b'echnicalCorner PreventingBuild-Up of theIce Dams Ice dams are build-ups ofatC ses oflce D ssnow at the upper part of the roof iceau amthe lower edge or eaves of aIcicles are only indicators ofwill melt and run down the roof to roof and in gutters. They are formedthe interactionsroof-sn -iceemerge from the protective snowofowwhenin heat escapes intodams. Decorative icicles hangingblanket, freeze and build into an terior theattic andthrough theroofbeyond the eaves are solidifiedice dam that blocks snow water on decking.eaves, or roof over snow-wa that is out and overthe upper part of the roof. This Theter hang will stay as cold as thethe ice dams,are hazardousmay be a more vulnerable leak out and sideair,evenwhentheupperonly tothosewhocarelesslypositionthanatthegutteror emSuc secondaportion of the roof is warmed byknock th down.eaves.hry ice dams, the heat escaping from the hou Thevisible troublemakeronwhich are often m tiple ice dams se.ulMelting of the snow occurs at thesnow-covered buildingsisthehigher on the roof,visible to are snow-shingle interface and runsmassive ice formed from succes observers who take the time and downwardunderthesnowassiveflowsofroofsnow-waterwinter-cold discom tofortexamowever theowners snow-water.H , whenitfreezing as it emerges from theinereaction of home reachesthecoldeaves,itprotective insulating blanket ofor building owners to the "rake or refreezes and ice builds up into asnow on the roof. The disru ivesh l-it-off" adviceinexpeript ove of dam. Its size will depend on cli forces of expanding ice may dam encedauthorities.Complete mactic conditions, the roof pitch,ageroof shingles andtheroofremoval of the snow offroof, the type of deck and the size of thed king. The glacier-like forcesof course,dam forec prevents ice overhang.on the roofs and valleys,partic mations. in tly A great amount of water canular, deserve better considerationAmateurs,whofrequenpondbehindanicedam.Theby buildingappear innews as injured or designers.the water b up under the shin Ra gutters are often blamedkilled,not risk walking on acksinshould gles, drips through nai holes andasice dams. Ice slippery roofs.should pru-Iresponsible forNor betweenlapjoints in the woodfilledrain gut-decking or r sheathing and intotersmay oof thehomeorbuildingwherecontributeto extreme damage can be done toconcentrated the interior ceilings andofoverloads at the~ inside the extension walls.It can alsoeaves. Massive stain, blister and cause peeling oficeinand wood siding, as well as soak andaroundeaves~ rotfascia and soffit boards.initiallyslows the Ice dams develop on buildingsmeltingand wherever androof-snowinterfereswith whenever accumulates on roofs toofroofdrainage depths aninchortwoandwhentheandrun-offs. weather turns or remains gener However,rain ally below freezing for three orgutters, like icifour days. Generally, the deepercles are simply the snow, either by single snowsymp ic tomat of fallby accumulations, and thesnow-water or lower andmorepersistenttheactions,rather subfreezingtemperatures,thethan causative.dent bu owners permit such ilding more in itable and sizable arewalking or stomping around on evSecondary Ice Damswinter-embrittled roofs th were theiceformationsfortypicalat houses.With onlypartialremovals,not designed or manufactured to'