Gurus:

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI

wrote:
This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

A two-layer roof is done for one reason, and one reason only -- it saves money
in the short-term.

You want the longest-lasting option, you go with option #1.

Tear-off is double the price in my neighborhood. The best way to do it
obviously, but much more expensive.

If you are planning on living in the house for another 30 years, tear off is
a good way to go.


wrote in message
oups.com...
Gurus:

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI

wrote:
Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on
new roof.

That is the only option if you want a long-lasting, leak-free roof job.

If cost isn't an issue, ask your contractors about options for upgrading
the roof covering - such as tile over a modified bitumen underlayment
system. Good for 50 years or more if done right.

There is a benefit to tear off.
The roof deck is exposed and any problems solved.
TB

while i agree, option 1 is the 'best'. but if your roof isnt leaking now,
if you factor in price vs how long it will last, you may find option 2 may
be viable.

i am also assuming that there is only one layer of roof already (i.e. hasnt
already been reshingled over another layer). if there are multiple layers
already, tear it down.

lastly, if you want the longest lasting roof, i'd go with a metal roof.

randy

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI

I've lived in a house long enough to do it both ways. The first time
was putting one on top of the other. For the next 12 years, we lived
with little leaks showing up and having to repair them. one leak got
so big, we ended up with mold and a $40,000 repair bill. Thank
goodness for insurance. Some will say we must have had a shoddy job. I
don't think so. It was done with 40 year shingles by one of the better
known companies in our area. Its just that the old roof was not a good
foundation for putting on the new one.

When we re-roofed, we tore everything off and put down all new
sheathing. The roofer told us that roofing companies had abandoned the
practice of putting one on the other and building codes have changed in
many areas so its not allowed.

In my book, your option #1 is not even an option for any length of
time. You paid the money for a house. The price of maintaining it
properly is not cheap.

Bob

wrote:
Gurus:

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in
pretty good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on
new roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI

Just a thought. My roof was hail damaged. The insurance company agreed
to a replacement. One of their requirements was a tear-off. They would not
cover the new roof without the tear off, which they were paying for. They
thought it was worth the cost. I sure was not going to disagree.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math

My vote is for #1. It makes for a lighter, stronger roof in the long
run. Layers of shingles can make a roof sag.

On 2 Mar 2005 12:40:54 -0800, wrote:

Gurus:

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI

Covering over a roof is still accepted by building codes as a viable and
useful option and shingle manufacturer's accept the process as well.

If an interior and exterior inspection of the roof sheathing yields no
problems, there is little reason to rip off and replace the existing
layer.

Replacing your automobile tires if you get a flat is also an option if
you can afford it.


--
manhattan42
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manhattan42 wrote:
If an interior and exterior inspection of the roof sheathing yields no
problems, there is little reason to rip off and replace the existing
layer.

There are two very good reasons to remove the existing layer of a
shingled roof.

1) To reduce the weight of the roof covering. The roof structure may
not be designed to carry the weight of two layers.

2) Primary weatherproofing comes from the bottom underlayment felt,
which ages and becomes brittle. Just the act of walking on it and
nailing an additional layer of shingles may cause it to crack, which
raises the risk of water intrusion and ice dams.

Phisherman wrote:

My vote is for #1. It makes for a lighter, stronger roof in the long
run. Layers of shingles can make a roof sag.

On 2 Mar 2005 12:40:54 -0800, wrote:


Gurus:

This summer we plan to replace our 24-year-old shingled roof with
long-lasting dimensional shingles. The old shingles are still in pretty
good shape and the house has had no ice damming problems.

Contractors are pushing two schools of thought for the old roof.
1. Tear it off and put down ice and water shield before putting on new
roof.
2. Shingle over the old roof and utilize the old flashing.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom
Milwaukee, WI


also you may have bad boards that need fixed or flashing. also check out
metal shingles. i paid just 1/3 more than 40 year reg shingles.

On Fri, 4 Mar 2005 08:13:06 -0600, manhattan42
scribbled this
interesting note:


Covering over a roof is still accepted by building codes as a viable and
useful option and shingle manufacturer's accept the process as well.

If an interior and exterior inspection of the roof sheathing yields no
problems, there is little reason to rip off and replace the existing
layer.

Replacing your automobile tires if you get a flat is also an option if
you can afford it.

