B08_Attach 3 Report 4_Condition Assessment Historic Masonry.pdf

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 1 of 7

PROJECT: CRLA 198641 REPORT DISTRIBUTION LIST:

Steel Visitor Center Crater Lake National Park Bryce K. Klug, Senior Associate

Crater Lake, Oregon RIM Architects

Steve Jones, Preservation Architect Quinn Evans Architects

Ruth Mills, Historian Quinn Evans Architects

Stephen R. Mark, Historian National Park Service

Kirsten Hardin, Chief of Facility Management

National Park Service

CLIENT: Bryce K. Klug, Senior Associate, RIM Architects, Anchorage, Alaska

RE: REPORT NO. 1 CONDITION ASSESSMENT, HISTORIC MASONRY - DIVISION 4

ASSIGNMENTS: Observations on original 1932 historic stone masonry construction and recent repairs; collect original mortar sample from exterior mortar joints on the west elevation for testing; inspect interior finishes including basement; review chimney construction; discussed core drilling approach compared to interior slot approach for stabilization

DATE: Wednesday, August 7, 2019 TIME: 7:30 a.m. – 12:00 p.m.

WEATHER: Sunny TEMP: High: 60°F HUM. Did not measure

PRESENT AT SITE DURING CONDITION ASSESSMENT INSPECTION:

Stephen R. Mark, Historian, National Park Service;

Steve Jones, Preservation Architect, Quinn Evans Architects, Ann Arbor, Michigan;

Ruth Mills, Historian, Quinn Evans Architects, Ann Arbor, Michigan;

John Speweik, Historic Masonry Specialist, Speweik Preservation Consultants, Inc.

CONDITION ASSESSMENT:

John Speweik, of Speweik Preservation Consultants (SPC), conducted an onsite condition assessment inspection visit on Wednesday, August 7, 2019. This field report contains observations on original 1932 historic stone masonry construction with a focus on the seismic stabilization approach and process. After careful review of the original drawings and onsite observations, my opinion on the best approach to stabilization is no longer to use the interior slot method but rather now to implement core drilling. SPC must be able to identify the through-wall stones in order to penetrate them to be used as anchors during the coring approach. SPC is researching non-destructive testing in order to identify the through-wall stone

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 2 of 7 units. The change from interior slot method to core drilling is based upon observations of the exceptional condition of the exterior stone masonry bond strength between the mortar and stone specifically. In addition, the core drilling approach would be less invasive to the historic building and be a better option given the original wall design. The core drilling option would also provide full access to the footing at the first course of stone.

Also, the level of challenge in penetrating the interior surfaces to the proper depth required in the slot method would pose limitations especially at the crawl space area. Interior floors would need to be removed and even then it’s difficult to determine the technique in getting down to the footings from the crawl space. This approach would also only be stabilizing the interior courses of stone and preclude the exterior courses. In addition, core drilling maybe required through both individual wythes of stone rather than only in the center of the wall to stabilize the entire wall system. The results of the non-destructive testing and use of ground penetrating radar (GPR) will assist in supporting this decision.

FIG 1: According to the original construction drawings the loadbearing stonewalls are 30 inches wide at the plinth course and attenuate to 19 inches at the top of the wall. There are 2 individual stone courses both exterior and interior with stone rubble and mortar as infill in the center of the wall.

SPC observed the stone thickness at the corners of the building (yellow arrow, less than 30 inches).

Masons would set through-wall stones within the courses to strengthen the walls. These stone were wide enough to be set flush with the exterior and interior surfaces to bridge the 2 individual courses. They typically were required every 5 square feet of wall area.

Note the non-original mortar in the joints at this location.

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 3 of 7

FIG 2: A mortar sample was collected from the west elevation, center of the building, at 2 head joint/bed joint intersections at the plinth course level.

SPC inspected interior finishes to be removed for interior slot approach and confirmed that this approach would be harmful to the historic character of the building and should be discouraged.

SPC inspected the basement walls and found them to be in excellent condition.

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 4 of 7

FIG 3: The wide mortar joints are performing well with minimal shrinkage cracks occurring due to the large aggregate within the mix design.

