Re-pointing DIY defined for the layman
A re-pointing project is the name given to the method of replacing old mortar between the bricks with new mortar, matching it. It is done to maintain the strength and stability of the walls of a building.
Major causes of a Re-pointing Need
Constant exposure to hot and cold weather, rain, wind, frost and hails stones, damages and destroys the mortar holding bricks or stones of a building together on an external wall to crumble bit-by-bit and fall out. On older constructions especially heritage sites, the pointing will be of a harder mortar than the bonding mortar. Once this is dislodged, the softer bonding mortar gets exposed and wears away very quickly, so re-pointing is needed.
This sort of destruction cause by natural elements happen over decades but it is vital to repair the pointing or else water will seep through and damage the wall bought externally and internally. In case the damage is restricted to a small patch, only that area can be repaired, however the re-pointed area will tend to then stand out. Generally, an entire side of a wall will have weathered in a similar fashion, so complete re-pointing of the wall must be done.
Tools required for Re-pointing DIY
There are certain tools that you need to have in your possession before starting a re-pointing DIY.
You must buy several chisels like one with a small pointed end for pointing up small areas;
- A plugging chisel which is long and flat for removing large portions where there is little space.
- Mortar tools like a tuck pointer, hawk and a pointed trowel are necessary for re-pointing bricks.
- Tuck pointers are small flat trowels while you will need a long trowel for pressing the mortar between bricks.
- An angle grinder (small -about 4.5 inches or 5 inches) with a diamond-tipped mortar blade or attachment and a dust guard.
- You will also need a brick jointer, which is a small, curved metal bar which is used to make a concave line between the bricks. This is water resistant and so is much more useful than a flat line of mortar that would be easily washed away.
- A couple of buckets, a large wire brush and a large brush with soft bristles to clean the surface and a water spray.
- For the re-pointing DIY material, you need to buy cement, sand and hydrated lime or PVA.
- If the re-pointing DIY has to be done at a higher level, it is essential to have an access ladder or scaffolding, as working from a ladder is not advisable.
- In addition to this, it is imperative that you arm yourself with a pair of good quality gloves, goggles, safety shoes and an industrial helmet or hat to protect your head.
Mixing mortar and sand for the Re-pointing DIY
The common proportional mix of mortar for re-pointing DIY is a mixture of 6 parts builders sand, to one of hydrated lime and one of cement or a mixture of 3 parts sharp sand to 1 hydrated lime. Measure each amount with a measuring cup for an even colouring.
Do not use ordinary sand and cement mixture, as it will trap water inside the wall and the trapped frost will loosen it. It also tends to set too quickly and forms a weak bond to the bricks.
Mix only small amounts of mortar (about half a bucket at a time), as re-pointing DIY takes time and you will be unable to cover a very large area before the mortar begins to go off.
The mortar must be just the right consistency; it needs to be fairly firm so that you can slice it into strips with the trowel. The best way to test it is to see if the mortar will stand in peaks on your trowel. It should not collapse or fold.
Restoring the wall step-by-step with Re-pointing DIY
Now that your mortar mixture is ready you may start. Always begin from the top of the wall as the dust will fall below and the lower portions will have to be cleaned.
- Take out the old soft mortar using a club hammer and a plugging chisel or you could use a hook and an old screwdriver. Strike at the vertical joints of the mortar first and then work on the horizontal ones, until you get down to solid mortar. Break the mortar to at least 1 inch and remove all decomposed bricks. If the joint is very narrow, use a hacksaw blade. Ensure that the old mortar has been removed from all areas, so that the new mixture can stick.
- Clean the area with a wire brush and the vacuum it to remove all dust particles.
- Wet the space between the bricks with a hand mister or a water spray. Place the mortar on the hawk and then place it against the brick wall. Now pack the open space with mortar using a pointing trowel or a jointer. Line the horizontal joints first and then go for the vertical ones.
- Once the mortar is semi-dry, sculpt the joints to match the surrounding mortar. Give a slight inward curve into the mortar, using a professional jointer or use your gloved finger.
- Using a wire brush clean the surface of the bricks before the mortar completely dries. Add a little moisture to the joints so that the mortar does not crack when it dries
Re-pointing DIY finishing techniques
Flush Finishing: This is done by drawing a long piece of wood about 6mm thick, 12mm wide and 100mm long along the joints once the mortar begins to go off. This is probably the easiest finish for a new person to achieve, even though flush finishing may be difficult to achieve because of the irregularities of commercially produced bricks.
The Hollow Key Finish: This is done by pulling a suitable curved or round shaped piece of tube or metal along the joints. You could use your gloved finger for the same effect.
The Weathered Finish: This type of finish does not allow water to rest on the surface of the wall and is very durable but difficult to get a good finish for a re-pointing DIY beginner. The blade of the small trowel is used to make a joint that tilts a bit inside on top and backwards alongside the joint. The trowel always touches the base of the bricks above the joint being worked on. For the vertical joints, the trowel edge is in contact with the brick on the side and inclined by the same degree as the horizontal joint. Keep the direction of the strike same for the vertical joint, all over the wall.
The Recessed Finish: This finish requires that the mortar be scraped out to a certain depth from the face of the wall and then it is pressed back firmly with the help of a metal jointer tool called a chariot or a piece of wood. This type of finishing is not recommended as a re-pointing DIY project, since water will accumulate in the joints.
The Freeze Thaw Project and Re-pointing
Bricks, stones and slabs often have tiny fissures (cracks) in their composition, which fill with water if it is wet. This water freezes during winters to form ice which expands, exerting pressure within a crack. The crack expands a bit under the pressure from the ice. During the summer months the water evaporates or runs off leaving a larger crack, which fills with water when it rains. Eventually, the brick will either be badly damaged or fall off. This process is called the freeze thaw action and greatly damages the external walls of buildings. In the case the only solution is to remove individual bricks and replace them.
Replacing Bricks for Re-pointing
Bricks are affected by and get destroyed mainly due to wind and water weathering. Though replacing bricks isn't a Herculean task, it does involve the use of your power drill along with a lump hammer, a 6 mm drill bit, and chisels, including jointing or plugging chisels. A sand and mortar mixture will also be needed for this re-pointing DIY project.
First, drill holes in the brick and the surrounding area. Try to drill as few holes as possible but enough to get the brick out with the chisel. Clean mortar with the plugging or jointing chisel, sweep with the wire brush and wet the area. Now place the mortar on the bed of the area and on the sides. Apply mortar on the brick and press it, to help it stick to the surface. Put the brick into the opening. The excess mortar will squirm out from all sides. With the pointing trowel push mortar into any space left behind. Then level the new joints to come up to the original level and shape.
Re-pointing is certainly a time consuming DIY project if you wish to achieve a good overall appearance but is definitely worth the effort. Avoid doing it on days when rain or frost is expected.
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