Control of rain is fundamental, and there are numerous strategies to this end—specifically, barriers, drain screens, and water storage systems.
Flat And Pitched Roofs
The primary purpose of a roof is to resist water. Two popular roof styles are flat and pitched. Flat roofs slope up to 15° and built to withstand standing water. On the other hand, pitched roofs shed water. However, they do not resist standing water—which can occur during wind-driven rain or water accumulation and ice damming in gutters. Typically, residential pitched roofs have an underlayment material beneath the roof covering as the second line of defense against the elements. Residential roof construction is also vented to remove moisture.
Walls And Exterior Siding
Walls are not as prone to leaks as roofs but can still leak water if they are not designed or constructed properly. In the Pacific Northwest, larger eves and drip edges prevent water from directly hitting or dripping on to exterior wall siding. Unfortunately, we see many multi-story new homes, without drip edges and eves that extend far enough out from the walls to protect the home’s siding. In our opinion, this is a construction defect due to poor design, where performance gave way to an aesthetically pleasing exterior.
Types of wall systems regarding water penetration are the barrier, drainage, and surface-sealed walls. a Barrier wall allows water to absorb but not penetrate. A drainage wall allows water that leaks into the wall to drain out. Ventilation used to aid drying by using a rainscreen or pressure equalization wall system. Sealed-surface walls do not allow any water to penetrate the siding materials. Most materials won’t remain sealed over the long-term, and this system is minimal. Conventional residential construction treats walls as sealed-surface systems relying on the siding and an underlayment layer. We prefer Dupont Tyvek Products.
Control of airflow is essential to ensure indoor air quality, control energy consumption, avoid condensation (and ensure durability), and provide comfort. Control of air movement includes flowing through the air barrier system or through components of the building envelope itself and into and out of the interior space (which can affect building insulation performance significantly). These are air movements within a wall or ceiling that may result in up to 20% heat loss.
The physical components of your home’s exterior envelope include the foundation, roof, walls, doors, and windows. The dimensions, performance, compatibility of materials, and installation process are the main factors that determine the effectiveness and durability of your home’s enclosure system.