I wonder if anyone has experience of placing fibreglass over an
existing flat roof?

I have a building which is simply a flat roof fixed between rendered
brick walls. The problem is the steel profile sheeting was laid too
flat and the gutters of the adjacent roofs overflow, the subsequent
deluge overwhelms the flat roof and water gets in via the overlaps. I
have painted these with resin sealant but this hasn't survived the
movement of the panels over time, I also think some water is getting
past blown render.

I am considering just tanking the roof and up stands with fibreglass
but wonder if this should be applied directly or a membrane used to
allow for differential movement?

AJH

In message ,
writes
I wonder if anyone has experience of placing fibreglass over an
existing flat roof?

I have a building which is simply a flat roof fixed between rendered
brick walls. The problem is the steel profile sheeting was laid too
flat and the gutters of the adjacent roofs overflow, the subsequent
deluge overwhelms the flat roof and water gets in via the overlaps. I
have painted these with resin sealant but this hasn't survived the
movement of the panels over time, I also think some water is getting
past blown render.

I am considering just tanking the roof and up stands with fibreglass
but wonder if this should be applied directly or a membrane used to
allow for differential movement?

I use butyl sealing strips under the laps and then stitching screws at
18" intervals. OK for rain splash but not guaranteed for immersion.

Can you not sort out the gutter issue?

I think there are roofers specialising in glass fibre work but I have no
direct experience.
--
Tim Lamb

On Mon, 16 May 2016 06:26:01 +0100, wrote:

I wonder if anyone has experience of placing fibreglass over an
existing flat roof?

I have a building which is simply a flat roof fixed between rendered
brick walls. The problem is the steel profile sheeting was laid too
flat and the gutters of the adjacent roofs overflow, the subsequent
deluge overwhelms the flat roof and water gets in via the overlaps. I
have painted these with resin sealant but this hasn't survived the
movement of the panels over time, I also think some water is getting
past blown render.

I am considering just tanking the roof and up stands with fibreglass
but wonder if this should be applied directly or a membrane used to
allow for differential movement?

About 5 years ago I helped a friend replace a leaking felt roof on a
flat roofed garage and kitchen extension with fibreglass laid directly
onto the boarding underneath the felt we stripped off. One side was
the house wall and we used a fillet trim similar to
http://www.glasplies.co.uk/category-s/2032.htm to make a neat join to
the wall. No problems at all with it since.

"Tim Lamb" wrote in message
...

In message ,
writes
I wonder if anyone has experience of placing fibreglass over an
existing flat roof?

I have a building which is simply a flat roof fixed between rendered
brick walls. The problem is the steel profile sheeting was laid too
flat and the gutters of the adjacent roofs overflow, the subsequent
deluge overwhelms the flat roof and water gets in via the overlaps. I
have painted these with resin sealant but this hasn't survived the
movement of the panels over time, I also think some water is getting
past blown render.

I am considering just tanking the roof and up stands with fibreglass
but wonder if this should be applied directly or a membrane used to
allow for differential movement?

I use butyl sealing strips under the laps and then stitching screws at 18"
intervals. OK for rain splash but not guaranteed for immersion.

Can you not sort out the gutter issue?

I think there are roofers specialising in glass fibre work but I have no
direct experience.

I have two experiences of fiberglassing roofs:

First experience entirely positive, I formed a box valley between the house
and a garage I'd built. Made the channel shape in exterior ply, and laid two
(or may be three?) layers of resin and fibre matting - worked superbly

Second experience partly positive. I had a leaking PortaKabin roof -
galvanised overlapping flat sheets. The plan was to sheath it in fiberglass
so I bought a kit and went at it. Day was overcast, sheets were cool. I
measured their temperature and mixed the resin accordingly. Started off
fine, went down well, until the clouds cleared, the sun beat down and the
sheets got very hot very quickly. The resin set before I could flatten it
down properly and it looks a right mess (luckily it's not visible unless you
climb up there!) however it cured the leaks and we've had no rain in for two
or three years now

Andrew

On Mon, 16 May 2016 09:27:44 +0100, Tim Lamb
wrote:


I use butyl sealing strips under the laps and then stitching screws at
18" intervals. OK for rain splash but not guaranteed for immersion.

I had used a fibre reinforces acryl paint

The problem was exacerbated by a build up of leaves effectively
damming the furrow of the profile sheet, so after a recent deluge the
gutters overflowed from the two adjacent roofs and the flat roof
probably had 50mm of standing water on it, water that did flow off the
lower edge overfilled the gutter, which was half filled with debris
and seeped back into the void between the joists and ran back between
the roof sheets and ceiling.

The infill was amazingly poorly though out but it currently provides
60m2 of storage and I cannot find a home for the bits and pieces in
order to start again.

I need a solution which doesn't require more than annual cleaning. I
will fit deeper gutters and drop them by a couple of inches.

AJH

On Mon, 16 May 2016 11:10:35 +0100, "Andrew Mawson"
wrote:

Second experience partly positive. I had a leaking PortaKabin roof -
galvanised overlapping flat sheets. The plan was to sheath it in fiberglass
so I bought a kit and went at it. Day was overcast, sheets were cool. I
measured their temperature and mixed the resin accordingly. Started off
fine, went down well, until the clouds cleared, the sun beat down and the
sheets got very hot very quickly. The resin set before I could flatten it
down properly and it looks a right mess (luckily it's not visible unless you
climb up there!) however it cured the leaks and we've had no rain in for two
or three years now

Andrew

Looks don't matter, no one can see it. So the thermal expansion of the
steel wasn't a problem? It looks more promising, espaecially as one of
the guy's father is a GRP boat builder.

AJH

On Mon, 16 May 2016 10:56:55 +0100, Peter Parry
wrote:

About 5 years ago I helped a friend replace a leaking felt roof on a
flat roofed garage and kitchen extension with fibreglass laid directly
onto the boarding underneath the felt we stripped off. One side was
the house wall and we used a fillet trim similar to
http://www.glasplies.co.uk/category-s/2032.htm to make a neat join to
the wall. No problems at all with it since.

Yes I've seen decks sheathed in fibreglass so I know it's ok with
wood, I was a bit concerned about laying it direct onto steel.

I think I'd lay it right up the walls to the eaves as looks don't
matter.

AJH