Assessment of realised masonry
Quality starts with the product. MBI produces high-quality facing bricks. However, the final result of the façade is also very much determined by the processing method. It can lead to a mismatch between expectations and realisations. Fortunately, in the Netherlands we have an Assessment Guideline (BRL2826-1) that can provide a solution.
- Are the bricks placed correctly?
- Was the stone placed with the visible side facing forward?
- How was the mortar applied?
- Shading due to a shallow or distant set-back joint?
- Is there a lot of dirt / blemish on the facade?
- Are the (ribbon) joints constant
- Are the bricks lying straight?
- Is the masonry bond good and neat?
- Flatness of the masonry?
- Etc.
BRL 2826-1
When masonry work is carried out by a certified masonry company in accordance with BRL 2826-1, the requirements for the appearance are clear and the result verified by a third party. The contents of BRL 2826-1 Masonry Constructions can also be used when specifying in advance and assessing the masonry appearance afterwards. This ensures clarity, prevents dissatisfaction and results in ‘beautiful’ masonry.
Objective and measurable
The term ‘beautiful’ is not objective and is related to personal taste. The appearance of masonry is a sum of a series of factors. For example, variation in joint widths, the course of joints or the ‘bulging’ of a façade surface. BRL 2826-1 objectively describes the criteria to all relevant aspects of appearance. The methodology for assessment and measurement is also detailed, including examples and necessary measuring equipment.
Making agreements
The parties should agree on masonry appearance requirements in the specifications, other contract documents and/or with the help of a reference wall. BRL 2826-1 can be used for this purpose. If this BRL has not been agreed in advance, the parties should agree to apply the BRL when assessing afterwards.
Concrete requirements
Chapter 7 sets requirements for finished masonry. The surface criteria has six aspects: flatness, butt joint width, threaded ribbon joint, ribbon joint direction (level), layer size (ribbon joint thickness) and regularity of masonry bond. There are two classes: for brickwork with standard or high appearance requirements. Making arrangements with a reference wall is also described.
Class High: for brickwork with higher visual requirements. This class is recommended if unevenness and irregularities in masonry are quickly visually perceptible due to the use of certain types of bricks, masonry bond (e.g. tile bond) or joint types (e.g. thin or narrow joints) or combinations thereof.
Class Standard: for masonry with normal visual requirements. This class is applicable for a certified masonry company if the specifications or other contract document does not state the applicable class, deviating requirements or reference wall.
Trial wall and/or reference plane
In deviation from the described criteria, the surface criteria can also be determined by a test wall and/or reference plane. A permanent masonry fragment should be designated in the work to serve as a reference plane. Approval of the reference plane should be recorded in writing, clearly describing the location and size of the reference plane. Finally, the client and contractor can lay down any additional requirements, for example when using bricks with a special surface structure or size.
Assessment of masonry
In general, masonry should first be visually assessed at a distance of 3 to 5 metres. Preferably with a dry surface and diffuse light. So no direct sunlight or floodlight. If this visual assessment casts doubt on the performance, measurements can be taken. For each facade (section), establish visually which masonry fragments (of 1m² ) are eligible for measurements to assess the masonry on the established criteria. Perform the measurements in accordance with section 7.3. If the masonry fragment does not meet the specified requirements, this does not automatically mean that the standard has been exceeded or that the entire masonry has been rejected. Use additional measurements to determine whether the masonry fragment is representative of the façade or façade section.
Permitted incidents
Assessment of the six aspects mentioned above is done on the basis of measuring deviations. The measured deviations are related to the requirement. To prevent incidental exceeding of the requirement from leading to rejection of the masonry (fragment), the BRL includes a table of permitted incidents for each assessment aspect. This includes the severity and extent in which the permitted incidents may occur. Severity and extent of incidental exceedances determine whether the performance delivered is acceptable.
Source: KNB infoblad 37, knb-infoblad-37-criteria-surface-assessment-masonry-new.pdf (knb-keramics.nl)
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