A short wall dividing two flat roofs absorbs rainwater, which leaks from
the brickwork into the roofspace below. The top and sides of the wall
were treated with bitumen paint which worked for a few years before water
got in again. This is the wall:

https://i.postimg.cc/sx1Q95B7/roof-wall-20201003-A.jpg

My handyman will paint it again if I buy some sealant. The original paint
was "IKO-pro Flat Roof Renovator" which the tin says is for the flat roof
itself rather than a wall:

https://www.wilko.com/en-uk/ikopro-f...ator/p/0243442

There is also this IKO-pro Bitumen Paint (now discontinued). Is this sort
of thing better for that wall?

https://www.wilko.com/en-uk/ikopro-b...aint/p/0135507

I also saw this Thompsons High Performance Roof Seal:

https://www.screwfix.com/p/thompsons...oof-seal/46708

Igot spoilt for choice when I saw an acrylic sealant Polar Leakseal:

https://polarcoatings.co.uk/product/leakseal-500ml

I'm confused. Which one is best to use?

On Sat, 03 Oct 2020 22:12:15 +0100, Pamela wrote:

A short wall dividing two flat roofs absorbs rainwater, which leaks from
the brickwork into the roofspace below. The top and sides of the wall
were treated with bitumen paint which worked for a few years before
water got in again. This is the wall:

https://i.postimg.cc/sx1Q95B7/roof-wall-20201003-A.jpg

Remove railings, cap stones and first course of bricks. Cover exposed
top of wall with sheet lead that comes down the wall and over the top
the roof covering fillet, both sides. Relay new clean bricks and cap
stones, replace railings.

As a bit of lead to cover that width of wall and down the sides won't
be cheap you could probably get away with just lead flashing along
the edges and DMP immediatly above it. Ensure the lead and DPM have a
slight fall to the outside. The wall top covering needs to be
contiguos to stop water penetrating the wall. If there has to be a
joint the edges along the joint need to have a vertial bit of about
an inch and an inverted U cap over the top.

"Sealants" will just fail, again. Properly done lead/DPM will cure
the problem for good.

--
Cheers
Dave.

On 04/10/2020 00:33, Dave Liquorice wrote:

Remove railings, cap stones and first course of bricks. Cover exposed
top of wall with sheet lead that comes down the wall and over the top
the roof covering fillet, both sides. Relay new clean bricks and cap
stones, replace railings.

Could it be that the water penetration is where the cap stones have been
drilled through to fit the railings.? The bitumen may have sealed the
base of the railing posts but possibly these are the most likely to have
moved cracking any seal.


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Sun, 4 Oct 2020 01:03:12 +0100, alan_m wrote:

Remove railings, cap stones and first course of bricks. Cover
exposed
top of wall with sheet lead that comes down the wall and over the
top
the roof covering fillet, both sides. Relay new clean bricks and
cap
stones, replace railings.

Could it be that the water penetration is where the cap stones have been
drilled through to fit the railings.?

Possibly but there are still the joints between the cap stones to
fail and let water in.

--
Cheers
Dave.

On 00:33 4 Oct 2020, Dave Liquorice said:
On Sat, 03 Oct 2020 22:12:15 +0100, Pamela wrote:

A short wall dividing two flat roofs absorbs rainwater, which leaks
from the brickwork into the roofspace below. The top and sides of the
wall were treated with bitumen paint which worked for a few years
before water got in again. This is the wall:

https://i.postimg.cc/sx1Q95B7/roof-wall-20201003-A.jpg

Remove railings, cap stones and first course of bricks. Cover exposed
top of wall with sheet lead that comes down the wall and over the top
the roof covering fillet, both sides. Relay new clean bricks and cap
stones, replace railings.

As a bit of lead to cover that width of wall and down the sides won't
be cheap you could probably get away with just lead flashing along the
edges and DMP immediatly above it. Ensure the lead and DPM have a slight
fall to the outside. The wall top covering needs to be contiguos to stop
water penetrating the wall. If there has to be a joint the edges along
the joint need to have a vertial bit of about an inch and an inverted U
cap over the top.

"Sealants" will just fail, again. Properly done lead/DPM will cure the
problem for good.


All very true and something to do in spring. Meanwhile the wall needs
sealing as rain water is entering and I'm not sure if I should get plain
bitumen paint, roofing bitumen paint or acrylic sealant paint.

This was my shortlist:

https://www.wilko.com/en-uk/ikopro-f...ator/p/0243442
https://www.screwfix.com/p/thompsons...oof-seal/46708
https://polarcoatings.co.uk/product/leakseal-500ml

On Monday, 5 October 2020 13:15:33 UTC+1, Pamela wrote:

All very true and something to do in spring. Meanwhile the wall needs
sealing as rain water is entering and I'm not sure if I should get plain
bitumen paint, roofing bitumen paint or acrylic sealant paint.

This was my shortlist:

https://www.wilko.com/en-uk/ikopro-f...ator/p/0243442
https://www.screwfix.com/p/thompsons...oof-seal/46708
https://polarcoatings.co.uk/product/leakseal-500ml

FWIW I had a similar problem with a flat garage roof and just
used the cheapest bitumen goo I could find and put a reasonably
thick layer on. It definitely worked on cracks and small holes
but AIUI cracks and small holes indicate that a "proper job"
needs doing. It did, however, give me an extra 2 years of
leak-free garage action. But I'm glad that it was re-covered
properly so I don't have to play the rainstorm lottery anymore.

