May 12, 2003 First Parish Church

Structures NorthMilton, MA

May 12, 2003

FirstParishChurch of Milton

535 Canton Avenue

Milton, MA 02186-3218

Fax: 617-698-6435

Attention:Mr. Jay W. Beaulieu

Facilities Manager

Reference:Church Evaluation

Dear Jay:

During February and April of 2003, I visited the First Parish Church of Milton to investigate and document the condition of the meetinghouse structure below the steeple, which we had already been evaluated and restored at the time of this writing. The following is a summary of my observations and recommendations.

General Description

The FirstParishChurch is a timber-framed, wood-sided, gabled-roof style Unitarian Universalist meetinghouse in Milton Massachusetts. Originally, this structure, constructed ca. 1787 was situated on the site with a 90-degree orientation to its present axis. The tower, now located at the south end of the structure, was enlarged and re-supported over a new narthex (vestibule) in 1835, as the church was rotated onto its present axis. At the same time, the Meetinghouse was stylistically “Greek-Revivalized”, and the upper gallery level and porches were removed.

The Meetinghouse is a heavy-timber framed structure situated on a northeast-southwest axis. For the purpose of this report, the front of the Meetinghouse will be considered to face the southerly direction.

The Meetinghouse, proper, contains the sanctuary. At the front of the Meetinghouse is a Front Extension of similar cross-section but smaller size that contains an enclosed narthex and an organ loft, and atop which sits the tower. At the rear of the Meetinghouse is a small Rear Ell that contains parlor, bathroom and an office.

There is an attic above the sanctuary and organ loft in which all of the timber framing is exposed, accessed via a stairway from the organ loft. There is a separate, smaller attic over the Rear Ell which is accessible via a scuttle.

There is a crawlspace beneath the entire footprint of the structure, accessed via a stairway from the Narthex and via a bulkhead on the east exterior of the building.

Meetinghouse Structure-

The meetinghouse is constructed as a free-spanning “box”, with lines of solid timber posts within the perimeter walls that support the attic floor and roof. These posts support five timber trusses that span from east to west and support a system of purlins and rafters that frame the roof. The front and rear walls of the structure also contain truss-like elements but act more like load-bearing walls as they are continuously supported from below.

The sanctuary floor is constructed of timber girts (beams) running in the east-west direction between the perimeter foundation walls and across interior piers of brick and in some cases stone. Between the girts run floor joists, some of which have been raised below the pews.

The roof is constructed with primary purlins that run from truss-to-truss and support large rafters that run midway between the trusses. These support secondary purlins that run between the trusses, the rafters and rear bearing wall and directly support the roof planking that runs in the up-down direction.

Front Extension and Rear Ell Structures-

The Front Extension was constructed, surrounding the base of the tower, when the structure was rotated as it is framed in a slightly different, possibly later manner than the Meetinghouse. There are roof rafters that run in the up-down direction and span between the tower girts and the east and west walls, and the perimeter walls are of repetitive “stick” type construction.

Over the Narthex and Organ Loft the base of the tower is supported on four timber posts, two of which run to the foundation at the south wall of the narthex and two of which are supported by a steel transfer beam over the organ loft. This is supported by two steel pipe columns at the south wall of the Meetinghouse that run to the foundation. It is believed that the steel supports were added as reinforcement to the south roof truss of the Meetinghouse, which previously supported the north side of the tower, as was a common, contemporaneous method of support. The steel columns were spaced more widely than the tower posts in order to afford more openness at the north opening of the organ loft, hence requiring the steel transfer beam.

The Rear Ell is stylistically and construction wise from the Greek Revival period and is framed with early “stick” lumber that primarily spans in the east-west direction.

Foundations-

The entire Church rests upon coursed and uncoursed stone foundations.

Noted Conditions and Recommendations

From the field investigation and subsequent structural analysis, I noted the following as described below.