So far as I know, National Building Codes allow up to three roofs on a
house. Just because it is up to code does not mean it is ideal. A
house with more than one roof installed is more likely to develop
leaks (because the roof exposed to the weather is not installed over a
uniformly smooth substrate) and I've never seen a second roof like
this last as long as it should. In every case I've seen, a house with
a second, third (or more) roofs installed require attention far sooner
than they would if there had been only one roof.

The only reason to roof over an existing roof is because of money. It
takes more time and labor and dump fees to remove an existing roof.
Sure, it is up to code. Sure it is common practice. Yeah, it is
cheaper. Is it best practice? Nope.


--
John Willis
(Remove the Primes before e-mailing me)

On Fri, 04 Mar 2005 14:32:01 GMT, "Travis Jordan"
scribbled this interesting note:


2) Primary weatherproofing comes from the bottom underlayment felt,
which ages and becomes brittle. Just the act of walking on it and
nailing an additional layer of shingles may cause it to crack, which
raises the risk of water intrusion and ice dams.


I've seen this comment posted several times and I still fail to
understand how one comes to this conclusion. The surface exposed to
the weather should turn the water. No exception. Any penetration of
water through the shingles is unacceptable as if it happens once, it
will happen again and again and that is called a leak. On rare
occasion a unique combination of events may cause water to penetrate a
roof in such a way that may not ever happen again. When and if that
happens, then and only then does the quality of the felt come into
play. If water happens to penetrate the shingles in this manner, a
good felt job will indeed carry the water off and cause no interior
damage, but if it is a recurring penetration, that felt will quickly
fail (or the legs of the fasteners penetrating the felt will rust to
nothing, leaving the holes they made in the felt-a water penetration
point) and then the problem shows up inside the dwelling.


--
John Willis
(Remove the Primes before e-mailing me)

John Willis wrote:
I've seen this comment posted several times and I still fail to
understand how one comes to this conclusion. The surface exposed to
the weather should turn the water. No exception. Any penetration of
water through the shingles is unacceptable as if it happens once, it
will happen again and again and that is called a leak. On rare
occasion a unique combination of events may cause water to penetrate a
roof in such a way that may not ever happen again. When and if that
happens, then and only then does the quality of the felt come into
play. If water happens to penetrate the shingles in this manner, a
good felt job will indeed carry the water off and cause no interior
damage, but if it is a recurring penetration, that felt will quickly
fail (or the legs of the fasteners penetrating the felt will rust to
nothing, leaving the holes they made in the felt-a water penetration
point) and then the problem shows up inside the dwelling.

It is true that the exposed roof surface (ie. shingles, tile, metal,
whatever) will deflect the majority of the water. But wind blown rain
will get under this surface, and that is where the underlayment comes
into play.

On Fri, 04 Mar 2005 15:14:37 GMT, "Travis Jordan"
scribbled this interesting note:

John Willis wrote:
I've seen this comment posted several times and I still fail to
understand how one comes to this conclusion. The surface exposed to
the weather should turn the water. No exception. Any penetration of
water through the shingles is unacceptable as if it happens once, it
will happen again and again and that is called a leak. On rare
occasion a unique combination of events may cause water to penetrate a
roof in such a way that may not ever happen again. When and if that
happens, then and only then does the quality of the felt come into
play. If water happens to penetrate the shingles in this manner, a
good felt job will indeed carry the water off and cause no interior
damage, but if it is a recurring penetration, that felt will quickly
fail (or the legs of the fasteners penetrating the felt will rust to
nothing, leaving the holes they made in the felt-a water penetration
point) and then the problem shows up inside the dwelling.

It is true that the exposed roof surface (ie. shingles, tile, metal,
whatever) will deflect the majority of the water. But wind blown rain
will get under this surface, and that is where the underlayment comes
into play.


In which case it would constitute the secondary waterproofing as it is
the backup, hopefully failsafe, protection that is just-in-case the
occasional bit of water might penetrate the primary waterproofing
which is the first level the weather conditions will contact. At least
that is how I've always thought of it.


--
John Willis
(Remove the Primes before e-mailing me)

John Willis wrote:
In which case it would constitute the secondary waterproofing as it is
the backup, hopefully failsafe, protection that is just-in-case the
occasional bit of water might penetrate the primary waterproofing
which is the first level the weather conditions will contact. At least
that is how I've always thought of it.

I guess it is just semantics, John. Most roofers I talk to refer to the
underlayment as the 'dry in' or primary protection and the final
covering as secondary.

