The strength, clarity, and insulation value of greenhouse glazing make a big difference in performance — and Janssens gets it right. Unlike many competitors that use thin, flimsy polycarbonate or tempered glass, Exaco Janssens Royal Victorian VI 34 Greenhouse and other Janssens models are equipped with 4 mm tempered safety glass as standard, delivering significantly better impact resistance and weather durability. The thicker tempered glass holds up far better in wind, hail, and heavy loads, helping stabilize interior temperatures and protect plants year‑round. The full‑length glass panels also provide a cleaner look with fewer seams and better light transmission than the overlapping glass sheets found on many lower‑end greenhouses.