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