Roof estimate questions

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I am about to get a new roof done. I had a couple of estimates a year ago but then I put off doing it until now. The job is a complete tear-off and all new plywood decking. The present roof is old cedar shakes plus at least two asphalt shingle roofs on top of that. The rafters are all good, and the rafters have 1"x2" lathe strips nailed across them, and the old cedar shingles are on top of the lathe strips. The lathe strips are all in excellent shape.
On one of the old estimates there was a pre-printed line that said, "Install 8-ply (I think) plywood to all roof deck". The "8"(?) is crossed out and next to the line"All wood is 4-ply" was written in.
I assume that 8-ply is better and more expensive that 4-ply, but my guess is that 4-ply is also normal and okay to use. Anyone know if that's correct?
Another pre-printed line said, "Install 15/30 pound felt paper to all roof deck." The "30" is crossed out and the "15" is circled. And, next to the line "and Iceshield" is written in. Again, I am guessing that 30 pound is better than 15 pound, but that 15 pound is also normal and okay to use. Anyone know if that is correct?
The rafters are on 24-inch centers. The person who did this estimate said they would take the existing roofs off down to the lathe strips, and then would nail the 1/2-inch plywood on top of the lathe strips. The lathe strips are fairly close together (maybe an inch apart) and he said that even though the rafters are on 24-inch centers, 1/2-inch plywood instead of 3/4-inch plywood would be fine because the lathe strips add additional strength.
The estimate also specifies and includes a new ridge vent, new seamless gutters and downspouts, etc.
Another roofer who had looked at the job last year said that he would take the roof off down to the rafters and would use 3/4-inch plywood decking.
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what is it you want to know?
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wrote:

what is it you want to know? --------------
Thanks.
My two main questions are in paragraphs 3 and 4 of what I wrote -- in the last two sentences of each of those paragraphs.
I wrote the rest more as additional information just in case anyone saw anything in there that seemed to be out of whack or that I should be concerned about.
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wrote:

I didn't get past "The present roof is old cedar shakes plus at least two asphalt shingle roofs on top of that. "
Isn't that just wrong?
Besides that....Check your roofing company out thoroughly.
Jim
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I'm not sure what the 8 versus 4 ply difference makes, but I would make sure they sure they use at least a 1/2" exterior plywood. If you live in a high-wind area, specify hurricane clips between each sheet of plywood, especially with the 24" span between rafters. This will stiffen the roof. I would recommend removing the lathe strips (just my opinion). For the cost of the tar paper, I tend to go with the 30, instead of 15. I think this is an important part of the protection, and lends itself to a longer life of the roof. Also again if you live in a high wind area, make sure the installer follows the shingle manufacturer's instruction. Here in Colorado, my code inforcement required six nails per 3-tab shingle.
Another item to consider is that I've read that a lot of shingles are being stolen from big retailers and sold black-market, so make sure you question extremely low-bidders.
Robin
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wrote:

"conventional wisdom" was the second roof was the better roof.
That has changed ofer the years - but full felt (usually 15 lb) with ice-guard is now recommended - although many roofers will try to get away without installing the full felt. Before the ice-guard became common, 30 lb felt was common, and an inverted "starter strip" of shingles was often used along the bottom edge.
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snipped-for-privacy@snyder.on.ca wrote:
-snip-

That inverted starter strip was *way* too common- but it was also just plain stupid. Every bundle of shingles says to cut off the tabs. Inverting that row does nothing for you.
Jim
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wrote:

according to some old-timers, made a stronger bottom foot of rooding - where many roofs fail first (partly due to facsia boards being higher than the sheething, causing a little "valley" or "dip" across the roof just up from the eaves.)
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snipped-for-privacy@snyder.on.ca wrote:

Faster & simpler, sure-- but what kept the leading edge of tabs from flopping in the breeze? That tar isn't put there just to hold the little plastic strips. It keeps the wind from getting under the tabs. If you just turn the shingle around, the tar is about even with your nail line and nothing is holding the tabs.
Jim
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wrote:

UP, and STONE DOWN and is nailed to the roof. The first row of finish shingles goes on in the normal way, and the 'tar strip" bonds to the "back" of the inverted and flipped and nailed down "starter" shingle.
Some roofers put the "starter course" on stone side up - it works either way.
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Thanks...I'm at the mercy of the contractor. That's why I check them out thoroughly. :-)
I was just trying to picture asphalt tiles over cedar shakes. But I guess that's common.
The roofing company that did my last roof removed the old shingles and put down a rubbery material then the shingles (not sure if I saw any felt). I never did get the chance to ask them what the "rubbery" material was. This company has a sterling reputation as one of the best roofing companies in town.
You wouldn't happen to know what the rubbery stuff is?
Jim
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wrote:

valleys. Some "premium" roofers put down a full "torch down" membrane like is used on flat roofs. THAT is expensive, though.
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Thanks again! I think that sounds right.
Jim
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dont forget new drip edge

I would use him might cost a bit more but roofs are long term investments
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I'm not a roofer but done my share of roofing with asphalt shingles only so I can't really say much about the lathes. What I might comment on in this paragraph is to make sure the quote you get includes haul away AND dump fees of the old roof. That's a lot of material and weight being removed there.

You're lucky you're getting plywood vs OSB.

15lb is pretty much standard...on a standard roof.
What do you you have for a roof? I mean like the pitch, are there any valleys, subject to high winds, etc.?
Where are you located that iceshield is being specified? And where on the roof are they putting iceshield, ex, all valleys (they better!), all eaves. Grace Ice & Water Shield is considered the best.
If you have valleys, what type of valley will they install? Closed valley, open valley, woven valley?

Call your local building inspector. Ask them if 1/2" plywood is OK. And make sure roofer is using plywood vs OSB. Assume so. Roofer would not be discussing "plys" otherwise. OSB is OK but the minimum deck thickness depends on the material.

Is there an existing ridge vent? If not, has the roofer run the calculations to see if the soffit vents are adequate for the ridge vent?

They drop a lot of pumpking from airplanes there?

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wrote:

Half inch is adequate - and if the "lath" on the roof is solid it would be foolish to remove it and throw it away. It alone makes a strong roof-base - the plywood seals it up and gives a consistent nailing base to install the shingles to.
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On Dec 4, 10:33pm, snipped-for-privacy@snyder.on.ca wrote:

I'm not a roofer, so I'm just curious about how the lath "gives a consistent nailing base to install the shingles to."
The OP said "The lathe strips are fairly close together (maybe an inch apart)"
Seems to me that some spots will be an 1 1/2" base and other spots will be only be a 1/2" (the gaps between the lath).
How is that "consistent"?
Again, not arguing, just trying to understand what you meant.
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On Fri, 4 Dec 2009 21:47:09 -0800 (PST), DerbyDad03

Read it again. Get it? Read it AGAIN. The half inch plywood gives a consistent nailing base. You can put a roofing nail ANYWHERE and have it hit the minimum required half inch material to hold the nail. Without the plywood, you have a roughly 25% chance of not hitting wood at all, and a high chance of just catching the edge, splitting the wood and not holding the nail..
The lath gives the roof strength. The plywood seals it and holds the nail.

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Yes, the estimate does include all haul away and dumping costs. He said he will have a 30 yard dumpster.
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