Challenges of Insulating Existing Masonry Buildings:An Architectural Approach Based on Technical Knowledge

presented by

Laurie Soave, AIA, LEED APAssociate, Project ArchitectBruner/Cott & Associates, Architects

Presentation Goals• Understanding the Decision Making Process

– envelope construction and characteristics – methodologies of investigation– environments interior / exterior– existing materials properties and testing– owner involvement– third party experts– monitoring

• Audience experience input

Representative Projects

Harvard Blackstone Office RenovationMIT Building E60

Methodology• Step 1: Document Existing Building Statistics

1A: Weather1- Locate building site and determine exposures2- Map exposure of driving rain 3- Note building climate zone4- Note number of freeze/thaw excursions per season (Find this

information on website: http://www.energy-design-tools.aud.ucla.edu/ ) 1B: Interior Environment

1- Document existing building program use (i.e. dining/ offices/performance space, lab, art gallery, etc.)

2- Document existing RH factor based on program use and MEP systems

Methodology• Step 1: Document Existing Building Statistics

1C: Pressure1- Document the existing air pressure on the building (negative orpositive) based on the building use and mechanical systems)

1D: Construction1- Document existing envelope construction:

– Wall Construction and R-Value– Roof Construction and R-Value– Dew point locations– Document % fenestration and U-Value

1D: Construction (cont.)

2- Document roof construction, R-Value and dew point

3- Document conditions of vulnerable areas with potential of exposure to longer wetting periods:(i.e. beam ends, lintels, brick at window openings, spandrel panels below sills, etc.)

Methodology

1E: Testing of Existing Materials Properties (approach Building Science Consultant)

1- Approach Building Science consultant- Permeance testing of entire wall layering materials ( i.e. paint,

mortar, terracotta, bricks: face brick, core brick and interior brick)- Scrit test: Measures the degree of saturation in an existing masonry- Dry Density test - Water uptake tests- Thermograph documentation (infrared imaging) - Simulation Software

Methodology

Methodology• Step 2: Document Proposed Envelope Improvement

Goals

2A: Goals - Increase thermal resistance of wall assembly- Decrease air leakage of envelope assembly- Contain risk of freeze/thaw cycles- Reduce moisture load on brick façade

2B: Analysis of Improvements 1- Proposed envelope R-Value (in conjunction with MEP systems)

2- Proposed insulation materials- R-Value/in- Vapor & moisture permeance- Fire Rating- Installation sequence- Architectural enclosure options/implications - Flashing compatibility at openings

3- Calculate dew point location4- Air barriers5- Proposed condensation controls6- Implications for building systems installations7- Reversibility8- Toxicity9- Disposal (recycling) options

Methodology• Step 2: Document Proposed Envelope Improvement Goals (cont.)

1- Thermograph testing during and post construction2- Remote weather station and site monitoring: temperatures at wall face, wall core, ambient; RH levels.

Methodology• Step 3: Performance Monitoring – Post construction

(owner buy-in and consultant contracts)

Representative Projects

• Harvard Blackstone Office Renovation Originally Constructed 1890’s Masonry bearing walls with timber beam & floor structure Brick masonry 3 wythes Completed renovation for new offices

Harvard University Operational ServicesBlackstone Office Renovation, Cambridge, MA

Case Study – Vapor Migration and Exterior Wall Insulation• Design Goals

– Successfully manage the exterior envelope without creating damage due to increased and prolonged moisture content in the existing brick and mortar

– Target R-values for the overall envelope

• Concerns– Interior insulation that will not impede vapor passage – Continuous air barrier w/minimal cold bridging– Moisture management at brick – Moisture management at window openings– Comparable installations with empirical assessment and data

• Strategies– Proper repointing and masonry repairs and sealing of roof wall joints– Detail an interior insulation approach with continuous thermal break– Advocate quantitative approaches including monitoring of insulated and non-

insulated walls at various exposures– Provide operable windows

Existing Conditions Review• Visual Review

– Rust Jacked Lintels– Cracks – Spalling

• Test interior Finish – Vapor barrier

Load bearing masonry walls

Analysis of existing interior paint permeance

Process

Architectural Considerations

Exterior Wall - Alternate 1Faced Batt insulation

ProsProvides interior insulationAllows air spaceNo special installation

ConsRequires ventilation gaps R-Value far below goalNo continuous air barrierLimited run space for systems

Not approved

Process - Options

Process - OptionsExterior Wall - Alternate 2 Rigid Insulation

ProsMeets the R12 min. goalSemi Permeable insulationCreates continuous thermal breakAllows run space for systems

ConsConstructability is difficult / tediousNo continuous air barrierCareful treatment at penetrations

Selected option -Icynene Insulation

Exterior Wall - Alternate 3Icynene SPF insulation

ProsMeets the R12 min. goalVapor-permeable insulationCreates continuous thermal breakAllows run space for systemsDependable air barrierConstructability

ConsSpecialized tradeCareful treatment at penetrationsRequires thicker wall section

Process - Options

Process

existing interior VB paint

sandblast 75% paint3.5” (SPF open cell)

Results

Post Results

Recent site visit to begin investigations into vapor/moisture in wall and insulation material performance

Efflourescent noted at interior non-insulated stairwells walls.

Saturation at north wall bricks

Representative Projects

• Arthur D. Little Building; MIT Building E60 Originally Constructed 1917 Masonry Bearing Wall with concrete floor structure Brick masonry with interior wythe of clay tile Under renovation for new office and conference space

Existing Conditions Review

• Visual Review– Rust Jacked Lintels– Cracks – Spalling

• Tested Brick– Cold Water Absorption, ASTM C67– Boiling Water Absorption, ASTM C67– Capillary Uptake, ASTM C67– Dry Density, ASTM C642– Critical saturation (Scrit) Frost

Dilatometry• Tested Mortar

– Chemical Analysis– Aggregate Composition– Type Identification

• Test interior Finish – Vapor barrier?

Develop Proposal

• Establish Design Conditions• Establish Performance Criteria

with HVAC• Design Insulating System

– Air Barrier– Vapor Barrier– Insulating Layer– Finish

• WUFI Analysis

Denotes line of temperature across existing uninsulated masonry

Detail

On-Going Concerns• Structural elements embedded in wall• Steel or Wood vulnerable to water• Channels to the exterior

Exposed rebar at concrete lintel

Voids within wall at sill SCT cores at header courses

Audience Experience Discussion