B09_Amendment_3_MALU_293291_Canopy_Roof_and_Window_Sealants_Evaluation_Attachment_10_0003.pdf

Martin Luther King Jr National Historical Park

Canopy Roof and Window Sealant Assessment

Greenville, Tennessee

May 3, 2022

WJE No. 2021.0190

PREPARED FOR:

DHM Design

900 South Broadway #300

Denver, Colorado 80209

PREPARED BY:

Wiss, Janney, Elstner Associates, Inc.

2055 Sugarloaf Circle, Suite 250

Duluth, Georgia 30097

770.923.9822 tel

Greenville, Tennessee

May 3, 2022

WJE No. 2021.0190

PREPARED FOR:

DHM Design

900 South Broadway #300

Denver, Colorado 80209

PREPARED BY:

Wiss, Janney, Elstner Associates, Inc.

2055 Sugarloaf Circle, Suite 250

Duluth, Georgia 30097

770.923.9822 tel

Victor C. Martin, PE

Senior Associate

Christopher W. Giffin, AIA, RRC

Principal

WJE No. 2021.0190 | MAY 3, 2022

CONTENTS

Introduction

Background

Construction Documents

Existing Construction

Condition Assessment

Leak Survey

Gutters

Metal Panels

Other Items

Glazing and Exterior Sealants

Discussion

Canopy Roofs

Glazing and Exterior Wall Sealants

Conclusions

Canopy Roofs

Glazing and Exterior Wall Sealants

Recommendations

WJE No. 2021.0190 | MAY 3, 2022 Page 1

INTRODUCTION

At the request of Ms. Michaela Kaiser with DHM Design (DHM), Wiss, Janney, Elstner Associates, Inc. (WJE) performed an evaluation of the canopy roof, the perimeter sealants of the glazing systems, and masonry walls of the Martin Luther King Jr. National Historical Park Visitor Center building located in Atlanta, Georgia.

The building is currently owned by the National Park Service (NPS) and serves as a Visitor Center with exhibits, an auditorium, and office areas for the Martin Luther King Jr. National Historical Park complex.

Based on information provided to WJE, the forecourt canopy structure along the eastern portion of the

Visitor Center has experienced historic leakage in several areas. DHM is in the process of designing extensive renovations to the building, and as part of this process, WJE was requested to evaluate the forecourt canopy and reported leakage, as well as evaluate the window and wall sealants, so that necessary repairs can be incorporated into the comprehensive renovation design.

BACKGROUND

The building is located at 449 Auburn Avenue in Atlanta, Georgia and was constructed in 1996 (Figure 1).

It is a two-story brick-clad building, with glazed storefronts and punched openings, and a low-slope modified bitumen roof system. The adjoining forecourt canopy roofs are supported by steel tube columns and glue laminated timbers (glulams) and wood truss framing (except for the central canopy roof which is supported by tube steel framing concealed by precast concrete and wood trusses). The roofs are prefinished architectural snap-on standing seam metal panels. Some of the canopy roofs have glazed skylights at the tops.

Figure 1. Aerial photograph of the Visitor Center and adjoining Forecourt Canopy roofs.

Visitor Center

Forecourt canopy roofs

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CONSTRUCTION DOCUMENTS

Copies of the original construction documents were provided by DHM Design and reviewed by WJE.

These included the architectural and structural drawings and were dated June 29, 1994 and prepared by

Turner Associates.

Several pertinent items were identified in the reviewed construction documents.

The overall roof plan (Figure 2) depicts the various canopy roof areas. There is one larger pyramidal shaped canopy (central canopy roof) with a glass skylight situated to the east of the main entrance to the

Visitor Center which is flanked with twelve smaller pyramidal shaped canopies to the north and south. Five of the smaller canopies have pyramid-shaped skylights, and the others are capped with a low-slope standing seam metal roof, resulting in a truncated pyramid shape. The central canopy roof also has two radius dormers (on the east and west). In addition, there is a radius metal panel roof flanked by low-slope modified bitumen roofs over the main entrance vestibule.

A separate roof plan (Figure 3) depicts roof drain locations and slope directions of the internal gutters

(which are specified to be slope 1/4-inch per foot). The roof drains are located at column locations and were specified to discharge into 3-inch PVC downspouts run through 6-inch by 6-inch steel tube columns into storm piping.

