Masonry Block Work

Fair Face Jobs (Exposed Block work)

Check the block layer is a registered Licenced Building Practitioner (LBP). Ensure your block layer is aware you are after a 'Fair Face finish' and that the project is not going to be painted or plastered over.

Customer Expectations for appearance and quality should be checked prior to commencement of the job. It is a good idea to build a sample panel of the blocks prior to starting the project for the client to inspect. Make them aware that they may get chipping, joint size variations to compensate the size tolerations of blocks and that mortar colours may bleed into the block. I.e. Dark mortar against a light coloured block. Stack Bonded block work will also enhance any chipping or variations.

Different block profiles will vary in texture and colour as they are not produced in the same batch. Limit the amount of block types used in a job to achieve a better finish. This may require the block layer having to do extra cutting onsite. Allow for this in your pricing.

Be selective when laying the blocks - put stained, damaged or chipped blocks to one side and do not lay them in highly visible areas. I.e. near the front door. Chips of varying sizes may be evident on the edges and corners of the blocks. Complete product breakage may also occur during cartage, especially on long distance haulage or during unloading. These are an unavoidable part of distributing and manufacturing any masonry product. Minor cracks and chips can occur but are not recognised as block defects.

The use of a "raked" joints will emphasise chipping to the edges of the blocks. Concave or flush joints will tend to hide these minor chips. Please note that "raked" joints are also not recommended for external walls as the joint may retain water.

Any product which has been rejected by the customer or their layer due to chips or breakage will be the customer's responsibility. A wastage percentage should be applied to every project and typically an extra 10% should be ordered to compensate for this.

Chipping should be limited to 5% of a consignment containing less than 12.5mm in any dimension and any cracking to be less than 0.5mm in width and less than 25% of the nominal height of the unit.

Chips and imperfections should not be evident when viewed from a distance of not less than 6.1m of the constructed wall, under diffused light. As per ASTMC90, which has been adopted as the industry standard for viewing brick and blockwork.

Block work should be kept dry during the construction process and prior to sealing.

When placing the order, you must:

  • Inform “Bowers Brothers” that this is a “Fair Face Job”.
  • Place the order for the “entire” job, not just load at a time.
  • Allow for extra time for the order to be selected.

This will allow us to be able to select different block types from batches that have the best possible colour match.  However, this is in no way a guarantee.

On Site Honing

Please make note of all aspects covered in Fair Face block work as these also apply to honed block work.

Honed masonry is from the standard range of 10,15,20 and 25 series hollow blocks. The block surfaces are ground back, removing 2mm – 3mm off the block face giving a smooth finish that reveals the aggregate.

The results from the manufacturing process and delivery and may only become apparent after the honing process.

Hairline cracks, chips or other imperfections may be exposed after the honing process that were not evident during the construction of the wall. This is strictly an aesthetic issue which needs to be discussed with the client. Ways to rectify these should have been discussed prior to commencement of the honing and should be part of the honing contractors price. You should also allow for the block layer, having to cut out and replace the face of a block in the event of the honing process exposing something that the honer cannot rectify. These costs should also be allowed for.

Only contractors who specialise in Honing on Site should be used for this process.

As masonry blocks are manufactured using natural products, some variation in the shade and aggregate density should be expected.

Shot Blasted Blocks

Shot Blasted masonry is from the standard range of 10,15,20 and 25 series hollow blocks. The block surfaces are shot blasted, removing 2mm – 3mm off the block face giving a rough finish that reveals the aggregate.

Shot Blasting gives a similar appearance to Honed Blocks from a distance however it helps disguise chipping and joint size variations due to the rough texture.

Please make note of all aspects covered in Fair Face and Honed block work as these may also apply to Shot Blasted block work.

Shot Blasting is a secondary process that is carried out on a "Made to Order" basis and we do not except returns on Made to Order product.

Paving

As masonry paving is manufactured using natural products, some variation in the shade/colour, texture and size tolerations should be expected.

Paving for each job should come out of the same batch and you should blend off multiple pallets.

A “Batch” is deemed to be:

  • From which plant it is manufactured &
  • The date of manufacture.  (this may be over consecutive days due to manufacturing limitations).

It is advised that you check the batch details on all pallets prior to commencing installation in case there has been a loading error from the yard or your supplier.  It is easier to remedy any issues before the work has commenced.

It is also advised that you keep a copy of the batch details in case you run short of product.

Product laid is deemed to be product accepted.

Brick Veneers

As masonry brick veneers are manufactured using natural products, some variation in the shade/colour, texture and size tolerations should be expected.
Texture can be open and porous looking to smooth and slick looking across the same batch. This is just a natural occurrence in the manufacturing process.
Unusual discolouration patterns can be limited by blending the bricks. Should there be any concern regarding significant colour variation laying should cease and the manufacturer contacted.
Bowers Coal and Ironsands bricks, should be dry cut by the bricklayer to avoid slurry staining from a wet cut.

These variations make up part of the inherent beauty of brick.

Brick veneers for each job should come out of the same batch and you should blend vertically from at least three pallets to blend colour and texture variations. A bricklayer should regularly step back and view the laid product from a distance of 6.1m, to check the blending is acceptable.

