DIY Major Structural Modifications

Raising the roof, removing windows, changing the access door, fitting seats

Any of these modifications will require certification by an authorized engineer, and must be complianced in accordance with current Australian Design Rules (ADR).

Raising the roof

Older coaches often had a lowered corridor, with the seats mounted on a higher platform to accomodate wheel arches and under-floor storage-bins. This gave a 1.9m headroom when walking the corridor, but only around 1.6m at the sides with the curvature of the roof.

This does not present a problem for DIY builds with the fixtures mounted to the left and right, while retaining the corridor as a hallway. However, designs with flat floors using staggered or offset fixtures and internal walls lose this headroom, and in particular near the side walls when walking past bedrooms or bathrooms etc. Corridor coaches can also present problems with enough height for showers etc, often requiring the shower base to be recessed and sunken into the floor for taller people to get wet.

The alternative to this if you have a corridor coach and want to lay a flat floor is to remove the interior and exterior body sheeting, cut the roof supports and the fibreglass front and back mouldings, weld in extension tubes, re-sheet the bus, and re-fibreglass the roof sections at the front and back.

Removing and installing windows

Well designed motorhomes often have the original windows removed and re-sheeted over with caravan style windows fitted where necessary.

This will again involve removing the interior and exterior sheeting, welding and cutting in supporting beams and braces, before re-sheeting and sealing the sides and installing the new windows into the apertures created.

Window removal is often done to coincide with raising the roof.

Access doors

This is the main entry point into your motorhome. This door must open outwards as in a car, although the original folding door is also acceptable.

If you wish to replace the original air-operated folding door, then the replacement door must not only open outwards, but will be required to have an approved locking device, intrusion bars, and anything else the certifying engineer requires at the time.

You can not simply buy a wooden house door from Bunnings and attach it with screwed hinges, then fit a standard house front door lock and expect it to comply.

Fitting seats for passengers

You cannot simply leave 2 or 3 original seats, or just bolt in some bucket seats from the wreckers. The original seats may be fine, but they will need to be fitted with NEW approved seatbelts, satisfactorily mounted to your engineer's requirements. Other seats such as car seats from the wreckers will again require suitable welded and bolted mounting points, before being seat-belted as above.

However, you can simply fit seatbelts to lounge or dining positions to the specifications of the engineer. Sideways seating may only require lap belts, but all other forward or rear facing seating seems to require lap/sash belting now.

The exception is purchasing an ADR approved seat or seats that have an approved seatbelt system built in. Then you only need concern yourself with the mounting points for the seats.