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Replacing Roof Questions

3200 Views 25 Replies 8 Participants Last post by  craig11152

I am in need to replace my roof soon. There are many problems, and the roof is probably more than 20 years old. Too many shingles are curling up/wearing out and the whole roof is just wavy. Just this winter, I had to climb up there (it's not too bad, about a 6 to 7/12 pitch) and patch a hole, which I have no clue where it came from (maybe the neighbor's tree). I used some metal flashing and roofing tar under the shingles since the plank was totally gone. I doubt this repair job will last long. I have patched a lot of other things on this roof as well, including the electric mast, and tarring many shingles back down. The shingles on the back utility room is also disintegrating. The gutters are in rough shape, so I'm planning to install the gutters after the roof goes up.

Now onto the questions. I've found one company who I saw a lot of people used around town. I thought they may be ok, better than the guy who gave me a 1-hour powerpoint presentation and quoted me a ridiculous price. However, they said they are going to use 1/2" OSB on top of the current wood planks and patch any bad spots with new planks. First of all, I made this a point to him and he did not care, nor was he willing to quote me a price for plywood instead. And he said up front that removing the planks will be a lot more labor/cost. I told him I heard that OSB should not be used around moisture, and from experience OSB just soaks up water like a sponge. He told me the roof should not get wet at all from the felt paper protecting it. I said, yeah, it shouldn't, but it WILL as we all know...

In the end he quoted me a price where I have to go buy ~60 boards of plywood and deliver it to the job site, and he'll put them up. I'm pretty sure OSB is bad for roofing, has anyone heard otherwise? I also asked him that day whether or not they are using Exterior-grade OSB, and he said no. Of course this guy gets an A on Angie's List regardless. He did quote me a lot lower than the first guy though.

Oh and another question, to remove the waviness from my roof, am I correct in assuming that removing all the old material is necessary, and using 5/8" plywood with H clips is the best way? Or am I going overboard, and using 1/2" is fine? I'm not an expert which is why I am asking you guys! Oh and .. is this possibly a DIY project with my dad? He's saying "if we go up there we can get it done in 2 days!" :vs_worry:

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OSB is fine for roof decking as long as it is inside the guidelines (i.e. span). The span is mostly a non issue in your case given the current deck boards as well.

Don't really need the clips for bracing, but spacing is still a good idea in this case.

It is pretty back breaking work. While I prefer plywood, I don't see it being a huge deal breaker here to run OSB. My bigger issue with OSB is some concerns about holding power (information is mixed on this) and that is a complete non issue in this case with the decking layer below the OSB.

They will probably nail down and semi-level the decking boards with just additional fasteners before dropping down the OSB. The new sheathing should conceal all of the waviness if done properly.
The new sheathing should conceal all of the waviness if done properly.
The guy from the roofing company told me that even after everything is done, the roof will probably still be wavy. (probably to protect his company) but I was thinking about it, OSB is not as stiff as Plywood, and adding another layer is just like adding another layer of paper to a wavy paper, which in the end becomes wavy anyway..?
Not quite. OSB is plenty stiff and it if prints through on OSB, it will, to some extent, on plywood. If the roof is that wavy, you can only do so much to level it up short of strapping the roof and re-decking it.

I am sure he is managing your expectations as well.
"It takes longer for water to soak osb and conversely, once water gets into osb it is very slow to leave. The longer that water remains within osb the more likely it is to rot."

I've done a lot of rehabs and wet OSB is never any good. Putting it on the roof is kind of risk in my eyes, especially if you're trying to make something last for 25+ years. I'd happily pay the $500 extra difference in this case. Although this is not a osb vs plywood post, nor do I intend to make it that, everyone has difference preferences I agree. I don't know why he did not quote me a price on plywood, which is why I offered to supply it.

I'm more interested in knowing whether or not I should have all the old wood planks removed or not. Are most roofing companies against doing this, since it takes a lot of labor?
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Go find a real roofing company, not some sales person who bored you with an hour of nothing.

The board that they use for roof decking, looks more like Chip Board. 5/8's is the norm. You should not be buying or paying for anything out of your pocket and having it delivered. That is what you are paying them to do. Also if you have a ABC warehouse locally. All of the roofing materials should be coming from them.

Go shopping some more. Our first bid was nothing more than a sales pitch with the costs to do the work, as if we had a 2500 sqft home. The guy I went with, was a small business owner, small crew, third generation construction, very well recommended, along with him and his father work on the historical properties in our town.

His price was around $3500 with everything by the book and Elkco Shingles, which actually has the tar at the bottom on the back of the shingle, instead of where the nails go, which causes lift. You cannot even lift the shingle after a week on the roof. They are just that good. After 8 years, you cannot even see any lifting or problems, and they still look as good as the day that they were put on.
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If the wood planks are solid, I would leave them. They should be able to shim as needed to level the new layer.

One reason he may want to use osb is large contractors may have a warehouse full from when the price was low or have made a deal where their supplier is holding that extra inventory at a low contract price.

