Dear Mr. Marantz:
I hope you can shed some light on a puzzling problem that occurs in very cold weather. The roof on my older home gives off very loud cracks and some are as loud as the loudest slamming of a door! It’s worse at night when the temperature is at its lowest. It can be very startling, to say the least. What causes this and how can it be remedied?
The asphalt roofing was installed about 15 years ago and it is in good condition. I might add that this is not a new problem, but no one else seems to be bothered by these gunshot-like cracks. Do I need more insulation or ventilation in the attic?
Unusual noises in older homes are a common and often frightening occurrence. These noises are often mistaken for tree limbs falling on homes, slamming doors and windows, animal intruders or even ghosts and other supernatural phenomenon. These noises can vary considerably from squeaks and rattles to the loud bangs you are experiencing. Some of these have simple explanations and causes, but the majority are not traceable.
The common explanation for these audible problems is that “the house is settling”. This may be somewhat true, but is not entirely accurate. Settlement in a home is normally described as the movement, minor or major, over a period or time in the overall building. It is common for additions and porches on homes to move independently of the main house and this may be the cause of some common “settlement” noises heard. In many cases, this does not cause serious structural problems, but may occur regularly with changes in seasons and conditions outside the home. Check for cracks in the exterior and interior walls between any additions and the main house.
The most likely explanation for the noises you are hearing is that they are due to thermal expansion and contraction. What this means, in plain terms, is that the components in the home are shrinking and expanding with changes in temperature. These changes can be subtle and unnoticeable in the overall home, but may cause building materials of differing composition to expand and contract at different rates. When these dissimilar materials are in contact with each other and tightly secured with nails or fasteners, they will resist these thermal changes. When the pressures become too great to resist, the energy may be released suddenly, causing loud noises. These are the loud cracks that you are describing. They will likely be the most noticeable in the dead of winter, due to the large variation in daytime and nighttime temperatures. This is compounded on sunny days, where the sun may cause considerable thermal expansion to house components in direct sunlight.
The noises may appear to be emanating from the roof or attic, but may have the source in that location or anywhere in the structure. The sound is likely amplified by the large space in the attic. If the noises are from the interior or exterior walls of the home, there may be little or nothing that can be done to eliminate them. If the noises are due to expansion and contraction of the ceiling joists or coverings, then additional insulation may help. The difficulty is in determining the area that is actually causing the cracking noises.
If you are quite sure that the noise is coming from the attic and there is minimal insulation currently, adding insulation above the ceiling may help. If the noise is caused by nighttime contraction of the ceiling components, then added insulation will keep these building materials warmer and may help minimize the large temperature swings associated with them. If the noise is due to movement in the roof rafters, trusses or sheathing, then increased insulation may help slightly to dampen the sound, but will do little to stop the cause of the banging. Increasing attic ventilation will help reduce the winter daytime temperature in that space and may minimize the amount of expansion and contraction, as well.
The noises associated with thermal expansion and contraction of building materials in homes rarely is a sign of any serious problems, except for the disturbances caused by the loud sounds. Adding insulation and ventilation in your attic, if there is a minimal amount currently, will improve the heat retention in the home and lower heating costs but may do little to help the sounds stop. In situations like this, trial and error may be the only method to employ in attempting to stop the annoying bangs and cracks. Adding more attic insulation along with proper venting for this space will certainly not add to the problem, but the benefits may only be better energy efficiency in the home.