Brewery Stair Canopy Ryan 9 Mar 09! RYAN S. HELLWIG, PE ! STRUCTURAL ENGINEER !
! 28 ALDRICH STREET ! NORTHAMPTON, MA 01060 !
! VOICE 413-584-HLWG (4594) ! FAX 413-584-HLWFax (4593) !
March 9, 2009
Austin Design, INC
16 Call Road
Colrain, MA 01340
Re:The Northampton Brewery
11 Brewster Court
Northampton, MA
Subject:Existing Stair Canopy w/ New Solid Roof
Because the fabric is removed for the winter, the existing canopies were not designed for snow loads, in
order to keep the structure as light as possible. New roofing material of corrugated plastic is proposed to
cover the stairs year-round. Therefore the canopy must be able to support the full snow load. The flat roof
snow load is 35 psf, per the 6 Edition, which was in force when the permit for this work was granted.th
The existing rafters are 2-½" nominal diameter Schedule 40 pipes have a maximum cantilever of 6'-4".
There is some doubt as to the grade of steel that was used in the original construction, which dates to
1995. The design drawings from that time do not show the steel grade. The pipes are adequate with an
ballowable bending stress of F = 42,000 psi, which corresponds to ASTM A500 Grade B. For ASTM
bA53, with F = 35,000 psi, they would only be adequate up to a 5'-10" cantilever.
The cross beams are not adequate for support of the rafter pipes. Some reinforcement would need to be
welded underneath the existing pipes. The minimum section must be 1" thick by 3" deep solid steel.
Other sections are possible, such as a 5" x 5" “tee” beam.
The columns consist of two 3x3x¼ tubes at the upper landing and two W6x12 at the intermediate landing.
The columns are adequate for support of the roof loads. They are also able to support wind loads.
When this canopy was first designed in 1995, there were triangular bracket plates at the tops all four
columns. It appears that these brackets were removed from the W6 columns, probably when the stair was
relocated for construction of the Garden Room. These or similar brackets should be restored after
reinforcing the lower cross beam, as they contribute to overall stiffening of the canopy structure.
I hope that you find this satisfactory. Please let me know if you have any questions.
Respectfully Submitted,
Ryan S. Hellwig, P.E.
Massachusetts Professional Engineer #37300 - STRUCTURAL