The elements of brick masonry include: BRICKS & MORTAR
Masonry is a key element in defining the character for historic buildings. The texture and patters of brickwork. Much more advance planning is required for successful masonry repairs to historic structures than is normally necessary for the maintenance of contemporary masonry buildings.
The key to successful maintenance of historic masonry is understanding the materials and methods of original construction and carefully evaluating the cause of deterioration.
Masonry problems occur in area that are heavily exposed to moisture or significant temperature fluctuation. Some common places are:
- Masonry Cleaning- This is the first step for improvement and usually the least important requirement for proper maintenance. Cleaning may be a necessary part of a larger repair project that involves re-pointing or replacement of a damaged section of a wall. Please note, harsh cleaning may also damage the historic masonry. Specifications for cleaning historic masonry often calls for the use of nonionic detergents that avoid using harmful chemicals into masonry. One key suggestion is to test a small area prior to taking on the full job.
- Repointing or Tuck-pointing– is the raking and refilling of the outer face of the mortar joints. Properly done, and undertaken when needed, can prevent moisture infiltration.
- Caulk and Sealants- Frequently caulking and sealants are inappropriately used for sealing joints when mortar should be used. Sealants are appropriate to use where masonry abuts wood or metal such as around window frames.
- Repair and Replacement of Deteriorated Stone and Brick– It may be necessary to replace or repair seriously damaged individual bricks to ensure that the wall remains . It is important to be considerate to the size and type of brick when replacing the existing damaged one.
Mortar and Erosion and Mortar Deterioration
What is mortar?
Most basically, it joins the irregular surfaces of the masonry units and to keep water out of the masonry. Masonry mortars can be lime-based or Portland cement-based and, to confuse matters, some mortars may be combinations of the two.If you are hiring a mason to do repair work, ask him questions about the mix he is going to use and, more importantly, ask him why. Have him point a small area (perhaps a couple square feet) so you can evaluate the color match. With the information you have collected about your house, you should be in a good position to discuss the most appropriate formulation. Don’t be afraid to insist on a softer mortar.
Some types of Mortar:
(note your contractor or architect can advise you specifically on this)
- Type N is of medium strength, which means it is the best choice for projects with bricks that are not load bearing. Garden walls, chimneys, and barbecues are common applications for this mix. Type N is also preferred for soft stone masonry. This is the mortar most often used by home owners. It is easy to work with and is appropriate for most brick projects that the typical home owner would attempt.
- Type S is known for its strength and is used outdoors. Patios, foundations, and retaining walls all use Type S. It is used for its ability to absorb most impacts. It is still an easy product to work with, but homeowners should have some experience working with brick before beginning any type of project that requires this product.
- Type M is the strongest mix that you will find in a home improvement store, Type M is typically used only with stone. Type M is preferred with stone because the strength of the mortar typically mimics that of the stone being used. It is also used in situations where being able to bear heavy loads are important, such as retaining walls.
Key words to know when looking compromised brick
Is similar recyrstallization of soluble salts beneath the surface of masonry. It often occurs in conjunction with efflorescence and may seriously damage the masonry units by causing the surface to spall or flake away. Here is an excellent diagram from Building Science Information’s website:
One key component to consider is that repointing or aqueous cleaning should be done when there is no danger of freezing. It is prudent to restrict work to seasons when the night temperature will not fall below 40 degrees. Freezing of wet mortar damages it and dramatically reduces its durability while wet pours stone and brick are susceptible to damage from frost spalling.