HomeMy WebLinkAboutB17-0282_Hill Building Snow Review_1501079160.pdf 0
Snow
0 Country
Email:jpaine@snowcountry.bc.ca www.snowcountry.bc.ca Consultants ltd.
#3_8030 Nicklaus North Blvd,Whistler, B.C.—VON 1B8 —CANADA —TEL(604)932-8818
Snow Review: June 29, 2017.
To: Andy McRae LEED AP Principal - Eiimm Ile 2017- ' - )Valleyb Iho x+
4240 Architecture Inc ..)
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3507 Ringsby Court Suite 117 — ' aflelVa. -
Denver Colorado 80216 ° Dal
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Project: Hill Building Renovation, Vail Colorado - Snow Review -
The following review and comments are based on the May 26 2017 Design Development
drawings. The review and analysis focuses on safety and functionality for the proposed design
in the Vail climate. Further review of details can be performed at the CD stage as required.
Qualification:
This document is for the owners and architect of the above project to assist in dealing with
winter conditions. Any other use is unauthorized. By using this document the reader
acknowledges that the interaction of buildings with snow and ice is weather related and
therefore inherently unpredictable. As such there is the risk of circumstances that can create a
danger. The purpose of a snow management review is to reduce the risk to occupants, although
the risk cannot be completely eliminated. The analysis and comments are for the benefit of the
owners and architect who may decide which, if any, of the recommendations will be incorporated
into the project. The building has been tested for the anticipated climate conditions. The
ultimate responsibility for the design lies with the architect, not Snow Country Consultants Ltd.
The interaction between snow and buildings is inherently unpredictable since it is a weather
related phenomenon. My analysis and comments are based on experience gained over 35
years living and working in heavy snow areas and is my best prediction as to what may occur
with the proposed building design. I do not accept liability for damages or injuries that arise as a
result of snow and ice.
A. History:
The original building is more than 50 years old with several renovations and additions over the
years. Although the footprint and main floor remain mostly in place, the upper structure and
roofs vary from the existing with changing roof lines.
Hill Building, Vail—Snow Review June 29, 2017. Page 1 of 22
B. Climate Conditions -Vail Colorado:
Vail has a typical Rocky mountain climate with cold light snow and many sunny winter days.
High elevation areas typically have cold dry weather during the deep winter, with rain possible in
the late fall and early spring. Ice dams along the roof edges are common as roof snow melts
due to strong sunshine even as temperatures are below freezing. The wind direction is dictated
by the valley orientation with winds typically from the west or east.
Elevation: Approximately 8,200 feet.
Typical storm winds, cornices & ice: Winds are most commonly from the west and
variable. Cornice formations (wind formed snow overhangs) are common on north and east
facing roof edges. Roof ice dams are observed on the north and east shady sides of roofs and
are concentrated at valleys.
Typical total snowfall: The town receives an annual snowfall of approximately 180
inches. Accumulated snow on the ground in the town area is typically 2' to 4' but can vary
dramatically year to year.
Typical one day snowfall: Occasionally, 12" in 24 hour snowfall occurs, however, 5" to 10""
would be more common.
Average winter temperatures: Winter temperatures are typically well below freezing through
December, January, and February.
Freeze thaw cycles: Beginning in March, daily freeze thaw cycles are typical due to the
strong high altitude sunshine and cold nighttime temperatures.
Typical snow densities: 15 pounds per cubic foot (pcf) for settled snow. Roof snow
densities in late spring after settling and compaction due to age and temperature changes are
more in the 20 pcf range.
Ground snow load: The ground snow load given by the Town of Vail is 142 pounds per
square foot (psf) confirm for each site. This equates to approximately 7' to 8' of settled
compact snow using a density of 20 pcf.
Town of Vail Design Criteria: http://www.vailgov.com/departments/community-
development/building-safety-inspections
Seismic Winter Ice Barrier Air
Ground Snow Speed Topo . Frost
Design Veatherng Termite DesignJnderlayment Freezing
Load (mph) Effects ategory Line Temp Required Index
142 115 B B Severe 48 jht/Mod. -5 Yes 2500
http://www.sterlingcodifiers.com/codebook/index.php?book id=560
Section 1510.7 - Snow Retention: Section 1510.7 is added, to read as follows:
"New roof assemblies shall be designed to prevent accumulations of snow from shedding onto
exterior balconies, decks, pedestrian and vehicular exits from buildings, stairways, sidewalks, streets,
alleys, areas directly above or in front of gas and electrical utility meters, or adjacent properties. The
design of snow retention devices shall be provided by a licensed structural engineer or as
determined by the building official. Exception 1: Roof areas with a horizontal dimension of no more
than 48 inches that will not receive snow shedding from a higher roof. The horizontal projection shall
be measured perpendicular to the exterior wall line from the edge of the roof or eave to any
intersecting vertical surface."
