Hail, fellow Northerner!
NW OH, here, and I hear a lot of neighbors complaining of this exact
same thing. (When we get snow, anyway.)
There isn't a lot available online that deals specifically with ice
damming and cathedral ceilings. Some of what I did find wasn't very
heartening:
"If you have a CATHEDRAL CEILING, then your problems are generally
even more complex and expensive to fix because you may have to replace
all the existing insulation with insulation specifically designed for
cathedral ceilings, or you may have to install baffles in order to
provide an air space to allow proper venting. Either way will involve
demolition of the ceiling or the roof in order to get at the
insulation."
Roofhelp.com - Cold Weather Issues
[ http://www.roofhelp.com/winterroofing.htm ]
"Ice dams caused by cathedral ceilings are more difficult. The same
principles apply to preventing ice dams — stopping house air leaks,
good insulation, perhaps ventilation — but cathedral ceilings are
harder to get to. If you have ice dam problems with cathedral
ceilings, you can fix the problem when re-roofing. Remove the
sheathing, seal and fill the cavities with insulation, and replace the
roofing material. A well-sealed roof will not need ventilation. If you
are uncertain whether the sealing can be done effectively, leave a
ventilation channel under the sheathing from the soffit to the peak.
Sometimes insulation can be added to the ceiling inside, although this
approach will not catch the air leakage."
"Attic Venting, Attic Moisture, And Ice Dams"
[ http://www.cmhc-schl.gc.ca/en/burema/gesein/abhose/abhose_ce13.cfm ]
Ouch.
The state of Alaska, unsurprisingly, addresses the issue in a somewhat
less alarming fashion. On page three of the following document, you
can find diagrams detailing how to handle ventilation for a cathedral
ceiling (you'll need Acrobat Reader installed):
http://www.ahfc.state.ak.us/Department_Files/RIC/Construction%20Manuals/AHM/ch6-attic-roof.pdf
HandymanWire.com suggests installing flashing:
"Ok, either you have alot of insulation and ventilation and you still
have ice dams, or, you have cathedral ceilings or a roof attic design
that makes adding those impossible. In that case you can have an ice
belt installed.
An Ice Belt is Metal flashing installed all the way along the eaves
and extends to the area of the roof above the attic. It covers the
area where the ice will form. It serves two purposes, first it
provides a surface which permits the snow and ice to just slide off
preventing most dams. Second it provides a surface that water won't
flow up under as it as it does with shingles."
Handyman Wire - Ice Dams
[ http://www.handymanwire.com/articles/icedams.html ]
I did find some great diagrams explaining how a "cold roof" system
works:
The Family Handyman - Defeat Ice Dams!
[ http://www.familyhandyman.com/200009/features/ice_dams/main.html ]
The first page briefly describes what ice dams are, then, over the
course of three pages, explains how to stop them with a cold roof
system. The third page of the article notes that the "cold roof"
solution may be difficult to implement on attic-less home (because of
ventilation issues), but does suggest secondary strategies to help
alleviate the problem). Terrific pictures here, very easy to
understand.
A brief paragraph at Repair-Home.com suggests a different solution to
prevent ice dams - roof ridge vents. Though the paragraph talks
specifically about attic ventilation, it's my understanding that roof
ridge venting may be used for attic-less homes as well:
"Often over looked, Attic Ventilation is necessary for proper cooling
of your home in summer months and prevention of ice dams during the
winter months. Older homes rarely provide adequate ventilation
systems. The old wood rectangular vent system generally lack the vents
in the soffit area to properly create and maintain a cold roof in the
winter. Similarly, during the summer months, the system does not
create a draft when there in no wind. The results causes the roof to
warm too fast in the winter, melting snow and ice, which re-freezes at
the ridge of the roof. When the frozen run off builds up an ice dam
occurs. During the summer the attic get extremely hot, straining the
A/C system and cause premature damage to roof shingles. There are
several solutions available. One of the most popular are the roof
ridge vents. These vents, couple with vents in the soffit, creates its
own draft on still, hot days and maintains a consistent cold roof on
cold winter days. Expect to pay around $500.00 for a 40 linear foot
ridge vent and the soffit vents, installed."
[ http://www.repair-home.com/price/singleitem.html#avent ]
In virtually every page I've come across, poor roof ventilation has
been mentioned as *the* number one cause of ice damming. There is an
article here discussing, in mostly layman's terms, the importance of
proper roof ventilation:
Ventilation
[ http://www.resercon.com/Ventilation.html ]
...and one here with simple diagrams:
[ http://www.factsfacts.com/MyHomeRepair/ventilation.htm ]
Obviously, every roof is different, and to get a good handle on a
solution for your particular roof, you'll need the services of a
skilled professional to determine where exactly the problem lies, and
how much you can expect to pay.
Searching at the National Roofing Contractor's Association with the
49503 ZIP code in Grand Rapids, for registered contractors within a 25
mile radius, yielded a short list:
http://www.nrca.net/directory/contractor/dmgvicinity.asp?zip=49503&Miles=25&WorkType=RES&submit=Submit
I hope this information is of help to you! Good luck!
missy-ga
Google search links:
[ ://www.google.com/search?q=%22cold+roof%22&hl=en&start=0&sa=N ]
://www.google.com/search?q=%22ice+dams%22+cathedral+ceiling&hl=en&start=0&sa=N |
