Hi,

We have a "built up" (I think that is the term for it -- technically,
it has a "membrane" but I suspect it is closest to "built up"...
layers of roofing felt, flat, etc.) roof.

Above the back patio, there is no "ceiling" so the underlayment (plywood)
for the roof is visible. It is obviously rotted in one section though
there are no visible signs of wear from above (except this small portion
of the roof doesn't bear weight as well as the rest of the roof).

[It's a *small* area -- smaller than the size of a shoe!]

First question: I assume this is caused my water getting under the
roofing material (membrane/felt)? I've not discovered any means
by which that could have happened (everything looks "sealed", "intact")
but water is a sneaky devil!

Second question: is this a self-limiting process? Or, will the damage
continue to spread (even though there are no signs of a water path)

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

In alt.home.repair, on Wed, 19 Aug 2015 12:49:45 -0700, Don Y
wrote:

Hi,

We have a "built up" (I think that is the term for it -- technically,
it has a "membrane" but I suspect it is closest to "built up"...
layers of roofing felt, flat, etc.) roof.

Above the back patio, there is no "ceiling" so the underlayment (plywood)
for the roof is visible. It is obviously rotted in one section though
there are no visible signs of wear from above (except this small portion
of the roof doesn't bear weight as well as the rest of the roof).

[It's a *small* area -- smaller than the size of a shoe!]

First question: I assume this is caused my water getting under the
roofing material (membrane/felt)?

What's the top layer of the roof?

I've not discovered any means
by which that could have happened (everything looks "sealed", "intact")
but water is a sneaky devil!

Water was several times investigated by the House Unamerican Activities
Committee, and the majority agreed that it was sneaky.

Second question: is this a self-limiting process? Or, will the damage
continue to spread (even though there are no signs of a water path)

I don't think it will spread very fast, but you can keep your eyes open.

I have shingles and tarpaper, and when my roof was removed, there was a
little damage to several sheets of plywood. He replaced one sheet and
used sheet metal to cover a couple corners I guess so they woudln't be
soft spots underneath the new shingles, because the sheet metal woudln't
keep any damage from spreading. I assume that he thought, and that
it is true, that when it doesn't get wet anymore, t he damage won't
spread.

So I'd just wait until the roof has bo be replaced, whatever is on top,
and replace seriously damaged plywood then. And patch with some sheet
metal slightly damaged wood.

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

On 8/19/2015 3:28 PM, micky wrote:
In alt.home.repair, on Wed, 19 Aug 2015 12:49:45 -0700, Don Y
wrote:

Hi,

We have a "built up" (I think that is the term for it -- technically,
it has a "membrane" but I suspect it is closest to "built up"...
layers of roofing felt, flat, etc.) roof.

Above the back patio, there is no "ceiling" so the underlayment (plywood)
for the roof is visible. It is obviously rotted in one section though
there are no visible signs of wear from above (except this small portion
of the roof doesn't bear weight as well as the rest of the roof).

[It's a *small* area -- smaller than the size of a shoe!]

First question: I assume this is caused my water getting under the
roofing material (membrane/felt)?

What's the top layer of the roof?

The top *manufactured* layer is a membrane. Of course, there's
many layers of paint on top of that...

I've not discovered any means
by which that could have happened (everything looks "sealed", "intact")
but water is a sneaky devil!

Water was several times investigated by the House Unamerican Activities
Committee, and the majority agreed that it was sneaky.

Second question: is this a self-limiting process? Or, will the damage
continue to spread (even though there are no signs of a water path)

I don't think it will spread very fast, but you can keep your eyes open.

My concern is for things that I'm *not* seeing. E.g., the interior
of the plywood. Hence the thought that I may want to remove and replace
now before it becomes a bigger problem.

I have shingles and tarpaper, and when my roof was removed, there was a
little damage to several sheets of plywood. He replaced one sheet and
used sheet metal to cover a couple corners I guess so they woudln't be
soft spots underneath the new shingles, because the sheet metal woudln't
keep any damage from spreading. I assume that he thought, and that
it is true, that when it doesn't get wet anymore, t he damage won't
spread.

It is very dry here -- 11 in of precip annually. So, the fact that
there is *any* damage has me wondering where the water infiltration
occured (or is occuring!)

So I'd just wait until the roof has bo be replaced, whatever is on top,
and replace seriously damaged plywood then. And patch with some sheet
metal slightly damaged wood.

Roof is 20 years old (average for replacement/repair around here would be
closer to *7*). I intend on getting another 10 out of it! :

(The "membrane" system is no apparently longer used/available. I credit
it -- plus my vigilance -- with the roof's longevity. Neighbors who have
replaced theirs -- with felt -- have been regularly replacing them ever since!)

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

On 8/19/15 3:49 PM, Don Y wrote:
Hi,

We have a "built up" (I think that is the term for it -- technically,
it has a "membrane" but I suspect it is closest to "built up"...
layers of roofing felt, flat, etc.) roof.

Above the back patio, there is no "ceiling" so the underlayment (plywood)
for the roof is visible. It is obviously rotted in one section though
there are no visible signs of wear from above (except this small portion
of the roof doesn't bear weight as well as the rest of the roof).

[It's a *small* area -- smaller than the size of a shoe!]

First question: I assume this is caused my water getting under the
roofing material (membrane/felt)? I've not discovered any means
by which that could have happened (everything looks "sealed", "intact")
but water is a sneaky devil!