A section provided through the smaller canopy roofs (Figure 4) depicts the roof slope as 12:12, except for the low-slope roofs on the truncated pyramid shaped roofs, which is depicted to be sloped at 1/4-inch per foot. The decking for the sloped roofs is depicted to be 3/4-inch exterior grade plywood. The framing is depicted to consist of glue laminated beams along the perimeters with wood trusses with 3x6 members.

There are details provided which depict the specified construction of the internal gutters along the perimeters of the individual pyramidal-shaped canopy roofs (Figures 5 and 6). The internal gutters are depicted to consist of an ethylene propylene diene monomer rubber (EPDM) membrane, which is terminated beneath the eaves of the standing seam metal roof panels and beneath aluminum coping on the exterior facing areas. The gutters are sheathed with exterior grade 3/4-inch plywood. The details depict tongue and groove pressure treated wood decking at the undersides of the gutter assemblies which conceals the plywood gutter sheathing. A vapor retarder was depicted on the top of the tongue and groove decking.

A detail was provided for the gutter along the central canopy, which has exterior precast concrete beams rather than glulam beams (Figure 7). This detail indicates “roofing felt” is to be installed over the sheathing and beneath the metal panel roof covering. There is also a flashing provided at the metal panel to gutter interface, unlike the gutter detail for the smaller canopy roofs. The soffit beneath the gutter is annotated as “lathing and portland cement plaster”.

The construction documents provide a detail for the interface of the low-slope modified bitumen roofs which flank the radius metal panel vestibule roof to the adjoining brick wall (Figure 8) as well as the interface of the modified bitumen roof to the radius metal panel roof (Figure 9). Detail 10/A2.8 indicates an expansion occurs between the canopy structure and the brick veneer. The brick veneer continues past the canopy roof but has a through-wall flashing noted to be provided.

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Figure 2. Roof Plan (1/Sheet A 2.7) depicting the forecourt canopy roof areas.

Figure 3. Roof Plan (1/Sheet A 2.4) depicting the drains and gutter slope directions for the forecourt canopy roof areas.

Skylight

Radius Metal

Vestibule Roof Mod. Bit.

Vestibule Roof

Central

Canopy Roof

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Figure 4. Wall Section (Sheet A 5.3) depicting a section through the smaller canopy roofs.

Figure 5. Detail 2/A8.2 depicting section at perimeter gutter of canopy.

Figure 6. Detail 1/A8.2 depicting section at internal gutter of canopy.

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Figure 7. Detail 5/A8.1 depicting section at internal gutter of the large canopy roof, with precast concrete beam face.

Figure 8. Detail 10/A8.2 depicting the modified bitumen roof to brick interface at the east vestibule.

Figure 9. Detail 7/A8.1 depicting the BUR to radius metal panel roof at the east vestibule.

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EXISTING CONSTRUCTION

WJE reviewed the as built roof assemblies and accessories for the canopy structure along the eastern portion of the Visitor Center (Figures 10 through 13). General descriptions of the roof various components are provided below.

The construction was generally consistent with the drawings with some exceptions.

An EPDM membrane lined gutter is provided along the perimeter of each pyramid-shaped canopy roof.

The gutter is sloped to internal roof drains, which reportedly discharge into PVC leaders concealed by the tube steel columns into the stormwater drainage system. The gutters are internal where canopy roofs adjoin (Figure 14). Along the exterior of the smaller canopy roofs, there are perimeter gutters (Figure 15) where a sheet metal flashing / facia piece integrates the EPDM membrane with the exterior glulam beams for the smaller canopy roofs. At the central canopy roof (Figure 16), there is a perimeter EPDM membrane lined gutter which is integrated with sheet metal flashing/fascia with exterior precast concrete beams

(Figure 17).

Figure 10. Typical framing of smaller canopy roofs Figure 11. Typical wood trusses supporting canopy roof

Figure 12. View of smaller canopy roofs in foreground and larger (central) canopy roof in background

Figure 13. Central canopy roof with radius dormer roof

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Figure 14. Typical EPDM internal gutter between two metal canopy roofs

Figure 15. Typical perimeter EPDM gutter

Figure 16. Steel tube column partially concealed with rounded precast concrete elements supporting glulam beam with steel bracket.