For a better quality of osb I use AdvanTech, but it is more expensive. But I do like plywood.

Still begs the question as to why and how water is going to be getting into the OSB.

Don't make me an OSB apologist as we run plywood in our cases, but it isn't unacceptable if the roof is done properly and dried in in a timely manner. Either way, the delta is only a few bucks a sheet in most cases so you are looking at less than $200 difference in most cases. Ask from for the plywood or get another roofer.
Exactly Wash. Seen plenty of roof decking that is either OSB or Ply, that dries out with no issue. Outdoor rated has the wax type coating, so I really do not see how it is going to soak up water like a sponge, if you do not happen to get the Grace on the first 3' at the gutter edge, and same with at all valleys, then either Tar or the new Grace product that is better then Felt tar paper, since it does not tear as easily.

Been watching for the past two weeks the roof on the clinic that I go to for PT, get the roof replaced. They have had rain off and on and even while they are trying to rush the rain after ripping off the old shingles, there has been no problems if the sheeting gets wet, while they are trying to tarp or put the felt down.
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I find osb to more consistent than the junk plywood that's around now. 7/16 or 1/2" over your boards is more than sufficient.
They both fail when they get wet repeatedly, they just fail differently. Osb swells while plywood delaminates, buckles and curls.
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I agree that OSB or plywood is fine. If they are going over existing 1x decking I would use either 3/8 ply or 7/16 OSB. The added cost and weight of 1/2 is pointless as the support comes from the original deck underneath.

If the original decking is removed and your decking to rafters the "norm" around here is 1/2". If your rafters/trusses are 16" on center 3/8' ply is not outlandish although I wouldn't go there.
I believe codes allow for 3/8" on 24" centers if the 3/8 is rated 24/0
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For the waves, I'd look at the rafters first. There are a few reasons why the shingles don't lay flat, even the tar paper that wrinkled from the beginning. 1x boards are actually better than the sheets, although there are more joints for the nails to miss (it's harder to feel for hit or miss with air nailers). Leave the boards and cover with 3/8 ply or 1/2 osb - 1/2" because 3/8 osb may actually cost more. OSB calls for 1/8" space between all 4 joints.
OSB's bad reputation started when it was left open to weather during framing. Also because of the individual chips. Many times, framing would be delayed. Roofing is going to be covered quickly.
Why don't you take a photo of your roof? At least you will get some pointers about where you should be careful. You can spend 30 minutes each day for a month and you will get a fair idea of how to roof/flash - even if just a book learning. Since many inspectors, home or town, engineers and architects are like this, it is valid to learn as such.
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Here you go, the company who came today gave me a ridiculous quote again, with minimal work, not even tear down nor adding a layer of sheathing. They just wanted to replace any bad plywood, they were able to tell that it is plywood on top currently by looking through the soffit. They're also supposedly booked until September... shady stuff. What do you guys think? Does this roof still have life in it, and I could repair the bad parts? If not, is this something I should attempt to DIY :D


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Close ups of problem areas


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Your roof is gone. It needs a total tear-off and replace, including repairing any fascia, repair of any joists/rafters that may be rotted, decking, and then Grace for bottom row, then at least #15, maybe #30 felt and some good shingles.

A company may be "shady" in your opinion. As for them being booked until September. That is basically them giving you the signal that they are not going to sit around and wait for you to make your decision.

At this point, they know that you are just playing with them and really have no real intentions to do the roof as it should be. Stop playing games, find a roofer and spend the money to have the job done right.
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I would say she is due for a replacement based on the cursory look from these pics.

Typically...once you start getting blow offs, the rest of the roof has lost its bitumen seal and you are on borrowed time.
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A company may be "shady" in your opinion.

At this point, they know that you are just playing with them and really have no real intentions to do the roof as it should be. Stop playing games, find a roofer and spend the money to have the job done right.
$12,000-16,000 was the range of the work that they gave me, to do a full tear off and replace, depending on what extras I needed. That's for normal asphalt architectural shingles. If they went with the bare min, it would be $9k, to repair any bad spots and lay shingles on the old plywood. This roof is only 17 squares they said, and to buy the shingles I told them would only cost about $500 from Lowes. I'm dumb but I'm not stupid. I would love to get your price that you said earlier in the post Greg!
Just a small point, but check your math. Shingles might be $30 a bundle but it takes 3 bundles to cover a square (10' x 10').

As for the actual quotes I can't help being a few thousand miles away. If you feel the prices are too high and I agree but don't have all of the details, then you simply need to get more quotes.

Tip, never mention to another contractor that you already have some quotes. Make a list of what you want to hear and make notes.

THERE ARE GOOD CONTRACTORS out there but it can be difficult finding them because they are often busy and don't need to play games to get new business.

Good luck.
This roof is only 17 squares they said, and to buy the shingles I told them would only cost about $500 from Lowes. I'm dumb but I'm not stupid.!

At my Lowes just the laminated shingles are about $1275 for 17 square. That is before any other materials which would include ...
ice shield
metal drip edge
cap shingles
pipe collars
step flashing
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