In the case of tile or metal coverings the underlayment is a two-ply or
greater system that provides virtually all the waterproofing
protection - since even heavy rain will run over the sides of the tiles
and onto the underlayment. The tile / metal keeps the UV off the
underlayment and extends its life.

On Fri, 04 Mar 2005 15:50:37 GMT, "Travis Jordan"
scribbled this interesting note:

John Willis wrote:
In which case it would constitute the secondary waterproofing as it is
the backup, hopefully failsafe, protection that is just-in-case the
occasional bit of water might penetrate the primary waterproofing
which is the first level the weather conditions will contact. At least
that is how I've always thought of it.

I guess it is just semantics, John. Most roofers I talk to refer to the
underlayment as the 'dry in' or primary protection and the final
covering as secondary.

In the case of tile or metal coverings the underlayment is a two-ply or
greater system that provides virtually all the waterproofing
protection - since even heavy rain will run over the sides of the tiles
and onto the underlayment. The tile / metal keeps the UV off the
underlayment and extends its life.


This is also how the rough and thick cedar shake (as opposed to cedar
wood shingle) roofs are waterproofed. I'm merely addressing typical
asphalt composition roofs in my previous comments.


--
John Willis
(Remove the Primes before e-mailing me)

Travis Jordan Wrote:
manhattan42 wrote:
If an interior and exterior inspection of the roof sheathing yields
no
problems, there is little reason to rip off and replace the existing
layer.

There are two very good reasons to remove the existing layer of a
shingled roof.

1) To reduce the weight of the roof covering. The roof structure may
not be designed to carry the weight of two layers.

2) Primary weatherproofing comes from the bottom underlayment felt,
which ages and becomes brittle. Just the act of walking on it and
nailing an additional layer of shingles may cause it to crack, which
raises the risk of water intrusion and ice dams.

1)This sounds more like silly reasons contractors give to justify
making more from a customer when the facts don't warrant it than
anything else.

Adding and extra layer of shingle to a roof adds less than 1 pound per
square foot of live load.

If shingle weight was really an issue, a contractor could walk on that
roof without it collapsing nor could the roof stand up to a stiff
breeze or moderate snowfall.

If an extra layer of shingles will cause weight problems with the roof,
you have a structural and not an added shingle problem.

2)This is a presumption not based on observabel fact, however, and is
tantamount to a scare tactic to get the customer to spend more money.

I mean, you tell this to a customer and he gets scared and buys the
story, pays more to have the contractor rip off the old shingles and
paper, THEN discovers that both the paper AND sheathing are in good
condtion and its too late for the customer to change his mind and the
contractor gets paid more no matter what.


--
manhattan42
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John Willis Wrote:


So far as I know, National Building Codes allow up to three roofs on a
house. Just because it is up to code does not mean it is ideal. A
house with more than one roof installed is more likely to develop
leaks (because the roof exposed to the weather is not installed over a
uniformly smooth substrate) and I've never seen a second roof like
this last as long as it should. In every case I've seen, a house with
a second, third (or more) roofs installed require attention far sooner
than they would if there had been only one roof.

But that is not the observed fact by shingle manufacturers nor the Code
agencies. There is no more lilkelihood that a covered roof will fail
prematurely than one over a fresh substrate all things being equal.

Which is why manufacturers offer FULL warranty of their products and
Code Officials allow the practice.

Likewise, I have NEVER seen a second layer fail prematurely in my 25+
years as a professional contractor simply because it was a second or
third layer.
If they failed, it was due to issues completely unrelated to the number
of shingles.

So just because one rips off and installs a primary layer instead of
installing a second one only does not guarantee that the job will be
surperior and justify the added cost. Especially if half the time once
the roof has been ripped it has been found that the paper and plywood
is in good condition and didn't need it in the first place.

Yes, the issue is money, and more often than not it is money the
contractor wants to needlessly put in his own pocket at the expense of
a gullible homeowner.


--
manhattan42
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The only reason to roof over an existing roof is because of money. It
takes more time and labor and dump fees to remove an existing roof.
Sure, it is up to code. Sure it is common practice. Yeah, it is
cheaper. Is it best practice? Nope.

============================
I have to agree with you....but that does not mean that I
did not save a few bucks, (a good thing)...and save a hell of a lot of
Time & work removing the original roof...(both good things) when my
original roof needed replacing...

Next time (if I live so long) everything will be removed and I will
still save a lot of time and Money..since I will only be writing the
check not doing the job myself...getting too old for that kind of
work...

