conditions will prevent rain soaking into the bricks.

Repointing Brick How to Look After Walls, Brickwork

  • There are three types of joints. Make sure you repoint (make good) defective joints to match those used previously. Flush joints are the most common. These leave a flat surface. They should be used where a wall is to be painted.
  • Weathered joints are slanted to make sure rainwater slides off, thus preventing it settling and sinking into the mortar. Rubbed joints are formed with a half round length of metal or timber.

Rust can occur in the mortar joints between the bricks. One of the ingredients used to make mortar is sand. The rust caused by ironstone present in the sand. Chip out the old mortar and fill the joints with freshly mixed mortar.

Repointing: If the mortar joints have started to crumble or crack, the whole wall will soon look shabby. Even sound, discolored joints can ruin the appearance of attractive brickwork. In both cases it is worthwhile raking out the old mortar and filling the joints with new. If any mortar drops on to the face of the bricks, do not try to clean it off immediately; you will only succeed in spreading it further over the surface. Allow it to dry and then scrape it off with a trowel. Then lightly brush the surface of the brick with a wire brush. The correct mortar mix should be used when re-pointing and as a small amount will go a long way it is advisable to purchase a proprietary ready-mixed bag such as Marley Mix. Water is then added as required. Match up to the existing mortar joint which will usually be a rubbed, flush or weathered joint. If a large amount of mortar is needed, make it by mixing Portland cement, fine sand and some PVA adhesive (plasticser) – and water. The mix must be neither too stiff nor too runny. A ‘buttery’ consistency is best. Follow manufacture’s instruction when using p PVA adhesive.

  • Use the small sharp cold chisel and club hammer to cip out the old mortar to a depth of 3/4in. brush out all dust and soak the cavity with water. Wetting first prevents the bricks from absorbing too much moisture from the mortar.
  • Use a trowel to press the mortar into the cavities. Leave the mortar slightly proud of the surface.
  • When the mortar is partially dry, rub off the excess. Use a half round length of timber or a short length of pipe.
  • Use the edge of the trowel to shape the horizontal joints. Complete the vertical joints by drawing the trowel back towards the right-hand bricks while pressing inwards with the left side of the trowel. Use the edge of the trowel to slice surplus mortar off the face of the bricks.
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