As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

On Sunday, 3 November 2019 12:16:38 UTC, wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

You can buy a liquid roof seal that can be applied even underwater.
https://www.rawlinspaints.com/home/r...ak-repair.html

There are other manufacturers too.

On Sunday, 3 November 2019 12:30:09 UTC, harry wrote:
On Sunday, 3 November 2019 12:16:38 UTC, wrote:

As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

You can buy a liquid roof seal that can be applied even underwater.
https://www.rawlinspaints.com/home/r...ak-repair.html

There are other manufacturers too.

bitumen is fairly usable in wet conditions. Or you can often dry things out temporarily with a heating, tarp, etc. I've no idea whether GRP & bitumen are compatible.


NT

On 03/11/2019 17:16, wrote:
On Sunday, 3 November 2019 12:30:09 UTC, harry wrote:
On Sunday, 3 November 2019 12:16:38 UTC, wrote:

As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

You can buy a liquid roof seal that can be applied even underwater.
https://www.rawlinspaints.com/home/r...ak-repair.html

There are other manufacturers too.

bitumen is fairly usable in wet conditions. Or you can often dry things out temporarily with a heating, tarp, etc. I've no idea whether GRP & bitumen are compatible.


NT

The Aquashield MSDS is a bit weasely but I'd not be surprised if that
isn't, in fact, bitumen based.

Shouldn't be a problem with bitumen on GRP, especially for a short term fix.

In message ,
writes
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well
and they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to
be porous where the flat roof meets the old roof, this despite
appropriate flashing and 3 layers of mat. The cure would be fairly easy
(with another layer of GRP) if the weather was dry and warm, but it
isn't now and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp
surface.

Have a look through this and you will know as much as any in he-)

https://www.fixmyroof.co.uk/videos-a...lacement/how-t
o-fibreglass-a-roof/

I take it your construction involves a shallow valley. The video above
advises one layer of glass mat (if it is not a trafficked area) plus a
gel coat on top.

They show how to *bandage* joints in the roof boarding and close off any
apertures. One point of interest to you is that the recommended cleaning
solvent, acetone, is soluble in water which may make drying off the
surface ready for a re-coat easier. Lots of rubbing down with 60 grit
glass paper!

Connecting *pin holes* through three layers seems unlikely and you don't
mention a gel coat.

No leaks found in my d-i-y one, yet!

--
Tim Lamb

That sounds very handy. I can think of few uses for that.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"harry" wrote in message
...
On Sunday, 3 November 2019 12:16:38 UTC, wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp
surface.

You can buy a liquid roof seal that can be applied even underwater.
https://www.rawlinspaints.com/home/r...ak-repair.html

There are other manufacturers too.

In article ,
wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

Aquapol ain't cheap but worked very well on this felt flat roof that is
nominally well past the usual life. It has cracked where it was bent up
under the flashing. Used their reinforcing gauze too. Only intended it as
a temporary fix, but it's done three winters so far.

--
*One nice thing about egotists: they don't talk about other people.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sun, 3 Nov 2019 20:40:42 +0000, Tim Lamb
wrote:

snip

Connecting *pin holes* through three layers seems unlikely and you don't
mention a gel coat.

Quite, especially as many boats are lighter built than that. ;-)


No leaks found in my d-i-y one, yet!

Excellent, but then I know how much attention to detail you generally
apply to such things.

I have laid up quite a bit of fibreglass in my time and also come
across some pretty poor example of both amateur and professional work
(too 'dry' being the worst).

Many seem to put the resin on like a paint, rather than stippling it
through with the right sort of brush, therefore not 'wetting' the mat
/ roving out properly.

You don't want to over-work chopped-strand-mat either or you can start
to impact the consistency too much.

Re gel-coat, I've only ever applied it directly to a mould where it's
then followed by the resin / fibreglass and because std gel is
anaerobic (?), you don't need to prep the gelcoat to get the resin to
bond effectively.

