Spongy roof sections...


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Old 06-06-06, 07:50 PM
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Spongy roof sections...

I'm having some concerns about the state of my roof. There are a few areas where if you walk on the roof it has a spongy feel to it. I believe it is either water damage or improper venting in the attic. I'm leaning toward the latter for two reasons...one is that I don't have any visible water damage or indicators and two, I purchased my house from a relative six years ago and the roof was redone probably 10 years ago.

I've been researching roof venting and am totally confused. My house currently has an attic fan venting directly out of the top of the roof and I also have vented openings on either side of the attic walls (gable vents?) Is this adequate? I've been reading about soffit venting and I only have a soffit on half of my house in the front...on the other half of the house the outside wall meets with the end of the roof. Where the soffit area is it seems there is plywood underneath the vinyl panel and the wood has holes drilled into it...I assume this is for airflow. Is this normal for a soffit...to have plywood with drilled holes or should it be constructed out of something else?

I know I have a lot more research to do and have asked a lot of questions. The venting is my number one suspect and if I go through the expense of having the roof redone I want to make sure I dont have the same problem in the future.
 
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Old 06-06-06, 10:18 PM
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Lots of roofs have sections that feel "spongy", especially if they have been added on to. Most often, it's due to undersized rafters and/or undersized roof sheathing. It also could be that a few pieces of plywood were oriented the wrong way. (my dad used to do that ALL the time.) And then there's the guys who use 3/8" plywood for roof sheathing. whoa boy.

If a large area deflects, its usually the rafters. If it's just a small area around your feet, then it's the sheathing.

I did a couple weeks volunteering in Louisiana this spring and I couldn't believe how spongy the roofs there are. (no snow load) The roof can barely hold it's own weight, let alone someone throwing down a bundle of shingles on it. Of course, hopefully building codes have come a long way since some of those homes were built.

So I wouldn't worry about it too much unless you inspect the roof from the inside and determine there is a leak, or that you have high moisture inside the attic. Roofs are usually designed to hold their own weight and a certain amount of load per square foot. I dunno how much you weigh, but if you put all your weight inside one square foot and jump up and down, you could bust right through a roof that way- it's obviously going to deflect, but then again, that's more weight than your roof will ever see in one spot. If the roof is straight and isn't leaking, then that's great.
 
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Old 06-09-06, 06:56 AM
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xsleeper,

thank you very much for taking the time to reply to my post...I appreciate it. Being that there are no leaks I am going to hold off until after the summer to decide what I'm going to do to fix the problem. My house has been the money pit lately and even though I try and do most of what needs fixing there are just some things that require some professional attention.

thanks again for the info!
 
 

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