In April 2004 I built a 12ft x 8ft shed in my garden to a plan I found
in an American book. I modified the plan where necessary to suit the
materials that are available locally (I live in SW Scotland).

The main modification was the type of exterior cladding for the walls.
In the book they used 10" x 1" planks laid vertically with battens
over the joins - I couldn't find a timber merchant selling boards in
these dimensions so I used 15mm x 150mm treated t&g weatherboarding
from my local timber merchant. I applied 2 coats of Ronseal or
something similar after it was finished.

During persistent heavy rain when the wind is blowing from the same
direction, the water seeps through the t&g joins & gathers at the base
of the interior wall. I first noticed it in December - it was a very
wet month here, probably much wetter than average for the time of
year, & windy too.

I'm a little worried that if this happens every winter I'll get wet
rot developing in the vertical studs, the bottom plate where it joins
the base of the shed, and the floor (18mm ply).

Anyone got any suggestions? I'm thinking of applying a 'second skin'
of more weatherboarding, probably just on the 2 sides facing the
prevailing wind, as I don't think applying more Ronseal/whatever will
make a difference.

On 11 Jan 2005 10:24:07 -0800, (Tony
Carrigan) wrote:

In April 2004 I built a 12ft x 8ft shed in my garden to a plan I found
in an American book. I modified the plan where necessary to suit the
materials that are available locally (I live in SW Scotland).

The main modification was the type of exterior cladding for the walls.
In the book they used 10" x 1" planks laid vertically with battens
over the joins - I couldn't find a timber merchant selling boards in
these dimensions so I used 15mm x 150mm treated t&g weatherboarding
from my local timber merchant. I applied 2 coats of Ronseal or
something similar after it was finished.

During persistent heavy rain when the wind is blowing from the same
direction, the water seeps through the t&g joins & gathers at the base
of the interior wall. I first noticed it in December - it was a very
wet month here, probably much wetter than average for the time of
year, & windy too.

I'm a little worried that if this happens every winter I'll get wet
rot developing in the vertical studs, the bottom plate where it joins
the base of the shed, and the floor (18mm ply).

Anyone got any suggestions? I'm thinking of applying a 'second skin'
of more weatherboarding, probably just on the 2 sides facing the
prevailing wind, as I don't think applying more Ronseal/whatever will
make a difference.

Hi,

Sounds like you could do with a layer of vapour permeable membrane,
Tyvek 'housewrap' or similar, behind the cladding. This will stop wind
and water getting further inside the shed without trapping damp
inside.

If you can space the cladding away 1 or 2" away from the membrane with
treated battens, to allow air to circulate, even better. BTW ensure
the bottom ends of the cladding are well treated and coated with
Ronseal or they will rot.

cheers,
Pete.