I think you can apply gelcoat to the outside of some (cured)
fibreglass but I think it's different or needs further coating (wax?)
to get it to fully cure?

I am lucky that I don't seem to react to fibreglass itself, lucky
because I spent much of my youth stuck in lockers or other confined
spaces glassing stuff up for Dad on our various boats. It was like a
modern day version of the kids used to sweep chimneys. ;-)

I was thinking of putting a fibreglass roof on my (10x6') shed that is
still in Mums back garden but I imagine the materials would cost quite
a bit these days?

Cheers, T i m

On 03/11/2019 20:40, Tim Lamb wrote:
In message , writes
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well
and they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to
be porous where the flat roof meets the old roof, this despite
appropriate flashing and 3 layers of mat. The cure would be fairly
easy (with another layer of GRP) if the weather was dry and warm, but
it isn't now and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this
section of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp
surface.

Have a look through this and you will know as much as any in he-)

https://www.fixmyroof.co.uk/videos-a...lacement/how-t
o-fibreglass-a-roof/
Thanks

I take it your construction involves a shallow valley. The video above
advises one layer of glass mat (if it is not a trafficked area) plus a
gel coat on top.
It's slightly difficult to describe the roof. An existing single storey
pitched roof runs into an existing vertical wall. The new roof is 90
degrees to the single storey bit and has a hidden flat roof (middle
dotted line, below). This flat section slopes back to the single storey
roof and also slopes away from the vertical wall, so the water runs back
and then down the valley (V). All pitches are 62 degrees'ish. The
problem area is where the flat roof meets the original pitched roof,
along the middle dotted line.
__________
|
|
-------------|
/\ |
V/ -\---|
V/ \--|
---V/------\

They show how to *bandage* joints in the roof boarding and close off any
apertures. One point of interest to you is that the recommended cleaning
solvent, acetone, is soluble in water which may make drying off the
surface ready for a re-coatÂ* easier. Lots of rubbing down with 60 grit
glass paper!

Connecting *pin holes* through three layers seems unlikely and you don't
mention a gel coat.
I checked this morning, and found that I'd got that wrong. I don't know
why I thought it was 3 layers, but it's only 1.
The top coat isn't on yet because the guys want to first make sure the
main layer isn't leaking.

No leaks found in my d-i-y one, yet!

In message ,
writes
On 03/11/2019 20:40, Tim Lamb wrote:
I take it your construction involves a shallow valley. The video
above advises one layer of glass mat (if it is not a trafficked area)
plus a gel coat on top.
It's slightly difficult to describe the roof. An existing single storey
pitched roof runs into an existing vertical wall. The new roof is 90
degrees to the single storey bit and has a hidden flat roof (middle
dotted line, below). This flat section slopes back to the single storey
roof and also slopes away from the vertical wall, so the water runs
back and then down the valley (V). All pitches are 62 degrees'ish. The
problem area is where the flat roof meets the original pitched roof,
along the middle dotted line.
__________
|
|
-------------|
/\ |
V/ -\---|
V/ \--|
---V/------\

Sadly that doesn't display well on my set up.

They show how to *bandage* joints in the roof boarding and close off
any apertures. One point of interest to you is that the recommended
cleaning solvent, acetone, is soluble in water which may make drying
off the surface ready for a re-coat* easier. Lots of rubbing down
with 60 grit glass paper!
Connecting *pin holes* through three layers seems unlikely and you
don't mention a gel coat.
I checked this morning, and found that I'd got that wrong. I don't know
why I thought it was 3 layers, but it's only 1.
The top coat isn't on yet because the guys want to first make sure the
main layer isn't leaking.

After 24 hours, any further coats (including the gel coat) require a
thorough sanding followed by a wipe off with acetone.

I think the video suggests a second layer of *thin* mat if there is any
doubt.

I ended up with 2 gel coats because it is much slower to cure than the
resin and it rained that night:-(

If you do seal it with bitumen you will need to start over for a fresh
glass fibre job. Resin and any sort of tar/grease do not go well
together.

