Soft and Spongy Roof

Soft and Spongy Roof

Soft and spongy sounds like a toy for the bathtub, huh? You know like the little yellow ducks you used to see all the time when our children took a bath. The softer and spongier they were the better. The kids had fun and they couldn’t get hurt with them. Well that’s fine when you’re talking about bathtub toys but when you’re using the words “soft and spongy” to describe what you feel when you’re walking on your roof, well that’s another story. Your roof should not be “soft and spongy” it should be “sound and sturdy.” What causes your roof to become soft and spongy? There are several reasons why they may be in this condition.


The most common reason is “water damage.” Moister has been able to penetrate the shingles and underlayment and has damaged the roof’s decking. Usually water damage is only found in certain areas of the roof where moister has been able to soak into the plywood decking causing it to rot. In the case of water damage the old shingles, underlayment and plywood will have to be torn out and replaced only in the area found to be damaged. The rest of the roof should be firm and solid when you walk on it.

Another reason a roof may be soft and spongy is “inadequate ventilation.” Proper ventilation is important in order to prevent under roof moister. Above-roof temperatures and below-roof temperatures can cause a buildup of moister inside your attic due to the lack of adequate ventilation. The roof decking can absorb the moister causing it to become soft and spongy. A roofing or ventilation specialist can help you in determining if your ventilation system is inadequate and needs to be re-designed.  In some instances an entire new roof may be needed depending on the amount of damage found.

“Inferior design” can also be the reason a roof may be soft and spongy. Using plywood decking that is not thick enough, or up to code, can cause a roof to have soft or spongy areas between the rafters when you walk on it. Or, if the rafters are spread too far apart to adequately support the plywood decking. Whether it is building design or lack of sound building code this creates a problem for the homeowner who truly cares about the quality of aesthetics and soundness in their home.

Ok, so you already know this. But, sometimes a guy just needs to take a walk. You can learn a lot by taking a walk and paying attention. Your roof may be trying to get you pay attention to those waves and dips you can see up there. It may be inviting you to come and take a closer look. The best way is to get on your roof and take a walk. What is your roof saying tol you? Pay attention to your feelings. Do you feel those “soft and spongy” areas when you are walking on it?  If you do then it’s time to do something about it. Call a qualified roofing contractor asap to give you his professional opinion.