Frequently Asked Questions - Contractor

The number of brick required is based on the actual size of the brick. The larger the brick the fewer number of brick required. Add up the total surface area of the wall. Subtract out windows and doors and throw in a value for waste. Most installers assume that an additional 5% should be added to cover waste. The web calculator will provide th is information. The calculator can break up the wall area into rectangular sections. A maximum of 8 sections are allowed. If you have more sections that 8, try running the calculator multiple times as required and add the quantities by hand. Refer to wall calculator on the web.

Generally, water repellents are only an interim solution to any water penetrating a brick wall since they loose their ability to repel water after 1 to 10 years. However, in cases where all other options have been exhausted, it may be considered as long as one is aware of the inherent nature of water repellents.

There are basically two t ypes of water repellents: films and penetrants. Films such as acrylics, stearates, mineral gum waxes, urethanes and silicone resins form a thin membrane over the brick. Penetrants such as silanes, siloxanes and blends actually penetrate the brick surface. Films are good at repelling water but poor at permitting water vapor transmission which allow the wall to breathe. Penetrants, on the other hand, are good at both. They will usually have a matte finish while films may produce a higher sheen. Penetrants are more acceptable since they allow any water present in the brick to exit the wall. However, penetrants will not provide graffiti-resistance to a wall while some films will. 

Application of a water repellent does not negate proper brick construction and detailing procedures. Any deficiencies in a brick wall such as inadequate flashing, weep holes, mortar joints or broken brick should be corrected prior to the application of a water repellent. The wall should also be cleaned and allowed to th oroughly dry before administering a water repellent.

For additional information on water repellents, see Technical Notes 6A.

As always, the wall should be thoroughly saturated with water before and after any cleaning application. Also, a small inconspicuous area of wall should be tested to confirm that any solutions used will not harm the brick.

Freshly applied paint can be removed with a solution of trisodium phosphate mixed with water at a rate of 2 lb. per gallon of wat er. Apply the solution to the brick; allow it to soften paint; and remove with scraper and stiff bristle brush. Proprietary chemical compounds are also available through local distributors to remove fresh paint.

Existing paint which has been in place for some time is more difficult to remove and may require using abrasive techniques with non-steel scrapers or sandblasting by a professional. Certain brick should not be sandblasted. Proprietary chemical compounds from local distributors in the form of a gel solvent may be necessary to soften existing paint. Numerous applications may be necessary depending on the number of paint layers.

For additional information on removing paint from brickwork, see Technical Notes 20.

Repointing or tuck-pointing existing brickwork may be in order when mortar joints have softened, deteriorated or exhibited pronounced cracking. Generally, repointing involves carefully removing existing damaged mortar while not disturbing or cutting the existing brick. The joint is then repacked with mortar in layers. It is important to rem ember that the mortar should always have slightly less strength than the brick. Usually, the best mortar for use in repointing is what was in the wall to begin with. For most walls less than 70 years old, generally Type N or O mortar should be used when repointing. For structures older than this, it is best to try and determine what the original mortar consisted of and match that.

For more information concerning repointing, see Technical Notes 7F.

The temperatures of the air and the materials - thin brick, adhesive, and the surface to which the thin brick will be applied - must be between 45 degrees F and 90 degrees Fahrenheit. This temperature range must be maintained for 48 hours after the application has been completed.

A flexible base consists of compacted crushed stone, gravel or coarse sand. Only mortarless brick paving is suitable for this type of base. A semi-rigid base consists of asphalt concrete, commonly referred to as asphalt. Once again, only mortarless brick paving is suitable over this type of base. A rigid base is defined as a reinforced or unreinforced concrete slab on grade. Mortarless or mortared brick paving may be placed over this type of base.

