Table of Contents
The pergolaA structure with open wood-framed roofs, often latticed and supported by regularly spaced posts or columns, and covered by climbing plants such as vines or roses, shading a walk or passageway. Pergolas are distinguished from “arbors,” which are less extensive in extent and structure. in this example is 9m (30ft) long x 2.4m (8ft) wide.
The project is broken into sections (pages) which include working plans, construction details, roof details, and materials. Each section contains it’s own instructions and diagrams etc.
The lumberAny of the framing wood. list is at bottom of this page.
Lumber required for the lean-to pergola
| <spanThe horizontal distance between supporting structures.>LUMBER | USED FOR | AMOUNT |
| 100×50 (2×4) suitable for exterior use | rafters 13 @ 2.4m (8ft); purlins and ledger 50m (166ft) | 82m (270ft) |
| 100×100 (4×4) suitable for exterior use | posts 5 @ 3m (10ft) | 15m (50ft) |
| 200×50 (2×8) suitable for exterior use | BeamA supporting member. 2 @ 4.5m (15ft) | 9m (30ft) |
| 150×25 (1×6) fasciaExterior horizontal visible flat front trim board that caps the rafter tail ends. bdSee BOARD | front fascia bd and side barge bd. | 18m (60ft) |
The plans
The plans for the lean-to pergola. An example of working plans for a lean-to pergola and roof, 9m (30ft) long x 2.4m (8ft) wide.
Below is an example of working plans for a lean-to pergola and roof, 9m (30ft) long x 2.4m (8ft) wide.
The Site Plan
This plan shows the placement of the pergola in relation to the existing house and boundaries.
The Flat Plan (footprint)
The flat plan is an arial (looking down) view of the pergola addition.
It shows the overall dimensionsAny of the three linear measurements, length, breadth and depth. of the project and information such as footingA base (in or on the ground) that will support the structure. placements, bearerA sub-floor wood supporting the floor joists. and rafterStructural member of a roof that supports the roof load and runs from the ridge to the top of the side walls. placement and spacings between rafters.
The Cross-Section Plan
The cross section plan is a plan taken from a cross section of the flat plan. The cross section shows lumber sizes and footing size.
A detail plan is accompanied to give clearer detail.
A detail plan is a blow up (magnified) part of the plan.
The Elevation Plan
The elevationSide view of a building. plan is more like a drawing of the outside of the addition rather than a plan although is still drawn to scale. The elevation plan gives a good perspective of the addition to the untrained eye.
The construction
This page shows construction details for making the pergola frame along with variations on how to fixTo secure with nails or screws. the pergola roof frame to the eavesThe part of the roof which extends beyond the exterior side wall. The projecting lower edge of a roof where the gutters are located. The eaves are made up of both the soffit (covering for underside of an overhang) and the fascia (A horizontal trim fixed to the ends of the roof rafters). or house.
About lumber sizes.
The lumber sizes referred to in this project are the nominal sizes. The nominal sizeThe rough-sawn size of a piece of lumber. Before the lumber is surfaced, planed or dressed. The nominal size is usually greater than the actual dimension. e.g. 100x50 (2 x 4) actually equals 90x45 (1 1/2" x 3 1/2"). of a piece of lumber is the size of the lumber before it is surfacedSee Dressed./dressed or seasoned and is the size generally referred to when purchasing from the lumber yard. The actual sizeThe finished (dressed) size as opposed to the nominal size of a piece of wood., or dressedSurfaced; planed; smooth; even surface; gauged. size of the lumber will be less than the nominal size so please make necessary allowances. For example, a piece of 100×50 (2×4) lumber when dressed may be 90×45 (1 1/2″x 3 1/2″) actual size.
STEP 1: The footings and posts.
Dig five footing holes 350×350 (14″x14″) and 500 (20″) deep. Refer to flat plan for hole positions. Max span between any two posts must be no more than 2400mm (8ft)
Place at least 100mm (4″) thick pad of concreteA mixture of sand, gravel, water and cement which hardens to a stone like condition when dry. at the bottom of the footing holes, place the posts in position and fill the footing holes up with concrete. Check the posts for plumbVertical; Upright. (verticalPlumb, upright.), braceTo make rigid. if necessary and leave till concrete sets.