Figure 17. Precast concrete beams on east facade of the central canopy roof and stucco perimeter soffit.

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CONDITION ASSESSMENT

WJE performed an assessment of the various roof areas, both to attempt to diagnose possible causes of observed and reported leaks, and to evaluate the condition of the various roof system components. Our assessment consisted primarily of visual observations of the roof and areas beneath. The following is a summary of the pertinent conditions that were observed.

WJE’s scope of work included limited water testing to evaluate four reported leak locations at the canopy roofs. However, during our second day of mobilization on April 4, 2022, a rain event occurred and more leaks than the reported four were observed. Based on the number of leaks and the observations, which included relatively obvious paths for leakage, WJE did not perform targeted water testing. Based upon this rain event, WJE prepared a figure depicting the approximate locations of leakage beneath the canopy roofs (Figure 18).

Figure 18. Figure depicting approximate locations of leakage observed beneath the canopy roof areas during rain event.

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Leak Survey

Leak at Vestibule:

A leak was reported, and peeled paint and damaged gypsum ceiling was observed along the east vestibule, beneath the low-slope modified bitumen roof to radius metal panel roof interface.

Leakage During Rain Event:

View of puddles and ponding in numerous areas beneath the northern section of the canopy roof area during a rain event.

Leaking from Stucco Soffit:

Water was observed dripping from the stucco soffit beneath the interface between the perimeter EPDM gutter and eastern radius metal panel dormer. Dark staining and cracking were also noted in the area of leakage.

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Leakage at East Dormer Valley:

Water was observed dripping from beneath both radius metal panel dormers, along the dormer to valley interface. Staining was also noted on the wood framing and decking in these locations.

Leakage from Internal Gutter:

Water was observed dripping from the tongue & groove decking beneath internal gutters between canopy roof areas at numerous locations. The decking also exhibited dark staining.

Leakage At Steel Brackets:

Leakage and corrosion were observed at numerous steel brackets, which are situated where gutter intersections occur.

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Leakage At Steel Brackets:

Additional view of water dripping at steel bracket.

Gutters

Exterior Glulam Beams:

The exterior Glulam beams exhibited splitting between the laminated layers. The wood was soft and easily penetrated with an awl using minimal hand pressure.

Glulam Beam Connections:

The exterior Glulam beams intersect at column locations where they are supported by steel brackets bolted into the faces of the beams. At numerous of these locations, the beams have shifted and warped.

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Deformed Glulam Beam:

View of warping of a glulam beam, having shifted inward towards the internal gutter.

Torn EPDM Membrane at Mitered Glulam

Beam Intersection:

View of torn EPDM gutter liner membrane at a glulam beam intersection which exhibited shifting / warping. Note that the metal coping has also shifted. An active leak was observed directly beneath this location.

Shifted/Deformed Glulam Beam:

View of space between face of glulam beam and steel bracket at a glulam intersection.

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Shifted Coping at LVL Beam Intersection:

View of sheet metal coping/fascia where it has separated at an exterior glulam beam intersection.

Shifted Glulam Beam:

View of glulam beam misaligned to the support bracket.

Cut in EPDM Gutter Lining:

View of a cut in EPDM gutter liner exposing plywood decking underneath.

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Void at EPDM Splice:

View of a void at a splice in EPDM gutter liner.

Voids such as these were typical at locations where

EPDM strips and patches were integrated with primary EPDM gutter membrane.

Void in EPDM Splice:

View of a void at an EPDM gutter liner splice.

Debris:

Various debris was observed in the gutters including rocks, leaves, and steel angle.

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Radius Metal Panel Dormer to Gutter

Interface:

View of the interface of the radius metal panel dormer on the central canopy roof to the perimeter

EPDM membrane lined gutter. Note that the panel extends to the horizontal surface of the EPDM membrane, and leakage and staining was observed beneath this area (from the stucco soffit).

Radius Metal Panel Dormer to Gutter

Interface:

A close-up view of the metal panel to EPDM gutter conditions identified above where a tear/void was noted at the interface of the eastern metal panel dormer to gutter interface, with exposed plywood observed. Note that an active leak was observed beneath this location, emanating from the stucco soffit.

