I'm planning on building a 3-sided lean-to timber shed up against my garage
using the garage wall as the 4th wall to the shed. I think I'm happy with
the dpc/dpm detail but can anyone please advise the best way to butt the
flat roof up against the garage wall for a water-tight junction detail?

The garage wall has a spar-dash render finish and although I suspect it
might be asking too much I would like to avoid having to chase into the
existing wall.

Thanks

In message m, DIYer
writes

The garage wall has a spar-dash render finish and although I suspect it
might be asking too much I would like to avoid having to chase into the
existing wall.

There is flashing tape, in various widths, but I'm not sure how well it
would seal against a rendered finish.

http://www.screwfix.com/p/flashing-t...mm-x-10m/72438
--
Graeme

On Monday, September 19, 2011 8:10:43 AM UTC+1, DIYer wrote:
I'm planning on building a 3-sided lean-to timber shed up against my garage
using the garage wall as the 4th wall to the shed. I think I'm happy with
the dpc/dpm detail but can anyone please advise the best way to butt the
flat roof up against the garage wall for a water-tight junction detail?

The garage wall has a spar-dash render finish and although I suspect it
might be asking too much I would like to avoid having to chase into the
existing wall.

Thanks

You could clad the wall above the lean-to and flash from under the cladding onto the lean-to roof. But then you'd be drilling into the wall so you might just as well cut in.
The stick-on flashing will never work. You could use some torch-on mastic to form a good seal with some bitumen flashing - run it at a slight angle so the "top" of the flashing drains off.
However, all this may be more hassle than cutting in the flashing in the normal manner.
Simon.

DIYer wrote:
I'm planning on building a 3-sided lean-to timber shed up against my
garage using the garage wall as the 4th wall to the shed. I think
I'm happy with the dpc/dpm detail but can anyone please advise the
best way to butt the flat roof up against the garage wall for a
water-tight junction detail?
The garage wall has a spar-dash render finish and although I suspect
it might be asking too much I would like to avoid having to chase
into the existing wall.

If you don't chase into the wall, you're going to have to use some form of
gunge, which will make more of a mess than a nice neat cut with an angle
grinder.

use a length of timber placed on top of the wallplate as a straight edge,
6X2 or similar, and cut at least 40mm into the wall so that the flashing
goes part way into the brick rather than just the render, then use 250mm
lead, wedged in with lead wedges and pointed with fairly strong mortar.

On Sep 19, 8:10*am, "DIYer" wrote:
I'm planning on building a 3-sided lean-to timber shed up against my garage
using the garage wall as the 4th wall to the shed. *I think I'm happy with
the dpc/dpm detail but can anyone please advise the best way to butt the
flat roof up against the garage wall for a water-tight junction detail?

The garage wall has a spar-dash render finish and although I suspect it
might be asking too much I would like to avoid having to chase into the
existing wall.

No realistic alternative if you want to do the job properly.

MBQ

On Sep 19, 8:10*am, "DIYer" wrote:
I'm planning on building a 3-sided lean-to timber shed up against my garage
using the garage wall as the 4th wall to the shed. *I think I'm happy with
the dpc/dpm detail but can anyone please advise the best way to butt the
flat roof up against the garage wall for a water-tight junction detail?

The garage wall has a spar-dash render finish and although I suspect it
might be asking too much I would like to avoid having to chase into the
existing wall.

Thanks

Just to add a bit more to your problem, I hope you are not going to
felt the roof and are going to use something like Onduline. Creates a
bit more of a problem for the junction seal, but it is far easier,
quicker and seriously less messy to install than felt and has a far
greater life.