Me too! (not a sneaky devil, wouldn't want that made public)

Second question: is this a self-limiting process? Or, will the damage
continue to spread (even though there are no signs of a water path)

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

Dry rot progresses whenever the moisture content of the wood, related to
relative humidity in the air, is above a certain point. If it's dry rot,
solar warming can reduce the moisture content enough to halt the
process. Drying it further will kill the fungus, but it could return if
the wood gets wet.

Where I find rot or see that it might start, I use a garden sprayer to
apply a mix of sodium borate, glycol, and water. Currently, Bora-Care
and Shell-Guard are two such products, if you don't want to cook it in
your kitchen.

On 8/19/2015 8:00 PM, J Burns wrote:
On 8/19/15 3:49 PM, Don Y wrote:

Second question: is this a self-limiting process? Or, will the damage
continue to spread (even though there are no signs of a water path)

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

Dry rot progresses whenever the moisture content of the wood, related to
relative humidity in the air, is above a certain point. If it's dry rot, solar
warming can reduce the moisture content enough to halt the process. Drying it
further will kill the fungus, but it could return if the wood gets wet.

Ha! It never occurred to me to consider what the actual "cause" was;
thanks, I've learned something today! :

Where I find rot or see that it might start, I use a garden sprayer to apply a
mix of sodium borate, glycol, and water. Currently, Bora-Care and Shell-Guard
are two such products, if you don't want to cook it in your kitchen.

So, I guess the first step is to get rid of the current damage
(and figure out its cause); then, watch to see if it wants to return
(perhaps there is some aspect of the roof in this area that leads to
more frequent "failure")

On 8/21/15 3:01 PM, Don Y wrote:
On 8/19/2015 8:00 PM, J Burns wrote:


Where I find rot or see that it might start, I use a garden sprayer to
apply a
mix of sodium borate, glycol, and water. Currently, Bora-Care and
Shell-Guard
are two such products, if you don't want to cook it in your kitchen.

So, I guess the first step is to get rid of the current damage
(and figure out its cause); then, watch to see if it wants to return
(perhaps there is some aspect of the roof in this area that leads to
more frequent "failure")

If the current damage is tolerable, you can keep it from progressing
with a borate spray. The glycol helps it penetrate wood deeply. It
will kill fungus and bugs and keep them from reappearing, as if you'd
built with pressure-treated wood.

On 8/21/2015 4:20 PM, J Burns wrote:
On 8/21/15 3:01 PM, Don Y wrote:
On 8/19/2015 8:00 PM, J Burns wrote:


Where I find rot or see that it might start, I use a garden sprayer to
apply a
mix of sodium borate, glycol, and water. Currently, Bora-Care and
Shell-Guard
are two such products, if you don't want to cook it in your kitchen.

So, I guess the first step is to get rid of the current damage
(and figure out its cause); then, watch to see if it wants to return
(perhaps there is some aspect of the roof in this area that leads to
more frequent "failure")

If the current damage is tolerable, you can keep it from progressing with a
borate spray. The glycol helps it penetrate wood deeply.

Even if the wood surface is painted? I.e., does the solution permeate
the paint *or* do I have to rely on it gaining access via the "rotted"
portions?

It will kill fungus
and bugs and keep them from reappearing, as if you'd built with
pressure-treated wood.

Thanks! I think I have to open things up to see what's really going
on, there. It's a small portion -- but exactly coincides with my first
footfall when leaving the ladder. I.e., it could be that mechanical
stress is what has weakened the roof *seal* in that area (despite the
fact that no cracks or tears are visibly evident).

On 8/22/15 5:24 AM, Don Y wrote:
On 8/21/2015 4:20 PM, J Burns wrote:

If the current damage is tolerable, you can keep it from progressing
with a
borate spray. The glycol helps it penetrate wood deeply.

Even if the wood surface is painted? I.e., does the solution permeate
the paint *or* do I have to rely on it gaining access via the "rotted"
portions?

It will kill fungus
and bugs and keep them from reappearing, as if you'd built with
pressure-treated wood.

Thanks! I think I have to open things up to see what's really going
on, there. It's a small portion -- but exactly coincides with my first
footfall when leaving the ladder. I.e., it could be that mechanical
stress is what has weakened the roof *seal* in that area (despite the
fact that no cracks or tears are visibly evident).

In preparing to repaint a shed, I sprayed exposed edges where there were
signs that rot might be starting. I don't remember how many days I
waited to paint, but the paint stuck.

When mixing, more water means less penetration. The standard is 1:1, but
the instructions says you can use 2 parts water if the wood isn't over
2" thick. So two coats of 1:1 should penetrate more than 2" beyond where
you can spray.

The glycol (ethylene or propylene, the same as antifreeze) is intended
to draw the borate into the wood. I've read that the borate won't go
through paint, but the glycol will. I've read that if you spray a
painted surface with antifreeze, it will go through the paint and give
the underlying wood some protection. Not having tried it, I don't know
if it could loosen paint.

On Wed, 19 Aug 2015 12:49:45 -0700, Don Y
wrote:

Third question: suggested remedy? I figure I could cut out a portion
of the membrane/felt, remove and replace the plywood, then "patch" the
cut out portion of the roof to restore its integrity. But, I assume
I should first have a "smoking gun" that indicates exactly where/how
the damage has been caused in the past?

The cause of the leak is obvious. You used your smoking gun and shot a
bullet hole in it.