Our Condo Association is in the process of reviewing bids to have our units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles. One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?)
Some of the existing shingles have started to curl slightly.

I can't speak knowledgeably to the life issue but as a side note I
recently had a situation with one of my homes that I was selling which
had two layers of shingles. The buyer could not find an insurance
company that would write a policy for the house because it had two
layers. No insurance, no mortgage, no sale.

Fortunately while this was in process we had a severe hail storm and to
my surprise my insurance company removed all of my roof, redecked it and
reshingled it. Otherwise I would have been looking at upwards of $20K
of questionable expense.

RB

Jeff R. wrote:
Our Condo Association is in the process of reviewing bids to have our units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles. One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?)
Some of the existing shingles have started to curl slightly.

It may shorten the life of the new shingles, add a lot of extra weight to
the roof, and there will be the extra cost to bear when the roof has to be
reshingled again, because it will cost more to strip two layers instead of
one layer. If I had a vote, I would vote to remove the old ones before
doing the job. Hope this helps.


"Jeff R." wrote in message
...
Our Condo Association is in the process of reviewing bids to have our
units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles.
One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this
matter?)
Some of the existing shingles have started to curl slightly.

"Jeff R." wrote in message ...
Our Condo Association is in the process of reviewing bids to have our units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles. One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?)
Some of the existing shingles have started to curl slightly.

If the shingles have begun to curle, you may have problems beyond old shingles.
Also, check the manufacturers web sites.
Don't hesitate to e-mail them with questions.

TB

Tom Baker wrote:

"Jeff R." wrote in message ...

Our Condo Association is in the process of reviewing bids to have our units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles. One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?)
Some of the existing shingles have started to curl slightly.


If the shingles have begun to curle, you may have problems beyond old shingles.
Also, check the manufacturers web sites.
Don't hesitate to e-mail them with questions.

TB
Hi,
Just proper thing to do is to remove old shingles. Then you can check
integrity of sheathing underneath too.
They're trying to save cost of removal and hauling it out.
Tony

I don't know about that where I live there is quite a bit of hail damage so
houses get new roofs all the time. It is common practice to put a second
layer over the first then if there is hail again to tear off both layers.

I guess it would depend upon the reason for the roof replacement

Owens Corning web site varies depending upon the shingle but for your basic
3 tab this is from the web site

applied over recommended decks. If other decks are used, the

resulting construction may not qualify as Class A.

Regardless of deck type used, the roofing installer must

ensure that the attic ventilation meets or exceeds FHA Minimum

Property Standards.

Note: All roof structures, especially Mansard style construction, must

have complete through ventilation from bottom to top to prevent heat

build-up or entrapment of moisture-laden air that can cause premature

shingle failure.

(B) Handling: Use extra care in handling shingles when the temperature

is below 40°F. Shingles can be broken easily in cold weather

or their edges damaged in hot weather.

(C) Fastening: Owens Corning recommends nails as the preferred

If old asphalt shingles are to remain in place, nail down or cut away

all loose, curled or lifted shingles. Sweep the surface clean of all

loose debris just prior to applying the new roofing. Ensure proper

size and length of fasteners. If roofing over old wood shingles, cut

back the old shingles at eaves and rakes and apply wood edging

strips. Some local building codes may require the use of a No. 30

asphalt saturated felt over the old wood shingles prior to reroofing.

Consult local building code authorities. Surface must be smooth

before shingles are installed. Make deck smooth by nailing down all

loose and curled shingles, protruding nails, etc. Install beveled wood

feathering strips, if necessary.

When roofing over existing shingles with a 5" (5-5/8" metric) tab

exposure, the following procedure should be used for smoothest

finished appearance and ease of alignment:

http://www.owenscorning.com/around/r...structions.asp



Wayne

"Tony Hwang" wrote in message
news:t9LAc.806289$Ig.387090@pd7tw2no...
Tom Baker wrote:

"Jeff R." wrote in message
...

Our Condo Association is in the process of reviewing bids to have our
units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single layer of shingles.
One
of the
bidders strongly suggested that we strip the existing shingles first,
claiming that if we
didn't we would decrease the useful life of the new shingles by as much
as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of removing the
shingles but not if
it means we would only get 15 years out of the new shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this
matter?)
Some of the existing shingles have started to curl slightly.


If the shingles have begun to curle, you may have problems beyond old
shingles.
Also, check the manufacturers web sites.
Don't hesitate to e-mail them with questions.