--
Tim Lamb

In message , T i m
writes
On Sun, 3 Nov 2019 20:40:42 +0000, Tim Lamb
wrote:

snip

Connecting *pin holes* through three layers seems unlikely and you don't
mention a gel coat.

Quite, especially as many boats are lighter built than that. ;-)


No leaks found in my d-i-y one, yet!

Excellent, but then I know how much attention to detail you generally
apply to such things.

I have laid up quite a bit of fibreglass in my time and also come
across some pretty poor example of both amateur and professional work
(too 'dry' being the worst).

Many seem to put the resin on like a paint, rather than stippling it
through with the right sort of brush, therefore not 'wetting' the mat
/ roving out properly.

You don't want to over-work chopped-strand-mat either or you can start
to impact the consistency too much.

Re gel-coat, I've only ever applied it directly to a mould where it's
then followed by the resin / fibreglass and because std gel is
anaerobic (?), you don't need to prep the gelcoat to get the resin to
bond effectively.

It needs to go on within 24 hours or you have to abrade the surface
before applying.

I think you can apply gelcoat to the outside of some (cured)
fibreglass but I think it's different or needs further coating (wax?)
to get it to fully cure?

I am lucky that I don't seem to react to fibreglass itself, lucky
because I spent much of my youth stuck in lockers or other confined
spaces glassing stuff up for Dad on our various boats. It was like a
modern day version of the kids used to sweep chimneys. ;-)

I was thinking of putting a fibreglass roof on my (10x6') shed that is
still in Mums back garden but I imagine the materials would cost quite
a bit these days?

Ah! I have a can of resin, some accelerator about 4m2 of heavy chopped
strand matt and enough gelcoat for about 5m2. Plus the tools for which I
will have no further use.

I planned to offer it as an inducement:-) The telephone engineer is
booked for the afternoon of the 12th Nov!

--
Tim Lamb

On 04/11/2019 13:27, Dave Plowman (News) wrote:
In article ,
wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

Aquapol ain't cheap but worked very well on this felt flat roof that is
nominally well past the usual life. It has cracked where it was bent up
under the flashing. Used their reinforcing gauze too. Only intended it as
a temporary fix, but it's done three winters so far.

We've decided to construct a tent over the flat section and, if this
works, they will then re-do the GRP. If that fails then it will be
Aquapol or TekCryl to get through the winter and fix it properly in the
dry weather.

On Monday, 4 November 2019 13:35:34 UTC, Dave Plowman (News) wrote:
In article ,
wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp surface.

Aquapol ain't cheap but worked very well on this felt flat roof that is
nominally well past the usual life. It has cracked where it was bent up
under the flashing. Used their reinforcing gauze too. Only intended it as
a temporary fix, but it's done three winters so far.

I patched a split felt roof with 1 layer of bedsheet & bitumen just to get it through the winter before a full reroof. Plans changed & more work was never done, about 6 years on the patches are still fine. As for the rest... entire sections have gone.


NT

On Mon, 4 Nov 2019 18:42:23 +0000, Tim Lamb
wrote:

snip

Re gel-coat, I've only ever applied it directly to a mould where it's
then followed by the resin / fibreglass and because std gel is
anaerobic (?), you don't need to prep the gelcoat to get the resin to
bond effectively.

It needs to go on within 24 hours or you have to abrade the surface
before applying.

That sounds familiar. ;-)

snip

I was thinking of putting a fibreglass roof on my (10x6') shed that is
still in Mums back garden but I imagine the materials would cost quite
a bit these days?

Ah! I have a can of resin, some accelerator about 4m2 of heavy chopped
strand matt and enough gelcoat for about 5m2. Plus the tools for which I
will have no further use.

Ok ...

I planned to offer it as an inducement:-)

No 'inducement' needed mate, happy to pop over any time (but thanks
very much for the kind offer. With that in mind I'll leave the
'temporary' DPM on there (that seems to be holding for now) and wait
for the nicer weather). ;-)

The telephone engineer is
booked for the afternoon of the 12th Nov!

