While jacking or lifting vehicles off the ground, what is acceptable to use to safely keep it up. I think house bricks, block paving, and Concrete breeze blocks are a definate NO. Bricks are generally slippy, block paving the same, and breeze blocks crumble and fracture. That leaves purpose built stands that have a load rating and the material of choice Wood/Lumber. Ideally a large piece at the base and the distance packed with graduated pieces to make the blocking stable as It has to withstand both vertical lateral and longtitudinal forces. I allways worked thinking what if I had to go to court and explain my actions because either Jane or Johny from next door had come around looking for their ball and the unthinkable had happend, the vehicle had slipped, could I justify my actions. Another thing to check when liffting wheeled vehicles is has the axle with the parking brake left the ground? I think it is always policy to chock the tyres to inhibit the vehicle rolling away. They stopped fitting rollers to skip wagons stabilizers years ago because when they were deployed the axle with the parking brake was sometimes lifted clear of the ground and the vehicle could and sometimes did run away. There is no point being fastidious with the repair and cavalier with safety. If it goes wrong someone has to come and clean up the mess. It takes less time to do a good job of blocking up a vehicle than either waiting for medical help or filling in a statement. Sorry to go on but sometimes a wake up is required, It is the time of year when vehicles are being woken from their winter of rest and readied for whatever. A lot of jacking is going to be undertaken do it safely and everyone will go home in one piece and happy.