Fitness of Materials
When selecting materials for use in a building project it is important to consider the typical local climate, the necessary durability and the safety of use of such materials and any other relevant considerations based on the site in question.
While standardised testing methods is the most straightforward method of determining if a material is fit for use there are other ways to determine the suitability of a product:
Independent certification schemes by approved bodies such as the NSAI. To ensure that certification can be relied upon you should ensure that the certifying body is accredited by a member of the European cooperation for Accreditation for instance in Ireland the Irish National Accreditation Board (INAB).
Accredited laboratory undertaking testing which shows the material being in question is capable of performing as intended and required for its proposed use. Again, if the certifying body is accredited by a member of the European cooperation for Accreditation it offers a level of certainty with respect to the test results.
Performance in use. By providing details of materials performing as intended and required in similar situations it can be shown that materials are suitable for their use and satisfy the requirements of the Building Regulations.
It should be noted that the recommendations of IS EN ISO 9001: 2015 are intended to ensure a consistent quality of materials and are not to demonstrate compliance with any technical specifications.
Resistance to Moisture
It is important to ensure that any building materials that are likely to be affected by moisture, be that condensation, rain or ground moisture are adequately protected to ensure their performance is not affected. Building elements can be protected by constructing the building in such a way that will prevent the passage of moisture to elements that will be damaged by moisture or the materials themselves can be treated to protect them from moisture.
Further guidance on resistance to moisture is available in Appendix C and Technical Guidance Document C available on the Building Regulations app.
Resistance to Subsoil
Any materials that will be in contact with the ground should not be damaged by any material that may be present in the subsoil. A suitable site investigation should be undertaken prior to the selection of materials to ensure only materials suitable for use in the site-specific conditions are used.
Further guidance is available in Appendix C and Technical Guidance Document C available on the Building Regulations app.
High Alumina Cement
The use of high alumina cement in any form of structural work, foundations included is not permitted.
Clay Brickwork
Efflorescence
Salt formations on the surface of new brickwork is known as efflorescence. The substance is not harmful to the brick but does create an unsightly image for new brickwork. All bricks contain a small amount of soluble water; efflorescence is formed when the brick becomes saturated with water. As the brick dries out, the salt is transported to the surface of the brick where it manifests itself into crystalline salt deposits, giving the effect of white patches on the brickwork.
Mortar may also sometimes contain small amounts of sulfates too. It can contribute to efflorescence but only an insignificant amount. It usually occurs when the mortar is placed between two porous blocks/bricks that can allow some of the moisture to escape through absorption, drawing out the sulfates to form efflorescence on the surface.
Stages
Stage 1: Water dissolves soluble salt
Stage 2: Water evaporates and salt solution moves to surface
Stage 3: Salts are deposited as white crystals on surface
Efflorescence normally appears in spring in Ireland when the weather begins to improve and the new bricks are given the opportunity to dry out.
Avoidance
Efflorescence can be avoided mainly by trying to reduce the amount of moisture getting into the bricks in the first place, thus limiting the amount of drying that can occur. Some precautions can be undertaken to help this, these being:
Allow any damp bricks to dry before they are used.
Protect uncompleted brickwork against water/moisture by covering the external face with a damp proof material.
When cleaning the bricks, avoid saturation.
During storage ensure the bricks are located in a sheltered area and covered by a water resistant covering. Similarly, if a bale of bricks is opened but not fully used, ensure it has adequate protection from moisture.
By following the above precautions, there is a high possibility that the occurrence of efflorescence can be minimized.
Removal
Ideally efflorescence should be allowed to dissipate naturally from weather erosion. It can be removed by using a stiff brush to remove the heavy deposits and washed down afterwards to remove the final particles.
When washing down, it is important not to over-expose the brick to water that can be absorbed as this could lead to reoccurrence. Chemical methods should never be used to remove efflorescence as it can damage the bricks.
