Gentlemen, I have a single story conventionally framed roof structure with 2X8 ceiling joists 24 inches on center spanning 16 feet. I also have 2X6 rafters 24 inches on center. I would like to strengthen the load capacity of the ceiling joists, but I cannot install more 2X8's in the 24 inch space between the original joists--too much stuff in the way. My question is, do you think laminating 16 foot 2X4's on top of the 2X8's would serve any use in terms of adding capacity? The laminated joist combination would then be around 11 inches of nominal vertical height. My other question relating to the rafters is, can the 2X6 rafters support 5/8 inch sheet rock with R13 insulation? The angled spans run 15 to 20 feet in various areas. I was going to add knee walls and collar ties so that the run between would never exceed 10 feet. I was going to use the space for seasonal storage and toy train layouts. There would be a carpet and pad load and a minimum of furniture load. I sure would appreciate whatever input you have on this project. Thanks, Jerry

 

Jerry:
Forget the laminating 2x4 idea. Waste of money, no strength. Actually your 2x8's are plenty strong. If you did want to beef them up, attach helpers to them. Another 2x8 bolted or nailed (many many times) to the sides of your existing 2x8's. Your 2x6 rafters are fine, and can very easily hold your sheetrock and insulation. The knee wall is up to you. If what you are going to do with this space is as you described it, the weight is really negetible.