Composition Roof, Roof damage from improper installation, need advice

That’s a tough situation, but honestly, you’ve done a great job tracking down the root cause. I get why you’re looking for alternatives - full tear-off is a huge pain (and cost). Your idea to “

lifting up the shingles, removing the short piece, slipping in a full width of shingle

And yeah, moss is always a pain up here... I’ve seen it accelerate roof problems more than once.

Ever thought about using treated plywood or even a synthetic material for those patches? Might last longer than OSB in those trouble spots.

I’ve tried both treated plywood and OSB before, and honestly, the treated stuff held up way better for me, especially in the spots that stay damp. Moss is brutal here too - if you don’t keep it off, it’ll just eat away at everything faster. I’m with you on not wanting to do a full tear-off if you can avoid it. Just make sure you seal up any seams real good... I skipped that once and paid for it with a leak later.

I have now learned that there are special starter strip shingles that are to be split in half so maybe that installation is correct.  I had a few other friends, both experienced in construction, agree that the short starter strip certainly contributed to the problem.  Also, looking at some freshly discovered areas of water damage, the agreed that the damage must have started quite a few years, if not soon after installation.  The moss was not bad five years ago so even though it didn't help, it is unlikely the root cause.  I'm still considering options and will report back with some updates.  It won't rain here all summer so I have some time.  Thanks for the comments. 

That blue stuff with the green disks sounds like synthetic underlayment - some brands use those plastic cap staples. It’s supposed to be better than tar paper, but if the starter row was too short and the OSB didn’t reach the fascia, water probably just found its way in anyway. I had a similar issue on my old place (also PNW), and ended up patching with plywood strips and caulk to get a few more years out of it. Not pretty, but it held up until I could budget for a full tear-off. If you’re not seeing leaks higher up, limping along might actually work for a while, especially if you keep moss off and check after storms.

That’s a pretty accurate read on the synthetic underlayment - those plastic cap fasteners are standard now, and they do outperform felt in most cases. But yeah, if the OSB stops short of the fascia or the starter course is undersized, water will absolutely find its way in, especially in the PNW with all that sideways rain. I’ve seen a lot of “creative” patch jobs over the years, and honestly, plywood strips and caulk can buy you time if you’re diligent about maintenance. Just keep in mind, once the decking starts to rot at the edge, it can spread faster than you’d expect, especially if there’s any insulation packed tight against the underside.

One thing I’d add: check your drip edge (if you have one). Sometimes installers skip it or don’t overlap it right, and that can make these edge leaks worse. Also, moss is a real problem up here - if you let it build up, it’ll lift shingles and trap moisture, making everything worse. If you’re not seeing leaks higher up, you’re probably okay for now, but keep an eye on the soffit and fascia for soft spots or staining. That’s usually the first sign things are going sideways.

plywood strips and caulk can buy you time if you’re diligent about maintenance

I get where you’re coming from, but I’ve seen those quick fixes turn into bigger headaches down the road. Sometimes folks end up chasing leaks for years because the underlying issue never really gets addressed. Especially with all that PNW rain, water just finds new paths. Personally, I’d rather see a small section of decking replaced properly than keep patching - costs more upfront but saves a lot of hassle later. That said, moss is definitely a beast up here... I’ve lost count of how many times I’ve scraped it off only to have it come back twice as thick.

- Totally get the urge to patch, especially when it’s pouring and you just want the leak to stop.
- I’ve tried the caulk-and-pray method a few times... never lasted long with our weather.
- Replacing a section was pricier up front, but I stopped worrying every time it rained.
- Moss is relentless - power washing helped me, but it’s a yearly battle.
- You’re not alone dealing with this stuff. PNW roofs are just a different beast.

Moss is relentless - power washing helped me, but it’s a yearly battle.

Yeah, moss is a pain here. I tried zinc strips last year and it slowed things down, but didn’t totally solve it. As for patching, I get the temptation, but after a couple of failed quick fixes, I bit the bullet and replaced a whole section. Cost hurt, but peace of mind is worth it - especially with our sideways rain. If you’re seeing leaks from improper install, I’d check the flashing and underlayment too. Sometimes the problem’s hidden under the shingles.

