[Strawbale] Earth roof

Patrick O'Neill patrick at frdata....uk
Fri Sep 29 11:43:31 CEST 2006



Where are you my friend who is a gardener says look in local walls and
gutters for plants that are already growing locally in thin soil it will
proably be a sedum.  30mm of soil with 10mm of gravel is not much heaver
than tiles probably less than 100kg /m2 when soaked maybe some one else
knows the max load on bales. 


Roofing membranes.


The range of options  depend on the pitch of the roof and how sure you want
to be that it absolutely will not leak and how long you want it to last.


If you are doing anything other that a full commercial 25 year guarantee job
(see at the bottom) you can save money and worry, by using a “cold deck
construction”.  You do this by introducing a ventilated space below whatever
deck (probably plywood) that you are going put the membrane on this will
enable any moisture from “SMALL” leaks and condensation to dry out.  Keep
the insulation and final moisture barrier below the ventilated space.  This
form of construction also allows you replace the green bit of the roof
without letting water in to the house if you have a disastrous leak.


If you use cold deck construction and a pitched roof about 25 degrees you
can really cut corners and use any old scrap plastic (even bin liners)
nailed on like tiles and protected by old carpet.     If you want to spend a
bit more (which I would recommend) use a semi rigid studded membrane
(something like oldroyd  see
http://www.safeguardeurope.com/pdf_datasheets/oldroyd_xv_datasheet.pdf) or
anything else you can find that is cheap.  The studs trap water and stop the
earth slipping off.


On a flat roof use anything elastic there are several rubber membranes
available or pond liners.  As long as you prepare and protect the deck to
avoid snags and splinters and protect from sunlight you can use any flexible
membrane.  Avoid things like builders DPM that are not elastic because
unless you use lots of old carpet as movement layers they may be damaged
when the roof moves.  


Few of these things are environmentally sound but if you don’t nail the flat
roof membrane at all and only fix the pitched roof membrane at the top edge
at least it can be recycled.


Sorry that there is not a simple answer but if you let me know the roof
pitch and what insulation that you are using I can send you a sketch.




Note: Spec for a commercial guarantee job


•         18mm plywood deck.

Loose laid Sarnavap 2000 polyethylene vapour control layer.

SarnaTherm EPS-E CFC and HCFC Extruded polystyrene thermal insulation board
from Kingspan Insulation Ltd.

Sarnafil TG66-15 Flexible Polyolefine single ply membrane loose laid with
all overlaps hot air welded.  FLL approved for use without an additional
root barrier.

SarnaLite roof lights.

Sarnafil AquaDrain 20mm recycled polyethylene drainage and protection board.

65mm of lightweight growing medium formulated to the suit the local

Nature Mat® vegetation blanket consisting of a variety of flowering drought
resistant sedum, succulents and mosses installed over the prepared growing
medium for an ‘instant’ green roof.

Entire roof assembly, including the greening element, guaranteed by Sarnafil









From: strawbale-bounces at amper....muni.cz
[mailto:strawbale-bounces at amper....muni.cz] On Behalf Of Amit Kvint
Sent: 29 September 2006 08:25
To: Strawbale at amper....muni.cz
Subject: [Strawbale] Earth roof


Hi All, 

I am about to finish a small room (12sqm) SB, and interested in knowledge of
¨live roofs¨, should be light because its a load bearing construction with
clay plaster, any ideas for light soil roof? also what kind of water proof
membrane should I use?


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