Flexible bases include crushed stone, gravel or coarse sand. Applications for flexible bases range from residential patios to city streets. Flexible paving systems are typically the most economical to install since less labor and fewer materials are involved. A flexible paving system allows easier repairs to utilities located beneath the pavement. Flexible pavements also allow for water to percolate down through the system instead of running off on the surface. The thickness of each layer in a flexible pavement depends upon the imposed loads and the properties of each layer. A pavement subjected to heavy vehicular traffic requires a thicker base than a pavement subjected to pedestrian traffic. 

Mortared brick paving can be used for any type of pedestrian or vehicular traffic in both interior and exterior applications. This type of assembly is especially well-suited for heavy vehicular areas such as streets or parking lots and where surface drainage is necessary. 

The standard brick size is a 4 x 8 paving brick. We call this a True paver because the actual dimension is 4in.x 8in. It takes 4.5 brick to cover one square foot of area. Take the total area of desired patio space and multiply it by 4.5 to get the total number of brick needed. Most installers assume that an additional 5% should be added to cover waste. The web calculator will provide this information. The calculator can break up the paving area into rectangular sections. A maximum of 8 sections are allowed. If you have more sections that 8, try running the calculator multiple times as required and add the quantities by hand. Refer to patio calculator on the web. 

Please refer to our online technical documentation. Refer also to FAQ's 29, 30 and 31.

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Note:

  • 29 = How can I match existing brick? [NID-957]
  • 30 = What type of base should I use for brick paving? [NID-950]
  • 31 = Can brick pavers be installed over an existing concrete or asphalt driveway, patio or walk?  [NID-959]

Brick paving can be installed over existing concrete or asphalt as long as it is in reasonably good shape. To ensure an adequate foundation for the brick, the existing concrete slab or asphalt should be inspected and repaired as necessary. Any cracks, chips, holes, ruts or spalls should be repaired in order to achieve a flat surface. The brick can be installed either with or without mortar. If no mortar is used, a half-inch setting bed of coarse sand should be laid and compacted. An edging of metal or heavy-duty plastic should be placed around the perimeter of the brickwork and set to just below the height of the finished brick surface. Pavers can then be placed in the desired pattern on top of the sand. The bricks should be placed as close to each other as possible. It may be necessary to cut some of the brick near the edging. Once the brick are all in place, install mason's sand between the brick and over the surface. Sweep away excess surface sand and the brick pavement is ready for traffic. If mortar is used, the concrete slab should be prepared in the same manner as above. A half-inch mortar setting bed should then be applied upon which the bricks are set with mortar placed between the pavers. Only a small area should receive the setting bed at a time in order to ensure that it does not set prior to laying the brick. Mortared brickwork should not be laid on asphalt. For additional information on installing pavers, see Technical Notes 14 and 14A. An online course, "Paving Training Program: Clay Pavers" is also available.

A new brick pavement can be constructed on asphalt, concrete, or compacted gravel as a base. For asphalt and concrete bases, the base material should be installed according to standard construction procedure and then the brick can be constructed on top. (See previous question.) For a compacted aggregate base, the earth below should be well compacted. All brick pavements should have the earth graded to a minimum slope of a quarter-inch per foot for drainage. Then four-inches of crushed stone, followed by a layer of geotextile material, if desired, and one inch sand setting bed of coarse concrete sand is laid. An edging of heavy plastic or metal should be installed at the perimeter of the brick. The brick should then be laid on top of the sand and cut as needed at the edging. Mason's sand should then be spread on the top and in between the brick and consolidated with a plate compactor if necessary. Mason's sand should be added until all the joints are filled and any excess sand should be removed. For pavements such as driveways, a six to eight-inch gravel base should be installed and compacted with a plate compactor. Then a geotextile material should be installed and a one-inch setting bed of coarse sand laid. Placing edging, brick and mason's sand between the joints should then proceed as outlined above. Heavier duty pavements can be laid in the same manner, but the base is thicker. Adequate preparation of the earth before installation and compaction of the entire assembly after installation with a plate compactor are essential to a well-constructed brick pavement. For additional information on installing brick pavements, see Technical Notes 14 and 14A. An online course, "Paving Training Program: Clay Pavers" is also available.