2014-03 ueno nesea embedded joists-masonry for pdf · 3/4/2014 · nesea be14-masonry joist end...

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Embedded Wood Joists in Interior-Insulated Masonry WallsNESEA BuildingEnergy 2014March 4, 2014

Kohta Ueno

NESEA BE14-Masonry Joist End Moisture Monitoring2


AIA Best Practice SlideCredit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation



Learning Objectives Understand the moisture risks associated with

embedded wood members in masonry walls retrofitted with interior insulation

Understand the importance of controlling bulk rainwater in joist end durability

Explain some of the possible measures that can be taken to reduce risks in these cases, as well as their pros and cons



Embedded Wood Members After interior insulation,

wall and joist end will be colder

Less energy flow, higher RHs, wetter conditions

Wood can mold/rot How big is the risk?

NESEA BuildingEnergy14 Embedded Wood Joists in Interior-Insulated Masonry Walls March 4, 2014

Ueno © buildingscience.com 1 of 8



Terminology-“Beams” and “Joists”



2005 Monitoring Research (Canada)• In SK, joists stayed dry

(10-15% MC)• In ON, sometimes up

to 20% MC– Capillarity from

foundation?– Rainwater absorption

through face of masonry?



2009-2012 Previous Work Interior-sourced moisture risk (condensation) Historic methods of beam end preservation Charring, ventilation

“Gapped” insulation at beams (uninsulated) Wind-driven rain a huge factor in wetting vs.

drying patterns Other literature: Typically found few problems in the field Cracked facades → problems Adding heating to beam ends? Expensive



Ueno (2012) Simulations

Uninsulated Insulated





Ueno (2012) Simulations Also looked at joists vs. beams Added heat flow using passive “spreader” plates

1D hygrothermal simulations (WUFI) with boundary conditions from 3D HEAT runs

Inconclusive results Monitoring!



Embedded Joist Monitoring HfH Lawrence renovation Ongoing interior retrofit Joist moisture content: 3 measurements/joist 10 joists

Variables Orientation/exposure Wall type Insulated/non-insulated Air sealed



Interior Insulation Details

3x 2” (6” total) layers extruded polystyrene, adhered to masonry walls

Joist pockets insulated with XPS blocks, air sealed with spray foam kits



Joist Monitoring Package

“Upper”

“Lower”

“Cheek”





Joist Monitoring Locations (Basement)



Insulation Option Comparison (North)

Same orientation, 3 different insulation techniques Fiberglass = insulated but no air leakage control

BSMT‐N3Uninsulated

BSMT‐N2Fiberglass

BSMT‐N1XPS/spray

f



Joist Monitoring Locations (First)



‐13

5

23

41

59

77

95

‐25

‐15

‐5

5

15

25

35

12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27

Tempe

rature (F)

Tempe

rature (C

)

T Ambient T KLWM AirportT Hallway T Hallway‐EstimatedT Logger

Exterior/Interior Boundary Conditions

Some parts heated (“Hallway”), others unheated (“Logger”) → not very representative; being built

Construction heating added January 2013 Interior dewpoints ~identical to exterior dewpoints Many joists still uninsulated/unsealed





“Lower” vs. “Upper” & “Cheek” MCs RH tracking to moisture contents All pretty high MCs, especially “lower” “Mothballed” condition of building Rise in RH moving into summer, not winter

0

10

20

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70

80

90

100

0

5

10

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40

45

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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐N1‐Joist LowerBSMT‐N1‐Joist UpperBSMT‐N1‐CheekBSMT‐N1‐RHBSMT‐N1 (foam insulated, air seal, no heat)

North-Facing Basement Joists



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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐N2‐Joist UpperBSMT‐N2‐Joist LowerBSMT‐N2‐CheekBSMT‐N2‐RH

0

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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐N3‐Joist LowerBSMT‐N3‐Joist UpperBSMT‐N3‐CheekBSMT‐N3‐RH

North-Facing Basement Joists

BSMT‐N2 (fiberglass, no air seal, no heat)

BSMT‐N3 (no insulation, no air seal, no heat)

Not a big differences between 3 cases Maybe XPS wetter; unclear Heat added



Results: Joist Pocket Temperatures

Minimal interior heating in winter 2014 Small temperature differences N2 coldest (fiberglass) N3 (uninsulated) and N1 (XPS) almost identical

‐4

5

14

23

32

41

50

59

68

‐20

‐15

‐10

‐5

0

5

10

15

20

11/1 11/21 12/11 12/31 1/20 2/9

Tempe

rature (F)

Tempe

rature (C

)

T Ambient

T‐KWLM Airport

BSMT‐N1 Pocket

BSMT‐N2 Pocket

BSMT‐N3 Pocket



Left/right pairing (not upper/lower) Much drier MCs than north-facing (warmer) Lower RHs in joist pocket Sealed/insulated in spring 2013

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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐S‐JoistLeftBSMT‐S‐JoistRightBSMT‐S‐CheekBSMT‐S‐RH

South-Facing Basement Joists

Joist pocket air sealed & insulated

BSMT‐S (no insulation, air seal, no heat)





First Floor Joists All unheated, uninsulated, unsealed All in hollow clay tile walls

FIRST-N: 20-30% MCs, 100% RH pocket FIRST-E: 10-15% MCs 60-90% RH pocket

(seasonal cycle) FIRST-S: 9-12% MCs—very safe

Huge effect of orientation/exposure Basement East vs. First East



Adding heat drops MCs/RH Highest MCs/RHs in summer—inward T gradient

0

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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve

Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐W1‐Joist LowerBSMT‐W1‐Joist UpperBSMT‐W1‐CheekBSMT‐W1‐RH

Heated Basement Joists

Heat added BSMT-W1 (insulated, air sealed, heat)


Heat added



0

10

20

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90

100

0

5

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12/12 1/31 3/22 5/11 6/30 8/19 10/8 11/27 1/16 3/7

Relatitve Hum

idity

(%) in Po

cket

Moisture Co

nten

t (%)

BSMT‐W2‐Joist LowerBSMT‐W2‐Joist UpperBSMT‐W2‐CheekBSMT‐W2‐RH

BSMT W1 vs. W2—wetted by gutter? No noticeable difference

Heated Basement Joists

Heat added BSMT-W2 (insulated, air sealed, heat)


Heat added



Monitoring Conclusions All high MCs—20% recommended. But do they

operate this way already? Mothballed conditions—started at high MCs? Higher MCs/RHs in summer—inward drive? “Normal” in-service response not clear yet Orientation very large effect South-facing joists in the safe range North-facing joists among the wettest

Continued monitoring (2014 construction completion target, 10 units)





Takeaway Information/Recommendations Keep bulk water (rainwater) away from joist ends Pointing, reglets, sheltering details

Keep capillary water away (see BSI-011 “Small Sacrifices”)—near grade conditions, reglet?

Additional risk mitigation methods No risk: cut off end, support from masonry (steel ledgers)

or interior bearing wall or replace structure Leave uninsulated? → Condensation risks? Heat loss Borate “sticks” in joist ends? Heat spreader plates? → Passive ones not effective? Encapsulate embedded end in sealant? → Imperfections

have big risks



Questions?This concludes the American Institute of Architects Continuing Education Systems Program

This temporarily suspends the AIA CEU content



Questions?Kohta Uenokohta (at sign) buildingscience dot com



Questions?AIA CEU content is now resumed





Firecut Beams



Firecut Beams



BSI-011 “Small Sacrifices”



BSI-011 “Small Sacrifices”



2014-03 ueno nesea embedded joists-masonry for pdf · 3/4/2014 · nesea be14-masonry joist end...

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