You can't have a chair that's 1.5 in height. I mean... graphically you could, but you can't have a TILE that's 1.5 in height, and that's exactly what you're trying to do.
PHP Code:
setshape2(8,2,{
22,22,22,22,22,22,22,22,
22,22,22,22,22,22,22,22,
});
Notice how I organized my array. Basically, since my chair has a height of 2, I categorized the values of my array into two rows. One row for each vertical row of tiles. It makes it easier to understand exactly what you're doing.