[GSBN] The Reasoning For Hessien

Sarah Johnston sol_design at yahoo.com
Sun Apr 20 11:44:45 CDT 2014

 Thank you to those who replied to my earlier post.  Here is some background on this project/concept.

The reason to install the hessien is to stop  the lime from cracking as the body coat dries and the reason to apply the lime while the body coat is still wet is to keep the lime damp in a very dry and windy climate.  It is also very nice to be able to get all the plastering completed at one time rather than having to come back in 6 or 12 months.  While tarps are always used to protect the lime walls, it is very difficult to keep the tarps in place during 100km/hr winds.  Summer is too hot and winter too cold so the window of opportunity is very small for lime application.

While I have not personally used this technique, a friend who does use it is a true believer.  My concern is delamination in the long run and his experience can not debunk that concern.  

Does anyone have thoughts on the following......

The hessien is worked into the face of the body coat, wire brushed to lift the fibers then punch holes through the hessien to create a solid key into the body coat.  Lime would then be applied directly to the hessien and would key into the holes as well as the fine fiber of the hessien.  The hope is the hessien will prevent the cracking and the holes will provide a bomb proof key.  This technique could  help in situations that Derek has pointed out, when you have a lime that does not like to bond to the clay, the hessien and the holes create that key.   Test walls are being prepared.  We will try 10mm dia, 20mm deep @ 75 centers and 10mm dia, 15mm deep @ 50mm centers.  sorry if you do not speak mm, I have mostly used US spelling :)

This project is being covered by the TV show Grand Designs so the techniques that are used could be very well publicized, thus a double reason to make sure everything works very well! 

Would love to hear any thoughts!

Sarah & Sven Johnston 
Sol Design, Ltd. 
50A Connolly Street 
Geraldine 7930  New Zealand 
03 693 7369 
sol_design at yahoo.com 
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