am I correct in worrying that pressure washing will drive moisture further into the shakes

In my opinion, you are. If there is biological growth they will remove it (unevenly and unsuccessfully no doubt), with a significant amount of wood as well. 

Tw






-----Original Message-----
From: RLWALTR <[log in to unmask]>
To: BULLAMANKA-PINHEADS <[log in to unmask]>
Sent: Thu, Jun 9, 2011 4:22 pm
Subject: [BP] New tread/old threads


I have a marginally legitimate question again. 
 
 Our local historical society's HQ is in a 1740s farm house with a sawn cedar shake roof, which as I remember is about 23 years old (I used to be on the board, but haven't been in decades).  I am told by a friend now on the board that they are thinking about power washing the roof to get rid of whatever growies are growing in it, which makes me uneasy.
 
 What is the current state of the art Histo Presto thinking on maintenance of such a roof, and am I correct in worrying that pressure washing will drive moisture further into the shakes?  Are there chemicals they should use or avoid in power washing?
 
Thanks,
Ralph (9 days prostate-free)

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