While the outhouse has a cavity all around 4 walls(?) it is fairly
useless as a vapour barrier if the vapour has nowhere to go other than
to travel through the cement and block into a dryer space.

Others in here with know how may suggest a air-vent arrangement to
better equalise the 2 atmospheres such that the vapour takes the easier
route to the inside room rather than through the wall. The idea being,
to make the air in the cavity circulate as much of the cavity space as
possible.

I notice a lot of wet in the cement lines behind the storage. It's also
a good indicator of how much vapour there is in the cavity/room.

The outside skin of block is covered in a wood panelling. The wood does
not look capable of defending water off. Indeed it may be sourcing water
to the wall. This can help create a 'reservoir' that, itself, has to
evaporate before it will take the water(as vapour) from the outside wall
during the dryer conditions. Further more, it is likely that the panels,
or individual laps of wood are set on rising studs form floor to wall
top suggesting very restricted air flow under the wood and around the
outer wall surface.

You also have plant growth at the far side. Some plants, like creeper,
vine, will drill through cement and cross cavities which can help carry
water to the inner skin. I have seen them wrapped around whole internal
roof structure too. Very invasive plants.

As for the wood structure; a Mini is circa .5 ton. If these beams run
across the path of the car it seems that braking and accelerating in &
out of this space would have a tendency to 'roll' the beams as it
appears they are simply stood on edge independent of one another. They
don't look fixed at all other than to the ceiling. But there will
probably be enough bonding of the materials above

As for sagging. Elevate yourself so to get an eye-line view along the
bottom edge along the length of the wood. Choose a beam which you guess
is where the wheels of the Mini are. You may notice a difference when
the car is on the roof and when it is not. But, without doubt, there
will be sag of some amount.

I don't see where 'water', as in 'a stream of water', is getting in
directly. All I see is vapour problems.

As I said, it appears the wettest part of the room is where the storage
prevents venting or air circulation. Being in a sunken area may mean air
isn't moving around like you would want it to.


....Ray