Fernandez, Andy

Summary #9: Masonry Construction/ windows & Doors

IANO / FBC / Ching



Masonry buildings are designed with layers of protection from wind, water and temperature changes of the environment. Walls are built as composite walls (stone or brick veneer with a back up wythe of CMU) and could be either load-bearing or non-loadbearing. Cavity walls prevent water penetration and include multiple components to repel water. Flashing is used in cavities to flush penetrated water out of the wall system. Thru weep holes. Flashing are usually installed in junctures of window and door openings (punch-holes) on the wall. Once installed, they are embedded into the wall. Load-bearing walls can be built with or without reinforcement (Re-Bar). CMU walls can be reinforced by post-tensioning the vertical steel Re-Bars.


Thermal insulation can be added in form of rigid foam against CMU walls to control a thermal transfer of heat. Vapor barriers are applied to the CMU surface to keep water vapor and condensation from forming in the interior of the building. Furring strips (metal or wood studs) are used to attach gypsum boards (interior finish). Furring could be sized according to insulation material, electrical and plumbing specifications. Expansion joints are added to the masonry wall to allow for thermal expansion and contraction movement due to thermal changes. Masonry walls have good acoustic insulating properties.


Although masonry walls are very strong, the weakest areas consist of the mortar joints. Mortar is porous and can transfer water from the exterior to the interior of the building if not maintained. Mortars must be kept from freezing for at least 2-3 days after curing.


Above all, masonry is usually chosen based on its unique colors, textures, patterns, fire-resistance and its compliance to the building codes.


Windows/ Doors


Windows and doors are usually pre-fabricated and made with high precision standards and weather tightness in mind. There are many types of windows: fixed, single-hung, double-hung, sliding, hopper and casement among others. The following properties relate to windows and door alike: Window and door frames are made of wood, aluminum, steel or plastic. Wood frames offer good thermal insulation but are subject to decay. Aluminum frames are strong but are high thermal conductors (a thermal plastic or rubber break is needed) and used exclusively in residential and commercial applications. Plastic frames {PVC, vinyl ( 50% of all windows sold in U.S.)} are cheaper than wood but have high thermal expansion rates. Steel frames are very strong (allows for a slender frame) are less conductive of heat than aluminum but more than wood and plastic frames.

Most prefab frames are easy to install (usually with nails or bolts) and fit in place. Solar heat gain and wintertime heat loss contribute to 30% of all heating and electrical building loads in the U.S. Thermal conductivity of the window and door frames create a very high air leakage that require large amounts of heating/cooling of the building.