Installation on Sheds

INTRODUCTION

Many sheds are not strong enough to support PV systems. Ideally, the roof frame should be examined as part of a site inspection. Furthermore, tilt-leg systems require the roof frame to be checked by a registered structural engineer.

BUILDING CODE

Sheds are Class 10a (non-habitable) structures under the Building Code of Australia. Sheds with a floor area greater than 10 m2 require a building permit.

STRUCTURAL SUITABILITY

Many sheds have been constructed without reference to the building code, or without a building permit. In comparison with dwellings, sheds have a greater risk of being structurally unsound, or have little capacity to withstand higher loads. Commonly, small sheds have minimal triangulation in their roof frames. Therefore, caution and care should be exercised prior to installing PV systems on sheds.

LOADS CREATED BY PV SYSTEMS

As a rough guide, a flush mounted system doesn’t increase the load on the roof frame very much. In contrast, a tilt-leg system can almost double the load on the roof frame. This is why the roof frame needs to be checked by a structural engineer.

CHECKS

Prior to installing a PV system on a shed, installers should confirm the following:

- The shed complies with the building code

- The shed was constructed with a building permit

- The roof is trafficable

- The frame is capable of withstanding the higher loads created by the PV system

MEASUREMENTS

The following assessments and measurements should be made:

- General condition of the frame (rust, borers)

- Batten material, size, gauge (thickness), span and spacing

- Rafter (truss or frame) material, dimensions, span and spacing.

For Further information

For further information contact Sunlock on 1300 655 554 or order@sunlock.com.au.

Fasteners

Introduction

SunLock uses machine screws (also called bolts), washers and nuts in a variety of locations. This technical bulletin describes how to prevent a fastener from loosening.   (Carroll Smith’s nuts, bolts, fasteners and plumbing handbook, 1990, page 116. )

Lock washers

 A serrated or star washer can be effective when machine screws bear onto a relatively soft surface such as aluminium.

Helical Spring Washers

Helical spring washers are ineffective, as the spring force created by the washer is far less than the axial tension in the bolt. They effectively act as a flat washer. 

Nyloc nuts 

Nylok nuts create friction directly between the nut and the bolt, which prevents them from rotating and loosening. These are effective. 

Durlock nuts

Durlock nuts have a serrated surface on the lower face, which is easier to tighten than to loosen. These are effective.

Reference

Barrett (1990) Fastener Design Manual, NASA 

Smith (1990) Carroll Smith’s nuts, bolts, fasteners and plumbing handbook, Motorbooks International 

Tomotsugu (2008) Bolted joint engineering: Fundamentals and Applications, Beuth 

For Further information

For further information contact Sunlock on 1300 655 554 or order@sunlock.com.au.