lecture 14 Flashcards
waterlogged
what is ground water?
the water held underground in soil or permeable rock
hydrostateic pressure
this is the pressure at a point in a fluid at rest due to the weight of the fluid above
what is the first rule of dealing with ground water?
do not let the water enter the ground at the building
SLOPE the site away from the building
- make sure the downspouts are directed away from the building
what makes the groundwater become hystrostatic pressure?
gravity
not horizontal movement
what is the best ways to treat a building below grade to prevent groundwater intrusion? (2)
dampproofin
water proofing
what is dampproofing
a way of treating the foundation of a building to prevent moisture intrusion from the surrounding soil
what is bituminous
a coating spray or painted on the surface as a protective coat
underground mansonry walls need to be
parged
parging is
a thin rough coat of Portland cement plaster applied to masonry walls
waterproofing has what characteristics
self adhering membrane
flexible
liquid-applied product
continuous
the applicaiton to prevent groundwater intrusion must be protected during
the backfill process
how do we protect during the backfill process
we can use a board product
or
drainage mat
or
rigid insulation
how do we deal with draining excess groundwater away from the building as it moves toward the footing?
drainage mats- they carry water down to the footing from above
then at the footing we install a drainpipe that runs around the building- it is perforated to allow water to enter
drain pipes are what
- footing drians- drain tile
it is set in a bed of crushed stone/gravel to allow for easy water flow
what is wrapped around the gravel area to preven soil intrusiton
filter fabric
the drainage pipe is sloped to allow for
the water to run into the storm draing
what materials can the drain pipe be
concrete, pvc, cast iron, or clay
what is water vapor
the gaseous form of water found in some quantitiy in virtually all air on the planet
saturated air-
air that contians the max amount of water vapor it can hold
this ammount increased as the temp of the air increase
relative humdity
the measure of the amount of water vapor in the air as a factor of how much total water vapor that air can hold
dew point-
the temp of the air at which the water vapor satruation of the air has become 100%
as the air cools the max water vapor contents
drop
as the air reached the dew point
the air becomes fully saturated
condensation-
water that had returned to a liquid state after being forced out the fully saturated air
if the dew point occurs inside your wall you can run into some major issure : (4)
decay
mold
destruction
mayhem
water vapor wants to achieve
equilibrium
in gerneral what direction does water vapor more?
always moves from the warm side of an assmebly to the cold side of an assmebly
water vapor moves through
creacks and holes
also through the assembly
air retarder-
= building wrap=
a membran that is wrapped over the exterior wall of a building prior to installing the exterior wall clading to slow air diffusion
what does the air retarted allow?
water vapor to freely pass thorugh
what does the air retarder prevent?
the air and water from moving throught
must be sealed at joints
vapor retarder-
a material of low permanence installed in a constructin to preent moisrute from entering and reaching a point where it can condense into a liquid
the vapor retarders are normally placed
on the warm side of the construction in temperate of cold climates
in hot humid places they may have to move the retarder to the outside of the construction
what are the 3 primary wats that rain water can enter the building:
gravity
surface tension
- capillary action
wind
you must seal what to ensure water does not get within your buildin
JOINTS
- sealants degrade over time and need to be replaced
all horizontal planes are
sloped
what is a typical roof or other large surface area for slope?
1/4” : 1’
the drip edge, groove, or slot does what on the roof
overhangs
how does surface tension force water into the bulding?
surface tension allows a thin film of water to travel horizontally along a soffit edge or the like
creates capillary forces
how do you prevent surface tension from forcing water within the building?
include a capillary break at joints
seal any porous materials
how does wind force water into a building?
wind forces impart kinetic energy
to prevent this provide overlap between members meeting at joints
us L or Z flashing
what is a impervious wall?
EIFS - needs ongoing maintenance
what is a mass wall?
a wall that sheds most rain at the exteiror face and absorbs the rest which is released as vapor as the wall dries out
moisture can occasionally get all the way thrrough
what is a drainage wall?
a wall that utilizes a drainage plane or moisture barrier between the exterior classing and supporting wall for additional moisture resistance
rainscreen is what?
a wall consisting of an outer layer of cladding, an air cavity, and a drainage palne with a rigid, water resistance, and airtight support system
a good example of a simple rainscreen is
a veneer brick wall
lapped siding
the air cavity is used for
water drainage but also air circulation