Hill Building, Vail—Snow Review June 29, 2017. Page 2 of 22
Cornices & Pillowing:
Due to its cohesive nature, snow falling onto a flat or
sloping surface can extend beyond the edge. As a s� `—, ..)!Ade,
conn s
general rule snow can pillow out beyond vertical as - „,,iikli 04/
much as its depth, ie. a 3' snow pack could extend out ,
beyond the eave b as much as 3' or more.
Y Y � r
Overhanging snow be manually removed where it
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threatens people or property. Cornices are similar but
generally formed by wind driven snow deposits.
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' ��; " .'1 1i , ' 1 li ; C t.. .� , Photo: Vail.
r'_� . The combination of wind and sun
- s
I
' shading leads to overhanging
I1,i11.`.iliii{ ' ' " snow on the east and north roof
'I ' r' edges.
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Ice Formation: i'' '�4
Due to the frequent freeze thaw cycles and _ t,� -+ . = .• . , ! i
heat loss from buildings etc., snow that ' : + I
g
remains on roofs for several weeks or months
generally consolidates so that the bottom ) s
portion is nearly solid ice. This ice layer, . _
when lubricated with melt water, has a low ;
coefficient of friction between the ice and the ; ,
roofing surface. Large ice dams can form at ,i,
cold eaves. rt a� F
Photo: Vail home with large ice
w
l 111
dam extending up the roof over .interior area. . ''z
E - .
Hill Building, Vail—Snow Review June 29, 2017. Page 3 of 22
C. Snow Hardware - General Discussion:
Roof Snow Retention:
Snow retention devices such as clips and fences can be used to hold "most" of the snow on a
roof"most" of the time on slopes of 8/12 or less. Snow fences and clips do not prevent cornices
and overhanging ice from forming. There is a danger and likelihood of pieces falling even if the
retention system does not fail, especially as the snow depth increases. The purpose of snow
retainers is to arrest the movement of the snow and therefore reduce the frequency of snow
shedding as well as damage to valleys and build up of snow on lower roofs and surfaces. All
snow retention systems must be an engineered system designed to meet the load requirements
of the application. The supplier must design the spacing and installation of their system (clips or
fences) based on the roof snow load, slope, and roofing materials.
Heated Roof Edges:
The use of heated roof edges can reduce or eliminate ice formations and can be a useful tool if
there is exposure to occupants under the eaves, or if damage from an ice build up or ice falling
is a concern. The refreezing of meltwater onto lower surfaces must be considered. Heat tracing
systems should avoid the use of exposed cables as moving snow or snow removal crews can
easily damage them. Commercially available systems such as the Bylin (Pentair) "RIM" System
(www.bylinusa.com) and Heatizon (www.heatizon.com) work well but quantities should generally
be limited as these systems are expensive.
Heated Gutters and Downspouts:
Heated gutters are effective in removing meltwater
and reducing icicle formations along the eaves.
Gutters should only be used in conjunction with S�
snow retention to reduce damage from moving 'l.+d arty
snow, and must be located below the plane of the 'r
roof to lessen the chances of damage. Small well 4011
heated gutters are more effective than large cool _ = og
gutters that are susceptible to being clogged with -`' =►4, .d .
ice. Gutters are less likely to freeze on the sunny
side rather than shady side of roofs. The ' _ i�
downspouts draining the gutters must be heated ' �+
kw
until the water discharges into an area where ���
refreezing is not an issue, or until the drain is rl�i� ' `' ammo
below frost level. Rain water leaders should not ' rf.�
discharge onto walking surfaces where an ice slick '
will form.
Signage & Monitoring:
Many visitors to snow country are not familiar with the risks of accumulated snow on buildings.
The use of signage warning of the risks of snow and ice dropping from the buildings help create
an awareness of the local climate conditions. The occupants or
property managers must observe snow and ice accumulations and DANGER
mitigate any dangers. SNOW & ICE CAN
FALL FROM ROOFS
Hill Building, Vail—Snow Review June 29, 2017. Page 4 of 22
Roof Shoveling — Eye Bolts:
Most buildings will require manual removal of icicles and cornices during extreme conditions. All
personnel will be required to have safety harnesses that must be attached to roof mounted tie off
points such as eye bolts. Regulations vary but as a minimum tie off points should be spaced at
approximately 25' along the ridge.
Bylin (Pentair) RIM can help
reduce ice dams at eaves
and help keep ice out of the
gutter. It is more effective
_ than exposed zig-zag type
heat tracing.
4
Hill Building, Vail—Snow Review June 29, 2017. Page 5 of 22
11) Access
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TO REMAIN EL.=8179.9' '� �� s
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D. Overall Analysis & General Comments: Refer to the marked drawings for the following
reference numbers:
Hill Building, Vail— Snow Review June 29, 2017. Page 6 of 22
The winter weather conditions in Vail lead to overhanging snow on the north and east roof
edges. The addition of snow retention, heated eaves, and gutters will all help but not prevent
cornices. Operating staff will be required to perform regular monitoring of roof edges and
manual trimming of any threatening ice and snow.
