An automatic opener is the finishing touch. After attaching the lid to the frame, it is time to add a solar
vent opener ($50, charleysgreenhouse.com, No. 3515), which relies on a wax-filled piston to open the cold-frame
lid auto matically on sunny days to prevent overheating.Let the lid shed
water. To assemble the
lid, clamp the acrylic
sheet between the 1x2s.
Use 1^1 ⁄ 4 -in.-long deck
screws spaced about
every 12 in. to attach
the layers together.
Leaving off the bottom
strip allows rain and
snow to glide off rather
than puddle on the
surface. Along the front,
use pan-head screws to
fasten the acrylic to the
wood.2x2s guide the sides. Screw two 71-in.-long boards into the butt ends of two 31^1 ⁄ 2 -in.-long boards so that
they make a shallow box. Attach the 2x2s in each corner to align the second and third layers and to fasten
everything together.341 ⁄ 2 in.careful
with that
drill
Predrill all screw
holes to avoid
splitting the wood
or cracking the
acrylic. Take care
not to penetrate
the other side of
the material you
are predrilling.tip
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