Insulation and Ventilation

name two purposes of house ventilation

1 - flushes moisture from unconditioned spaces from winder and heat from spaces in summer. 2 provides fresh air for people

list 4 common forms that insulation material may be found in

1 - loose fill, 2 - bats or blankets, 3 - rigid boards, 4 - foamed in place

indicate two reasons we are interested in controlling air movement through building walls and roofs

1 - minimize heat flow to exterior/interior. 2 - minimize moisture flow to building components

describe in one sentence each, 4 general approaches to insulating flat and cathedral roofs

1 - treat as an attic with a little insulation and air space. 2 - completely fill roof space (stops air flow), 3 - insulate above sheathing roof membrane applied over insulation, 4 - insulate below roof structure, lower ceiling heights but provides good insulation

the term " ventilation " might mean two very different things with respect to homes. explain the two different types of ventilation

1. venting of wall and roof spaces to flush warm moist air out of the building components. 2 - exhausting stale air and supplying fresh air to the living space

what is an appropriate ratio of vent area to roof area

1/150 ( 1 sq ft venting per every 150 sq ft roof space)

what percentage of the total venting should be at the soffits

50%

what percentage of the total venting should be high on the roof

50%

what is meant by drying potential

ability of a material or assembly to dry out after it has gotten wet

list 7 areas where floors over unheated spaces may feel cold

above garages, above porches, over cantilever areas, over breezeways, below windows projecting out from building, over unheated crawlspaces, over open areas below houses with pier foundation and no skirting

is it more important for an air barrier or vapor barrier to be continuous

air barrier

what are the implications of air/vapor barriers that are missing or incomplete

air leakage, rot, insulation gets wet from condensation

3 functions of roof vents

allow warm moist air out of attic, reduce attic temp in summer, help prevent ice dams in winter by keeping attic cold

list 3 safety issues involved in inspecting crawl spaces

animals, wet floors, dark/dirty GHOSTS

list 3 common problems with roof vents and their implications

birds nest = inadequate venting, mechanical damage = mold/rot from condensation, undersized opening = may not be enough venting for area of roof

the primary function of insulation is to:

control heat loss

list 3 things that can make attics dangerous

electric shock, fall through ceiling, irritate lung eyes and skin

what is suggested by mold or rot on rafters and sheathing

exhaust fan dumping warm moist air into attic

basement wall insulation is necessary? true or false

false

list 10 common insulation materials *hint* vermiculite and perlite only count as one. there are two types of polystyrene

fiberglass, celulose fiber, mineral wool, vermiculite/perlite, expanded polystyrene, extruded polystyrene, closed cell phenloic plastic, polyisocyanurate, polyurethane, isocyanate/polyisocyanate

describe two possible strategies for keeping floors over unheated spaces warm

heated cavity between floor and insulation below, spray in place foam that fills entire cavity

what is suggested by snow on attic insulation below roof vents

if soffit venting is missing rain and snow may be drawn into roof vents

when can soffit venting be ommitted safely

if there are gable vents at opposing ends

list 4 common access hatch problems and the implications of each

inaccessible, not insulated, not weather stripped, missing

describe in one sentence each, two general approaches to insulating crawl spaces

insulate walls creating a conditioned crawl space, insulate floor above creating an unconditioned crawl space

list 9 common problems with insulation and ventilation in basement and crawlspace areas

insulation too little or incomplete, exterior insulation not suitable for below grade use, exterior insulation not protected at top, insulation missing at rim joists, insulation sagging / loose/ voids, exposed combustible insulation, air/vapor barrier missing/incomplete or wrong location, no moisture barrier on basement walls, no moisture barrier for earth floor

what two things should you be looking for on ducts in attics

insulation, air/vapor barrier

what should you wear when inspecting attics - list 3 things

mask, goggles, long sleeves with tight cuffs

what are the implications of an inadequate air/vapor barrier

moisture may get into building causing damage

list 3 possible concerns with turbine vents

no ventilation on calm days, too much ventilation on windy days, noisy or seized

should power vents be operating in the winter, why or why not

no, they can depressurize the attics increasing heat loss

under what circumstances should insulation cover recessed lights? what is one inspection strategy to help identify recessed lights while in the attic?

only if light is marked as such or in drywall box, look for double shell or IC stamp

on a flat roof where will you most often see the vents

opposing fascias

indicate where the air/vapor barrier should be located in the wall assembly in a hot humid climate

outer part of wall or not at all

describe in two sentences each, two strategies for insulation basement walls

outside - keeps walls warm and no interior space loss. inside - inexpensive and can be done anytime. any insulation is suitable - could be difficult to detect leaks

what do soffit vent baffles do

prevent insulation from covering vents

describe the function of a vapor barrier

protect building from moisture damage. designed to protect from moisture due to vapor diffusion not air movement

describe one possible way to get a look at insulation in a flat roof

remove ceiling light fixture or exhaust fan covers with power off, pop fascia vents off and look in holes

how are mansard or gamble roofs ideally vented

required at the ridge and bottom of upper section. none is required for steep section

a vapor retarder is designed to:

restrict vapor difusion

how should insulation be handled around masonry chimneys

should have non combustible insulation surrounding them

list 4 types of roof vents

soffit, ridge, roof, gable

what things might suggest wet insulation

staining, sponginess, dampness on ceilings

define relative humidity

the amount of moisture in the air relative to the amount it could hold if saturated expressed as a percent

what is the function of an air barrier

to stop air movement through building walls and roof

list 5 common problems found with flat roof insulation systems

too little, wet compressed or void, missing or incomplete air/vapor barrier, missing or inadequate venting, venting obstructed

what is the purpose of a heat recovery ventilator

transfer heat from air exhausted from the house into the fresh air coming into the house

all crawlspaces should be vented, true or false? explain

true - if unheated vent to outdoors to remove warm moist air in cold climates

what are the implications of insulation that is only two inches thick, wet, compressed, interrupted by gaps or voids and missing

two inches thick = heat loss, wet = won't work well, damage to finishes, compressed = reduced R value, gaps/voids = localized heat loss/ice damaging, missing = heat loss/ice damaging

list two other names for vapor barriers

vapor retarder/defusion retarder

how should insulation be handled around metal vents

vent is contained in boxed in area to keep insulation away

describe two strategies used to deal with venting of flat roofs

vent roof space, seal roof cavity

should the vapor barrier be on the warm side or cold side of wall assembly

warm side

should the vapor barrier be on the warm side or cold side of wall assembly in a hot humid climate

warm side

why are roofs vented in the winter in cold climates

we were not able to completely stop air leakage into cool roof spaces, so we need to get rid of the warm moist air

is it possible to over ventilate an attic? if so why is it an issue

yes, ceiling is not well sealed can cause negative pressure in attic that promotes warm moist air to enter at a faster rate

will you ever see walls in attics? where? should these be insulated?

yes, skylights or light wells, yes insulated