TB
Hi,
Just proper thing to do is to remove old shingles. Then you can check
integrity of sheathing underneath too.
They're trying to save cost of removal and hauling it out.
Tony

Have lived San Diego, Chgo, and now far North East US. In
our experieince: Two layers shingles SOP all places.
Warranties, materials AND labor AND installation identical
whether one or two layers. Only dependency I know of is a
deck inspection; if there is excessive rot, past leakage,
past fire/water/storm damage, etc., the roof must be
stripped. Inspections must include fascia and ?? (forget
the word) mounts, etc. for integrity of attachment. Usually
for a 30 yr warranty to be any good someone has to guarantee
the integrity of the deck or the 30 yrs drops to twenty or
even ten. Be sure to read all the small print.
If the contractor's warranties (not just one contractor)
differ based on two layers vs one, then it'd matter. If
not, assuming it's a good warranty, plus the warranty on the
materials, well ... why spend the extra money?
HOWever, after 50-60 years (two layers) there can be a
VERY expensive project coming up. Won't matter whether it's
one or two layers - so watch the warranties AND contractor
reputation! Do NOT let a newbie do it! You get what you
pay for usually, so you must pay attention to the details.

Pop


"Gustov" wrote in message
...
It may shorten the life of the new shingles, add a lot of
extra weight to
the roof, and there will be the extra cost to bear when
the roof has to be
reshingled again, because it will cost more to strip two
layers instead of
one layer. If I had a vote, I would vote to remove the
old ones before
doing the job. Hope this helps.


"Jeff R." wrote in message
...
Our Condo Association is in the process of reviewing
bids to have our
units
reshingled
with 30-year fiberglass (GAF or Tamko) over a single
layer of shingles.
One
of the
bidders strongly suggested that we strip the existing
shingles first,
claiming that if we
didn't we would decrease the useful life of the new
shingles by as much as
50%! Other
people I've spoken to say that 2-4 years is more likely.

Obviously we would like to avoid the additional cost of
removing the
shingles but not if
it means we would only get 15 years out of the new
shingles. Can anyone
provide more
insight as to the actual impact of NOT stripping first?

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt
(does this
matter?)
Some of the existing shingles have started to curl
slightly.

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?

No.

Some of the existing shingles have started to curl slightly.

Should be ok if you choose a dimensional(cedar look) shingle.

Guys putting up cheap shingles must do a tear off. Poor quality
shingles look awful going over anything but sheathing. We put 30 year
shingles over decent roofs all the time. It's called a "roof over" and
exact directions are on every bundle sold. 99% of the country allows
upto three layers of shingles with some regions allowing four.

The second part of the scam is that the lowest bidder saying a tear
off is needed, always "happens" to find a lot of damage. Possibly
charging $100 or more a sheet to replace the sheathing. Only when
everything is said and done do you realize they were actually the
highest bidder.

Andrew J. wrote: 99% of the country allows
upto three layers of shingles with some regions allowing four.

Hmmm, most places I've worked allow only 2 layers.. Hoidy-toidy, I guess. Tom.
Work at your leisure!

AndrewJ wrote in message . ..

Thanks in advance, Jeff R.

--- Other Info ---
We are in the Midwest.
Believe the existing shingles are asphalt organic felt (does this matter?

No.

Some of the existing shingles have started to curl slightly.

Should be ok if you choose a dimensional(cedar look) shingle.

Guys putting up cheap shingles must do a tear off. Poor quality
shingles look awful going over anything but sheathing. We put 30 year
shingles over decent roofs all the time. It's called a "roof over" and
exact directions are on every bundle sold. 99% of the country allows
upto three layers of shingles with some regions allowing four.

The second part of the scam is that the lowest bidder saying a tear
off is needed, always "happens" to find a lot of damage. Possibly
charging $100 or more a sheet to replace the sheathing. Only when
everything is said and done do you realize they were actually the
highest bidder.

This question comes up every few months. Just Google it for
essentially the same responses as above. There is always somebody who
will put layer after layer on and swear by it. The truth is that the
50% longevity of a "roof over" is often the case. Plus, the appearance
is often not as good. And the cost of the next replacement when it
does come will be higher.

I'd consider looking into a metal roof. Probably would get y'all a
reduction in your insurance, and would last a lot longer, too.

wrote in message om...
I'd consider looking into a metal roof. Probably would get y'all a
reduction in your insurance, and would last a lot longer, too.

A metal roof is great, but it would cost two or three times what a
shingle roof runs. I believe any reduction in insurance would be
minimal unless he was converting from wood shakes.
A roof is not just a covering to the dwelling. It is a system or part
of a system. The insulation and ventilation all work together with the
roof material. This is why a system that is set up to vent with a
single layer of roofing will not breath properly with two layers. A
metal roof does not breath at all and needs additional venting.
If the first roof system performed properly over the expected
lifespan, then duplicate that with a tear off and replacement rather
than adding layers or engineering a completely new system.