It was noted that mortar joint repairs have been carried out on all elevations. The replacement mortar does not match the original color, profile finish of the joint, or the texture. In many areas, the replacement mortar was smeared on the surface of the historic stone units. The question was raised if we should remove these repairs. It is likely that the repairs are 50 years old and are in there own right now considered historic. The performance of these replacement mortars, while not matching in all respects to the original mortar, is still performing well. The mortar is not causing damage to the historic stone units and thus should be left intact.

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 5 of 7

FIG 4: Hairline cracks in the face of some stone units were observed. These cracks were typically located in the water drip lines from the roof overhang. The cracks can be treated using a Dispersed Hydrated Lime injection technique called DHL Injection. The material and approach was developed in Germany over 20 years ago. Note the non-original mortar in this image that does not match the historic mortar color or texture.

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 6 of 7

FIG 5: It was noted that the wood lintels were set 12 to 13 inches from the window and doorjambs. The chimneys were in good condition; however, some water infiltration has been reported around the flashing details. SPC is of the opinion that the metal bracing at the top of the chimney may be carefully removed.

The chimney should then be fully inspected for displaced stone and cracked mortar joints.

The contractor is responsible to ensure that each mason working on the project has completed all necessary requisites for the masonry treatments assigned. The contractor is responsible to ensure that all installed materials meet the mock-up standard of workmanship quality, color, texture, and finish. Speweik Preservation Consultants does not direct or approve work. SPC assists the contractor in self-evaluation of work performed in comparison to the approved Mock-ups / Test Panels and offers suggestions for improvement through demonstration and education.

Special consideration is given to this historic building being unique in its masonry construction and design. The quality workmanship depicted is a result of the careful approach to the work scope during the season in which it is performed. Techniques, timing, and sequencing all must be continually evaluated during the course of the project in order to reduce the risk of work being later rejected as non-compliant by the Architect, Owner, or National Park Service.

CONDITION ASSESSMENT INSPECTION Steel Visitor Center, Crater Lake National Park MAINTENANCE OF HISTORIC MASONRY- 04 01 20 Report No. 1: August 12, 2019

Report Distribution Date: Friday, August 12, 2019, revised September 10, 2019 Page 7 of 7

ITEMS TO VERIFY:

• Mortar sample to be shipped to laboratory for testing, expect a 3 to 4 week turn around for results.

• Core drilling approach for seismic stabilization rather than the interior slot method previously proposed.

• Non-destructive test methodology in order to identify the through-wall stones within the façade.

• SPC to perform a chimney inspection down to roofline after steel bracing is removed from cap.

ITEMS VERIFIED FROM LAST REPORT:

• Mortar testing results confirm a cement sand formulation in the original mix design. SPC supports the labs recommendation of using an ASTM C270, Type S, proportion specification mix design with a matching aggregate (and pigment if required) for the replacement mortar formulation.

• SPC is working with Jensen Hughes (JH) for the non-destructive testing. One JH engineer is anticipated to travel to and from Crater Lake, Oregon, to perform a site evaluation for one day.

The JH engineer will perform non-destructive testing using ground penetrating radar (GPR) and impact echo (IE) between two sets of windows from grade to roofline spanning approximately 10’ by 8’ on the west elevation. The results of the work shall confirm three conditions vital to the design of the core drilling efforts. 1) confirmation of through-wall stones within the façade, 2) if the wall is constructed of two individual wythes of stone, 3) verification of void spaces at the center of the stone walls. A detailed report will be issued on findings.

ATTACHMENT VIA SEPARATE PDF FILE:

• 19-132 ANA_Mortar Analysis Report – Chemical & Acid – revised 9-9-19

SUBMITTED BY:

SPEWEIK PRESERVATION CONSULTANTS, INC.

John Speweik, CSI, ASTM

Speweik Preservation Consultants, Inc.

3163 Heritage Pkwy Elgin, IL 60124 Phone: 224-856-7449

Speweik Preservation Consultants Inc., © 2019 All rights reserved.

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