A “Batch” is deemed to be:

  • From which plant, it is manufactured &
  • The date of manufacture. (this may be over consecutive days due to manufacturing limitations).

It is advised that you check the batch details on all pallets prior to commencing installation in case there has been a loading error from the yard or your supplier. It is easier to remedy any issues before the work has commenced.

It is also advised that you keep a copy of the batch details in case you run short of product.

During transportation bricks may rub together on the pallet. This can sometimes cause light rubbing on the face of the bricks. Excessively rubbed bricks should be discarded or used for cuts.

Be selective when laying the brick veneers - put damaged or chipped bricks to one side and do not lay them in highly visible areas i.e. near the front door.

Chips of varying sizes may be evident on the edges and corners of the bricks. Complete product breakage may also occur during cartage, especially on long distance haulage or during unloading. These are an unavoidable part of distributing and manufacturing any masonry product. Minor cracks and chips can occur but are not recognised as brick defects.

Due to the nature of bricks no two bricks are the same and no brick is perfect when examined close-up.

ASTMC90 has been adopted as the industry standard for viewing brickwork from an aesthetic standpoint – A workmanship quality standard is achieved if imperfections, including chips, are not visible when viewed from a distance, of not less than 6.1m under diffused light as per ASTM C90.

ASTM C216-04 specifies that bricks must contain less than 5% visible cracking when viewed from a distance of 6.1m.
ASTM C216-15 for a general-purpose face brick (FBS textured) basically has the following requirements:

  • Chips from the edge should not be deeper than 8mm
  • Corner chips should not be deeper than 13mm.

When all the length of the chips is added up, that the total does not exceed 10% of the perimeter of the brick face (as an example, the accumulative lengths of the chips for a 230mm x 75mm brick shall not exceed 61mm).

It is important to discuss with your bricklayer the aesthetic look you are hoping to achieve with your brick veneer and if possible, include them in your selection process.

We strongly advise that all parties involved in the construction process (builder, brick layer & client) are made aware of and have read the Brick & Block Layers Federation of New Zealand, Brick Veneer Best Practice Guide. Product laid is deemed to be product accepted.

Mortar

Bowers recommends colour matching your mortar to your brick colour.
Using a dark colour mortar with a light colour brick or light colour mortar with a dark brick will cause the mortar to:

  • Colour bleed into the brick & will highlight any imperfections in the veneer or the laying.
  • Cause staining, giving the brick a patchy dirty look.

For example:
Premium white mortar looks best with the Ice coloured bricks & a black mortar needs to be used with Coal or Ironsands coloured bricks.
The Bricklayer must regularly sponge off thoroughly with clean water to prevent the mortar staining the surface of the bricks.

Sealing

As with all Masonry products, to enhance the life and durability of the product we recommend the use of a suitable exterior clear sealer.

Coal and Ironsands bricks must be sealed to prevent fading, reduce the chance of efflorescence and enhance the appearance. The use of a tinted sealer will give an even greater depth of colour to black bricks.

Seal brickwork as soon as possible as per suppliers recommendations. Any Efflorescence should be removed before sealing.

Refer to the Technical Information Page in the Resources Section, on our website, for application details.

Efflorescence

Efflorescence is generally a “whitening” look on the surface of the brick veneer. It can vary in appearance from a thin hazy layer which is sometimes confused as surface fading to a thick calcified white crust. It is a common phenomenon experienced in a variety of degrees by all forms of product that has cement and should be anticipated on any job.

Efflorescence occurs where excessive amounts of water enters a veneer that has soluble salts present. When the water evaporates, the salts are then deposited on the surface of the veneer. Soluble salts can enter the veneer from various sources:

  • Mortar components, particularly cement.
  • Soil or fill in contact with the wall.
  • Sea spray in coastal areas.

We recommend that Veneer walls should be protected or covered from inclement weather during the construction process to avoid the walls being saturated as this will promote efflorescence.

Persistent efflorescence may act as a warning sign that water is entering the wall through faulty copings, flashings or pipes.

Why do we get Efflorescence?

When the cement reacts with water Calcium Hydroxide is formed. The Calcium Hydroxide migrates to the surface of the brick through capillary action and forms Calcium Carbonate when it encounters Carbon Dioxide. The in-soluble Calcium Carbonate is essentially limestone.

Cleaning Efflorescence

The initial appearance of efflorescence (Primary) can be scrubbed off with a stiff plastic brush and some detergent whilst it is still in its powdered form.

An alternative dry method is to brush the efflorescence loose and vacuum the deposit off and out of the pores.

If efflorescence is left on the wall for a period of time and is allowed to calcify (Secondary), it is extremely difficult to remove.
To remove Secondary efflorescence, will require an acid wash and should be done by a professional following the supplier’s recommendations.

Extracts are from www.bbfnz.co.nz “Brick Veneer Best Practice Guide”.

Pinto Concrete

Very rarely concrete develops an appearance called “Pinto” which causes unsightly irregular light and dark blotches on the concrete surface. The exact causes of the “Pinto” effect are not well understood but is influenced to some degree by environmental conditions such as temperature, humidity and exposure. Mostly the “ Pinto” effect lessens over time but occasionally may require “acid washing” to moderate. The “Pinto” effect is not caused by the supply of concrete and Bowers cannot be held responsible.

 

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