insulation retrofits to address wall/ceiling moisture damage · brief background 2002 – hud onap...
TRANSCRIPT
Insulation retrofits to address wall/ceiling moisture damage
Jeffrey R. Gordon & William B. Rose Building Research Council School of Architecture University of Illinois at Urbana-Champaign
HUD Sponsored
Research funding provided by: US Department of Housing & Urban
Development Office of Healthy Homes and Lead
Hazard Control
Project Genesis
The seed of this project germinated in an Indian Casino diner near Michigan’s Upper Peninsula, where, over lunch, some guys drew up competing ideas on napkins aimed at solving a nasty moisture and mold problem,
Specifically . . .
Wall/Ceiling Juncture Moisture
Brief Background
� 2002 – HUD ONAP mold project � 2002 – 2003, site visits to a couple dozen
reservations � 11/2003 – Report to Congress on mold
problems in Native American Housing
� Counted and categorized moisture problems
Wall-Ceiling problem showed up all over the place
Lac Courte Orielles
Wisconsin
Wall-Ceiling Juncture
Saginaw/Chippewa Michigan
Spirit Lake North Dakota
Wall-Ceiling Juncture Cherokee
Oklahoma
Fort Belknap Montana
Wall-Ceiling Juncture Walker River
Nevada
Nisqually Washington
Wall-Ceiling Juncture White Earth,
Minnesota
Seneca New York
What is in common?
� Ranch houses from the 60’s and 70’s.� Low slope roofs constructed with light-frame
trusses, prior to raised heel trusses
What causes this problem? A conspiracy toward chilled surfaces
� Thermal bridge at double top plate
� Geometry � Questionable
insulation
� Wind washing � Interior air flows,
and zone of stagnation
1. Wind through soffit vents chill the corner
Mold Site.
Insulation
2. Inadequate insulation over the corner
3. Indoor currents of warm air do not enter into corners.
Project Aim
� Design and field test insulation treatments.� Determine if insulation retrofits could
improve the thermal conditions at the wall-ceiling juncture and reduce the likelihood of mold growth or discoloration.
� Go from the back of the napkin to reality
Research Partnership
Turtle Mountain Housing Authority -Belcourt, North Dakota
� A poster child for mold-related issues � Extensive applicable housing stock � High plains winter, 4 miles from Canadian
border � A strong, no-nonsense Director of the
housing authority (yea, but)
Shell Valley Housing
Bottom Truss Chord
Rafter Chord
Double 2 x 4 Top Plate
Stud Cavity
Interior Gypsum Board
1” Foam Exterior Sheathing
Soffit Trim Board
Wood Exterior Siding
Attic
Point A: Soffit Cut Point
Point B: Soffit Hinge Point
Fascia
Plywood Soffit
Note: 2 x 4 Top Plate Block
4
12 Roof Sheathing
Three Insulations approaches
� Two exterior approaches � Manufactured foam top plate “pillow” � Site applied insulation “pack”
� One Interior approach � Insulating interior “crown” molding
Foam Top Plate Pillow
� Functional installation critical
� Polypropylene foam insulation
Top Plate Insulating Pillow
5”
5”
Insulation “Pack”� Fiberglass batt
insulation and 1”foam board
1” Rigid Foam Insulation
Fiberglass Batt Insulation
Existing insulation pushed up against baffle New cellulose insulation Attic vent baffle New rigid foam, sealed with spray-applied foam.
Actual treatment
Interior Insulating Crown� Expanded
Polystyrene � Fire-rated finish
Installation
� Jerry and Todd � Opening the
soffit
Installation � Interior Crown
Research Design
� 2 approaches to examine thermal performance: � Group 1 Houses – 15 houses documented
with regular thermal imaging � Group 2 Houses – 3 houses hard-wired with
thermocouples � Thermal Modeling
Group 1 Houses
� Each of the 3 approaches applied to 5 houses – total of 15 houses
� All on North elevation � IR Snapshot � 120 x 120 thermoelectric
array � Accuracy 3% of scale � Adaptable software
Group 2 Houses
� 3 houses, each with all 3 retrofits
� 12 single-ended Type T thermocouples crown control pillow pack
crown control pillow pack
Living rm/kitchen
BdrmBdrm
Bdrm Bath
Other Measurements
� Weather station � Interior temperature and RH with HOBO
dataloggers � Cost study (not reported on here)
Results – The Metric
The basis of the temperature analysis used inthe project is “Percent temperature drop”(D).
