How do I measure angle before cutting drywall?

I'm installing a product called DensShield in a shower stall----it's an alternative to the usual cement tile backer board. I have a 4'x8' sheet that I will cut to fit the larger inside wall of the shower stall. The piece, after its cut, will be about 46" wide by the full 8' tall. The narrower end-walls are already done.

Is there a trick to measuring the angles of the side walls and bottom before I cut the sheet so I won't end up having any large gaps afterwards? I know the end walls and lip of the shower stall are not quite level. The sheet is 5/8" and VERY heavy so I need to cut it once and set it in place and screw it in.

I've thought of just taking three measurements of the inside wall of the shower stall (bottom, middle, top) but I don't think that will take into account the angles of the side walls and bottom.

Is there a trick to doing this?

Thanks for any ideas.

 

The pros probably have their own tricks, but the old stand-by of creating a paper template always works. Cover the target wall with paper, taped together so it is one continuous piece. Trim it to fit exactly as you want. Patch if you need to make adjustments. And then remove and use as a guide to mark and cut your material.

Bud

 

Just take measurements about every 12" all the way up the walls. Mark each measurement on your piece and cut. Rasp to fit if needed. Is does not need to be tight as you will be "taping" the seams and installing tile (I assume)

 

What I do is look for the square corner if there is one. Then you know that two sides of the piece will fit. Then measure all the other sides.

If this is trapezoidal in shape then find the center of the top of the piece and mark a line plumb from that at the bottom. Then measure from your plumb lines both ways and transfer those measurements to the sheet.

Measure more than once before making any cut. Draw it all out on the piece of rock and then double check your measurements again.

A big piece of card board is a little easier to work with than a paper template. That way will work as well.

What are you going to screw to on the right side?

By the way, that sure is a good picture of the back side of plaster.

 

Thanks for the ideas. That little gap on the right side is only 1-3/4" wide. Since I'm using 5/8" DensShield, I'm thinking that a tiny unsupported edge like that will be ok. Does that sound right? I will, of course, screw it every 6" along that vertical 2x4.

I like the idea of the paper or cardboard. Not sure I can find one piece of cardboard in size 4x8 and taping pieces together seems a little risky if one slips slightly without me noticing. They do have thin insulating foam sheets that large that are cheap at the local H.D.

It seems a tool for this would be handy----something like a frame with wing nuts on each corner so you could just shape the frame around the sides/corner, lock it in-place and then set it on-top of the drywall and make your cuts.

 

Ummmm.... I hate to bring this up....but the Denshield already installed isn't sitting all the way down on the shower pan is it?

Did you leave a gap per the install specs...?

And if it were me...I'd at least install some blocking in that gap.

 

Georgia Pacific suggests a minimum 1/8" gap. I left a 1/4" gap which I will caulk with silicone.

 

OK..great...just checking...

 

Take preliminary measurements of the angles with a framing square. Then make a template outline using 3 in. wide strips of 1/4 in. plywood. Install one corner brace so the template will hold its shape. Fasten the corners of the template with short screws. Place the template on the DensShield and mark your cut lines. Good luck with your project.

 

You could also template it in the same manner that some granite countertop guys make templates. Cut strips off the edge of a 2x4 that are about 3/16" thick. Cut 2 pieces that are the length of the opening and 2 pieces that are the width of the opening. Put contact cement on the corners where the pieces will overlap (two-part catalyzed contact cement works best) and then just put the pieces together tight against their respective walls. It will be a perfect template of the opening.

Granted, your sheet doesn't have to fit perfectly, but it would be a foolproof way to duplicate a complicated shape. Just thought I'd mention it!

 

You should put support in that corner. If someone leans on it, it will probably crack the corner joint. It won't take much to do that.