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 8/19/15 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 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 8/19/2015 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 8/22/2015 8:42 PM, J Burns wrote:
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.

OK. Did the painted surface *prior* to your adding that new coat (of paint)
show visible signs of having been sprayed? I.e., if I opt to spray it,
would I then have to paint it afterwards?

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.

So, for plywood underlayment, this is a lead pipe cinch! (?)

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.

frown I think the best course of action is for me to remove that portion
of the underlayment and replace it (then paint it and repair the roof
covering).

Then, I can examine the damaged piece more thoroughly -- to see how far
the damage had progressed beyond what was visible. And, spray it
to see how the paint behaves -- as well as cut the treated board open
to see how well the stuff penetrated.

I.e., learn specifics in case I encounter something similar in the
future.

Thanks!

On 8/22/2015 8:42 PM, J Burns wrote:

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.

On a related note...

We have "decorative" 4x10 (or 12?) lintels on the exterior of the house.
Over the years, these have also failed (moisture, etc.) Of course, as
they are purely cosmetic, you'd never know it unless you went poking
around!

Rather than using a composite to replace them (expensive!), the cheap
fix is just buy more lumber, paint it and hang it.

Would this sort of "treatment" be as good as (better?) than buying
pressure treated lumber? Consider that this *is* a cosmetic issue
and if it takes another 30 years for the replacements to deteriorate...

On 8/24/15 1:20 AM, Don Y wrote:
On 8/22/2015 8:42 PM, J Burns wrote:


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.

OK. Did the painted surface *prior* to your adding that new coat (of
paint) show visible signs of having been sprayed? I.e., if I opt to
spray it, would I then have to paint it afterwards?

I don't recall. That's the only time I've sprayed paint, and it was
just at the edges in certain spots. If I'd seen and worried about
visible borate, I guess I could have wiped it off with a wet cloth.

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.

So, for plywood underlayment, this is a lead pipe cinch! (?)

It should soak in a long way.


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.

frown I think the best course of action is for me to remove that
portion of the underlayment and replace it (then paint it and repair
the roof covering).

Then, I can examine the damaged piece more thoroughly -- to see how
far the damage had progressed beyond what was visible. And, spray
it to see how the paint behaves -- as well as cut the treated board
open to see how well the stuff penetrated.

I.e., learn specifics in case I encounter something similar in the
future.

Thanks!


AFAIK, antifreeze doesn't damage house paint, but I don't know. If you
replace the damaged underlayment, you won't step through the rotted
place one day!

On 8/24/15 1:30 AM, Don Y wrote:
On 8/22/2015 8:42 PM, J Burns wrote:


On a related note...

We have "decorative" 4x10 (or 12?) lintels on the exterior of the house.
Over the years, these have also failed (moisture, etc.) Of course, as
they are purely cosmetic, you'd never know it unless you went poking
around!

Rather than using a composite to replace them (expensive!), the cheap
fix is just buy more lumber, paint it and hang it.

Would this sort of "treatment" be as good as (better?) than buying
pressure treated lumber? Consider that this *is* a cosmetic issue
and if it takes another 30 years for the replacements to deteriorate...

I faced a similar question seven years ago when I replaced my cellar
hatch (a door sloping to the ground at 45 degrees) because the
pressure-treated lumber had failed.

I had scrap pallet boards, scrap shingles, and leftover borate, so I
built it that way as an experiment. The bottom of the door is submerged
in rainy weather, and borate is supposed to leach out from long submersion.

Since then, I have once sprayed a little more borate on the bottom ends
of the boards when I happened to have it in the sprayer for another job.
I haven't seen any rot.

Borate would probably protect lintels from rot, but if it's plywood,
maybe the glue failed.

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.