pondering a green roof for me garage/store extravaganza....

any pointers anyone to design/construction/ issues/ Bldg Regs issues
etc all gratefully received...

Andy - from a quick google on here I believe you recently did one?
using perlite/vermiculite etc - care to share?

Cheers
JimK

On 28 Mar, 16:29, JimK wrote:

Andy - from a quick google on here I believe you recently did one?
using perlite/vermiculite etc - care to share?

I've one that's currently an almost completed brown mud roof, waiting
for an afternoon's trim work and for the "green" bit to start growing
properly. If I have time, I'll do a proper write up.

Over Easter (In my Copious Free Time) I'm planning another ultra-
budget green roof on a concrete sectional garage, just to make it look
less ugly from a distance. Writeup likewise.

More later...

Andy Dingley wrote:
On 28 Mar, 16:29, JimK wrote:

Andy - from a quick google on here I believe you recently did one?
using perlite/vermiculite etc - care to share?

I've one that's currently an almost completed brown mud roof, waiting
for an afternoon's trim work and for the "green" bit to start growing
properly. If I have time, I'll do a proper write up.

Over Easter (In my Copious Free Time) I'm planning another ultra-
budget green roof on a concrete sectional garage, just to make it look
less ugly from a distance. Writeup likewise.

More later...

There's a sedum mat round the corner here (actually just a roof for a
wheelie bin house) that seems to be thriving. I guess the plant must be
virtually drought and frost proof.

On 28 Mar, 16:29, JimK wrote:
pondering a green roof for me garage/store extravaganza....

Information sources are hard to find. There are some nice books out
there at the architectural scale, but little about constructional
details for DIY. However the big-scale books can be useful for
justifying the roof at all (Look dear, It's not just hippies, look
real architects are doing them!) and the plant guidance is useful.
Planting Green Roofs and Living Walls
Nigel Dunnett and Noёl Kingsbury
http://www.amazon.co.uk/exec/obidos/ASIN/0881929115/codesmiths

Most UK-based information of small-scale projects seems to come from
Sheffield Uni. CAT at Macynlleth were depressingly clueless.

The Living Roofs website has a downloadable PDF for a tenner(ish) that
is worth getting, as it's dealing with the sort of project scale we're
interested in. Free sample pages too.
http://www.livingroofs.org/diy-guide-green-roofs.html
Be warned, I had a lot of email trouble dealing with them and actually
getting hold of my copy. Nice people, but it was an uphill struggle
and their webbery isn't working right.

There's a lot of commercial project information out there too, from
people like Oldroyd who make sophisticated membranes
http://www.safeguardeurope.com/products/oldroyd-green-range.php
Don't let the pricetag put you off immediately. This stuff has major
advantages for convenience and speed of working. You can do better
with zero-charged DIY, but if you're building a lightweight (i.e. thin
layer) roof with employed labour, these membranes would have a lot
going for them, especially for steeper pitches.

You need some careful design, i.e. spreadsheets. Estimate your
thicknesses, your weights, and your materials costs - including
planting costs. There are several ways to build a roof and they do
vary by cost / workload / pitch angle / weight / soil demand / plant
compatibility. Your choice, but understand what these compromises are
before starting and choose something that suits your needs, budget,
looks and plants before starting to build it.

On 28 Mar, 16:29, JimK wrote:

Andy - from a quick google on here I believe you recently did one?
using perlite/vermiculite etc - care to share?

My small workshop roof is 8' x 24' and began as flat corrugated iron.
The green roof was to make it look nicer, fix its obvious plan to fall
down imminently, and to get some insulation in there. It's now almost
flat, with 3" of soil over 1" of vermiculite, over 1" of polystyrene
insulation.

Construction began by discarding the old roof and the top foot of
wall, owing to original poor construction. A course of cement blocks
and a course of bricks on one long wall, tapered at the end walls.
Joists were 4"x2" on 400mm spacings, laid on top of this new wall and
held up by noggins between at the ends. They stopped an inch short of
the outer wall edge. Roof deck on top of this was 3/4" OSB screwed
down - fortunately my shed is a convenient 6-sheet multiple, so
everything fell out of standard lengths quite nicely, helping with the
budget. A surrounding upstand wall of 3/4" OSB was made, screwed into
the edge of the OSB, with long screws through the foam (see below) and
into the noggins, then against the outer masonry edge - no overhanging
eaves. The entire external woodwork was then coated with black bitumen
paint (runny stuff - real fibre-reinforced exterior grade is
impractical to apply over OSB) . 1" of polystyrene foam went down on
top, to make an insulated warm roof. This same foam was used around
the edges of the joist, between the noggins and the upstand wall to
avoid a cold bridge there.

Around this time, I still needed a ladder to the roof, but no longer
needed to move the ladder around as I worked. So I rawlbolted the wall
and tied my strongest and steadiest ladder down to it. This was a
_very_ good move.

The first waterproof layer went down on top of the polystyrene foam.
As it was polystyrene, not yellow PIR, and was a green roof anyway, I
didn't bother with a moisture barrier beneath. This layer was
geotextile around the edges (didn't bother over the polystyrene foam)
and then a double layer of 1200 gauge polythene DPM. This was then
carefully tucked into a "swimming pool" around the edges and stapled
down to the outside of the upstand. Triangular firrings of polystyrene
were used to smooth out all the internal corners before the liner.

