Expert: Bruce E. Johnson - 11/19/2010

Question
QUESTION: Hi Bruce,
Recently had large window installed. Taking out the gap between two existing
windows. We have water pouring in when the weather hits the house from the
front. The installer has told us that water comes in all houses but runs down
the gap. They are proposing to take off the internal window framing and put
in a polythene sheet to redirect the water down the sides of the window into
the gap. Is this right? Could the rendered patch be porous allowing the rain
in? Would a weathercoat sealant be the answer or are there other courses of
action? I'm afraid their remedy may cause me other problems.
Regards,
Frank

ANSWER: Hi Frank, What?! Water goes into every house when it rains?  You are being taken advantage of if the contractor is telling you this story.  A properly installed and flashed window will not leak unless there is something wrong with the installation.  I don't know what "gap" you are talking about but if there is any gap around the window it should be properly caulked and flashed.  Without seeing your problem it's hard to say exactly how it should be flashed or caulked.  If you would like to send me a photo of the installation I could give you a better idea of how to solve your problem but for now don't take any guff from the installer.  He needs to fix the leak and quit giving you the runaround.  Installing a vapor barrier on the inside of the wall is not the answer.  The water has to be stopped at its source which is the outside not the inside.  I hope this information helps feel free to write again regarding this or other matters sincerely bruce e johnson..bejohnsonconsulting.com

---------- FOLLOW-UP ----------

QUESTION: Hi Bruce,
The gap is the space between the outside wall and inner wall of the house.
Advanced Windows, the installer, said this normally gets water from the
outside in all houses and this is why they are wanting to instal a membrane
along the top of the window from the inside to redirect it to the sides. It
sounded fishy to me. They have already recaulked around the window and the
bedroom one above. Could the cement patching that the pebble dash is on
be porous? I will take a photo of the work done and send it on. Thank you so
much for your advice and time.
Much obliged,
Frank

Answer
Hi again Frank, It sounds like you are describing a double wythe masonry wall with an air gap between the two walls with hopefully weep holes at the bottom of the outside wall to let the trapped moisture run out.  If this is the case then yes the gap between the two walls is used for weeping any moisture that may get through the outside wall, however, it is not common for the walls to leak.  The air space is there "in case" water penetrates or wicks inside through the porous surface of the outside wall. The wall should not be leaking around the windows if they have been installed properly.  I hope this information helps feel free to write again regarding this or other matters sincerely bruce e johnson..bejohnsonconsulting.com