They used to sell silicon in a solvent liquid that you sprayed/brushed on
the outside masonry to make it waterproof to the weather. I saw it still in
a hardware store a few years ago. However, I understand it lost popularity
because of causing spalling of bricks in some cases, and it required
repeated applications because it deteriorated with the sun.
This was not a vapour barrier, as that is to be applied on the inside of the
house to prevent household water vapour from penetrating the wall framing
and insulation and condensing on the outside sheathing/covering.
I have a 100 year old house and was thinking of a few ways that I
could save on insulating and vapor barrier. The house has already been
re-drywalled once laminated over the existing plaster by the former
owner so I would rather not get into a huge reno that for certain
reasons is not required. I know one of the ways to vapor barrier can
be achieved by stuccoing the exterior walls but that is even more
expensive. One of the advantages to stucco is that the vapor barrier
ends of being on the exterior protecting every thing behind it which
in my case is the bricks, wood firing channel and drywall.
So my cheap alternative to something expensive was to use a product
such as Thompson water seal as an exterior vapor barrier given that
it's duty is to protect bricks from moisture thus perhaps sealing the
house. Fill in any cracks with concrete or some other product, spray
over with the water seal and Voilà. Does anyone know of a product that
can do this or is Thompson's products good enough?