Damaged Stucco Soffit:

View of cracked/stained stucco soffit beneath radius dormer roof to EPDM gutter interface.

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Damaged Stucco Soffit:

View of stucco soffit from above photo which is offset from the adjacent precast concrete panels.

Metal Coping/Fascia Fasteners:

The interior vertical face of the sheet metal coping/facia of the gutters was observed to be fastened with pan-head screw-type fasteners. At numerous locations, these fasteners were missing or exhibited eccentricity and corrosion.

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Metal Panels

Denting of Metal Panels:

Numerous dents were observed among the metal panels, with some areas exhibiting more severe denting than others.

Missing Ridge Cap Flashing at Dormer:

The metal ridge cap flashing at the west radius/barrel roof was observed to be missing.

Missing Ridge Cap Flashing at Dormer:

The metal ridge cap flashing at the east radius/barrel roof was also observed to be missing.

Exposed, stained plywood decking was also visible.

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Unhooked Snap-on Seam

Throughout the metal panel roof areas, several snap-on standing seam covers were observed to be loose and no longer attached.

Corroded Clips:

Where the snap-on standing seam covers were loose, missing, or poorly engaged, the underlying metal clips were exposed. Many of these clips were rusted and corroded.

Gaps in Snap-on Seams:

Where the metal panel roof transitions from the steep slope (12:12) section to the low slope

(1/4-inch per foot) at a truncated pyramid-shaped canopy roof areas a single metal panel was used and folded over the form this transition. The standing seams were snipped and cut to allow for this transition with many of these now being open and unsealed.

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Gaps in Snap-on Seams:

Close-up view of the cut, open, and unsealed standing seams at the transition angle change.

Inadequate Snap-on Seam Coverage:

View of exposed clips and vertical panel returns.

Unhooked Metal Hip Flashing:

View of metal hip flashing which exhibited mechanical damage and was also noted to be unhooked on one side from the underlying Z-clips at the top of the panel.

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Unhooked Metal Hip Flashing:

Close-up view of metal hip flashing which was no longer hooked to the underlying Z-clip.

Metal Roof/Gutter Flashing at Precast

Concrete Beams:

Metal roof and gutter flashings at the precast beams (perimeter of the central canopy roof) were typically fastened vertically with lead expansion anchors into the precast concrete.

Metal Roof Flashing at Precast Concrete

Beams:

Where the exterior metal radius/barrel roof terminates at the rake edge numerous cuts were made in the vertical flashing leg to accommodate the curvature of the roof.

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Radius Metal Vestibule Roof to Masonry

Wall Flashing:

Where the radius/barrel roof terminate at the masonry wall, the counterflashing contains several short sections that are surface-mounted to the masonry and sealed.

Other Items

Radius Metal Vestibule Roof to Modified

Bitumen Roof and Brick Wall Interface:

View of interface of the metal radius/barrel vestibule roof with brick masonry wall and low-slope modified bitumen roof. Note that there was a reported leak (as well as evidence of leakage observed) beneath this location. Note the apparent attempted repairs with mastic and sealant.

Low-Slope Modified Bitumen Vestibule

Roof to Masonry Wall Flashing:

View of surface-mounted counterflashing with gap in sealant at interface between low-slope modified bitumen vestibule roof and brick masonry wall.

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Dislodged Skylight Gasket:

View of a dislodged gasket on the skylight of the central pyramidal canopy roof area. Note that an active leak was observed directly beneath this location during a rain event.

Glazing and Exterior Sealants

Precase Concrete Panel Sealant Joints

Overall view of sealant joints in the precast concrete panels along the perimeter of the central canopy roof.

Precast Concrete Panel Sealant Joints

View of typical condition of precast concrete panel sealant joints. Note the cracking and crazing.

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Rounded Precast Concrete Column Element

Sealant Joints:

Overall view of vertical sealant joint in precast concrete column elements surrounding tube steel columns which support the canopy structure.

Rounded Precast Concrete Column Element

Sealant Joints:

View of voids in precast concrete columns and damaged sealant.

Paint on Ridge Caps:

The paint coating on asbestos ridge caps of the addition roof was deteriorated.

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Brick Control Joint:

The brick expansion joint on south facade of the building was filled with sealant.

