Ice Dam Prevention – How to Stop Ice Dams

Are you ready for the upcoming winter? What about your home, and more importantly the roof?

The combination of cold winter weather and the heat escaping through the roof of a building can result in an ice dam. If an ice dam forms on your home it can cause serious problems, so it is important to learn how to prevent these ice formations if you live in an area that experiences snow and ice during the winter.

What Is An Ice Dam?

Ice dams are ridges of ice that form along the edges of a roof when snow has melted and then refrozen. Water can then build up behind this ice dam as more of the snow melts. If enough water builds up, it can seep between the roof shingles and cause damage inside your home.

Ice dams can occur when snow builds up on a roof. Normally, the snow will remain frozen until the weather begins to improve. As the temperature rises, the snow will either evaporate harmlessly into the air or melt and run away into the gutters, leaving the roof unharmed. However, under certain conditions, the snow can melt and refreeze. This can cause problems.

If the heat is rising up into your attic and escaping through the roof, it can melt the snow, particularly at the apex. Hot air rises, so it will heat the highest parts, in the roof’s center more than the edges. The melted snow runs down towards the cooler roof edges, where it refreezes into ice. This ice can accumulate along the roof edges, forming an ice dam, behind which water will accumulate as more snow melts. Once the ice dam has reached a certain height and enough melted snow has built up behind it, water can begin to leak through the roof shingles.

Ice damp causes water to leak inside the house

Causes and Effects

Ice dams are most likely to occur during extended periods of cold weather, when there is a lot of snow and ice. This means that ice dams are more likely to occur in some areas than in others, although it is important not to ignore the problem just because you have experienced a series of mild winters. If cold weather is likely to occur at some point in the future, you should make sure that your home is protected against the snow and ice. Spending money on prevention now could protect you against serious damage and repair costs for many years to come.

Other factors can also affect the likelihood that an ice dam will develop on your roof. Poorly insulated or ventilated roofs are at a higher risk. Ice dams are more likely to cause problems on roofs with smaller slopes since it will take less ice to start blocking the path of the melted snow. Although an ice dam can sometimes extend into the gutters, the belief that guttering can cause ice dam formation is false.

It is the difference between the temperature outside your house and the temperature inside that causes the formation of an ice dam. If the temperature difference is reduced, by milder weather, or if the heat inside the house is prevented from rising up to the attic or affecting the roof, then an ice dam will not form. The attic needs to be warm enough to melt the snow on the roof, but the exterior temperature must be cold enough for the melted snow to refreeze as it reaches the roof’s edges.

Icecles and Ice Dams on the roof

You can usually see an ice dam forming. You may be able to locate the warmer parts on the roof as they may be completely clear of snow, while snow and ice are still lying on the roof’s cooler areas. Another common sign of an ice dam is the development of icicles along the roof’s edges. These icicles can grow very large.

An ice dam can cause extensive damage that can be very expensive to repair. When an ice dam results in a backup of melted snow that begins to seep through the roof, it can result in water damage, damp and mildew problems in your home.

How to Prevent Ice Dams

Keeping the roof cool to reduce the temperature difference between it and the air outside is the best way to prevent ice dam formation. This will prevent the snow from melting, leaving it to dissipate gradually as the temperature outside rises.

The two main ways in which you can prevent ice dams formation are as follows; by making a proper use of insulation and ventilation in your attic. Insulation can help reduce the amount of heat that rises up into your attic, which can prevent the snow from being melted. Ventilation helps to drive warm air out of the attic onto the street. Thus, having a well ventilated attic can help prevent the heat that does reach your attic from building up and causing a problem.

If you want to prevent ice dam formation, you should consider investing in laying some additional insulation in the attic. This can simply be laid on the attic floor or blown in, depending on the type of insulation you are using. You should not push the insulation into the corners where the roof and the attic floor meet, as this will result in the roof’s lower parts becoming colder than the rest of it, which will encourage the formation of ice dams. There is a limit to how much insulation you can use before the law of diminishing returns comes into effect. At a certain point, adding more insulation will not result in any appreciable benefits. As well as adding more insulation to the attic floor, you can add weatherstripping and insulation on the attic stairs or hatch.