STEP 2: TrimThe finish materials in a building, such as narrow boards applied around openings (window trim, door trim) and vertical corner battens. the posts
Trim the top of the 5 posts at the desired height. Refer to the cross-section plan.
Work out the height of the top of the posts in relation to the required rafter fallOf roof; Pitch; The incline angle of a roof surface..
The fall should be at least 10 degrees (1 in 5.7) if possible.
In this example, trim the top of the posts off 316mm (12 1/2″) below the highest point of the underside of the rafter. (see drawing).
STEP 3: The beam
Check out the top of each postsee PILE for the beam by marking a horizontalParallel to the horizon, flat, level. line 200mm (8″) down from the top outside edge of each post.
Cut along the pencil mark with a power saw to a depth of 50mm (2″) (the thickness of the beam) Do this to all posts. Scribe a line 50mm (2″) in from the outside edge of each post from the top, down 200mm (8″). Cut down that line using a sharp handsaw.
BoltA metal rod that has a head on one end and threads on the other and is used to fasten together lumber. The most common bolts used or referred to in projects within this website are coach/carriage bolts and hex bolts. the 200×50 (2×8) beam to the posts using m12 (1/2″) galvanizedCovered with a protective coating of zinc. bolts and washers. (see diagram). Ensure all posts are plumb (vertical) and parallelBeing of equal distance from each other at all points.
STEP 4: The ledger plateThe top or bottom horizontal framing member of the wall.
In this example the ledger plate is bolted to the fascia boardThe top horizontal board cappingCovering the top ends of the rafters. just below the spouting.
Sometimes this is not possible due to lack of free fascia boardA piece of sawn, or dressed lumber of greater width than thickness. Usually 19mm (3/4") to 38mm (1 1/2") thick and 75mm (3") or more wide. or fixing area below the spouting in which case the ledger plate will have to be fixed to the house wall beneath the eaves.
SCENARIO (1) FIXING TO THE FASCIA BOARD
Mark a level line just below the spouting. Use a spirit levelTool used to ensure surfaces are level or plumb by means of a bubble in a tube of liquid fitted to the level. or a water level .
Fix the ledger plate to the level line on the fascia board using coachAre round headed bolts with square shoulders that resist rotation when located or driven into place. They can be called coach bolts or carriage bolts depending on which part of the world you live in. The head end of the bolt does not need a washer, but the other end of the bolt (the nut end) usually does. screw at least every 1200mm (48″) apart, penetrating through the fascia board and into solid timber, usually the end of a roof rafter or eaves sprocketTool used to ensure surfaces are level or plumb by means of a bubble in a tube of liquid fitted to the level..
SCENARIO (2) FIXING TO THE HOUSE WALL. \
Mark a level line just below the eaves. Use a spirit level or a water level . Fix the ledger plate to the level line with coach screws penetrating through the claddingThe exterior surface of a building. and into the studs (house frame uprights) or lintels (beams above windows and doors). Seal around coach screws with weatherproof silicone sealantA pliable substance used to seal a surface to prevent passage of a liquid..
If the wall is masonry (concrete, brick, blockBlocking. A pieces of wood that runs between other members (studs, joists, rafters) to provide support, add strength and/or act as a solid support between panel joins.) fix the ledger plate to the wall using masonry anchors every 1200mm. Before fixing, place DPC (Damp Proof Course) between the ledger plate and the wall.
STEP 5: Rafters, purlins, fascia and brace
Cut the rafters to length and angle cut each end to suit. Work out the rafter length to suit the roof sheets if possible (so as the roof sheets wont need cutting). In this example cut the rafters 2280mm (91 1/4″) long for 2400 (96″) roof sheets. Thus ledger 50mm (2″) + rafter 2280mm (91 1/4″) + fascia 20mm (3/4″) + roof overhang 50mm (2″) = 2400mm (96″)
Refer to the plans for reference if necessary.
Fix the rafters @ 750crs (30″ O.C.On center; (See CENTERS)) that is, spaced every 750mm (30″) apart, to the ledger with joistOne of a series of parallel members used to support the floor. Part of the framing that provides the structure for a floor. hangers and to the beam with skew nails (nails angled in, toe nailed) and angle clips or Z nails. Ensure the rafters are square, at right angles to the building.
Fix four rows of 100×50 (2×4) nogs on edge in-between the rafters as in the flat plan These are the nogs (purlins) that the roofing is fixed to.