Failed Brick Control Joint:

The sealant in the brick expansion joint was deteriorated and missing in several locations with the underlying backer rod exposed.

Brick Control Joint:

The sealant was cracked and crazed in some areas of the brick expansion joint.

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Failed Exterior Outlet Sealant:

Failed sealant was observed around the perimeter of the exterior electrical outlet.

North Facade:

View of the north facade of the Visitor Center building. Hollow core metal service doors were located at various points along the building exterior.

Sealant at Service Door:

Painted perimeter sealant was observed around the perimeter of the hollow core metal service doors.

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Typical Punched Opening and Sill:

View of a typical punched window opening in masonry veneer with a precast concrete sill.

Void in Sealant at Punched Opening:

A void at jamb to sill interface at punched opening was observed.

Punched Opening Perimeter Sealant:

The sealants around the perimeter of punched window openings were cracked and crazed.

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Precast Concrete Sill Sealant Joint Failure:

Missing sealant was observed at one of the precast concrete sill sections on the south facade of the

Visitor Center building.

Storefront at Main Entrance:

View of glazed storefront systems along main

(east) entrance of the Visitor Center building.

Storefront Perimeter Sealant:

View of perimeter sealant at the storefront system.

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Storefront Glazing Gaskets:

View of glazing gaskets on glazed storefront system at main entrance.

Void in Storefront Perimeter Sealant:

A void was observed in storefront perimeter seal at the head condition of south facade near the main entrance vestibule.

Void in Storefront Perimeter Sealant:

Additional view of void observed in storefront perimeter seal at the head condition of the south facade near the main entrance vestibule.

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DISCUSSION

Canopy Roofs

Exterior wood, unless from naturally durable species, requires treatment (e.g. preservative treatment, paint, stains, sealers, etc.) for long term performance. Film-forming finishes (e.g. paint), stains and sealers require periodic reapplication and maintenance. Based on our review of the construction documents, no information related to the treatment of the exterior glulam beams was provided. The most vulnerable areas of these beams are the end grain conditions. Chronic water intrusion into the end grain of the beams would accelerate deterioration and swelling, and resulting warping/twisting, and/or shifting of the beams.

Compared to heat welded thermoplastic membranes (e.g. TPO, PVC, KEE, etc.) EPDM is more vulnerable to long-term seam performance issues. EPDM seams use adhesives and are typically weaker in tension than heat welded seams should movement occur. Furthermore, to prevent EPDM membrane from sticking to itself when it is manufactured and stored on rolls, a parting agent is typically applied during manufacture.

During installation, if these parting agents are not suitable cleaned, long term adhesion issues and debonding may occur. Another disadvantage of EPDM is that it is relatively puncture-prone, being vulnerable to sharp metal panel edges, fasteners, etc. and can be more easily cut.

Metal panel roofs and EPDM membrane roofs typically have expected useful lives of approximately 30 years and 20 years, respectively, though actual useful life depends on a number of factors including maintenance, slope, quality of installation, climate, etc.

Glazing and Exterior Wall Sealants

Based on the consistency and appearance of the various exterior sealants observed, they appear to be polyurethane, which has a relatively shorter expected useful life than silicone. The condition of the sealants ranged from fair to poor, with the majority evidencing some level of crazing and cracking, and some (especially the south facing wall brick expansion joints and rounded precast concrete column elements) evidencing voids. In several locations the sealant was missing altogether.

The perimeter sealants for the hollow core metal service doors were concealed by paint, which appeared to be well maintained. Painting of urethane sealants can provide additional protection of the sealants, shielding them from ultraviolet light, extending their service life.

CONCLUSIONS

Canopy Roofs

The majority of the observed leaks beneath the canopy are occurring due to voids/cuts/tears in the EPDM membrane gutter liner. There are numerous causes of these voids:

• Swelling, warping, twisting, and shifting of the exterior glulam beams resulting in tears of the membrane

• Cuts and tears possible due to debris

• Delamination of EPDM seams

• Contact of sharp metal roof panel edges of the radius metal roof with the EPDM membrane gutter liner

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However, there also leaks at the radius/barrel roof dormer to sloped metal panel interfaces on the central canopy roof, which appear to be related to missing ridge cap flashing in these locations. There is also a leak beneath the skylight on the central canopy roof, where a dislodged glazing gasket was observed above.

