question on how to fit shelf

[Paul Ray Moore]

I have a friend that wants to put a shelf on his wall from one corner to the other. There will be no brackets from the underside. We will use L brackets on the top of the board to hold it up. He wants this to be one solid shelf so there won't be a joint in the board. How do you fit one so that there won't be a gap on the ends?
The wall is 11' but I'm sure the corners aren't square.

[Philip Rodriquez]

Sorry, I'm in a hurry but I didn't want your post to go un-answered.

Scribe it to the wall. Myself, I hate those metal brackets; therefore, I would go for a floating shelf look.

[geoff wood]

you first must make a template of the two walls, scribe a piece of cardboard to the back and side walls. it doesn't have to be a full 11' just so you have the profiles of each end. then make a two sticks about 6' long, and butt the rear of the wall, you will pencil a line to mark that length on each stick, repeat the same for the front. this is more accurate then sticking your tape into the corner. the last step is to mark the length and mark with the templates. i hope i explained it well enough.

[Russell Hudson]

you first must make a template of the two walls, scribe a piece of cardboard to the back and side walls. it doesn't have to be a full 11' just so you have the profiles of each end. then make a two sticks about 6' long, and butt the rear of the wall, you will pencil a line to mark that length on each stick, repeat the same for the front. this is more accurate then sticking your tape into the corner. the last step is to mark the length and mark with the templates. i hope i explained it well enough.

We make templates from time to time. This is needed when doing stone countertops, compound curved walls, etc., but unnecessary here. Cross cut your shelf length by an extra half inch, put it in position against the wall (slightly bowed) and use a compass to scribe the back edge to the shape of the wall behind it. As well, you can scribe the ends left and right. If your looking for THAT snug of a fit on the ends just remove less than you think you're supposed to and then do it again until it's perfect. This is the way you 'cope' crown moldings, etc.

[Paul Ray Moore]

I appreciate the ideas. I had thought about making a template and also doing a slight bow and then pushing it down so that pushed the ends into the sheetrock. We'll be working on it this weekend. Once I'm done I'll post some pictures.