7/30/2019 JointingBrickwork Advice

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JOINTING BRICKWORK AS PART OF THE BRICKLAYING PROCESS

Brickwork joints generally vary in thickness between 8

and 15 mm. This thickness also depends upon thedesired architectural image of a wall and the variationin the dimensions of the bricks chosen. The jointcomprises 20% to 25% of the total wall surface.

In 1993, analyses of damage in relation to the quality of thejoints in brickwork (in some cases less than 10 years old)resulted in the SBR-CUR publication "The quality of

joints in brickwork."In addition to the introduction of hardness classes for

joints and the quality levels to be realised formechanically compacted joints, it was alsorecommended that brickwork be jointed by smoothingand lightly compacting the joints as part of thebricklaying process.

The entirely mistaken assumption is often made that it ispossible to make brickwork waterproof by pointing the

joints later after the bricklaying process has been finished.This is far from the truth. After all, a joint is still a porousfilling between the bricks.This mistaken assumption is often made in connection withhalf-brick masonry work in garages and storage sheds wherethe joints are raked out on both sides, as a result of which theremaining thickness of the mortar layer between the bricks issometimes barely 6 cm. The assumption that the joint appliedlater will ensure that the brickwork remains waterproof isfrequently proved wrong in such cases.In particular for brickwork where recessed joints are desired,

jointing the brickwork by smoothing and lightly compactingthe joints as part of the bricklaying process is to be preferredrather than pointing the joints at a later stage.

When using bricks that have only a very weak

tendency to absorb water (class IW1 according totable 4 of BRL 1007), it is recommended that thebrickwork be jointed by smoothing and lightlycompacting the joints as part of the bricklayingprocess.

I f t ra d i t iona l jo in ts a re po in te d in th is ty pe o f b r ic k work , the fa c t tha t the po in t ing m orta l i s s l igh t ly da m p m e a ns tha t i t w i l l bond on ly we a k ly to the s ur fa c e o f the b r ic k a nd pra c t i c a l l y the on ly bond tha t w i l l be fo rm e d is w i th the unde r ly ing br ic k la y ing m orta r .

Royal Verbond van Nederlandse Baksteenfabrikanten(Royal Association of Dutch Brick Manufacturers)

Tel. + 31 (0)26 - 3845630

The bricklaying process itself should be carried out using an

ample supply of mortar so that the vertical joints as well asbed joints are amply filled with mortar. The bricklayer thenfinishes the joints by raking out the excess mortar andfinishing them off with bricklaying mortar.A special roller jointer has been developed especiallyfor this purpose, which makes it possible to strike thebrickwork joints and recess them to a constant depth(between 5 mm and 15 mm). Flush joints cannot berealised with this technique.By using special profiles, it is also possible to give the

joint a special outward appearance. The surface ofthe mortar in the joint is also compacted somewhat bythis process. As a result, the bricklaying mortar formsa monolithic entity between the bricks.

If brickwork is jointed in this fashion, joint bonding will alwaysbe good. The quality of brickwork jointed in this fashion istherefore high. However, this jointing technique does require adifferent technical skill of the bricklayer.

Manufacturers of prefab mortars have developed specialjointing mortars for this purpose, which allow one to havemore control over the exact time when the joints arefinished without the stability of the mortar being impairedwhile it is being worked with or compacted. The choice ofthis prefabricated jointing mortar should be adjusted tothe category in which the brick falls in terms of initialwater absorption. These mortars are also available invarious colours.

There is a trend towards making brickwork that is jointed inthis fashion without vertical joints. The vertical joints arethen not filled with bricklaying mortar and have atheoretical width of 2 mm. This type of brickworkemphasises the horizontal lines of the design, particularly ifthe jointing process also results in recessed joints.

In some cases, after the bricks are laid out in an amplebed of mortar, the joints are simply raked out to the desireddepth, after which the brickwork is brushed off with a hardbroom. A point to remember in this regard is that thevertical joints and bed joints must be raked out to the samedepth and width. This method is suitable only for recessed

joints.

Velp, March 2009

The KNB and third parties called on by the KNB do their very best and take the greatest possible care to provide a level of service that issatisfactory in all respects. However, it is always possible that an omission, a fault and/or inaccuracy, error or incomplete information may bepresent in a recommendation or product. The KNB as well as third parties called on by the KNB can accept no liability whatsoever for anydamage which could result from or be considered to result from the above.