There is a leak beneath the interface of the radius/barrel metal vestibule roof, south-adjoining low-slope modified bitumen roof, and west-adjoining brick masonry wall. Based on the construction documents, the brick wall is a cavity wall, and through-wall drainage is specified where the modified bitumen roof interfaces with the brick wall. No through-wall drainage provisions were observed at this interface, nor at the interface of the radius metal roof with the brick wall.

The EPDM gutter liners exhibit widespread damage and seam delamination and should be replaced.

However, replacement of the membrane gutter liners is complicated by the adjoining elements; namely, the glulam exterior beams and the metal roof panels. The glulam exterior beams have swelled, shifted, warped/twisted in numerous locations resulting in gaps at beam intersections, which allow further water intrusion into the vulnerable end grain of the beams which will accelerate further swelling and decay. A replacement gutter liner membrane should be installed on a sound substrate and structure. Thus, the glulam exterior beams will need to be addressed either by in-kind replacement, or an alternate approach.

In any case, given the deformations observed in connection with these beams, they should be structurally evaluated.

Except at the central canopy roof, the EPDM membrane gutter liners are terminated beneath the sloped metal panels, and proper replacement of the membrane would require either removal of the panels at the gutter interface or cutting them and installation of a new metal flashing to integrate the panels with a new gutter liner. The central canopy has a metal counterflashing which extends over the interior vertical leg of the EPDM membrane gutter liner, which could be cut and lifted, and then subsequently set back in place subsequent to membrane gutter liner replacement.

The metal panel roofs are generally in fair condition, exhibiting denting and damage in numerous areas as well as unclipped / unhooked hip and ridge caps in some locations. The panel clips which were observable in areas where snap-on seams had become unhooked exhibited corrosion.

Glazing and Exterior Wall Sealants

The exterior sealants, with the exception of the perimeter sealants of the hollow core metal service doors and the glazed aluminum storefront at the main (east) entrance to the visitor center have met or exceeded their service life. There is a limited area (along head of the south facade of the main entrance vestibule storefront) with failed sealant, but the other areas were in fair to good condition and are functioning as intended.

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RECOMMENDATIONS

Based on the observations and information reviewed regarding the roofs of these buildings, WJE recommends the following:

Forecourt Canopy

Perform structural evaluation of the glulam exterior beams which would serve as a basis for remediation of the beams. Replacement in-kind may be appropriate.

Replace the EPDM membrane gutter liner and associated coping/fascia. At a minimum this would include cutting the metal panels at the membrane interface in order to install suitable flashing to integrate a new membrane with the panels. Replacement of the EPDM gutter liner for the central canopy roof would only require cutting of the radius/barrel dormer metal roof panels at the gutter interface as a counterflashing is provided at the other metal panel to gutter interfaces.

Replace two areas of stucco soffit along east perimeter of the central canopy roof which exhibited chronic leakage, staining and cracking. New stucco panels should include perimeter weep provisions.

Cement board panels with textured finish could also be considered.

Wet seal central canopy skylight.

Install proper step flashing, with horizontal cut reglets at radius metal vestibule roof to brick wall interface.

Provide through-wall flashing at brick transition to low-slope modified bitumen vestibule roofs and as well as the transition to the radius metal vestibule roof and properly integrate with the low-slope modified bitumen roof system and radius metal roof system. Given the age, condition, and relative size and cost of replacing these isolated modified bitumen roofs, it may be feasible to replace these in conjunction with the flashing repairs described above.

Repair various other metal roofing deficiencies (e.g. missing radius metal dormer ridge caps, unhooked metal hip flashing caps and snap-on seams).

Given the age and overall condition of the metal panel roofs and complexity and relative cost of repair and modification to integrate new membrane gutter liner, it may be more feasible to replace the metal panel roofs.

Exterior Sealants

Replace precast concrete (e.g. rounded column element, central canopy beam, window sill, and precast wall panel) sealants.

Replace brick expansion joints.

Replace perimeter sealant of punched openings.

Repair sealant at head condition of south facade of main entrance vestibule storefront.

Silicone or hybrid sealants should be considered as a replacement option due to increased durability and longevity.