Bob Griffiths

manhattan42 wrote:

....
...There is no more lilkelihood that a covered roof will fail
prematurely than one over a fresh substrate all things being equal.
....

But, there's the rub...all things are not equal between the two
cases...

If the old roof is in reasonable condition and there's no underlying
other fault, yes, a 2nd-layer roof may last--but that's far from the
case many times.

I'm seeing a real trend in insurance companies here to not accept the
2nd-layer owing to them having seen higher costs in subsequent years on
previous work....to me, that's pretty conclusive--they've got probably
the best database in existence on the actual cost and aren't known for
being extravagent in making settlements.

manhattan42 wrote:
So just because one rips off and installs a primary layer instead of
installing a second one only does not guarantee that the job will be
surperior and justify the added cost. Especially if half the time once
the roof has been ripped it has been found that the paper and plywood
is in good condition and didn't need it in the first place.

Unless your house was built before there were building codes that
required good nailing of the sheathing, and you want to renail to
prevent the house from coming apart during the next hurricane (Florida)
or tornado (almost anywhere).

Unless you want to put down secondary waterproofing, or an ice-and-water
shield layer.

On Fri, 4 Mar 2005 14:08:49 -0600, manhattan42
scribbled this
interesting note:

John Willis Wrote:

So far as I know, National Building Codes allow up to three roofs on a
house. Just because it is up to code does not mean it is ideal. A
house with more than one roof installed is more likely to develop
leaks (because the roof exposed to the weather is not installed over a
uniformly smooth substrate) and I've never seen a second roof like
this last as long as it should. In every case I've seen, a house with
a second, third (or more) roofs installed require attention far sooner
than they would if there had been only one roof.

But that is not the observed fact by shingle manufacturers nor the Code
agencies. There is no more likelihood that a covered roof will fail
prematurely than one over a fresh substrate all things being equal.

Just because Code says something does not make it true. A laminated,
dimensional, five and five eighths inch exposure shingle, such as GAF
Timberline, installed over a five inch exposure wood shingle roof will
have leaks before an identical installation, except where the
substrate is smooth decking instead of wood shingles. Why? It has to
do with how the exposure of the faces of the different materials align
with each other. In the first example a careful observer will notice
horizontal waves across the plane of the roof-a kind of frequency
based on the difference in the exposure of the different materials.
Those waves represent areas where leaks are likely because the top
shingle is not flat, in fact it is somewhat dish shaped across its
horizontal axis, which means water tends to travel a bit farther on
that horizontal axis in those areas. If fasteners or the butt ends of
the shingles happen to be in the wrong place in those areas, leaks
will happen, and they will happen more quickly than they would if the
installation had been over a smooth deck. Why? Because over a smooth
deck that water would not have had the ability for that horizontal
travel as all the shingles lay flat and none are dish shaped. Physics
is physics and nothing code or the manufacturers say will change that
fact.

Which is why manufacturers offer FULL warranty of their products and
Code Officials allow the practice.

Code allows lots of things I personally wouldn't do when building my
own house. Just because it is supposedly safe and code allows it does
not mean it is ideal or can't be improved upon. As for the warranty,
in these cases the shingles haven't failed, the installation has, so
of course the manufacturers don't care if you install a second roof
over a first. All they warrant is the shingles will last a certain
length of time. They don't warrant anything about the installation!

Likewise, I have NEVER seen a second layer fail prematurely in my 25+
years as a professional contractor simply because it was a second or
third layer.
If they failed, it was due to issues completely unrelated to the number
of shingles.

All the above that I've written is also based on over 25 years of
professional experience in the field of residential roofing and
roofing contracting. BTW, if a three tab shingle is installed over
loc-tab shingles, it gets even worse and I've seen examples of this
kind of installation fail in as little as five years. The best
solution in those cases is to remove all the roofs and start fresh
again.

So just because one rips off and installs a primary layer instead of
installing a second one only does not guarantee that the job will be
superior and justify the added cost.

This much is very true. In fact I would rather have an excellent
installer put on a second roof than a poor installer put on a first!

Especially if half the time once
the roof has been ripped it has been found that the paper and plywood
is in good condition and didn't need it in the first place.

Yes, the issue is money, and more often than not it is money the
contractor wants to needlessly put in his own pocket at the expense of
a gullible homeowner.

If you get good performance from installing a second roof over an
existing roof, good for you. I've found that it is always better to
tear off a roof and start fresh.


--
John Willis
(Remove the Primes before e-mailing me)