If you have a furnace in your attic then it will be more difficult to prevent ice dams. However, you can still achieve an improvement using insulation. First, you will need to install some polystyrene air channels in the rafters. These will enable the flow of cold air up under the roof. You should then install insulation in the areas between the rafters, allowing enough space for air between it and the roof deck to prevent the formation of condensation. Insulation blankets or batts can then be installed over the heating ducts of the furnace to reduce the amount of heat escaping into the surrounding attic space.

Even if your attic has been well insulated, a certain amount of heat will still be able to enter it, from your furnace or the house below. If there is not enough ventilation, this heat will not be able to escape and it will gradually build up under the roof, where it can start to cause problems. Ideally, there should be approximately 1 square foot of vent per 150 square feet of attic space. However, if you have an older home, it can be difficult to accomplish this ratio. You can increase the ventilation in your attic by adding vents into the overhangs, adding a ridge vent along the roof peak, or converting small gable vents into larger ones. When you have both overhang and ridge vents, cold air can enter through the side vents, rise up through the attic, and exit through the ridge vent. This will help to keep the air circulating. An additional benefit of ventilation in the attic is that it will help to remove moisture as well as heat, which can help to prevent problems such as rot. If you cannot generate enough air movement using vents alone, then you may want to consider installing a motorized vent.

Heating cables mounted on the roof are another possible solution for ice dams. These cables are intended to create a path along which melted snow can flow to escape an ice dam. You need to turn the heating cables on in order to prevent ice dams from forming, but you cannot just leave them running as they will burn out. You will also need to have a source of energy, so you cannot rely on heating cables if you are in an area that is prone to blackouts. Another problem with heating cables is that if the ice dam forms above them, they cannot help.

Getting Rid Of an Ice Dam

Preventing ice dam formation will be an easier and longer term solution to the problem than removing ice after it has formed, but there are ways you can deal with an ice dam and repair the damage if you have failed to take preventative measures and you find an ice dam developing on your roof. However, this will not stop the problem from returning, so you will also need to take preventative measures in order to protect your home in the future.

Pushing the snow - Ice Dam removal

If you suspect that an ice dam may be forming on your roof, there are a few simple techniques you can use to prevent it from becoming a serious problem. You can clear snow from your roof to help slow the formation of an ice dam. If ice is already forming, you can chisel grooves into it in order to allow the melted snow to drain away from behind the ice dam. This can be a good option in an emergency when you need to stop water leaking into your home. Another option is to fill a pair of old pantyhose with snow melt made from calcium chloride and then to lay this on the ice dam, which it will melt. You should avoid using rock salt as this could stain the roof. This technique is most effective with small ice dams.

If you are suffering from the effects of an ice dam, then you may need to perform some repairs on your house. The effects of an ice dam can be reduced by ensuring that your roof has been installed properly, as this will make it more difficult for water to seep through. If you have experienced leaks, due to ice dams or other weather conditions, then you should consider repairing or replacing your roof in order to stop the problems returning. Once water has found its way through your roof, it will be able to enter again, unless you block its path. If you live in an area that is prone to cold weather, then you should make sure that a roofing underlayment is installed across the entire roof. You should also ensure that high quality roofing shingles are used, with the proper amount of overlap. Flashing and ice and water barriers around the roof edges and valleys should also be installed.

Mildew is a common problem resulting from ice dams. It often appears in parallel lines across the ceiling, where the trusses in the attic above have generated cold strips. This happens because the trusses themselves are not insulated, even if the attic floor is covered with insulation. The trusses therefore act as a thermal bridge between the cold attic and the ceiling below. The resulting cold strips on the ceiling lead to the formation of condensation. This moisture can then cause the growth of mildew, which will appear as shadowy, parallel lines on the ceiling. In order to get rid of mildew, you should prepare a solution of one part bleach to three parts warm water. Use this solution to clean the affected areas, rinse with water and then allow the clean ceiling to dry. If the area remains stained or discolored, it will need to be repainted, but you should apply a primer to stop the stains from showing through before the topcoat.

Ice dams can also cause cracks in the joints of the walls and ceilings. These occur because the trusses can be lifted during the cold weather. It is possible to prevent uplift from causing cracks be using special brackets that will allow some movement without damaging the drywall. If your home was not built with these types of brackets, then you may need to cope with these types of cracks after the formation of an ice dam. You can do this by nailing a piece of molding that is large enough to cover the cracks to the truss, in such a way that it will be free to move up and down.


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