I transport panels and timber on my roof rack a lot...I've had a couple of incidents in the past, years back. One when I was carrying a couple of sheets of 9mm ply and the wind lifted the front and the top sheet snapped in half, blew off and (looking in my rear view) narrowly missed a BMW driving behind me!
Another time I had to hammer on the anchors approaching a roundabout when a car came flying around it...the panels on my roof slid forward and down my bonnet
You'd think I'd of learnt my lesson, but I still use the roof...but cautiously...Small loads, ratchet straps (always) and clamps along the front edge of packs of panels...and or course a
slow n
steady ride...and not get too bothered at folk beeping me for doing 50mph on the dual carriage way
I've always wondered what the official rules were...I guess (hope) weight limits and common sense?
I've always had Estate Cars...what I find frustrating is in an effort to make them more 'sporty' looking they now have these impractical low profile roof rails offering poor purchase for 'Aero Bars' and the inability to strap down to the car by wrapping around the rail!
Try to distribute the weight to the outside edges, close to the rails and fixings and away from the centre of the rails.
Jim