Foundations and Exterior-

  • From the exterior, the roof appears to undulate between abrupt high points and gently curving low points. This is actually caused by two effects, one being the simple deflection of the purlins between the trusses, which act like relatively rigid supports, and the other being caused by slippage in several of the trusses. The first case is a common trait in structures of this age and type, however, the second is of immediate concern and should be addressed (see item #RA-1).
  • The exterior siding and trimwork on the Church seems to be in generally good condition and has been well maintained.
  • There are small cracks in much of the exposed stonework of the foundation. Normally these would be of little concern, however, given the relative thinness of the foundation, the mortar plays an important role in keeping the walls stable and should be kept in intact condition. Some of the cracks were caused by curing shrinkage in the mortar itself and some were caused by foundation movements. All cracked joints should be cut and re-packed and pointed with a compatible, lime and cement- or hydraulic lime- based mortar (item #FE-1). Stones that have shifted from their proper positions (of which there are several) should be re-set as part of the work.
  • The exterior walls of the structure waiver up and down along their lengths by several inches, as can be seen by sighting along the windowsills, clapboards or the watertable. The apparent low points seem to be nearer the corners of the structure. This waivering may be caused by compression of the sill or vertical settlement of the foundation itself. Some damage was detected in the sill timbers (see item #FC-3, below) but not enough to have caused all of the apparent movement. This, plus the presence of cracks in the foundation suggest that the stonework itself has moved downward in several places. The foundation should be carefully exposed and evaluated where there appears to be movement. The soil on which it bears may questionable (as was found below the front steps) as well as the construction of the masonry itself (appearing in some places to be as little as 8” thick). An evaluation should be made to determine what corrective measures, if any, should be taken. The required repairs, which might include restoration or underpinning, should then be made (item #FE-2).
  • There are randomly oriented cracks (“map cracks”) on the mortar-parged east wingwall of the rear steps suggesting that this element is deteriorating from within. The damaged masonry will eventually need to be replaced (item #FE-3).
  • The east chimney over the rear ell is in very poor condition, with deteriorated bricks and mortar joints and vertical cracks that run from the foundation up through the roof of the ell. It is also leaking and letting water enter the office below. This chimney should be removed or reconstructed in its entirety (item #FE-4).
  • Water was actively flowing into the crawlspace through a hole in the east wall, theoretically from an un-drained downspout. The water should be properly channeled away from the structure and the hole in the foundation filled (item #FE-5).

Roof Framing and Attics-

  • The roof construction in general is in remarkably good condition, having been well constructed and the roofing well maintained during the structure’s life. There are only a few structural conditions that need to be addressed.
  • There are what appear to be carpenter ant holes in the bottom of the second truss’ king post (as numbered from the back wall of the tower). There also appears to be, or to have been some beetle activity at the top of this member. This is hopefully not an active infestation but should be treated by an exterminator as a precaution (item #RA-1). The extent of damage did not seem sufficient to warrant structural repairs but should be inspected more closely, especially where the top of the king post will need ropes and ladders in the attic for access.
  • There is a limited amount of beetle-related material loss in many of the timbers that are exposed within the attic. Generally, this loss is confined to the sapwood, leaving the heartwood, which makes up the bulk of the members, untouched. None of the beetle damage that I saw seemed to seriously weaken the timbers, however, I recommend treatment by an exterminator as a preventative measure (item #RA-2).
  • There are horizontal splits in several of the primary roof purlins that started at the bottoms of the end tenons and run toward the middles of the members. Unlike typical season checks, which they may also be, the splits occur at a point of local stress concentration in these members and weaken them. The splits, which occur near the third and fourth trusses, should be injected with epoxy adhesive and cross-pinned with lag screws (item #RA-3).
  • The lower top chord member at the east side of the fifth truss actually dips downward, which is the opposite of the upward bow to which all of the other lower top chords are bent. Because there are not signs of bending failure and nothing to have pushed it into this odd shape, this timber probably came from a tree that grew on the side of a hill or had leaned sideways and contained “reaction wood”. Later, after foresting and installation, the member warped uncontrollably as it dried, resulting in the present geometry. The downward curve geometrically weakens the truss as the combined effects of bending and compression would tend to add to each other rather than canceling each other (as with a “counter-flexed” member). A compression strut should be added between the bottom of the curve and the bottom of the kingpost, near the intersection of the existing diagonal strut. This will help stiffen the sagging chord against buckling (item #RA-4).
  • The base connections at the both ends of the first truss and at the west end of the fifth truss appear to be slipping. These connections restrain the bottoms of the top chords from sliding outward with respect to the bottom chord and are important to maintaining the geometrical and structural stability of the trusses. The actual loads that would be on these connections were frequently underestimated by the original builders and such slippage is unfortunately quite common. Fortunately, the first truss has the redundancy that is provided by the supplementary support steel below the tower and the other trusses have the redundant lower top chords which are attached to the bottom chords far from their ends with little chance of sliding outward. All three of the slipping connections should be gusseted to provide for the proper transfer of the roof loads to the bottom chords (item #RA-5).
  • Several of the roof rafters over the rear ell are pocketed into the side of the east chimney. These will need to be re-supported when the chimney is removed and the opening closed in if a new chimney is not re-built in its place (item #RA-6).