1. Roofing Material & Snow Retention: The main roof areas are shown as 3.5/12 with
copper shingle panels. Snow on slippery metal roofs will accumulate and if not retained
will slide and shed off the roof. The choices of snow retention include clips (cleats)
spaced over the entire roof surface that hold snow in place, or snow fences near the
eave. The current drawings indicate both clips and a single or double row of fence
closer to the eave. Given the high pedestrian traffic as well as exposed balconies
below sloping roofs, the use clips and fences combined is warranted.
Although clips alone could be used, the addition of snow fences is an added security for
snow shoveling crews if overhanging snow needs trimming. Snow fences should run
to within inches of a gable end to leave as little roof as possible unrestrained.
I have dealt with snow shed problems on roofs where the fence is located 2' or more up
from the eave with slippery roofing below the fence releasing large pieces of snow.
The lowest row of snow fence should be located within inches of the heated roof edge
leaving as little unrestrained roof as possible.
•
The lowest fence should have "ice flags" or mesh to prevent thin
g
PM ICE SCREEN
layers of snow and ice from sliding under.
ICE SCREEN
ATeler WITH
UBOLT
Another suitable choice for roofing is asphalt shingle. The ?
combination of high friction granulated finish and snow fences ~� `
without clips would be sufficient to hold snow on the roof without
major snow shedding.
There are several manufacturers of snow retention hardware that are suitable for
copper shingles including TRA Sun & Snow (http://trasnowandsun.com) and Alpine
Snow Guards (http://www.alpinesnowguards.com/).
The drawings should include a note similar to the following:
Snow Retention Drawing Notes:
a. The snow restraint system is shown diagrammatically only to show the intent of the
areas of roof to be retained. The supplier is to provide an engineered system
designed for the local conditions, taking into account the roof snow load, roof slope
and roofing material. Samples of the proposed snow retention hardware will be
required for approval along with shop drawings.
b. The supplier is to provide engineered shop drawings indicating layout of their system,
spacing of all hardware, details for attachment and waterproofing, design criteria, and
specific conditions used in the design of the retention system.
c. The engineered snow retention system is to be supplied by TRA Snow and Sun Inc.,
Alpine Snow Guards or approved equal.
Hill Building, Vail—Snow Review June 29, 2017. Page 7 of 22
d. Snow Brackets: The manufacturer is to recommend a snow bracket suitable for the
roofing type. The bottom row nearest the eave is to have half the spacing of the
upper rows (ie. double the number of brackets for the bottom row) unless combined
with a snow fence.
e. Snow Fences: The manufacturer is to recommend a snow fence suitable for the
proposed roofing. Unless specified otherwise, use a two bar system. The snow fence
closest to the eave is to be within a few inches of the eave leaving as little
unrestrained roof as possible. The lowest fence is to have ice flags or mesh to
prevent thin layers of snow and ice from sliding under.
Recommendation:
* Use an engineered snow retention system as supplied by TRA Sun and
Snow or Alpine Snow Guards or approved equal. Shop drawings will be
required. The supplier is to confirm that their product is suitable for the
specified roof shingle.
* Snow fence fastening must be coordinated with the structural engineer for
any required blocking or reinforcing.
* Snow fences should extend to within inches of the gable end of a roof
section unless the area is fully retained with snow clips.
* The lowest snow fence should be at the bottom of the roof within inches of
the gutter or heated eave so that as little snow as possible is unrestrained.
2. Roof Assembly & Cold Roof: The roof assembly is shown as a non-vented system
with an approximate R52 of insulation above the structure. Although heated roof edges
will help reduce ice dams and icicles, a cold roof system, consisting of a vented layer
can reduce the amount of melting due to heat loss from the building. The vented cavity
of a cold roof system acts like a thermal break between the inside and outside as well
as carrying away heat loss by convection.
Tobiasson and Buska have a good article on the advantages of a cold roof system
compared with a non-vented system. For the proposed roofs a minimum airway height
of 1" would be suitable with venting along the eave as well as at the ridge.
http://www.poa.usace.army.mil/Portals/34/docs/engineering/MP-02-
5778,%20Guidelines%20for%20Ventilating%20Attics%20and%20Cathedral%20Ceiling
s%20to%20Avoid%201cings%20at%20Their%20Eaves.pdf
If a cold roof system is considered, further calculations of the required inlet and outlet
areas for venting can be verified.
