Technical Papers

Growth of Brick in Freezing Climates

In the maintenance of existing traditional brick buildings, one will occasionally encounter the presence of cracks whose formation does not conform to the application of service loads, thermal expansion, or other commonly understood behaviors of brick walls. Upon examination one can find these cracks in the face material do not extend through the wall. Such cracks are the result of volumetric expansion of backup brick. Such growth in backup brick can occur through a phenomenon known as freeze growth. This phenomenon is consistent with brick structures where exposure of elements can readily freeze especially in more exposed parts–parapets, belfries, unheated towers, and the like. Buildings that are finished with plaster readily transmit building heat to the exterior thereby limiting the chance of freezing in backup brick. Renovated buildings in which new insulation is applied to the interior face of walls will move the freezing point deeper into the wall thereby increasing chances of cracks developing in face brick because of backup freeze growth. This report summarizes the writer’s knowledge and experience of freeze growth.