DIY Garden Greenhouses & Trellis shelters.
Constructed with VIVAK® PETG (Polyethylene Terephthalate Glycol)
Tender plants,humans & animals all enjoy winter warmth from garden
shelters! Erection of a glasshouse however may incur serious costs
and planning, and tight inner city sections often do not suit standard
commercial glasshouse sizes. Although temptingly cheaper plastic
versions are appearing at chain and hardware outlets, these tend to
flap annoyingly in winds and soon tear with UV light,animal and kids
activities. Typically they need to be written off after just 2
I've long been a fan of trellis ( well- who isn't!?), and some years
ago created a sturdy and attractive garden shelter at our home here in
Eastbourne (coastal Wellington,NZ) over an old concrete pad. This largely
used walls of standard trellis panels,with rain and dew kept off by
overhead corrugated plastic sheeting,conveniently allowing outdoor
clothes line drying even in threatening weather.Energy savings against
using an indoor drier were very apparent, as was reduced panic when
rain threatened washing still on the outdoors clothesline! The
shelter's ambience was particularly popular for kids activities,brunch
and family cats on "garden duty".
Winter winds however still kept conditions rather exposed, especially
when further trellising offered space for outdoor table tennis and
BBQs. I was keen to retain the trellis appeal and "transparency",
without detracting from the sturdy nature of the structure,so was
unhappy with the prospect of agricultural or corrugated plastic for
the walls. Glazing involved substantial framing, planning,safety and
costs- so was also dismissed.
After searching hardware stores to little avail, I pondered a
versatile plastic previously used for electrical equipment inspection
safety covers, obtained via Mulford Plastics ( Seaview- but NZ wide
outlets). This "VIVAK" PETG 1mm sheeting costs ~US$25 for a ~1.2x 2.4
sheet,readily cuts with sturdy scissors, and bends,drills or nails
without complaint. Initial trials with VIVAK fastening to trellis soon
showed galvanised clouts ideal for securing, additionally making the
trellis sections themselves more rigid. Abracadabra - within
hours,using just simple hand tools, the entire shelter was clad, and
best of all still appeared as bare trellis from even just a few metres
The thermal effects within are predictably MOST satisfactory,with a
complete absence now of wind and drafts.Interior temperatures remain
higher as well, to such an extent that a small raised garden inside
is still producing mid winter tomatoes, and self sown pawpaw, avocado
and passion fruit are making table tennis increasingly more of a
jungle slashing activity! Absolutely no degradation of the VIVAK seems
to have resulted, even though the bulk of the cladding is now
approaching 10 years duty.
The trellis/VIVAK combo may also suit smaller structures such as
seasonal tomato houses or even kids play houses. The latter often tend
to be built by devoted dads into property corners that defy the
structures eventual removal without near total demolition. If the
simple framing of a trellis version was screwed rather than nailed, it
instead could suit easier breaking down into stackable panels.
Lightweight versions could even be shifted by 2 adults to suit outdoor
seasonal sunshine, shading or housekeeping as well. Additionally the
resulting "ginger bread" version could look more attractive than
normal solid walls, and the trellis transparency should allow adult
supervisors to better keep an eye on activities instead of the
classic query -"Things have gone very quiet in there- what's going on?! "
The idea involves simply nailing 1mm "Vivak" plastic sheeting to
trellis, so as to create an attractive (but versatile) warm wind proof
siding, that from even a few metres away just looks plain trellis.
I've had several of these up for ~ 10 years with no problems or
plastic degradation, & wonder why more folks don't consider this
approach for garden rooms or simple DIY greenhouses etc. The plastic
is available form larger hardware stores, although Mulford's here in
L.Hutt, NZ stock it in abundance as normal sized sheets.
Unlike corrugated plastic, Vivak sheets of course will roll up for transport. Also,in
contrast to cheap agriculture grade plastic or $100 hardware store green
houses, it doesn't flap or hole thru' with cats scratches or kids
mischief! Curves can readily be formed with a hot air gun as well,
even though the plastic is good to normal high NZ summer temps without
Wooden pailing fence top trim makes an ideal neat surround for trellis/Vivak doors. The multiple nailed joints of course stiffen the door structure so no diagonal bracing is normally needed. NB- it's worth providing much wider doors that you think you'll need, both for bulky items access & better summer ventilation.
Early days while still attaching trellis & Vivak, but the shelter is already popular. Compare this pix with the same position some years later. NB- square tellis is easier on the eye- avoid diagonal as it can look too "busy".
The overhead corrugated clear plastic cladding may not be needed in localities with good low angle winter sunshine "views"- solid roof cladding may be cheaper & more suitable. You may be also better off with solid walls on shaded sides too.
Overhead mid summer sun in NZ (latitude 41 Sth) can be so strong, that extra shading has to be put up to stop the greenhouse overheating. Provide plenty of summer ventilation (wide doors or lift off panels etc) or your plants will be cooked! Choice of "theme" plants (we find grapes suitable) can provide automatic seasonal solar screening- even then leaf burn may occur.
Gardens in the interior need watering of course, but conditions are so balmy that almost anything will grow, & grow & grow - it can become hard to get in the door!
NZ winter - cool outdoors but normally sunny, & thus warm in the shelter. Conditions hence particularly suitable for clothes lines & cats!
Exterior view of first shelter erected ~10 years ago in the late 1990s. Note- there's usually little point in having trellis right to ground level , as timber rot & ankle level vegetation screening issues may arise, as can damage from kids footballs etc.
A low nib wall (readily made from old bricks etc) is recommended for more permanent structures- bricks may be cheaper than trellis/Vivak & also serve to retain some warmth! 50x100mm timber laid on this (with damp proofing & mortared bolts) then makes for a secure durable attachment. Although the low exterior wall shown behind "Jack" is typical ( & it matches the interior wall trellis footing), this is quite recent (as evidenced by the mortar), having been simply erected to contain the expanding outdoor garden.
Painted "domestic" version- paint trellis BEFORE attaching Vivak of course!
Screen here is mounted as a veranda
sunny end wall, & allows sunlight thru' without rain or wind.
Erected mid 1990s - only slight clouding of VIVAK now
apparent, & NZ has high UV levels as well! Wellington, NZ . March 7th 2009
Step 9: Years Later !
December 2010 - Eastbourne, Wellington, NZ. Still going strong! Here's the much grown young man himself now at work, c/w ever faithful canine supervisor "Jack". (See how they've both aged by reference to the 2002 frame 3 picture) This particular 6' x 8' greenhouse is near the property entrance, so fretwork "gingerbread" has been added to make it more attractive.
Step 10: Finished!
Finished- now doesn't this look a treat! It's become not only a greenhouse, but also a warm sunny garden room. The roof cladding is "baby" corrugated PVC. Total cost of structure perhaps US$300 -roof framing used recycled lumber. Note the added rain water tank (~100 litres or 25 gallons) collecting roof runoff, suiting gentle watering, hand washing - or emergencies!