Hill Building, Vail—Snow Review June 29, 2017. Page 8 of 22
Product such as Atlas CrossVent, 5.5" panel with •
1" air space gives an R 23.6. This adds 1" to the . •
proposed assembly but gives an air way that will
reduce snow melting from internal heat loss and
will reduce ice damming along the eaves, giving the heated eaves and gutters a better chance of -
eliminating ice.
http://roof.atlasrwi.com/products/acfoam Standard�,r„$nsrars
nailable-polyiso-roof-insulation/acfoam- � shown. C+Jsfarrr
drmerasoons aua raNe
crossvent/
As indicated in the proposed roof assembly, a continuous layer of ice and water shield
is required under the shingles to prevent leaks from ice dams. The self adhering
waterproof membrane should run at least 24" up all adjacent side walls.
Recommendation:
* Consider using a cold roof system by introducing a minimum 1" air space
as well as venting at the eave and ridge..
* The self adhering waterproof membrane (Ice & Water Shield) should run
up any adjacent side walls at least 24".
3. Gutters & Eave Heat: Gutters and heated eaves are indicated at all roofs. Although
snow retention and heated eaves and gutters cannot guarantee that there will be no
overhanging snow, the combination will reduce the possibility as much as possible.
Where eaves are over publicly accessible area, the combination of snow retention
hardware and gutters is a necessity.
Although Bylin (Pentair) RIM is an expensive product, it has proven much more
effective than exposed zig zag heat cables that are easily damaged and ineffective at
best.
Heat trace in gutters should be held in place with either adhesive fastened clips at 24"
or foil tape in order to keep the heat trace in contact with the metal gutter.
sp Fasten heat tracing with tape or clips.
•
•
Heat tracing of rain water leaders (RWL) should continue until below
frost level into a storm drain system, or until day lighting into a planter
area capable of accepting dripping melt water where a glacier will
form. Do not spill onto walking surfaces. 4,
Hill Building, Vail—Snow Review June 29, 2017. Page 9 of 22
Recommendation:
* Use Bylin (Pentair) RIM at all eaves.
* Use heat traced gutters and RWL at all eaves. Fasten heat trace in gutters
with foil tape or clips. Continue heat trace in RWL until below frost level.
1, i 01011 .i I
1ed : .
0 - Photo: Copper Mountain. Jail bar effect caused by
Pi - rri,
'I 7� I zig zag heat trace at the eaves.
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snow cornices
un
above! '
2 EAST ELEVITN
East Elevation: Overhanging snow and ice expected due to shade and wind conditions.
Hill Building, Vail—Snow Review June 29, 2017. Page 10 of 22
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--r--a-v _ _ { rye • -- _It - 1 _ -}' { i'sx
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- 2) Roof Assembly %1`: - -------g.; Flat roof - – WINDOW
BAY
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4. Gable Valleys: The east facing gable creates a valley facing north east that will have
deeper snow than much of the roof and is likely to have an ice plug blocking drainage.
The addition of Bylin (Pentair) Valley Panel to the bottom half of the valley as well as a
short section down the main roof to the lower eave will help keep melt water running.
The west facing valley is not as susceptible to ice since it will receive solar melting but
because it is so flat, a valley panel is recommended.
Recommendation:
* Add Bylin (Pentair) Valley Panel to the bottom half of the north east facing
valley with a short section running down the slope to the RIM at the lower
eave.
* Add a valley panel to the shallow west facing valley with a short section
running down to the RIM at the lower eave.
Hill Building, Vail—Snow Review June 29, 2017. Page 11 of 22
5. Flat Roof: The 1/4" per foot upper roof assembly is not specified on the section but a
granulated modified SBS 2 ply membrane would be appropriate. The granulated
surface will hold snow in place with little or no movement. Metal panels or metal
shingles are not recommended since snow will creep and drop unless snow retention is
added.
A vented roof assembly is not recommended since
it would give little benefit on a low slope. The
exception would be if the upper roof is vented with
the lower roof also being vented.
--/-N
At the south end of the flat roof is a chimney with a
cricket diverting water to the south. The valley of
the cricket should extend slightly beyond the \\\\&)D
g Y Y ` ciU,ifr7a.
chimney so that it is not terminating at the corner, \
making flashing difficult and allowing water to run
down the stone. A cant strip down the slope along
the chimney will help keep water from running
down the stone.
The 3.5/12 roof above the flat roof should have
snow clips to prevent snow from creeping down onto the flat roof.
Recommendation:
* The 3.5/12 copper roof above should have snow clips.
• Confirm the flat roof assembly. A granulated membrane is recommended
to hold snow in place.
* If a slippery roof is proposed, snow retention will be required at the edge
of the flat roof. A 2 rail fence with ice flags is recommended. The snow
fence should be within inches of the gutter to leave as little snow
unrestrained as possible.
* The gutter and RWL should have heat tracing the same as other roof
gutters.
• Review chimney cricket details.
Hill Building, Vail—Snow Review June 29, 2017. Page 12 of 22
_ 0 4 i Photo, Mammoth, California: Ice flowing
` , q. , down the stone where a gutter terminates
' , , " , and overflows with ice.
