1. FIXING WALL PLATE TO WALL
If fixing under eave, the wall plate must have a minimum clearance
of 30mm to allow for roofing sheets. For fixing to a flat wall,
the height of wall plate should not be any lower than 2550mm from
deck level. In most cases it can be lower, but contact
Bullnose Roofing. for more details. Refer
2. FIXING SUPPORT POSTS
For best results use "Post Trim" post supports for ease
of plumbing posts. For post centre location, divide length of awning
into equal spaces. Maximum post centres using a 200 x 50 beam is
3000mm. Maximum post centres using a 150 x 50 beam is 2400mm. Greater
centres can be achieved with laminated beams. Contact
Bullnose Roofing for details. Fix post supports to deck
or concrete pad. Follow instructions in "Post Trim" packet.
Refer Detail B.
3. PREPARATION OF POSTS
CORNER POST - Notch out post top on two sides the depth and width
of fascia beam. Refer Detail
MID SPAN POST - Notch out post top on one side only the depth and
width of fascia beam. Refer Detail
Cutting post to length ensure deck or flooring is level. If not,
allow for it when you cut post. The minimum clearance height of
the fascia beam "underside" is 2050mm. Refer Detail
4. STANDING POST AND FASCIA BEAM
Place post on support base plate. Plumb post with the level and
brace. Ensure the rebates on posts are all level. Fix beam to posts.
5. FIXING RAFTERS
THE COMMON RAFTERS
- Notch out rafter at the bottom of curve to suit beam thickness
and 100mm in depth. Refer Detail
D and E. Fix front of rafter
to beam and fix back of rafter flush with top of wall plate. See
span tables for maximum rafter spacings.
THE HIP RAFTERS
- Cut 100mm off the curved end. This cut will sit on top of fascia
beam and post. Refer Detail
6. FIXING PURLINS
The purlin spacing is to be no greater than 1200mm apart as recommended
by BHP roofing table. For best fixing of sheets, the first purlin
should be placed 100mm past the finish of curved section of rafter.
Refer Detail I.
To fix purlin into position, simply skew nail or screw to rafters
and ensure top of purlin is flush with top of rafter.
7. FIXING GUTTER
First test a bulllnose roof sheet. Lay it on framework adn mark
a line on fascia beam where sheet finishes. Fix bottom of gutter
20mm below line mark on fascia beam to allow for sawtoothing (explained
later) when laying roof sheets. Install downpipe outlet. Refer
8. FIXING ROOFING SHEETS
A carpenter's level should be used to lay the first sheet. Place
level on top of curved part of sheet, lift sheet till it is level.
This will give you a sawtoothing effect. Refer
Detail F. Sawtoothing must
occur for sheets to remain square and level.
9. WEATHERING THE ROOF SHEET
Weathering is to ensure that wind assisted rain does not run over
the back of the sheet. with pliers or a shifting spanner closed
down to 2mm, grip valley of sheet and turn up 90 degrees or as far
as possible. Refer Detail
MGM Structural Curved Rafters have been tested
for strength to meet AS1720 design requirements for a stress grade
of F8. The instructions contained here apply to MGM Structural Curved
Rafters only and are not suitable for other rafters.
These instructions are also based on the assumptions that a) you
have building skills, b) the verandah or its foundations are in
place and c) you have completed plans and/or drawings with specified
verandah dimensions and a rafter plan
Although the diagrams herein show bullnose rafters, the same principles
of construction also apply to concave, convex and ogee.