D = ΔTi−s ΔTi−o
� Normalize the data � “How far toward the outside is the surface?” � Read as a percentage
Results – Critical Distinction
� Truss vs. Cavity � They are different building sections � They reveal different results
Group 1 Results: IR Data
Pillow Pack Crown House # Truss Cavity House # Truss Cavity House # Truss Cavity Bottom
3 Wired 43% 33% 3 Wired 40% 33% 3 Wired 31% 18% 19% 540 40% 33% 535 41% 33% 538 39% 22% 19% 545 41% 31% 536 41% 32% 552 32% 19% 24% 547 45% 37% 537 45% 28% 555 42% 24% 30% 548 47% 35% 550 44% 34% 556 40% 22% 25% 549 35% 28% 544 na na 558 46% 28% 31% All 41% 32% All 43% 32% All 38% 22% 25%
St Dev 9% 7% St Dev 8% 10% St Dev 9% 6% 8% N = 79 77 N = 64 62 N = 51 52 50
� 2 exterior methods performed the same
� Interior crown performed a littlebetter yet
Group 2 Results: Thermocouple Data
TABLE 2. Results of cabled temperature measurements house control-
cavity control -truss
crown-corner
crown-cavity-ceiling
crown-truss-ceiling
crown-wall-1
crown-wall-2
pillow-cavity
pillow-truss
pack-cavity
pack-truss
pack-corner
541 554 539
average used
15% 5% 5% -7% -2% -6% 10% 22% 14% 8% 18% 17% 20% 10% 19% 10% 14%1 19%1 13% 10%2 19%2 8%3
-8% 7% 8%
2% 14% 12%
13%
4
6% 20% 13% 16%4
-3% 16% 12% 14%4
2% 21% 14% 18%4
5% 19% 8%
13%
� D < ½ of IR findings, yet show same relative rankings
� Show this graphically in a moment
IR vs. Thermocouple
� Drift away from corner – it is inside � Thermal conductivity along 24 gauge wire � Size of thermocouple tip (vs. 1/8”2) � Possible radiant gain w/room surfaces � Did we find the coldest spot? Of course
not – we were guessing
Thermal Modeling
� Therm 5.1 � Conductivities from ASHRAE Chapter 25 � Design temperatures 0 oF to 73 oF � Interior air film � Listed 0.61 to 0.92 (hr ft2 degF)/Btu
� We chose 1.0 (hr ft2 degF)/Btu
Modeling results Control and Interior Crown
Modeling results Exterior treatments
At the CavityPercent temperature reduction at insulation conditions
0% 5%
10% 15% 20% 25%
30% 35% 40% 45% 50%
control-insulation pillow -insulation pack-insulation crow n-insulationceiling
Perc
ent t
empe
ratu
re re
duct
ion
avg. measured
model
IR ?
At the Cavity � All methods provide the same relative results,
but different magnitudes � Exterior methods reduce temperature drop by
one third, raising the temperature by 10 to 12 oF � Crown cut temperature drop in half, raising the
temperature about 16 oF � Exterior treatments should do even better
without the upright 2x4, which prevented insulation continuity
Percent temperature reduction at insulation conditions
0% 5%
10% 15% 20% 25%
30% 35% 40% 45% 50%
control-insulation pillow -insulation pack-insulation crow n-insulation-ceiling
Perc
ent t
empe
ratu
re re
duct
ion
avg. measured
model
IR ?
Why does the model underestimate the temperature drop?
� 2D not 3D � Convective effects – vented soffit � Radiant effects – exposed to cold roof sheathing � Zone of stagnation – just what is the resistance
value of the air film in this case?
At the TrussPercent temperature depression at truss conditions
0% 5%
10% 15% 20% 25% 30% 35% 40% 45% 50%
control-truss pillow -truss pack-truss crow n-trussceiling
Perc
ent t
empe
ratu
re d
epre
ssio
n
avg. measured
model
IR
?
At the truss
� Exterior treatments � Model says there is no improvement � Measured values and IR indicate 2% to 3%
improvement in D – only 1.5 to 2 oF � Interior Crown � Model predicts 5% improvement (47 raised to 50 oF) � IR results showed a 7% improvement (40 to 45 oF) � Measured values showed no improvement, but was a
small dataset
A Bridge too Far� We could not improve
the truss condition by more than a couple of degrees, even with the crown.
� Served to chill the bottom chord, and transfer the transition zone inward
Humidity AnalysisAverage Average Temp. D to Indoor Indoor Dew D to avoid at avoid
house room treatment Temp. RH point1 dewpoint2 80%srh3 T80% 4
middle 550 bedroom pack 70.1 38.8 43.1 47% 49.0 37%
living 549 room pillow 73.4 27.2 23.1 84% 28.0 76%
living 547 room pillow 71.8 39.3 46.6 43% 52.6 33% 545 kitchen pillow 75.0 37.2 45.0 49% 51.0 39% 540 kitchen pillow 71.6 35.1 39.9 54% 45.6 45% 538 kitchen pack 73.3 32.9 41.5 52% 47.3 43% 537 kitchen pack 71.5 29.3 32.0 68% 37.4 59% 541 bedroom all 3 71.4 29.6 35.3 62% 40.8 53% 554 bedroom all 3 72.6 49.4 54.4 31% 60.8 20%
The driving factor is relative humidity
Conclusions � The truss is the critical condition in solving the
wall/ceiling problem. � The thermal performance at the cavity were improved
with all the insulation treatments. � Thermal conditions at the truss showed only marginal
improvement, at best, with all insulation treatments. � Tested insulation strategies could only address
moisture damage in houses with borderline moistureproblems. Overall, the determining factor forwall/ceiling moisture problems is relative humidity.
� Addressing humidity control is the more beneficialapproach to the problem
Yes we can
� So these low-cost insulation “tweaks” don’t work, but is insulation completely off the table for this problem?
� Can we fix this problem with insulation?
Yes we can
Thanks, I’m Done