HomeMy WebLinkAbout401 Skysail Ln - Special Inspections/Engineering - 08/27/2014bl 5ly!y5a, I L,o
STRUCTURAL ROOF FRAMING EVALUATION REPORT
Job No. ARMR1-14434 I REGiST
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38390 -i a
Date signed: August 27, 2 1� .
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Armor Roofing ADNA�-
16,70 Seven Lakes Dr.
Loveland, Colorado 80538
Attention: Larry Wilson
Re: Structural feasibility of re -roofing the residence at
401 Skysail Lane, Fort Collins
Dear Mr. Wilson:
On August 20 I examined and measured the existing roof
framing at the above residence for the purpose of determining the
structural feasibility of re -roofing with new standard weight
concrete tile shingles having a maximum weight of 11.0 pounds per
square foot (psf). Structural design criteria includes: building
code is 2012 International Residential Code (IRC) as amended by
the local building jurisdiction; roof snow load of 30 psf; wind
speed is 100 mph 3-sec. gust, exposure C; seismic zone B.
The existing house roof framing consists of all 2 x 4 W,
double W special trusses with a 24" spacing, top chords sloped at
a 4:12 pitch, and spans up to 29'-6" between supporting walls; at
the living room, there were 2 x 10 rafters with a 24" spacing, a
6:12 pitch, and a 15'-0" span between supports; the existing shed
roof framing consists of 2 x 4 rafters with a 24" spacing, a 3:12
pitch, and a maximum 8'-0" span between supports. I saw a "30/50"
loading stamp on a few of the trusses, and performed computer
analyses on several of the special trusses and on portions of the
roof framing.
There is a likelihood of over 3/4" of deflection of the roof
framing under full 30 psf snow load conditions, which may result
in cracks in the drywall, particularly at the taped joints where
the interior partitions meet the ceiling. Some of this deflection
may occur as soon as the tile is installed. Other cracks and
deflections may occur under snow load conditions, because the
maximum mandated snow load is twice the assumed dead load for the
weight of the building materials. Per our analysis, the calculated
deflection will be within the limits of deflection as specified
in the 2009/2012 International Building Code.
It is my opinion that the existing roof framing will be able
to support any new concrete tile shingle having a maximum dead
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load of 11.0 psf without the need for additional reinforcement,
provided that the existing shingles are completely stripped off
and provided that the new shingles are installed according to
their manufacturer's specifications. Because I am specifying
shingles by weight rather than by brand name, it may be necessary
to include product brochures with this report when submitting it
to the Ft. Collins Building Department for a re -roofing permit,
so that they can relate the brochure and the maximum dead load
weight we have approved for the re -roofing installation.
Inasmuch as the site review of an existing structure for the
purpose of observing the structural conditions requires that
certain assumptions be made regarding existing conditions, and
because some of these assumption may not be verifiable without
expending additional sums of money or destroying otherwise
adequate or serviceable portions of the building, the client
agrees that, except for negligence on the part of the Engineer,
the Client will hold harmless, indemnify and defend the Engineer
from and against any and all claims arising out of the professional
services the Engineer provides, with the stipulation that if
conditions not identified in this report are discovered during
subsequent inspections or repair work, this engineer should be
contacted for appropriate re-evaluation and recommendations.
Thank you for retaining our firm to perform this structural
evaluation service.
Very truly yours,
MARK BENJAMIN, PE, MSCE, SECB, CPHC
jCertified in the practice of structural engineering
iCertified Passive House Consultant
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if so desired.