You’re spot on about leaks often coming from bad flashing or underlayment, not just the shingles. I’ve seen a lot of roofs where the real issue was hidden until we started pulling things up. It’s tough to bite the bullet and do a full section, but honestly, sometimes that’s the only way to stop chasing leaks every winter. Those quick patches rarely hold up in our weather. Hang in there - getting it fixed right is worth the hassle.

Couldn’t agree more about the hidden issues. I’ve lost count of how many times I’ve seen leaks blamed on “bad shingles,” when the real culprit was a missed step in the underlayment or flashing. Especially around chimneys, valleys, or where two roof lines meet - those spots are notorious for trouble if they’re not done right the first time.

It’s tempting to just patch things up and hope for the best, but like you said, those quick fixes rarely last through a full season, especially if you’re somewhere with heavy rain or freeze-thaw cycles. I’ve seen folks spend way more money chasing leaks over a few years than they would’ve if they’d just tackled a full section upfront. Not fun, but sometimes it’s the only way to get ahead of it.

One thing I’d add - sometimes the damage isn’t just water getting in, but what it does once it’s there. I’ve seen insulation soaked, mold starting in attic corners, even electrical getting corroded because a slow leak went unnoticed for a while. That’s why I always recommend checking the attic after a big storm, not just the ceiling inside. If you spot any dampness or staining, it’s a sign the problem’s bigger than it looks from outside.

If you’re dealing with a composition roof, especially one that’s older or had a few repairs already, it might be worth considering a full tear-off in the worst area. It’s a pain, but at least you know what you’re working with underneath. And if you do go that route, make sure whoever’s doing the work pays close attention to the flashing and underlayment details - those are the spots that’ll make or break the job long-term.

I know it’s a hassle, but getting it done right now saves a lot of headaches down the road. And yeah, nobody wants to hear “full section replacement,” but sometimes it’s the only way to stop playing whack-a-mole with leaks every winter.

You nailed it - patch jobs just don’t cut it long-term, especially with older comp roofs. I’ve seen folks try to save a buck and end up with moldy insulation or worse. Full tear-off in the trouble spots is a pain, but honestly, it’s usually the cleanest fix. Flashing details are where most leaks sneak in, like you said. It’s a hassle now, but way less stress later when storms roll through.

I get the logic behind full tear-off, but man, the price tag on that makes my wallet sweat. I’ve patched a couple spots on my comp roof (it’s about 18 years old), and yeah, I know it’s not a forever fix, but I’m hoping to stretch it another year or two. Curious - has anyone actually had luck with partial tear-offs? Like, just doing the valleys or the worst sections? Or is that just asking for trouble? I’m in the Northwest, so rain is a given... just trying to avoid a total gut job if I can.

Partial tear-offs can work, but in my experience, they’re a bit of a gamble - especially with all the rain we get up here. I did just the valleys on my old place and it bought me maybe three years, but matching the new shingles to the old ones was tricky and it never looked quite right. Did you notice any soft spots or rot when you patched? Sometimes that hidden damage is what really gets you...

Did you notice any soft spots or rot when you patched? Sometimes that hidden damage is what really gets you...

That’s exactly what I’m worried about. I poked around under a couple of the lifted shingles and didn’t see anything obvious, but I’m not sure how thorough I was. Is there a trick to checking for rot without pulling up a ton of shingles? Also, did you find the color mismatch got worse over time, or did it kind of blend in after a while? I’m debating if I should just bite the bullet and do a full tear-off, but the cost is intimidating.

Is there a trick to checking for rot without pulling up a ton of shingles?

I’ve run into this a few times. Sometimes you can feel for spongy spots by pressing down with your foot - if it gives more than the rest, that’s usually a sign. I’ve also used a screwdriver to gently probe around nail holes under the lifted shingles, but it’s not foolproof. As for color mismatch, mine looked pretty obvious at first but after a year or so, the sun faded everything enough that it blended in better than I expected. Still not perfect, but less noticeable. Full tear-off is pricey, but sometimes patching just kicks the can down the road... tough call.