I'll get her to put it in her diary.

I can't see there being any issues as we tested all we could from
different directions and I can't see anyone complaining about not
having to run cables. ;-)

Cheers, T i m

On Mon, 4 Nov 2019 18:29:11 +0000, Tim Lamb
wrote:

In message ,
writes
On 03/11/2019 20:40, Tim Lamb wrote:
I take it your construction involves a shallow valley. The video
above advises one layer of glass mat (if it is not a trafficked area)
plus a gel coat on top.
It's slightly difficult to describe the roof. An existing single storey
pitched roof runs into an existing vertical wall. The new roof is 90
degrees to the single storey bit and has a hidden flat roof (middle
dotted line, below). This flat section slopes back to the single storey
roof and also slopes away from the vertical wall, so the water runs
back and then down the valley (V). All pitches are 62 degrees'ish. The
problem area is where the flat roof meets the original pitched roof,
along the middle dotted line.
__________
|
|
-------------|
/\ |
V/ -\---|
V/ \--|
---V/------\

Sadly that doesn't display well on my set up.

Does Turnpike have the option to display Fixed Pitch font (or not), as
Agent does Tim? My default on Forte Agent is proportionally spaced as
it makes it easier to read but as it sounds like you have seen, it
screws up any ASCII art. By checking 'Fixed pitch font' makes it all
appear as intended. ;-)

Cheers, T i m

In article ,
wrote:
Aquapol ain't cheap but worked very well on this felt flat roof that
is nominally well past the usual life. It has cracked where it was
bent up under the flashing. Used their reinforcing gauze too. Only
intended it as a temporary fix, but it's done three winters so far.

I patched a split felt roof with 1 layer of bedsheet & bitumen just to
get it through the winter before a full reroof. Plans changed & more
work was never done, about 6 years on the patches are still fine. As for
the rest... entire sections have gone.

I was told 25 years was good for a felt roof. But on this one, the
majority of it looked to be just fine at over this. It was done by a local
company with an excellent reputation, though. And with decent ply decking.

--
*Toilet stolen from police station. Cops have nothing to go on.

Dave Plowman London SW
To e-mail, change noise into sound.

On 04/11/2019 20:12, wrote:
On 04/11/2019 13:27, Dave Plowman (News) wrote:
In article ,
Â*Â*Â* wrote:
As part of a small extension I needed a "hidden" flat roof section. I
got builders to do the groundwork, blockwork and roofing - although
their work in most areas has been good, the GRP roof did not go well and
they've run out of ideas, so I need some advice.
The flat roof slopes back (and sideways) to an existing tiled roof and
water then spills down a valley. The problem is that the GRP seems to be
porous where the flat roof meets the old roof, this despite appropriate
flashing and 3 layers of mat. The cure would be fairly easy (with
another layer of GRP) if the weather was dry and warm, but it isn't now
and probably won't be until the Spring.
Once the area is dry I think the answer will be to cut-out this section
of GRP and to glass-in some new mat, taking care to thoroughly
impregnate it with resin.
The question is: what can I/they do to make it watertight until it can
be fixed properly? It needs something that can be applied to a damp
surface.

Aquapol ain't cheap but worked very well on this felt flat roof that is
nominally well past the usual life. It has cracked where it was bent up
under the flashing. Used their reinforcing gauze too. Only intended it as
a temporary fix, but it's done three winters so far.

We've decided to construct a tent over the flat section and, if this
works, they will then re-do the GRP. If that fails then it will be
Aquapol or TekCryl to get through the winter and fix it properly in the
dry weather.

If you mean Acrypol, then my experience of it, when used over Isoflex
is that is expensive and useless. Lasts about a year.

On Tuesday, 5 November 2019 19:08:35 UTC, Andrew wrote:

If you mean Acrypol, then my experience of it, when used over Isoflex
is that is expensive and useless. Lasts about a year.

would that be an apocryphal story?