1 —
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a!
i , , ,,_ --._
, _ ,
..,.. in i : ",1 E.
11. 11x. - 1 ,
' r t
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MVP. 5) Flat R1pof: If
a sllppery,roof,
the snow ence
should be within
inches of he
6. Flat Roof at L3: The flat roof slopes and I gutter and have
will drain onto the balcony at L2 unless ice flags,
a
controlled. - - pm.f"
A high friction roofing is preferred as snow will -.Js - I ,� ' MN.—, „;,
stay in place without sliding. If a slippery roof --'-''''.. .."--4-----1,, --�'k ,± "" " yr R
yr oluoim
is used then snow retention must be added. + .7
' VA
The snow fence should be within inches of the
aaua•au
wrogutter and have ice flags. �.) Flat Roof' If mai,
fippery roofing
The detail section indicates a gutter similar tois used,add a
snow fence
the upper roof. The gutter and RWL should be �r close c tot — 6,
heat traced. _. uttei. DM/DEM
wa4narN
I _—
Recommendation: r _ -
* A high friction roofing is recommended ' — ' - •'� ' ='* r,
rl . .. r IRB 'PI
such as a 2 ply modified SBS membrane - '': : - ,,_-_,,,,,,,-,3%_.wiwaswamwww - -..,;,:. r
with granulated finish. :--�. ;.,;;_ j �,,�,
* If a slippery roofing is used, add a snow _
i I o 3roo,
1 a iuu
fence within inches of the gutter, complete : I - i-------2----'
with ice flags.
* Heat trace all gutters and RWL.
Hill Building, Vail-Snow Review June 29, 2017. Page 13 of 22
11) Access
Paints
BOULDERS9) Access Points:
RELOCATE ECONDARY IRRIGATION 5Y snow cornices above!
RELOCATED TRASH RES ', N `L ENTRY - `
STORAGE AREA[STAIR EW FLAT TDNF. -
DIRECTION&STORAGE y PAVING y I rot i
(ERSED FROM EXISTING) r , r _76 �If �-,1 J
6I* (DASHED) Ii -4',�+- 10) Flue ----- { .
� 4 til ,iti, - - _ _ 'I �+ n�Pn'i ' �~
- l iJ
-rte r .mss--- Y
+_. FOOT!
1- ‘ t A
y - . . ,. �+ ti — EAVE
1111'x y',a l '
1.--\ ` ____ 8) C imney \
...e.40.- ,t, vi o .:
•
7 Baleot & , j ' 6. v. R
Y `- ' -
Candens ers ti % - - � a _'� _ -
k p,,,p. el tkw,..
lir -- & J -`_j i4,--:p-- •
' 1
;� _ i �} } y' 1\ \ ! - NEW
' • �'��'' Y' ~ BOUL
+ ,_--• YII � IRRIG
04
' /! ".• --
\ - . T.
-- 0 NEW FIRES
I E_ -- r ,.. ,, 'WITH SW?.
'. '` ---. ::, ' w , AI k I�JErl
_ ��___ _ . 'BE(7D _
y iY" 5
'V ''4) a "p reel~ NCK v
-i, - 'd:?,. .. _ o 'r.. —•.- NEW DWARF-SE
7. Balcony & Condenser Area: The area is surrounded by building on 3 sides and will have
accumulated snow drifts. Due to the wind and shading, overhanging snow will occur at
the upper north and east facing roof edges. All upper roofs are indicated on the
drawings with snow fences, heated eaves and gutters as required.
As discussed in Item 4 above, the valley above this area should have a heated valley
panel.
The lower roof at B15 to B16 slopes onto the stair tower wall and should have a cricket
to divert water.
Hill Building, Vail—Snow Review June 29, 2017. Page 14 of 22
Drainage for the flat roof and balcony areas is not shown but should be treated as
typical flat roof drains. If the drain runs through cold space then heat tracing is
required. If the drain is over warm space, heat tracing is not required since heat loss
from within will keep the drain open.
Recommendation:
* As already shown on the drawings use snow fences, eave heat and
gutters.
* Add a diverter at B15 to B16 to lead water away from stair 310.
* Monitoring and manual trimming of overhanging snow will be required if
cornices form.
12c .f ITDR2if.) \-31-E-/--r- A%ciN4
O�S CoLo (12.0,50:
pzT�,E)� 6,...siDc_ -L ,v-
jah
— --- — _�
"A\ ^v '
ts, _4 . wr, -_,..r.r._
/• ,Prip — JUL, --J5
0.4111- 4's-61"...-,/wr.pr.r:wrocIF C..=LA A
1 04
.; till
IN)S-I
It ��! ^ I7 C.E.
llU &j7
'" �A��"1 y ,...,,,F„, SiI.GC..
