| Ice dams can be nightmares, potentially causing | | | | gable vents. |
| extensive water damage to their victim's homes. In | | | | Don't make this attic insulation boo boo! In an effort |
| 1993, record breaking snowfalls and an unusually long | | | | to fully insulate the attic floor, people sometimes |
| and cold winter caused tens of thousands of homes | | | | push the insulation deep into the corner where the |
| throughout New England to suffer ice dam related | | | | roof meets the attic floor. Not good! This causes the |
| damage. And many of these homes' roofs hadn't | | | | lowest part of the roof to be colder than the rest of |
| leaked in the previous 20 to 30 years! If anything | | | | the roof, setting up the possible formation of an ice |
| positive came of this disaster, it was that more | | | | dam. Inspect your insulation, and if you see this |
| people have become aware of what constitutes | | | | occurring, pull the insulation back away from the |
| shoddy roofing practices. We realized that roofers | | | | inside of the roof so air can reach it. If you have |
| had been getting away with installing minimally | | | | blown-in, loose insulation, there are styrofoam dams, |
| efficient roofs for years... all because the relatively | | | | available at most lumber yards, that can be installed |
| mild winters we had been blessed with never put the | | | | between the floor joists to hold the insulation back |
| roofs to the test! Whole housing and condominium | | | | from the inside of the roof. |
| developments were the victims of low quality roof | | | | If you have soffit vents, the same holds true. |
| installations by builders. And was there ever a price | | | | Insulation should not block the flow of cool air up |
| to be paid for this false economy... | | | | from the soffit to the ridge vent. |
| millions of dollars in interior wall, ceiling, and other | | | | What about roof mounted heating cables? Heating |
| property damage! How ice dams can cause such | | | | cables mounted on the roof are designed to form a |
| damage is a mystery to many people. Let me first | | | | path for melted snow to travel through an ice dam. |
| explain how they cause the damage that they do. | | | | The will not work if an ice dam forms above them. |
| Then, I'll offer some suggestions on how to | | | | They will also not work if you forget to turn them |
| bulletproof your house against them. A warning... don't | | | | on. |
| expect a sure cure to be cheap!! What is an ice dam, | | | | The biggest downside to these is that you cannot |
| and how does it form? When snow accumulates on a | | | | leave them running all the time, or they will quickly |
| roof, a cycle of melting and refreezing occurs. In a | | | | burn out. So you must remember to turn them on |
| perfect world, the snow would melt off the roof, | | | | and off. And if the electrical power goes out... forget |
| enter the gutters, and flow harmlessly to the ground. | | | | it! Most homes do not have electrical outlets located |
| Or the snow would evaporate from the action of the | | | | outside the house at the roof line to plug the heating |
| sun, and never really melt off unless the outside | | | | cables into. Whether you do the job yourself or have |
| temperature rose above the freezing point. However, | | | | an electrician do it for you, be sure to put a shutoff |
| two key factors interact to cause problems... the | | | | that controls all the cables at a convenient location. |
| outside temperature and the temperature of the | | | | Also, be sure that the circuit is protected with a |
| inside of your attic. | | | | GFCI (ground fault circuit interrupter). |
| The warmer your attic is, the more melt off that | | | | Having a properly insulated and ventilated attic is a |
| occurs at the roof surface. This melted snow would | | | | better solution, because it requires no ongoing |
| normally flow off the edge of the roof. Under certain | | | | involvement from you! So weigh the comparative |
| conditions, though, when air temperature is very low, | | | | costs of each solution before choosing one or the |
| the water refreezes at the edge of the roof, where | | | | other! Can anything be done to the outside of the |
| the interior roof surface is not being warmed by the | | | | roof to stop ice dams? Not to the roofing itself. But |
| attic. This refreezing gradually forms what is fondly | | | | a properly installed roof can eliminate much of the |
| known as an "ice dam", a growing heap of ice that | | | | damage they cause. Even if you did everything |
| blocks path of the melted snow. | | | | recommended above, ice dams might still form under |
| Once this dam forms to a certain height, the melted | | | | severe conditions. Modification or replacement of |
| snow that pools up behind it can suddenly leak back | | | | your roof is the only sure way to permanently stop |
| under the roof shingles and into your home! On a | | | | the leakage. The trick is to get your roofer to do the |
| roof with a low slope, it only takes a small ice dam to | | | | job right and not cut corners. Ditto if you do it |
| cause water backup and leakage. | | | | yourself! Roofing is one of the easiest parts of |
| Contrary to popular opinion, gutters do not cause ice | | | | building a house, but is labor intensive and potentially |
| dams. However, an ice dam can extend into a gutter | | | | dangerous. It is also a place where contractors tend |
| if weather conditions permit. | | | | to skimp, because the effects of a poorly installed |
| How can ice dams be prevented in the first place? | | | | roof may not become apparent for years... long after |
| The answer... insulation and ventilation! INSULATION... | | | | the check clears! A quality roof installation in the |
| Since we have determined the main cause of ice | | | | snow belt should have four components: proper |
| dams to be an overly warm attic, a good start in | | | | flashing, ice and water barrier installed on all roof |
