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Roofs and Siding
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Quick and long-term ice dam cures.
Ice dams are caused by warm roofs and cold eaves. When snow accumulates on a roof with insufficient insulation, the snow begins melting near the ridge where the hot air rises first. The melted snow runs down the warm roof under the snow pack until it reaches the overhang, which is not warmed by attic air. Here the water begins to freeze again. It may be seen as long icicles at first and the ice dam itself may not be evident under the snow.
Serious problems to a roof and house can result from the ice dam. As the dam grows higher, water backs up behind it and eventually seeps under the roof shingles, between the roofing felt, through joints in the roofing deck, and then into the house.
Electric heating cables strung along the lower edges of the roof are often used to prevent ice dams but have limited success. Ice dams often form above them and the damage continues.
Emergency solutions, however, are sometimes required. If water is leaking into your house because of ice dams, here is one way to deal with it safely and easily. Fill one leg of an old pair of panty hose with calcium chloride and lay it vertically on the roof across the ice dam. Calcium chloride (CaC12), which is highly effective at melting ice, will cut through the ice and open a channel to release the backed up water. Moreover, it will keep the channel open.
Working from a ladder, the socks full of calcium chloride can be positioned on the roof by using a rake or long stick. This eliminates the necessity to climb on a roof made perilous by snow and ice.
The best ice dam preventive measures are a cold roof and adequate air circulation in the attic. Warm air reaching the roof must be minimized by placing insulation not only between the ceiling joists, but also between the rafters. The insulation must be carefully installed with no openings for hot air to reach the roof. The ceiling insulation must run to the plate line (top of the stud walls) but not block any soffit vents.
Air must be allowed to circulate in the attic and be efficiently removed. A continuous ridge vent is the best means, but roof vents work well too. Fans on thermostats can also be mounted at screened openings on gable end roofs to remove warm air.
Another important preventive measure is to install an impermeable ice and water membrane under the roofing material. It should extend from the edge of the eaves to at least 2 feet past the perimeter wall line. This material has one sticky side that bonds to the roof deck. It also seals around nails driven through it.
How do I find a roof leak?
Often this is very difficult because water has a
tricky way of traveling a long way from the source before you see it. If water puddles around a
particular window only when the wind is blowing rain against it, you have a likely culprit. If the
leak is coming down a wall from the ceiling, start looking up. Go into the attic space with a strong
flashlight and backtrack from the spot above the ceiling toward the roof. Check both sides of
rafters because water may run down them to the wall. Look carefully around all vent pipes going
through the roof and around the chimney, if you have one. When the rain stops, inspect the roof from
the ground with a pair of binoculars. If you feel comfortable, go on the roof, but wear proper fall
restraint equipment. Look for missing shingles or water pooling in certain areas. Leaks often begin
around flashing or where two roofs join, particularly if one was added on later. If the valley is
clogged with leaves, water can back up beyond the valley flashing and penetrate the roof. This can
also happen if the valley is too narrow for the amount of water running down it. You can sometimes
narrow the search by running a hose over the suspect area to see if the leak resumes. If it is a
leak during winter in cold climates, ice dams along the eaves can force melting snow to back up under
the shingles and into the house.
What's involved in converting my flat-roofed house to a pitched roof?
Converting a flat roof to a pitched roof is a major
undertaking that requires skilled carpenters and roofers. Anyone contemplating this should weigh the
pros and cons: Is the new roof just for esthetic value, or would it serve a real purpose? Can you
readily afford it? The pitched roof will make the house cooler and will provide additional storage
area between it and the flat roof.
What are the pros and cons of composition shingle roofs versus metal roofs?
Both roof types come in many styles and colors. Metal is more fire resistant than composition or wood
roofing and can be applied more quickly. Metal roofs can usually be installed right over the old
roof. Some are guaranteed for 50 years or more. Metal roofs are more expensive and are easily damaged
if walked on incorrectly. Composition shingles come in several different grades, which are judged by
the guaranteed lifetime, usually 20, 30, or 40 years. The longer-lasting shingles are thicker and
their shaped appearance makes a more attractive roof.
Can I put siding over the existing shingles on my house?
The problem with installing siding, particularly
vinyl siding, over wood shingles or other wood siding is that it does not breathe, while the wood
underneath does. That causes the wood underneath to absorb moisture and ultimately decay. You would
be better off to strip the shingle siding and repair any damage, or add additional bracing, before
putting up the new siding.
How many layers of covering are permitted on my roof?
Generally, three layers on a roof are the maximum.
Check your local building codes. But if you have two layers and are thinking of adding a third,
consider that extra layers add significant weight, will create trouble with nails backing out on the
underlying layer, and that it will be difficult to seat the nails properly on the new layer. It also
might void your warranty.
Aluminum, vinyl, or natural siding: What are the pros and cons of each?
Aluminum siding dents easily, is difficult to find,
and costs more to purchase and to install. Vinyl siding is the least expensive, lasts a long time,
looks nice, and has virtually no maintenance. But it can cause moisture and decay problems when
improperly applied over wood. Natural siding, such as wood, brick, and stone, varies widely in price
according to your choice. It takes more maintenance but lasts the longest if painted and maintained.
Which are better roof vents, continuous ridge or box vents?
Roofing manufacturers' warranties require a minimum
of 1 square foot of ventilation for every 150 square feet of attic space for traditional systems, but
only 1 square foot of ventilation for every 300 square feet when the ridge vent system is used. That
is a good indication of the difference in efficiency. There are many good ridge vents on the
market, and the continuous vent, as opposed to the individual roof vent, is the most effective.
Continuous ridge vents allow hot air to readily escape from the roof peak. Most manufacturers now use
a durable plastic, or aluminum, to avoid rust. If using plastic in cold climates, make sure it is
rated to withstand subfreezing temperatures.
How can I tell whether it's time for a new roof?
Leaks from an old roof are good indicators, as are
worn, battered, or missing shakes or shingles. If the fine gravel embedded in composition shingles
is missing, or piling up in the rain gutter, it is time. On flat tar and gravel roofs, look for
bubbles in the tar and shrinkage near roof vents. Old shake roofs may have pieces missing,
particularly along the ridges.
Can I paint vinyl siding?
Not effectively. It can be painted, but the paint
will crack as the vinyl expands and contracts with temperature changes.
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