First Floor Framing, Sill and Crawlspace-

  • Approximately 10% of the sanctuary and first floor joist framing has been effected by beetles and/or rot and should be sistered and/or supplementarily supported (item #FC-1).
  • Several of the timber girts have also been affected by rot and powder post beetles, with the worst conditions typically occurring at the ends of the members at the east wall and within the crawlspace below the east half of the rear ell. These should be replaced with new timbers where possible, or at least the bad wood should be replaced with new white oak Dutchmen and the members supplementarily supported from below (item #FC-2).
  • The perimeter sills are of white oak, which is naturally resistant to rot. These are generally exceptionally good condition considering their age and exposure to humidity, however several sill sections have been adversely affected. Powderpost beetles and, to a lesser degree, rot have attacked the sapwood of these timbers but have in most cases seemed to have left the heartwood untouched. This is a common occurrence in softwoods, but less common in hardwoods. As a result, portions of the sill have lost ½” to 1 ½” of their effective thicknesses but have not actually failed or even substantially compressed, while other portions of the sill are more deeply damaged. Approximately 10% of the sills will need to be replaced with new white oak while another 10% to 20% can remain but will need localized Dutchman repair (item #FC-3).
  • The crawlspace is a damp, unfinished space and not a friendly environment for wood framing and timbers. As a preventative measure, all of the wood in the crawlspace should be treated with boric acid solution, which is an environmentally safe wood preservative (item #FC-4).
  • Several of the interior piers that support the wooden floor framing above are either of compromised brick construction or piles of loosely laid, unmortared stone. The damaged brick piers should be repaired and the piled stones should be replaced with new concrete block or exterior-grade brick piers on proper footings (item #FC-5).

Church Interior-

  • The interior spaces of the Church are in immaculately well-maintained condition.
  • Some of the wainscoting boards in the sanctuary are loose, probably due to the seasonal cycling of humidity and temperatures and the effect that the resulting dimensional changes in the wood have had in loosening the nails. The wainscoting boards should be left as they are unless they become more loose, for fear of splitting the wood with more rigid fasteners. Also, the wainscoting waivers vertically and horizontally as the wall has moved downward due to sill compression and/or foundation settlement.
  • There are small diagonal cracks in several of the plaster walls and ceilings that related to seasonal movements in the structure and possibly compression of the sills and/or foundation settlement. Cracks that have occurred at the tops of the stairs to the organ loft relate to the condition of the front sill, which was replaced during the previous round of renovations.
  • The entire Meetinghouse leans toward the easterly direction, with the east wall leaning eastward at up to ¾” in four feet and the west wall leaning eastward at up to ½” in four feet. This may have occurred during the repositioning of the structure and should generally not be of structural concern.
  • There is a stain on the ceiling of the Education Office in the rear ell that was caused by the damaged chimney above it (see item #FE-4, above).

Prioritized Summary of Noted Items

Urgency Budget

Item # Item Description (see below) Estimate

FE-1
/ Repair stone perimeter foundations- reset shifted stones and re-point weathered or cracked mortar joints. / 3 / $3,000
to
$4,000
FE-2 / Expose and evaluate sinking corner of foundation, underpin if necessary. / 3 / $500
to
$15,000
FE-3 / Remove and reconstruct wingwalls of rear steps. / 5 / $4,000
to
$6,000
FE-4 / Remove east chimney at rear over rear ell, reconstruct if needed. / 2 / $5,000
to
$20,000
FE-5 / Channel rainwater away from foundation, fill hole in foundation within crawlspace. / 3 / $2,500
to
$3,500
RA-1 / Treat beetle-affected timbers in attic, evaluate and repair most damaged timbers if needed. / 3 / $2,500
to
$15,000
RA-2 / Insect-treat all timber framing in attic. / 3 / $500
to
$1,000
RA-3 / Adhesive-inject and pin split roof purlins. / 3 / $1,500
to
$2,000
RA-4 / Add diagonal compression strut to brace downward sagging truss chord against buckling. / 3 / $1,500
to
$2,500
RA-5 / Repair slipping truss connections by pinning and gusseting outer ends of tops chords to bottom chords. / 2 / $45,000
to
$55,000
RA-6 / Re-support chimney supported rafter ends at rear ell with removal of chimney. / 2 / $1,500
to
$2,000
FC-1 / Sister and/or supplementarily support beetle-damaged, rotted and/or mis-framed sanctuary floor joists. / 2 / $7,500
to
$12,500
FC-2 / Replace and/or Dutchman-repair and re-support damaged sanctuary floor timbers. / 2 / $15,000
to
$25,000
FC-3 / Replace most damaged sill sections, Dutchman-repair damaged portions of sill that are salvageable. / 3 / $500
to
$10,000
FC-4 / Treat all wood in crawlspace with boric acid solution. / 3 / $2,500
to
$3,000
FC-5 / Repair and/or reconstruct damaged brick piers and substandard (rock-pile) interior foundations. / 3 / $2,500
to
$3,000

Degrees of Urgency: