Open Pergola With Notched Purlins

A free-standing open timber pergola on square posts with two long beams and cross purlins notched over them.

Details

Category: Pergolas › Open and Fixed Roof Pergolas

By Huu Khanh Nguyen · Updated November 5, 2026

Parameters

Name	Default	Unit
Length	3657.6	mm
Width	3048	mm
Post section	152.4	mm
Beam width	88.9	mm
Beam depth	203.2	mm
Purlin spacing	457.2	mm
Beam and purlin ends	classic
Timber	timberTreatedSoftwood
Post base	true
Lower base projection	57.15	mm
Lower base height	170.2	mm
Upper base projection	29.2	mm
Upper base height	43.2	mm
Overall length	(beamLength) + 2 * Math.max(0, (postBase ? baseLowerProjection : 0) - (postInset - postSize / 2))	mm
Overall width	(purlinLength) + 2 * Math.max(0, (postBase ? baseLowerProjection : 0) - (postInset - postSize / 2))	mm
Overall height	topHeight + (shadeSlats ? slatSize : 0)	mm
Purlin thickness	50.8	mm
Purlin depth	203.2	mm
Shade slats	false
Slat section	38.1	mm
Slat spacing	101.6	mm
Post length	2209.8	mm
Overall height	2565.4	mm
Post centre from the end	473.075	mm
Purlin count	Math.ceil((beamLength - purlinThickness) / purlinSpacing) + 1
Posts per side	beamLength >= 6096 ? 3 : 2
Slat count	Math.floor((purlinLength - slatSize) / slatSpacing) + 1