Diagram — what is being calculated
01 / Inputs
Plan distance from beam to ridge (verandah) or span perpendicular to ridge.
Tables 11.1–11.4: Verandah beams support the ends of rafters from a wall to a verandah beam. Ridge beams carry roof loads at the ridge, requiring support at each end. These spans apply to all wind zones per NZS 3604:2011. For continuous beams, a 10% increase may apply per Note 1.
02 / Result
Enter inputs to find maximum beam span
Outside table range:
All beam sizes at entered loaded dimension
| Size (width×thickness) | LD (m) | Max Span | Status |
|---|
NZS 3604:2011 — scope and limitations. Tables 11.1–11.4 apply to verandah beams and ridge beams in timber-framed buildings within NZS 3604 scope. Ridge beams must be supported at both ends. Verandah beams must be supported at the wall end and at the outer end (post or wall). Buildings outside NZS 3604 scope or with spans exceeding these tables require engineering design. All results must be verified by a Chartered Professional Engineer or Licensed Building Practitioner.
NZS 3604:2011 Table 11.1 — Verandah Beam Max Span (mm), Light Roof, SG8
Loaded dimension in metres. Source: NZS 3604:2011 Table 11.1. Add 10% for continuous beams. Heavy roof spans ~15–20% less.
| Size (mm) | LD 0.9 | LD 1.4 | LD 1.8 | LD 2.1 | LD 2.4 | LD 3.0 |
|---|---|---|---|---|---|---|
| 90×45 | 1400 | 1100 | 1000 | 900 | 800 | 700 |
| 140×45 | 2300 | 1800 | 1600 | 1500 | 1400 | 1200 |
| 140×90 | 2700 | 2200 | 2000 | 1800 | 1700 | 1500 |
| 190×45 | 3100 | 2450 | 2200 | 2000 | 1900 | 1650 |
| 190×90 | 3650 | 2900 | 2600 | 2400 | 2250 | 2000 |
| 240×90 | 4600 | 3650 | 3250 | 3000 | 2850 | 2500 |
| 290×90 | 5550 | 4400 | 3900 | 3600 | 3400 | 3000 |
SG10 values approximately 10–15% higher. All NZS 3604 wind zones.
NZS 3604:2011 Table 11.3 — Ridge Beam Max Span (mm), Light Roof, SG8
Loaded dimension = half the total roof width. Source: NZS 3604:2011 Table 11.3. Heavy roof spans ~15–20% less.
| Size (mm) | LD 2.4 | LD 3.0 | LD 3.6 | LD 4.2 | LD 4.8 | LD 5.4 |
|---|---|---|---|---|---|---|
| 140×90 | 2400 | 2100 | 1850 | 1700 | 1550 | 1400 |
| 190×90 | 3250 | 2850 | 2500 | 2300 | 2100 | 1900 |
| 240×90 | 4100 | 3600 | 3150 | 2900 | 2650 | 2400 |
| 290×90 | 4950 | 4350 | 3800 | 3500 | 3200 | 2900 |
Ridge beams must be supported at both ends. SG10 approximately 10–15% higher. All NZS 3604 wind zones.