Yeah, the color mismatch thing bugged me too at first, but you’re right - it does fade in over time. I’ve seen a lot of folks get away with patching for a few years, especially if the rot’s not too widespread. Pressing for spongy spots is a solid move. Sometimes you just gotta weigh the hassle and cost against how long you plan to stay in the house.

Sometimes you just gotta weigh the hassle and cost against how long you plan to stay in the house.

That’s pretty much where I landed too, after going down the rabbit hole of roof repair estimates last year. I had a patch of rot near the eaves - installer didn’t flash it right, so water snuck in. I was quoted everything from a couple hundred for a patch to several grand for a full tear-off. The color mismatch bugged me at first, but honestly, after a few months, I stopped noticing unless I was really looking for it.

I do think there’s a limit to how much patching makes sense, though. If you’re seeing spongy spots when you press down, or if the decking feels soft underfoot, that’s usually a sign things are worse underneath than they look on top. I poked around with a screwdriver and found some hidden rot that wasn’t obvious until I started pulling shingles. Ended up replacing about 4 feet of decking myself - wasn’t fun, but it saved me some cash.

One thing I’d add: if you’re in an area with lots of rain or snow, even small leaks can cause bigger problems faster than you’d expect. I’m in the Pacific Northwest, so moisture is a constant battle. If you’re somewhere drier, maybe you can get away with patching longer.

As for cost vs. hassle, I get being budget-conscious (I sure am), but sometimes spending a bit more up front saves you from a bigger headache later. If you’re planning to move soon, patching might be fine. But if you’ll be there another decade, it might be worth biting the bullet and doing a bigger repair now.

One last thing - if you do patch, keep any leftover shingles from the original batch if you have them. Even if they’re faded, they’ll match better than new ones from the store. Learned that one the hard way...

If you’re seeing spongy spots when you press down, or if the decking feels soft underfoot, that’s usually a sign things are worse underneath than they look on top.

That’s what worries me. I’ve got a couple spots near the ridge that feel “off” when I walk up there, but no visible leaks inside yet. I’m debating whether to just patch those areas or do a more thorough inspection and maybe replace some decking. For those who’ve pulled up shingles - how much hidden damage did you actually find compared to what you expected? I’m skeptical about just trusting surface signs.

I’m skeptical about just trusting surface signs.

I kind of get where you’re coming from here. When I bought my place last year, I had a similar situation - couple of spots felt a little “bouncy” underfoot, but no stains or drips inside. I was tempted to just patch over those soft areas and call it good, but after reading a bunch on here and talking to a neighbor who does roofing, I went ahead and pulled up some shingles to see what was going on.

Here’s the thing: sometimes those soft spots are just old plywood that’s lost its rigidity, but other times there’s rot or mold underneath that’s not obvious from the attic or ceiling. In my case, one spot near a vent looked fine from below, but when I pulled up the shingles, the decking was black and crumbly. Ended up replacing a 2x3 foot section - way more than I thought would be necessary based on just walking around up there.

But, honestly, it wasn’t as bad everywhere. Some areas that felt a bit “off” were still solid after checking under the shingles. If you’re worried about hidden damage, maybe try doing a small test section first? Just pick the worst-feeling spot and pull up a handful of shingles - see what the wood looks like underneath before committing to anything bigger. It’s not as intimidating as it sounds if you take it slow (and watch some YouTube vids first).

One thing I’d push back on is waiting for leaks inside before acting. By the time water gets through enough to show on your ceiling or walls, you could be dealing with insulation issues or even mold in places you can’t see. That said, if it’s only one or two spots and the rest of your roof is solid (especially if it’s not super old), patching might buy you another few years.

Curious if anyone else found less damage than expected? Or is it usually worse once you start pulling things apart? For me it was 50/50 - one spot was way worse than I thought, another wasn’t bad at all. Kinda feels like a coin toss unless you actually look underneath...