Frequently Asked Questions
As you can imagine we field alot of questions during the course of a day. We do not boast of knowing it all although where we excel is our desire to continuosly learn and share that knowledge. Everyone at Dube~Plus takes part in continuing education through the national and local homebuilder associtaions, seminars and roundtable discussions with our suppliers and subcontracors. If we don't have the answer we will get it for you!
Enclosed below is a list of Frequently Asked Questions regarding building or remodleing your home. If you have a question, simply click the ask button below and we will gladly respond personally via email and post the results in this forum.
ASK
Ice Dams
Q:Recently we had water leaking into our kitchen ceiling and have heard the term "ice dam" - can you explain, in layperson terms, what an ice dam is and how to stop them from occuring? BL-Milford
A: Great question BL. Certainly this winter has been extreme with the sheer amount of snowfall although it's not neccesarily the amount of snowfall that dictates the formation of ice dams, we have to look a little deeper than what Mother Nature dishes out during a typical New England winter.
Believe it or not the key to ice dams is inside the house in the form of inadequate attic ventilation. As diligently as we work at insulating our homes and implementing the latest technology we may always have some form of heat loss in our attic space. This heat loss can virtually heat an enclosed attic and melt every bit of newly fallen snow on our roof. Whats wrong with a clean roof? Besides a tell tale sign of insufficient insulation, nothing until that melting snow gently rolls its way down to an unheated portion of the roof (the eaves) and freezes. As more and more snow melts and hits this new leading edge of ice it backs up - creating a larger dam and a virtual pool of water behind the dam. More snow, more melting and finally we see evidence in the form of water leaking into our ceilings or around windows.
First let's discuss the immediate challenge of removing the dam. Physical removal can be dangerous to your roof and to you. Navigating a ladder in the worst of conditions is not for the faint of heart. And, once your up there you don't want to do any damage to the roof surface. I've seen people resort to axes or hatchets, 100% effective although now the shingles need to be replaced or potentially have created a larger leaking problem.
If you are not comfortable working on a ladder contact a professional roofer or contractor. If you do feel comfortable up there, the best approach is to lightly create small channels for the melting water to escape. You will be amazed to see those little rivers grow wider and wider as the volume of water escapes. Once you have established some moving water you can spread your favorit ice melting product and revel in the sounds of cracking ice!
Power washers can also be effective although temperatures below freezing make this challenging and can turn that ladder your standing on to ice with one erranat pass of the wand. In extreme cases I have seen ice covered roofs of large homes and commercial buildings actually steam cleaned.
If you have had ice dams in the past or fear this could be your year, purchase a roof rake. An aluminum rake with a 20' handle that allows you to pull the snow of the eaves afetr each storm. Keeping the eaves clear will prevent the formation of the dams. I'm not a big fan of the electric heat tapes that you see on older homes. They are not the most efficient and could pose other problems as they age. With that said they are effective.
Ok, spring has sprung, you have touched up the ceiling paint or had the drywall repaired and now its time to solve the problem and get that attic ventilated!
Todays codes require that we address attic ventilation. Below is Section R806.2 from the 2006 International Residential Code (IRC).
R806.2 Minimum area. The total net free ventilating area shall not be less than 1/150 of the area of the space ventilated except that reduction of the total area to 1/300 is permitted, provided that at least 50 percent and not more than 80 percent of the required ventilating area is provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above the eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents. As an alternative, the net free cross-ventilation area may be reduced to 1/300 when a vapor barrier having a transmission rate not exceeding 1 perm (5.7 x 10-11 kg/s . m2 . Pa) is installed on the warm-in-winter side of the ceiling
Yikes! What do you mean you don't know what 1 perm is.. .
Ok, I know, laymens terms, without the addition of roof ventilators (those big shiny round powered fan units), we have to provide a minimum of 1/150th of the square footage of the attic in ventilation. So lets say we have a attic space of 28' x 36', we have a total attic square footage of 1008. 1008 / 150 = 6.72 square feet of ventilation. In order to achieve a balanced flow we need to address intake flow and outtake exhaust. Simply divide 6.72 by 2 and we arrive at 3.36 square feet (484 sq inches) of intake flow and 3.36 sf (484 sq inches) of outtake exhaust.
Now that we know our minimum requirements, how do we provide for these numbers?
Intake ventilation needs to be supplied at the lowest portion of the roof (as heat rises) and outake exhaust at the highest point. Intake is typically provided by undereave soffitt or vented drip edge which provides up to 9 square inches of ventilation per lineal foot. While the most effective outake exhaust is in the form of continous vented ridge or shingle vent which can provide up to 18 square inches of ventilation per lineal foot.
Lets do some math! In our example above we have an attic space that is 36' long. This will allow 36 lineal feet of outake exhaust venting and 72 lineal feet (2 eaves at 36') of intake venting.
Intake venting: 72 lineal feet at 9 square inches = 648 square inches
Outake exhaust: 36 lineal feet at 18 square inches = 648 square inches
A total of 1296 square inches of ventilation or 9 square feet which surpasses the minimum of 6.72 square feet.
The premise of that excercise is only to illustrate that a properly installed ridge and soffit vent will adequately vent a roof and remove the threat of ice dams.
Existing homes can easily be fitted with ridge vents and while soffit venting can be a little more challenging it can certainly be handled be a professional contractor who will gurantee the work.
Keep that attic space cold through proper ventilation and assure a roof free of ice dams