5) Insulation and Ventilation

should power vents be operating in winter? Why or why not?

No, they can depressurize the attic increasing heat loss.

how should insulation be handled around masonry chimneys?

masonry chimneys should only have noncombustible insulation around them.

what are the implications of an inadequate air/vapor barrier?

moisture may get into the building structure causing damage.

list three common problems with roof vents and their implications.

problems: 1. bird's nest 2. mechanical damage 3. under-sized openings implications: 1. inadequate venting 2. mold / rot from condensation

A vapor retarder is designed to _________.

restrict vapor diffusion

what things might suggest wet insulation?

staining, sponginess or dampness on ceilings

indicate where the air/vapor barrier should be located in the wall assembly in hot humid climates.

the outer part of the wall, or not at all.

True or false. All crawl spaces should be vented. Explain.

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

how should insulation be handled around metal vents?

vent is contained in a boxed-in area to keep insulation away.

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

warm side

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

warm side

what is an appropriate ratio of vent area to roof area?

1 SF of venting for every 150 SF of roof

what are the implications of insulation that is only 2 in thick, wet, compressed, interrupted by gaps or voids, or missing?

1. 2in thick: result is heat loss. 2. wet: won't work well, damage to finishes. 3. gaps and voids: Localized heat loss, ice damming. 4. compressed: Reduces r value 5. missing: Heat loss, ice damming

will you ever see walls in attics? Where? Should these be insulated?

1. Walls indicate skylights or light wells. 2. They should be insulated.

list seven areas were floors over unheated spaces may feel cool.

1. above garages 2 above porches 3. in cantilever areas 4. over breezeways 5. hello Windows projecting out from the building 6. over unheated crawl spaces 7. over open areas below houses with pier foundations and no skirting

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

1. air leakage 2. rot damage 3 insulation gets wet from condensation

list three functions of roof vents.

1. allow warm, moist air out of the attic. 2. reduce attic temperatures in summer. 3. help prevent ice dams in winter by keeping attic cold.

list at least three things that may make attics dangerous.

1. fall through the ceiling 2. electric shock 3. irritate lungs, eyes, skin

list 10 Common insulation materials (hint: vermiculite and perlite only counts as one. There are two types of polystyrene)

1. fiberglass (comes in loose, fill, batt, board) 2. cellulose fiber (comes in loose fill) 3. mineral wool (comes in loose fill, batt, board) 4. vermiculite /perlite (comes in loose fill) 5. expanding polystyrene (EPS) (comes in board) 6. extruded polystyrene (comes in board) 7. closed-cell phenolic plastic (comes in board) 8. polyisocyanurate (comes in board) 9. polyurethane (foamed-in-place) 10. isocyanate/polyisocyanate (foamed-in-place)

name two purposes of house ventilation.

1. flushes moisture from unconditioned spaces in Winter and heat from these spaces in summer. 2. provides fresh air for building occupants.

describe two possible strategies for keeping floors over unheated spaces warm.

1. heated cavity between floor and insulation below. 2. spray in place phones that fill entire cavity

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

1. insulate walls, creating a conditioned crawl space. 2. insulate floor above, creating an unconditioned crawl space.

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

1. insulation 2. vapor barrier

list 9 common problems with insulation and ventilation in basement and crawl space areas.

1. insulation --- too little or incomplete 2. exterior insulation not suitable for below-grade use 3. exterior insulation not protected at top 4. insulation missing at Rim joists 5. insulation sagging, loose or voids 6. exposed combustible insulation 7. air/vapor barrier missing, incomplete or wrong location 8. no moisture barrier on basement walls 9. no moisture barrier on Earth floor

list four common forms that insulation materials may be found in.

1. loose fill 2. batts or blankets 3. rigid boards 4. formed in place

what should you wear when inspecting attics? List three things.

1. mask 2. goggles 3. long sleeves with tight cuffs

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

list three possible concerns with turbine vents.

1. no ventilation on calm days 2. too much ventilation on Windy days 3. noisy or seized

list four common access hatch problems and implications of each.

1. not insulated. Results in heat loss 2. not weather stripped. Results in heat loss and air leakage 3. missing. Results in heat loss and air leakage 4. inaccessible. Limits inspection

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

1. only if lights are proper type, or installed in drywall boxes. 2 look for double shell, or "IC" stamp

describe in two sentences each, two strategies for insulating basement walls.

1. outside --- keeps walls warm, no interior space lost, no interior living space lost, Etc., but only certain types of insulation are sustainable. 2. inside --- inexpensive, can be done at any time, any type of insulation is suitable, etc., but can be difficult to detect leaks

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

1. remove ceiling light fixture or exhaust fan covers (with power off); or 2. pop fasica vents off and look through holes

how are mansard or gambrel roofs ideally vented?

1. required at the Ridge and bottom of upper section. 2. none is required for Steep section.

list four types of roof vents.

1. soffit vents 2. ridge vents 3. roof vents 4. gable vents

list five common problems found with flat roof insulation systems.

1. too little insulation (results: heat loss, no damage to structure) 2. wet, compressed or voids (results: reduced R values, mold/mildew/rot) 3. missing or incomplete air/vapor barrier (results: mold/mildew/rot) 4. missing or inadequate venting (results: warm, moist air condensing and causing mold, mildew and rot) 5. venting obstructed (results: mold/mildew/rot)

describe in one sentence, four General approaches to insulating flat and Cathedral roofs.

1. treat as an attic --- with a little insulation and an air space 2. completely fill roof space --- in theory it stops air flow 3. insulate above sheathing --- roof membrane applied over insulation 4. insulate below roof structure --- lowers ceiling height, but provides good ventilation

describe two strategies used to deal with venting of flat roofs.

1. vent the roof space 2. seal the roof cavity

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

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

list three safety issues involved in inspecting crawl spaces.

1. wet floors 2. animals 3. dark and dirty

is it possible to over ventilate an attic? If so, why is this an issue?

1. yes, if the ceiling is not well sealed. 2. can cause negative pressure in attic that promotes warm, moist air to enter at a faster rate.

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 suggested by mold or rot on rafters and sheathing?

An exhaust fan dumping warm, moist air into the attic.

what is suggested by snow on attic insulation below roof vents?

If soffit venting is missing, rain and snow may actually be drawn into the roof vents.

when can soffit venting be omitted safely?

If there are gable vents at opposing ends.

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

Opposing fascias

what do soffit vent baffles do?

Prevent insulation from covering the vents.

what is meant by drying potential?

The ability of the material or assembly to dry out after it has gotten wet.

Define relative humidity.

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

describe the functions of a vapor barrier.

To protect the building from moisture damage. Designed to protect from moisture due to Vapor diffusion, not air movement.

what is the function of an air barrier?

To stop air movement through building walls and roof

what is the purpose of a heat recovery ventilator?

To transfer some of the heat from the air exhausted from the house into fresh air coming into the house.

list two other names for vapor barriers.

Vapor Retarder Vapor Diffusion Retarder (VDR

why are roofs vented in the winter in cold climates?

We are not able to completely stop air leakage into cool roof spaces, so we need to get rid of that warm, moist air.

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

air barrier

the primary function of insulation is to _____.

control heat loss

true or false? Basement wall insulation is necessary.

false