Fix the top row of nogs (purlins) 100mm (4″) down from the top of the rafters and fix the bottom row of nogs (purlins) 100mm (4″) up from the end of the rafters.
Fix the other two rows of nogs (purlins) equal distance apart.
Alternatively the purlins can be fixed on top of the rafters if there is enough room between the top of the rafters and the eaves.
Fix fascia board along the end of the rafters and also up the sides of the two end rafters (barge boardExterior visible flat trim board that follows the rake of the roof.).
Brace on top of the frame diagonally from corner to corner with metal strapShort lengths of metal strap 25×1 (1/16×1) used to fix members together to resist uplift. brace. see flat plan.
The roof
PVCPolyvinyl chloride. A common thermoplastic resin, used in a wide variety of manufactured products, including rainwear, pipes, garden hoses, phonograph records, and floor tiles. / Polycarbonate sheetAny broad, thin surface. roofing
Pvc and polycarbonate sheet roofing come in a variety of profilesBatter boards; Horizontal boards attached level to stakes, used to mark out the boundary of a construction and establish the levels and building line., sizes, and colors. Quality and prices vary immensely.
The most common profile is corrugatedHaving alternating ridges and grooves..
Quality varies enormously from cheaper pvc sheets up to lifetime guaranteed polycarbonate sheets and the price varies accordingly. Guarantees range from zero to lifetime.
Sometimes the cheapest is not the most cost effective. Pamphlets relevant to the type of sheeting required are usually available from most stockists, it is advisable to read them.
Roof pitch
Most type of PVC or polycarbonate manufacturers recommend a 10 degree pitch (approx 1 in 5.7 fall).
A lesser pitch could require additional weatherproofing such as extra flashings or appropriate sealants.
Cutting
Garden scissors or a fine tooth saw can be used to cut most sheets. The higher the quality, the easier the cutting. Sometimes a carborundum blade on a disk grinder will do the trick but only one sheet at a time or it could cause fusion and weld the sheets together.
Drilling
Pre-drill the holes in the sheets before fixing. The holes should be 8mm (5/16″) to 10mm (3/8″) and at least 2mm (1/8″) larger than the shaft of the screws to allow for expansion and contraction. Ensure the holes are in the high part of the corrugation. Sometimes it might be easiest to lay the sheets upside down on the ground and pre-drill. Another tip is to use a stick with a hole in it as a guide for the drill.
Fixing
Appropriate screws are readily available from any suppliers that stock the PVC or polycarbonate roof sheets. If the choice is available, hexagonalA plane figure with six straight sides. A regular hexagon is one with all six sides and all six angles equal, the angles all being 120°. Congruent regular hexagons can be fitted together to cover completely a plane surface. Apart from squares and equilateral triangles, these are the only regular polygons with this property. heads are the easiest to use. Most sheets should be fixed at every fourth corrugation and every second corrugation at gutters, ridging and overlaps.
Accessories
Accessories such as ridgeThe horizontal line at the top of opposing sloping sides of a roof running parallel with the building length. flashings, apron flashings and foam eave fillers are also readily available from any suppliers that stock the PVC or polycarbonate roof sheets.
I have generally followed this plan over an existing pergola, with modifications to suit my situation.
This site was the most helpful I have found.
For purlins (nogs) I reused existing 2x2s across the top of the rafters, planning to fix the Suntuf sheets to them directly.
This plan does not address painting, but I would observe that it is a helluva lot easier to paint structural wood components before installation. Most of the structure is the typical outdoor white.
Cut the rafters, angle the ends, and paint them on the ground, to save a lot of work.
After hammering or bolting the steel anchors and truss ties, I hit them with some white spray primer to hide the nail heads and hammer marks.
I am using the smoked gray Suntuf, and I wish I had painted the purlins more of a matching gray color (instead of white) before screwing them down to the rafters. I would prefer the purlins to fade out of view against the polycarb sheets.
The plan and equipment list make no mention of the foam closure strips offered by Suntuf, to match the contour of the sheets across the top of the purlins. I am planning to use them, hopefully to provide some noise damping, and wonder if paint will have any effect on them. They are supplied in bright white, which would upset my gray “camouflage” scheme.
Also, the closure strips are very lightweight and make placing the sheets difficult, especially if you are doing this singlehandedly. A couple little folded pieces of duct tape keep them on the purlin when sliding the sheet into place.