Rl7c f\CL .ks1 IN5rq�
1/\35u�Ld2,,-- r 7�' t com e Nil L 1 .. r
I� oDr VF-P,f { L 1 2,v, cf Lz.. f
8. Chimney & Flat Valley: Similar to Item 5, the cricket should be wider than the chimney
to help keep water from running down the stone.
The two east facing gables at L2.5 form a flat valley that has a shallow cricket to bring
water to the east. Since this area faces east and will be cold and shady, the two
shallow valleys would benefit from heat tracing. Add a valley panel to each valley.
Recommendation:
* Review chimney cricket and flashing details.
* Add a Bylin (Pentair) Valley Panel to each of the shallow valleys at L2.5.
Hill Building, Vail—Snow Review June 29, 2017. Page 15 of 22
I11. L
Ji
I NEW GAS FIHEPUZE "
�M JJ I
I■ 4 E — I 4— I If
IREIYENEERON �VEMER 1 1 999 - r -
UPC11:1 1■'
I —I :FY I
CARETAKER I
\:. _ - , , .
— EASTBALCQ _
..3
I ! G
BALCONY EU
i
11—
H. _
I— % 8) Heat trace the —L - ,
l 1 1 DS—A/ 2 shallow valleys. . i .1 _ 1_ } I I
t
o
1I I I_ I —` 1.I . 1 I I � I
os
L -r .. .--- .. --
- Hi ---
i1 1 I 1 I
9. Access Points & Snow Cornices: The east facing gables will occasionally form overhanging
snow cornices. Monitoring and manual trimming will be required when cornices are
threatening access points or balconies.
Recommendation:
* Operating staff must be prepared to monitor and trim overhanging snow.
- . .
,
rill- 1
,ti ./
'i,,.: ��r Photo: Cornices on the north
- I - .- and east roof edges.
,
r ,. ,..
�► ! .
MP Nciti 0}&VML 1001-r
.1 ,a'
Hill Building, Vail—Snow Review June 29, 2017. Page 16 of 22
`T) �T {]1� 30i (19� A 7 5 (%7`141 r `1E) Yn TI s (4� {3) 24
l I T
Cornices at 1 1 0) Iue )- I f ,___--
north
=
north and east I lam'. �� -{
roof edgs 1, I �� _ �.._ i ,
■■lam _ _ I �_
n�E oslfe xf., I aiiel •`�ifl�I" INF FIA rik. .A91 �'.__� _
4
I MN Ill
a. u.,x.L, _ .., is ■IIIk.
li�;:m�i o moi; 1 - -''_I -- j=� 11�r _ u — -�
n -, -61
w�,..„., r. —1 :.I"•. ��"�'.'.I:I�Iu1i�aSornfVAF,���r. - -- _
r.11. 17411-1111!"-AR I�F 'E j
��.usnlw now I-: moi:". -AI. � it
ql.,IMMUU I j - 1 tag - �L7. 11) Access Points. 11 1111 11. 11 -11 --[j II-- 11- 11 rt,
�.I.LO^Y°=URI,o� I _ Consider canopy ■ �h Nom.
y..,,,•. ---=---- --
--- 5., ,_ door --�
r - ,,, o ersair om a_ t
_ _ „IL_
-1
1
_,
E____ _ _ .. _ lm.. 11, EwAtm"mirmEn —1 - -.." . ____ -
uoxb.m..a — _I
j - 111 I lug � 6 I� I N, —
Ii..1j t4,! 1
sim
1-,--I,n.ol..u,:n. ';y Ts.u.�.rv.ol�l�uou.lm,�==-00J �'u ��"Tn� 1
North Elevation: Cold and shady, expect increased snow and ice on roofs as well
as overhanging snow at roof edges, drifts on ground.
11) Access
s ints BOULDERS 1k 9) Access Points:
---....4(-Q.) RELOCATE ECONDARY
IRRIGATION SY snow cornices above! "
RELOCATED TRASH RES N -L ENTRY
STORAGE AREA(STAIR EW FLA4'TDNE
DIRECTION&STORAGE f PAVIN •G
)I REVERSED FROM EXISTING) - a? 1
1 NEW PLANTING RED WITH r ' '
l'-13" 5s BOULDERS&DRIP -_. � y{ t4*�'r r $
J g4GRESS/E.ONE
IRRIGATION SYSTEM r�_ � a5' 11-:'',"1":-i
— ` , ' £AVEWASHEO)i � i '�
-- - 10) Flue ��11 � _
c!9 _ ,12) Balconies ,- -.±-----.
Y `� - - ( REDO
_ . ._ „ _
FOOT
� y � ) ) 1 ,`y LAVE
cn ' a 11 .�'Y -1---1-yr•s - '•} 't + ,. y o ` '-yr� G
8) C mne 'O
I Y iI1. . B 33
10. Gas Fireplace Flue: The chimney is well down the slope from the ridge so creeping
snow must be considered. With snow clips and fences combined with a cricket the flue
is unlikely to be damaged by snow. Another option to consider is using a direct vent
fireplace with a wall vent rather than a roof vent, avoiding the issue completely.