I now tested the liner by placing 2" of rain into it over the next
couple of days. Not ideal, but it's why I'd been working in the dark
to get the liner laid beforehand...

An 18"' strip of geotextile along the lower edge started the formation
of the 4" square shingle drainage gulley, as described in the
livingroofs guide. Their drain is a vertical outlet commercially
moulded into the liner (and outside the building plan, through the
eaves). Mine (as I had no eaves and didn't want an indoor drainpipe)
was PVC drainpipe, cut in through the side of the upstand. I sealed
this to the liner itself with bitumen mastic and hope. With the liner
in place, and the gulley liner held in place with masking tape, I half-
filled the shingle load to hold it in place.

The drainage layer of the main roof (a crucial aspect) was 1"
vermiculite (600 litres). This sits waterlogged beneath the soil
layer, so adds no insulation, but it's lighter than an equivalent
volume of soil and _far_ lighter than an equivalent water retention
layer of soil. This vermiculite was loose laid to about 1" depth (at
this point the rain switched to wind - being lashed with flurries of
damp vermiculite is delightful) and then a layer of geotextile over
that.

Next step was to begin soil loading. This was lifted bucket by bucket
(rope lift is easier than ladder carry, but a gibbet or gin pole would
be even easier) and first dumped around the edges to anchor the liners
down. A shallow sprinkle stopped me walking directly on the
geotextile, especially as I was now back to my digging boots, rather
than roofing slippers. As filling went on, I filled and shaped the
shingle gulley to match.

Total soil load was 3", which was 21 barrows (I was using a small
barrow), maybe 150 buckets. This took three partial days, spread over
months, to complete! The first day shifted the most, enough to
anchor, fill the edges and cover the liner from damage. After that,
and in the depths of winter, I became lazy.

To neaten and weatherproof the outsides, I attached 10" vertical
fascia board of Versapanel - a cement fibre board like concrete MDF.
This is weatherproof when painted. There was also a narrow capping
strip of the same, glued down crudely with mastic.

Planting has been done on the cheap - I have about £20 of assorted
sedum and sempervirens up there, which I hope will spread in time.
There are also a few handfuls of cheap crocus or similar small bulbs.
Then there's a boxful of mixed wild flower seed and also some basic
lawn grass seed. Patches within the roof are full-depth plain sand (no
soil), also some stacked broken bricks, stacked short bamboo tubes and
lumps of branchwood to give a variety of bug habitats.

Now the mistakes:

* OSB should be OSB3 (quality grade) to qualify for category 2 (usage
grade), such as roofing. I shopped local, wanting to support the
local merchant, and was instead sold OSB2 for use in roofing - it's
not up to it. My attempted remediation was to apply the bitumen paint.

* I've a (doubled) polyethylene DPM on top of polystyrene foam, rather
than a geotextile interleaf (as I used over the timber). Maybe this
will be a future issue with plasticiser leachout, as for PVC cables?

* The Verspanel fascia boards are purely decorative, but still too
thin. This stuff is always brittle - 6mm is unusable without extreme
care, 10mm is dodgy for anything outdoors. Livingroofs use 3/4" thick!

* October isn't a good time to build one, unless you have time
available to build it all in one blast. Otherwise you're off into
November, which then really isn't a good time to be doing it. My
combination of November worktimes being limited to weekends, and
unpredictable weather that I had to just work through anyway, meant
that I was laying liners in a gale. Although this was an excuse to
wear my copper hat and shout "All Gods are *******s!" while standing
on a roof in a thunderstorm.

* I ordered Perlite, but was delivered Vermiculite. There's not much
between them, but Perlite grains are less crumbly and a lot less wind-
blown. See above about working in storms.

* The fall (1 brick in 8') was insufficent, and I think the soil is
going to remain too damp over Winter. Should have used a whole block
height instead.

* My outfall pipe outlet through the liner is a bit of a hack and I
should have been more careful with it. Bitumen mastic hides a great
many sins.

* The outfall pipe was initially too high, so I dropped it by half an
inch later on. In combination with the shallow pitch, it just can't
drain the roof adequately and it leaves too much standing water behind
afterwards. I should probably have sunk it locally into the
insulation, to get another 1/2" below the majority of the liner.

Lessons:

* It works. Green roofs are a good thing. They're buildable, they're
buildable with simple materials and to a budget. You can do this, and
the results are rewarding.

* It looks a lot better than corrugated iron - even in winter.

* My meagre insulation transformed the usability of the workshop.

* They're more complicated than you realise. Mine has something like
13 distinct layers in there, some of those have measurable thickness,
and just that can be enough to push you very close to height limits
for planning. Draw out sectioned views beforehand.

* For a "flat" roof, too much fall is better than too little.

* You need to build right first time. The idea of partial dismantling
to fix something afterwards is terrifying.

* Materials sourcing is a problem. Builders' merchants are clueless
and will sell you what they have, not what will last.

* It's a _lot_ of soil!