If efflorescence is constantly reoccurring, it is a clear indication that water is entering the brickwork. Examinations should be carried out to drain pipes and guttering to ensure that there are no leaks allowing water onto the brick face; it is also worthwhile looking at other protective measures that can be undertaken.
I.S. EN 771-1: 2011 + A1: 2015 Specification for masonry units - Clay masonry units outlines a test for determining amounts of efflorescence, and clarification can be sought from the manufacturer regarding the possibility of the amount of efflorescence as determined from that test.
This standard also defines the permissible amount of soluble salt content allowed and the manufacturer should be able to confirm that bricks supplied are in accordance with the limits set down.
Sulphate attack
Causes
Sulphate attacks are normally caused when a reaction occurs between the bricks themselves and certain chemicals in the mortar solution. Tricalcium found in ordinary portland cement reacts with the sulphates in the brick, the resulting reaction causes the brickwork to expand and in some extreme cases cause the disintegration of the mortar joints. Luckily, sulphate attack in Ireland is very rare.
As all portland cement contains between 8 and 13% tricalcium aluminate, consideration needs to be taken at the design stage regarding the combinations of bricks and mortars to be used in the building and measures that should be taken to reduce the risk of attack occurring.
The likelihood of sulphate attack occurring can be influenced by weather conditions. Brickwork that is exposed to constant wetting and drying over a period of years can be susceptible to sulphate attack.
Prevention
Some measures that can be taken include:
Using sulphate resistant portland cement to stop the chemical reaction from occurring.
Using bricks that are specific to the area, have a low soluble sodium content, and/or have low rates of absorption to minimize risk.
Specifying a richer mortar mix to be used (e.g. 1:^1^/4:3 or 1:^1^/~2~:47~2~ or (better still) 1:5-6 with plasticiser in place of lime).
Frost Attack
Typically in Ireland, brickwork is not affected by frost to a large extent; issues arise where walls are subjected to a large amount of rain and frost. The frost attack occurs when the brickwork is laden with wind-driven rain. This should be considered at the design stage and depending on the location and its exposure levels, a determination should be made as to what types of bricks and mortar are most appropriate. If an area presents the risk of high exposure, it may be necessary to use a specialized brick with low water absorption and high compressive strength properties.
Engineering bricks are the common solution to these requirements as they have known water absorption rate. Ordinary bricks can have varying levels of water absorption. These can be found in the individual manufacturer’s specification.
Choosing a special quality brick could impose limitations on the range of brick colours and textures and this effect should be considered in the choice of materials for all other parts of the building. Despite intensive research over many years, there is no accepted test for frost resistance. The only requirement that the brick manufacturer must satisfy is evidence that bricks of the type required have given satisfactory results for at least three years in the locality concerned, and in conditions at least as severe as those proposed.
When a suitable brick has been found as a further precaution it is advisable to examine as many buildings as possible, that use the specific brick chosen located in an area experiencing the same weather conditions. Frost attack is likely to affect a building within the first three years, so buildings older than this using the same type of brick are a good reference point.
In particular, if bricks that have not been used previously are proposed, or, if the area has a high incidence of freezing and driving rain, it's advisable to obtain confirmation from the manufacturer that the bricks are suitable for use in that location.
Glazing
There are specific areas where glazing, if provided should be safety glazing in accordance with BS 6262 – Part 4: 2018. Technical Guidance Document D, available on the Building Regulations app details the areas in which glazing is required to achieve the safety standard. These areas due to their location are at a higher risk of people falling against then and as such the glazing needs to be reflective of this to ensure no serious injuries are caused to occupants.
As an alternative to toughened/safety glazing it may be possible to provide guarding to these areas, Technical Guidance Document K provides guidance on appropriate means of guarding.
Diagram HD1 - Critical glazing locations in internal and external walls - Extract from TGD D
Letter Plates
Where letter plates are to be provided in doors they should comply with the recommendation of IS EN 13724: 2013. Technical Guidance Document D, which is available on the Building Regulations app provides guidance on the positioning of letter plates.
Diagram HD2 - Positioning of letter plate - Extract from TGD D