Recommendation: Consider using a direct vent fireplace rather than a vertical
vent. Roof vents must have a cricket to divert water and snow and protect from
damage.
Hill Building, Vail–Snow Review June 29, 2017. Page 17 of 22
11. Access Points: There will be times when the roofs above the access to Stair 125 and
the secondary access to basement will have overhanging snow. Snow retention,
heated eaves and gutters will all help but will not prevent overhanging snow.
The options are to add a lower canopy over the doors to give positive protection, or for
operating staff to monitor and manually remove overhanging snow. Even with a canopy
to protect the doors, cornices should not be allowed to grow since the area each side of
the doors is easily accessed by the public.
The roof plan shows two rows of snow fence but if there are also clips covering the
entire roof plane, a single row of fence located within inches of the heated eave strip
will suffice.
Recommendation:
* If the door to stair 125 will be frequently used in winter, consider adding a
lower canopy to give positive protection from falling snow cornices.
* Operating staff will be required to monitor and manually trim overhanging
snow along the north and east elevations to reduce public risk.
* The snow fence nearest the eave must be within inches of the heated eave
(Bylin RIM) in order to leave little snow unrestrained. The snow fence
must have either ice flags or mesh to prevent thin layers of snow and ice
from sliding under.
------_. Ea Me
1 1
Photo, Vail:
'1 The snow boarder is oblivious
{ to the danger overhead.
= � �.",q" Periodic monitoring and
':r.°r,'_ I manual trimming of snow
I• 1 i •-ate•- , overhanging is required,
; .h
�' especially on north and east
F ' - facing edges.
10 m'71,, r -s
I
i wr 1.r; ,_ , , %.
i
Ate ,.. ,
Hill Building, Vail—Snow Review June 29, 2017. Page 18 of 22
12. Northwest Balconies: The roof edges over will have overhanging snow that will require
occasional trimming.
Balcony drainage is not indicated but the choices are to run water off the edge or collect
with gutters or drains. If water is collected into scuppers, icicles will form unless a bit of
heat tracing is added. Any cold gutters or drains will require heat tracing.
These comments apply to all balconies as far as drainage and watching for
overhanging snow.
Recommendation:
* Review balcony drainage options. Scuppers will form icicles unless heat
traced.
* Monitoring and manual trimming of overhanging snow will be required.
. 7
1 ,1L51 n7,f, tp
I, ,0) . ,„,,,, 02 (d A4' Cr; CFE) :g°) W�> Mn7
13) Chi ney Cricket l
i 1 i i I 1 iii i / .1. " _ _
1 - -RFWEIMI. i- -
�: . - mac um L�LJ
1 yip lip'. J .` llirli __ llp� lfll
,�;y � �rlirll i;-.- ',%-..11-4141.--
'� 14) West Bal �Tit►1
Zwfg �B�1ur
� r. - � ... ��n . _"1115 W •HH on 11u1 --- -- ---r-- - -
awn}r 3 '' _�_.:'� i - ::. : .
14 io- Ni1�H H o-11R8 I / _
FE-777- .�1J.i
��� .... mrJ_L n 31 W I i A_u riIIFI £jIIiiIhI
r�4iI i rru M1p -
ri
�:� iJiIjIjiiiIiiL..
�,.a
7-----, - _
..„. _ _. ., ,_
A ,
""„,,,,,„.,,r,„
. ,
1 --_ _,, \I ----1"- ' - 1 . _4.3FC0,191UM43-..
I1 -!t7-Eo-_
1 1 1 1 1 I 1 I 1 1 1 1 I
West Elevation: Afternoon sun and prevailing winds lead to less snow
accumulation as well as less ice damming.
13. Chimney: The chimney cricket should be wider than the chimney to divert water
around.
Recommendation:
* Review chimney cricket.
Hill Building, Vail—Snow Review June 29, 2017. Page 19 of 22
14. West Balcony: The west facing roofs above the balcony are not as prone to
overhanging snow as the north and east roofs. Although monitoring is still required,
trimming will not be required nearly as frequently as the shady sides.
The trellis is mostly covered by upper roof so only blowing snow will accumulate.
Occasional snow brushing may be required.
Recommendation:
* Monitoring of upper roofs will be required by operating staff.
C3i (7) ",-,:'�) J.) A �� �r� x _s;�� „6; 11D � �,
r Crickets and
14, - _-
flashing should
I
1®Ne�Fnsllx[x-"'
`r� - keep water clear X511"
MI - r7,-°;,7-
i
„:,,,";,',7„,"°0 � �� � \ I 4
-' ;"'Cr'''''' 1 l � a -= _. waterand ice do 2
=of stone so that
' ® m,xs rc
u - a tea. L
�,o,
aMetrgn r.rrt.x - .
x.--7.,v x not flow down
r�r.,xr r.� �, w
��■Nadi ali I, •� ; �- stone.
