How To Build a Fiberglass Greenhouse

How To Build a Fiberglass Greenhouse

How To Build With Fiberglass


Greenhouse Construction Tips

Great greenhouse tips and useful information to
keep your greenhouse running efficiently.


1.Use any good quality wood for your greenhouse framework.
Be sure to treat the pieces with a wood preservative
before assembly, even cedar or redwood. Copper
or zinc based preservatives are safest.

2. 2 x 4 lumber is adequate for framing, but use heavier lumber in snow zones
or where rafter length is more than 8 ft. (Check your local building

3. Space rafters and studs 2 ft. apart and install blocking every 24″ to 36″ in walls and between rafters.

4. Flat fiberglass is rolled out horizontally on roof, but can be installed
either horizontally or vertically on walls. (Corrugated fiberglass should
always be installed vertically.)

5. Caulk all fiberglass seams.

6. Secure flat fiberglass with wood lath on rafters and studs (no horizontal
lath). Nail fiberglass to blocking with aluminum washer-head

7. Provide for ventilation with an exhaust fan system, or large vents in

Framing Notes for Fans & Shutters

For the greenhouse:

Frame wall openings square and 1/2″ larger than fan blade and shutter sizes.

For finished sunroom:

Frame rough openings 3-1/2″ larger than fan and shutter size. Line opening with 2×4, offset
enough toward outside to project past siding. Install fan or shutter.
Finish inside by lining rough opening with 1×3.


Bayliss Solar-Powered Vent Controls

These “top of the line” controls will open and close greenhouse vents automatically without
electricity. Bayliss vent openers convert
energy from the warmth of the sun into mechanical energy to open vents.
The hotter it gets, the wider the vents are opened.

Materials: Bayliss openers are made from the best corrosion resistant materials: brass, stainless steel and satin-anodized aluminum. They are designed to give many years of service,
are covered by a 2-year guarantee, and can be repaired should the need


Capacity: The Bayliss can exert a force of 14 lbs. at the point where it is attached to the vent. A
threaded adjuster bolt can set the Bayliss to start opening the vent at
temperatures between 55º F and 75º F. Maximum opening of 12″ is reached at
approximately 20º F above the starting temperature.

Openers can be installed in a series on a long vent to replace worn out electric vent
motors. The adjuster bolt can equalize the loading so the lifters work in unison.

Installation: Easy to install with screws: top arm to vent, bottom arm to greenhouse frame. Illustrated
directions included. Openers are about 12″ long and fit neatly up close to
the glass.

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