• Barbecues
• Fireplaces
• Garden and boundary walls
• Screen surrounds, raised plant beds
• Storage and compost bins, sand pits
• Bench stands, bicycle stands
• Terracing
• Ornamental pools

Plans for certain types of these items may be obtained from particular suppliers and manufacturers. See also "Concrete at Home" published by the Cement & Concrete Association, Private Bag, Porirua or the "New Zealand Concrete Masonry Manual" published by the New Zealand Concrete Masonry Association.

Most DIY masonry projects around the home and garden tend to qualify for official description as "minor works". Anything beyond the limits of a "minor work" will require a Building Consent. Concrete block walls in addition to a consent will need to be concrete filled and reinforced. Such jobs may also require the services of a professional engineer and a qualified tradesperson. If in doubt, consult with your Local Authority.

Determining Quantities
In calculating the number of bricks or blocks required for any specific area, remember to allow for the mortar joints. Note that the actual dimensions of many masonry products are such that the addition of the normal joint allowance of 10 mm results in very convenient module sizes (100 mm, 200 mm, 400 mm, etc).

Brick being laid on mortar bed

Mortar Mixes
For convenience use Mortaplus and just add water. Volume requirements are on the Mortaplus bag.

If Mortaplus is not available use Holcim Ultracem and plasticising admixture.

Use a proper mortar sand. Materials classed as "concrete sand" tend to be overly gritty for masonry mortars.

Fresh mortar should have the consistency of soft whipped butter. Experiment with the mix proportions before settling upon the right recipe (not too runny, not too sticky) for the job in hand. Hollow-core concrete masonry units tend to require a mortar with more sand than a typical bricklaying mix.

Mix no more mortar than you expect to use over the next hour or so. Batch the same relative quantities of sand and cement for each successive mix using bucket measures. If the mix proportions vary between batches, so too will the final colour of the mortar.

Foundations, Footings and Piers
All forms of masonry construction need solid base support. The construction should sit back from the edge of the base by at least 150 mm or the thickness of the units (whichever is the greater). If the upper surface of the base is very smooth, the areas to receive the masonry should be roughened to give a better "key" for the bottom mortar joint.

Where a suitable base (such as a concrete pad or ground slab) does not already exist, some "foundation work" will be necessary.

In the case of small-scale projects, a level arrangement of precast concrete paving slabs bedded firmly and evenly in the ground will normally provide for adequate support.

Larger projects should be founded on a continuous strip footing of width no less than three times the thickness of the wall. For walls of height 800 mm or more, or where the ground comprises clay or peaty soil, set the thickness of the footing to 150 mm; otherwise a thickness of 100 mm is adequate. In the case of sloping ground, the concrete footing may be "stepped" upwards by the height of one or more courses of masonry at convenient intervals. In order to ensure continuity at any such step, extend the lower level of excavation for around 500 mm beyond the intended position of the step to produce a local region of double thickness.

As a strip footing is largely unseen, the construction requirements in relation to boxing, and finishing are minimal.

Calculate the volume of concrete required. For foundations on minor projects Holcim New Zealand's Easicrete-ready-to-use concrete to which you simply add water is a convenient solution. If you are mixing your own concrete for the footing use around eight parts of builders mix to one part cement.

Free-standing walls of single-skin masonry should incorporate simple piers to give added lateral strength. For small garden walls a pier at each end will normally suffice. Wherever a wall is "stepped", it is advisable to start off the higher level with an intermediate pier. Piers can either be constructed before or during the actual wall-building programme.

Ties ready for the next length of wall.

Basic Laying Techniques
Removal all dust and debris from the base. As a final check on dimensions do a "dry run" on the bottom course of the bricks or blocks laying out the units to line or length using scraps of timber 10mm thick to simulate the mortar joints.

To connect a brick or block wall to the piers use expanded metal lath or brick ties, as shown in the photograph, positioned in the horizontal mortar joints spanning the pier to wall junction. For concrete blocks place the connection strips in all the horizontal joints. For brickwork every third joint will suffice.

Concrete masonry units should be in a relatively dry condition at the point of laying. If the units are laid wet, subsequent drying shrinkage can lead to cracking problems. Fired clay products, on the other hand, may benefit from some pre-dampening, especially in warm weather when pre-dampening reduces the suction of water from the mortar making the units easier to lay.

Apply the mortar with a bricklayers trowel. Where final appearance is important, take care to avoid getting mortar on the outer face of the units. The applied thickness should allow for squeezing of the mortar when the masonry unit is first placed. In the case of solid units such as bricks, the mortar bed may be slightly furrowed. For hollow-core units the mortar bed should take the form of strips, both along and across. Note that the top and bottom bedding areas of hollow-core units normally differ. Having the larger area facing up makes it easier to place the next course of bedding mortar.

Mortar being laid in strips.

Tap the brick or block into its final position to give the proper line and level. Wherever possible work to an established string-line. Check the alignment (both horizontal and vertical) using a spirit level and straightedge. Don't spend too long in adjusting the final position of the unit. The original pliability of the mortar will decrease fairly quickly due to the "suction" of the masonry. If you find that you need more time for adjustments than the mortar will allow, modify the mix by making it a little wetter in the first instance.

Placing guided by a stringline.

After the unit is positioned strike off the excess mortar with the trowel (an upwards cutting motion is best), leaving the joints flush. Proceed to lay the next unit.

Walls longer than 6 m should include movement joints to prevent shrinkage cracking. Such joints need to be spaced at regular intervals no greater than 5 m apart and would normally occur alongside a pier. To create a movement joint at a pier, replace the normal brick ties with galvanised steel strips. Prior to embedment coat the section of the strip that will lie within the wall panel with grease.

Using a tooling iron.

As the job proceeds, take care to avoid smudging the appearance of your earlier work via mortar "droppings" from above. Where fresh mortar splashes do occur, it is best to allow these to dry off before brushing.

Smooth concave joints (as distinct from flush joints) may be produced with the aid of a bent-bar "tooling iron" or a special wheeled tooling device. This treatment should be delayed until such times as the mortar has stiffened to the point of resisting an easy thumb-print. Work ahead in the interim and return when the time is right. The same applies to most other forms of tooled joint, including raked joints. Remove any debris from the tooling operations with a light brush.

Architectural Patterns
Masonry units can be laid in different patterns to create the effect you desire

Single-Leaf

Double-Thick

Disclaimer
While the information presented within this web site is offered in good faith, Holcim (New Zealand) Ltd disclaims any and all responsibility for the application of the principals and procedures discussed.