. . . . 1 1 . /1.
// II {■■■ 1I •,pp,99■■■■ III. r■r.
ww I•I� I �I•I ��Ill I II II� �Liil i iiia �r i �RIIII II I
�.xrM `f �� �MIIMINIIM— 2— r
I
. ,rr.n •urr yJ ___— E
1 w
,r..lx„�I.r�o�., 1hii. iiiui. i I t
::=,=1 � � _ l'. I r if�„oo.
.Ir MMIIIii ...
_ r;--
rts
— ”
Ai .' Lin ilni ' le r_ _ - � EW,
A
mo
.S ID '{ —mull l.„p, .I.,L:..,wr 1\., u.,oL r..luwwur .,oma 1 TH Ell
El PI.5
South Elevation: Sunshine and the cross wind will leave less snow on the
south elevation.
E. Summary:
The intent of the design is to hold snow on roofs with little or no shedding. The use of 3.5/12
roofs with engineered snow retention hardware will successfully prevent major avalanches.
There is always a possibility of overhanging snow or icicles dropping to areas below,
requiring active monitoring and snow management.
The use of an engineered snow retention system on all roofs, combined with heated gutters
and eaves will reduce the possibility of snow or ice dropping from roof edges.
The amount of roof snow melting and subsequent ice dam formation can be reduced by using
a cold roof system. The use of a cross vented layer over the entire roof such as AC Foam
CrossVent are suitable for the project and recommended.
Hill Building, Vail-Snow Review June 29, 2017. Page 20 of 22
F. Owners & Building Operators Responsibility:
Buildings in heavy snow areas require a proactive approach by those responsible for
maintenance and safety. The final building design produced by the architect is an attempt to
respond to a number of requirements including site and environmental conditions. Dangers
and maintenance issues relating to snow and ice are weather related and as such are
somewhat unpredictable.
G. Physical Snow Management and Monitoring:
The operating staff of the building will need to monitor the build-up of snow and ice on roofs
and canopies, and be prepared to manually deal with overhanging snow or any other
threatening build up. The monitoring should be done on a daily and weekly basis during the
winter months, as well as a thorough review in the spring for any damage caused by the
winter weather. Close off any areas of hazard as necessary during high risk times, until the
hazard is eliminated.
The above comments are intended to raise major issues for discussion rather than be a
thorough review of all plans and details. Details can be reviewed as they are produced and
as the design is finalized. I look forward to further dialogue.
0 0
III O O
Jon han C. P Engem 0
Snow try4Consultants Ltd.
Hill Building, Vail—Snow Review June 29, 2017. Page 21 of 22
Appendix A: Climate Reference
Climate Averages:
[hide]Climate data for Vail, Colorado
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec I Year
II=Mil I.
Record 51 55 66 74 82 91 95 92 86 79 66 51 95
high °F (°C) (11) (13) (19) (23) (28) (33) (35) (33) (30) (26) (19) (11) (35)
N.
Average 29.0 33.0 42.1 49.7 60.7 72.2 77.7 75.3 67.1 54.1 37.6 28.1 52.2
high °F (°C) (-1.7) (0.6) (5.6) (9.8) (15.9) (22.3) (25.4) (24.1) (19.5) (12.3) (3.1) (-2.2) (11.2)
6.5
Average 5.7 8.5 16.4 23.6 30.8 35.2 41.2 40.4 33.0 24.8 14.6 23.4
(-14.2
low°F (°C) (-14.6) (-13.1) (-8.7) (-4.7) (-0.7) (1.8) (5.1) (4.7) (0.6) (-4) (-9.7) )
r (-4.8)
Record low -21 -32 -1 13 19 28 22 14 1 -16 -22 -32
°F(°C) (-29) (-36) (-18) (-11) (-7) (-2) (-6) (-10) (-17) (-27) (-30) (-36)
Average ar
1.87 2.08 1.80 2.22 1.83 1.49 1.95 1.86 2.07 1.72 1.91 1.61 22.41
ecipitation i
(47.5) (52.8) (45.7) (56.4) (46.5) (37.8) (49.5) (47.2) (52.6) (43.7) (48.5) (40.9) (569.1)
nches (mm)
Average
33.8 33.2 24.4 22.2 4.8 0.3 0 0 1.1 7.7 27.6 28.3 183.4
snowfall
(85.9) (84.3) (62) (56.4) (12.2) (0.8) (0) (0) (2.8) (19.6) (70.1) (71.9) (466)
inches (cm)
Average Fir
precipitatio
12 12 9 a 9 8 10 12 10 7 10 0 119
n days(>_
0.01 inch)
Source:Western Regional Climate Center"°j
Hill Building, Vail- Snow Review June 29, 2017. Page 22 of 22