On Mon, 05 Oct 2020 13:15:08 +0100, Pamela wrote:

Remove railings, cap stones and first course of bricks. Cover
exposed
top of wall with sheet lead that comes down the wall and over the
top
the roof covering fillet, both sides. Relay new clean bricks and
cap
stones, replace railings.

All very true and something to do in spring. Meanwhile the wall needs
sealing as rain water is entering...

As a "keep the wet out 'till the spring(*1)" solution I'd just get
some reasonable weight poly sheeting and a few bricks(*2) and simply
cover the cap stones, bricks along the edges every 2 to 3 feet. With
the sheeting an inch or two wider each side so water drips off onto
the flat roofs. The delux version would have a batten along the line
of the railings to enforce a fall on the sheeting and allow a bit of
ventilation underneath. Super delux tape any joins between sheets
rather than just having an overlap.

Trouble is we don't really know where the water is getting into the
wall. It could be through the joints in the cap stones or beteen the
wall and roofing fillet or both... try just the capstones if that
doesn't have much effect it's easy to put a bit sheeting under it and
down to the roof (weighted down of course) to fully protect the wall/
fillet as well.

The caps stones do have a drip groove underneath the overhang don't
they?

(*1) I'm assuming spring 2021, not '22 or '23... B-)

(*2) Such as scrounged empty feed bags from local farmers opened out
and spare rocks that are lying around or even a logs from the wood
pile.

--
Cheers
Dave.

On 04/10/2020 01:23, Dave Liquorice wrote:
On Sun, 4 Oct 2020 01:03:12 +0100, alan_m wrote:

Remove railings, cap stones and first course of bricks. Cover
exposed
top of wall with sheet lead that comes down the wall and over the
top
the roof covering fillet, both sides. Relay new clean bricks and
cap
stones, replace railings.

Could it be that the water penetration is where the cap stones have been
drilled through to fit the railings.?

Possibly but there are still the joints between the cap stones to
fail and let water in.


Also, there may not be a drip channel on the underside of the
overhanging lip of those slabs. All the rainwater pouring off
the edge will wick under and down the wall without a drip channel.

Window and Door external cills have a drip channel for a reason !.

Complete removal and the addition of a lead or copper flashing
right across the wall below would be the 'proper' fix.

On 05/10/2020 13:52, Dave Liquorice wrote:
The caps stones do have a drip groove underneath the overhang don't
they?

+1

On 17:23 5 Oct 2020, Andrew said:
On 04/10/2020 01:23, Dave Liquorice wrote:
On Sun, 4 Oct 2020 01:03:12 +0100, alan_m wrote:

Remove railings, cap stones and first course of bricks. Cover exposed
top of wall with sheet lead that comes down the wall and over the top
the roof covering fillet, both sides. Relay new clean bricks and cap
stones, replace railings.

Could it be that the water penetration is where the cap stones have
been drilled through to fit the railings.?

Possibly but there are still the joints between the cap stones to fail
and let water in.

Also, there may not be a drip channel on the underside of the
overhanging lip of those slabs. All the rainwater pouring off the edge
will wick under and down the wall without a drip channel.

Window and Door external cills have a drip channel for a reason !.

Complete removal and the addition of a lead or copper flashing right
across the wall below would be the 'proper' fix.

A drip channel was put in with an angle grinder. I think the concrete(?)
slabs weren't correct for the job and may be porous. Hence the sealant
paint.

The amount of water this arrangement let in to the room below during a rain
shower was amazing. Until the true cause of the water was discovered, the
roof was tanked with fibre glass like a boat (on the near side in the
picture) but it didn't help.

https://postimg.cc/N2qjQ9kj

Pamela wrote:

This was my shortlist:

https://www.wilko.com/en-uk/ikopro-f...ator/p/0243442
https://www.screwfix.com/p/thompsons...oof-seal/46708
https://polarcoatings.co.uk/product/leakseal-500ml

wickes liquid DPM

On 03/10/2020 22:12, Pamela wrote:
A short wall dividing two flat roofs absorbs rainwater, which leaks from
the brickwork into the roofspace below. The top and sides of the wall
were treated with bitumen paint which worked for a few years before water
got in again. This is the wall:

https://i.postimg.cc/sx1Q95B7/roof-wall-20201003-A.jpg

Would a quick run over with a blow touch re-melt the bitumen and reseal
any opened cracks?


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Monday, 5 October 2020 23:55:59 UTC+1, alan_m wrote:
On 03/10/2020 22:12, Pamela wrote:
A short wall dividing two flat roofs absorbs rainwater, which leaks from
the brickwork into the roofspace below. The top and sides of the wall
were treated with bitumen paint which worked for a few years before water
got in again. This is the wall:

https://i.postimg.cc/sx1Q95B7/roof-wall-20201003-A.jpg

Would a quick run over with a blow touch re-melt the bitumen and reseal
any opened cracks?

just paint more on, filling any sizeable cracks first. For something that may last, paint, add cloth, paint, sprinkle with sand. The latter has at least some movement tolerance.


NT