Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of
about 1m square stays wet until it evaporates.
Is this a problem?
The builder says the only solution is to strip and re-felt the whole
flat roof but this wasn't in his quote.
--
Dave S
(The return email address is a dummy)

"Dave" wrote in message
...
Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of

When I started work in the roofing trade in 1954, all felt roofs had the
outlet standing up about 1"or 25 mm to retain a wet surface, then came the
idea of lime stone chipping and now theve gone back to just plain mineral
felt as in the 50s. Flat roofing felt as change over the last 50 years so a
drop os water wont hurt only in your dislike of seeing it there.
about 1m square stays wet until it evaporates.
Is this a problem?
The builder says the only solution is to strip and re-felt the whole
flat roof but this wasn't in his quote.
--
Keith.765

tony green wrote:
"Dave" wrote in message
...

Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of


When I started work in the roofing trade in 1954, all felt roofs had the
outlet standing up about 1"or 25 mm to retain a wet surface, then came the
idea of lime stone chipping and now theve gone back to just plain mineral
felt as in the 50s. Flat roofing felt as change over the last 50 years so a
drop os water wont hurt only in your dislike of seeing it there.

about 1m square stays wet until it evaporates.
Is this a problem?
The builder says the only solution is to strip and re-felt the whole
flat roof but this wasn't in his quote.
--

Keith.765


Thanks for the reassurance Keith/Tony.

--
Dave S
(The return email address is a dummy)

In message , tony green
writes

"Dave" wrote in message
...
Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of

When I started work in the roofing trade in 1954, all felt roofs had the
outlet standing up about 1"or 25 mm to retain a wet surface,

Which is ok until a leak somewhere occurs...

then came the
idea of lime stone chipping and now theve gone back to just plain mineral
felt as in the 50s. Flat roofing felt as change over the last 50 years so a
drop os water wont hurt only in your dislike of seeing it there.

hmm, very much a case of it depends I think.

We used to have a fair amount of standing water on our flat roof. The
roof was surrounded by a low parapet wall and the felt went up onto
this.

This was always a weak point IMO where the felt bent upwards. The joints
would gradually open. In winter the water would lie for months against
this bit of the roof, freezing and melting, leaking through the rof here
was pretty much a certainty.

We solved it when the roof was redone, by levelling out the roof a bit,
and by putting in a sort of 'gutter' at one side of the roof.
--
Chris French, Leeds

chris French wrote:

In message , tony green
writes

"Dave" wrote in message
...
Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of

When I started work in the roofing trade in 1954, all felt roofs had the
outlet standing up about 1"or 25 mm to retain a wet surface,

Which is ok until a leak somewhere occurs...

Keeping the roof wet stops degradation of the felt in the first place.
A wet roof is much better than one that is kept dry, bakes in the sun,
expands, contracts and subsequently cracks. If its is properly done
in the first place, not covered in sharp stones and not regularly
walked on they can easily last 40-50 years.


--

No Spam wrote:
Keeping the roof wet stops degradation of the felt in the first place.
A wet roof is much better than one that is kept dry, bakes in the sun,
expands, contracts and subsequently cracks. If its is properly done
in the first place, not covered in sharp stones and not regularly
walked on they can easily last 40-50 years.

Covered in chippings. AH! You mention that! Why the D- do they do that
in the first place? Grr.

Chris Bacon wrote:

No Spam wrote:
Keeping the roof wet stops degradation of the felt in the first place.
A wet roof is much better than one that is kept dry, bakes in the sun,
expands, contracts and subsequently cracks. If its is properly done
in the first place, not covered in sharp stones and not regularly
walked on they can easily last 40-50 years.

Covered in chippings. AH! You mention that! Why the D- do they do that
in the first place? Grr.

To reflect the heat and so keep the felt cool - something water does a
bit better.


--

On Sun, 13 Mar 2005 10:02:51 +0000, Dave wrote:

... there's now a ridge (about 5mm) so an area of about 1m square
stays wet until it evaporates. Is this a problem?

If there is no join near (for capilary action) or under this water I'd
not be to worried. But if it's new felt bonded onto the old and the
water is lying along that join I'd not be happy about it lasting long.
The action of heat from the sun and water getting in and freezing will
soon open up that join.

--
Cheers
Dave. pam is missing e-mail

Dave wrote:
Some recent extension work involved slightly changing the run-off point
from a section of flat roofing. Where the new felt at the run-off point
was bonded to the old felt there's now a ridge (about 5mm) so an area of
about 1m square stays wet until it evaporates.
Is this a problem?

No.