| inoculating your home against ice dams is to reduce | | | | edges and over all valleys (places where two roof |
| the attic temperature. Installing additional insulation on | | | | lines meet), rolled asphalt underlayment over the |
| the attic floor is as easy as laying additional batts | | | | entire roof, and quality roofing shingles with the |
| across the existing ones, or having more insulation | | | | proper overlap. |
| blown in. | | | | If you have one specific problem area, though, and |
| However, there are limits to the usefulness of this | | | | your roof is otherwise sound, you can do the |
| procedure... regarding Murphy's Law of diminishing | | | | following repair procedure to fix the local problem: |
| returns. | | | | Remove all roofing material from 3 to 6 feet back |
| Once you reach the your area's optimal R-value (a | | | | from the lower edge of the roof. Repair or replace |
| measure of the insulating value of a material), further | | | | damaged or rotten plywood underlayment as |
| increases in the amount will not show appreciable | | | | necessary. |
| decrease in heat loss per dollar spent. | | | | www.owenscorning.com for more information. They |
| Visit Owens Corning's web site at http:// Install the | | | | have state by state listings of insulation standards |
| self-adhesive ice and water barrier over the plywood. | | | | and recommendations... the most thorough listing I |
| Since the barrier is three feet wide, install two | | | | have found anywhere. |
| overlapping courses if you want extra waterproofing | | | | Install weatherstripping and/or insulation on attic |
| or if the slope of your roof is low. | | | | stairways or hatchways, and on attic floor-mounted |
| Reinstall new roofing shingles. | | | | louvers for whole house ventilation fans. |
| If there is flashing in the leaking area, such as in a | | | | Be careful if there are any exposed recessed light |
| valley, and you suspect a problem with it, the basics | | | | fixtures or vent fans poking through the attic floor. |
| of the repair are as follows: Remove roofing material | | | | Some of these are not designed to be covered with |
| around the flashing giving yourself an additional two | | | | insulation. Get some information from the |
| or three feet of exposed underlayment. Do repairs | | | | manufacturers on the suitability of covering them! |
| to the plywood underlayment as necessary. | | | | VENTILATION... |
| Install ice and water barrier across the area to be | | | | Even with optimal insulation, there is still heat leakage |
| flashed, and cover all exposed underlayment with it. | | | | into the attic. This is where the value of ventilation |
| Then, install the flashing, followed by the shingles. The | | | | becomes apparent. Without adequate ventilation, |
| ice and water barrier will act as a diaper under the | | | | heat will build up regardless of the amount of |
| flashing if the roof cement that seals the flashing fails | | | | insulation. (As an added plus, ventilation removes |
| after a few years. And it will fail... eventually. | | | | water vapor also, which can condense in the attic |
| In this sort of repair, there is no need to install an | | | | and cause dry rot on wood and rust on metal items.) |
| asphalt felt underlayment. | | | | Increasing ventilation can be a major or semi-major |
| However, if you were to decide to replace the entire | | | | project. The usual recommendation for venting is 1 |
| roof, you should cover the entire roof, including the | | | | square foot of vent for every 150 feet of attic floor |
| ice and water barrier, with the asphalt-impregnated | | | | area. Most older homes don't even come close to |
| felt. CAUTION: Be sure that the ice and water barrier | | | | meeting this number. If you have small louvered |
| will not chemically react with the asphalt!! Other | | | | windows at either end of the attic, known as gable |
| methods for ice dam removal and prevention... | | | | vents, you may be able to replace them with larger |
| Mechanical removal of an ice dam could well destroy | | | | ones. This will take some carpentry skills, but is not a |
| your roof. However there are a few ways to | | | | really tough job unless you have difficulty getting to |
| improve the situation... | | | | either the inside or outside of the windows. |
| 1) Removing the snow from the roof can help slow | | | | If your house's roof overhangs the outside walls, add |
| down dam growth. On very low-sloped or flat roofs, | | | | vents into these overhangs (soffits). To complete |
| some folks shovel off all the snow! On a roof with a | | | | the ventilation system, add a ridge vent. |
| greater pitch, removing three or four feet of snow | | | | This is a specialized form of vent that mounts along |
| above the roof line will slow down the growth of the | | | | the length of the peak of the roof. Cold air entering |
| dam. There is a special tool for removing snow called | | | | the soffit vents rises along the inside of the roof and |
| a roof rake. Here's a shot of NH doing a little snow | | | | exits through the ridge vent, cooling the roof and |
| removal. Roof rakes are great to use if the show is | | | | removing moisture (that important fringe benefit) at |
| light and not very crusty. They also are somewhat | | | | the same time. This is the best form of ventilation, |
| dangerous to use on ladders. So be warned! (Yes, I | | | | but cannot be fully utilized without the soffit venting. |
| know, a sometimes a man's gotta do what a man's | | | | However, I would still recommend the addition of |
| gotta do!) 2) Chisel grooves into the dam to allow | | | | ridge venting into any home getting a new roof. Even |
| the water behind it to drain off. This is a good | | | | without the soffit vents, the action of the ridge vent |
| emergency measure... especially if rain or a sudden | | | | will lower the temperature and reduce moisture in the |
| thaw is coming! Careful with those those shingles!! | | | | attic somewhat, in conjunction with the |