so the basement ceiling was put together using scrap pieces... but never really finished (no tape applied, no spackle along the seams.
Rather than doing a ton of spackling or ripping off all those smaller pieces I am thinking the easier thing would be to simply glue on a full size 8x4 rock and then just spackle those joins

Would you recommend this ?
Is this do-able using construction adhesive ?
Maybe I should reinforce with a few screws ?

thanks !

 

You can glue sheetrock but it also needs to be screwed. Glue alone is not a good idea especially for a ceiling.

 

Not something I would consider. The original ceiling was done on a budget, and that is fine, nothing wrong with it. But the new drywall that you want to install is intended to be supported by properly spaced screws, and adhesive if you choose. By gluing another layer of drywall onto the first, you are effectively doubling the load on each of those original screws, which may or may not be properly sized and spaced. And if any of the original screws did start to pull through you would not have any of the usual early signs like pop marks in the ceiling, so it's very possible that the only indication of failure may be when it comes crashing down. Do you have engineered joists or 2 by's? With engineered joists, the odds of having a flat ceiling are better, but, with 2 by's, you can bet that it's not perfectly flat, meaning that those original smaller pieces are not all on the same plane, so even if you wanted to you could not likely achieve even distribution of adhesive, thereby increasing the load on some of those original screws even more. Drywall adhesive is very effective, but essentially adhering paper to paper over my head? No, I don't think so. If the existing drywall is otherwise in decent shape, I'd spend the time taping and mudding it, just like you would probably want to do on the new stuff anyway. Otherwise, if it's not in so good shape, well, yes, it's a pain, but I'd rip it down and start fresh.

 

makes sense and kind of what I was already thinking..... I hate to be taping and mudding everywhere there is a join now..... the current pieces are about 24x24 inch and do NOT run in one line.... it's like a checker board now with each piece randomly placed.
Putting single large sheet over and screwing it will cut the amount of spackling in half if not more.....

 

I would follow Aka Pedro's advice and remove the old patchwork of sheetrock then install new, full sheets.