[GSBN] thin concrete shell roofs

[Graeme North]

Hi All

I have just seen the thread on thin shell concrete roofs , and the  
notion of putting up roofs first-

I have been doing both of these techniques since the mid 70's on and  
off. I nearly got chucked out of architecture school for suggesting  
that roofs first were a fantastic idea and used "Winnie the Pooh" as  
my essay reference.  "We take architecture seriously - do you?"

I have placed my thin concrete roofs over hessian (or jute) that I  
can usually find second hand from carpet manufacturers. This is  
pinned over a pole roof structure of varying shape, a layer or two of  
reinforcing using one or two layers of chicken netting depending on  
span, and away I go with the plaster.  Th addition of latex I have  
not tried yet but it would certainly increase the roofs resistance to  
cracking and leaking.  Adding insulation is another tricky issue, bit  
I have use light weight concrete toppings (polystyrene balls) and/or  
internal insulation layers too.  I have done spans up to 3.6 m or 12 ft

Great roofs - look great and easily cover such complex shapes such as  
a reciprocal frame roof, or where a whole bunch of roof support  
members are bolted to the side of a post and form a rather jagged  
exterior.

On my own house I put up the roof first (not a concrete shell in this  
instance) and only lost 2 hours work to the weather in a whole year,  
and suffered no water damage - and this was in one of those years  
when it felt like we were living under a waterfall.  This is by far  
the best way to go for earth building and certainly strawbale  
building, especially in an unpredictable, and often wet, climate .

cheers


Graeme
Graeme North Architects
49 Matthew Road
RD1
Warkworth
tel/fax +64 (0)9 4259305

graeme at ecodesign.co.nz
www.ecodesign.co.nz


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