# Measuring and cutting odd subfloor shape...



## branimal (Mar 29, 2017)

Ripped out a lead pan shower today only to find 4” red oak hardwood flooring below.

I need to cut the oak and possibly the subfloor below out to replace the plumbing. 

How do I measure those angles? What tool should I get? 

Or do you put a piece of cardboard in there and trim until you get the best shape possible. Then use the cardboard as a template?

Also will a 4 x 6 sheet of plywood be adequate to fill that space? I can’t get a 4x 8 into my elevator. 




















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## Toolman50 (Mar 22, 2015)

I would leave the old floor and build over it. 
If you needed tp remove a few boards to access the plumbing (which may not be necessary) I would fix the plumbing and reinstall the floor.


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## branimal (Mar 29, 2017)

Toolman50 said:


> I would leave the old floor and build over it.
> 
> If you needed tp remove a few boards to access the plumbing (which may not be necessary) I would fix the plumbing and reinstall the floor.




Thanks toolman, but the manufacturer (schluter-kerdi) of the shower membrane wants a plywood floor. This floor has imperfections throughout. 


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## J_L (Apr 22, 2014)

Get the existing wood floor out of there. Take a look at the existing subfloor and see if it too needs to be replaced. If not, install your advantech over it. Schlueter wants a nice smooth surface for installation over.

As for cutting your piece, there are three ways to go about it - template (cardboard, door skin, etc), use your existing drawing with an angle finder to locate the angles, or expand on your existing drawing by taking more measurements of diagonals to locate every point.

With option 3 you're basically sketching out a bunch of points on to the new subfloor and then connecting the dots. For instance, starting with the 30 1/8 on the left side of the drawing. Measure from the bottom of the 30 1/8 up to the far side of the 24 3/8. Then on your plywood, swing an arc pivoting off of the bottom of the 30 1/8 marking the arc at your measurement to the top of the 24 3/8. Then swing a second arc pivoting from the top of the 30 1/8 out 24 3/8 and where this arc intersects the first arc, there's your point! Repeat this process around your piece. I normally like to check multiple points and swing multiple arcs to confirm (measure twice, cut once) or at least measure diagonals between various points.

This does look like it would fit on a 4x6 sheet of plywood.


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## Steve Neul (Sep 2, 2011)

Red Oak is bad to rot and should be removed even if you didn't have a plumbing issue. Anything you put back I would use pressure treated. You can get 3/4" treated plywood. 

Cut the replacement floor out of plywood before you demo the oak. Don't think about the angles. What you have to do is find the corners and connect the points. You can do this without ever knowing what the angles are. There is a 90 degree angle across the bottom and left side. At the first corner lay a framing square at that corner and measure the distance out from the left wall and the distance from the back wall to the square along the line in the flooring. Lay this out on the plywood you will use for the floor and draw a line from the two corners. Then measure the distance across the back wall and make a mark. Then put your square at the corner at the top of the picture and measure the next corner like you did the first one. From there measure the 25 5/8" across the bottom and make a mark and connect the line. Now if you are putting the drain in the same place measure and mark the center of where the drain will be. From there it should be just a matter of cutting it out.


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## shoot summ (Feb 21, 2014)

You have to establish a base line across the area, straight, and at least square to one of the walls, or door opening. Then mark the line at some increment, 4"-6" is a good place to start. Then measure from those points out to the walls on each side and record those measurements on a paper. Use a square from the base line to make sure you are perpendicular to the line at all times. Then transfer those measurements and lines to your sheet product, connect the dots, double check yourself, then cut.


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## woodnthings (Jan 24, 2009)

*I don't like measuring!*

I would never be able to layout that shape by measuring, even with all my drafting experience, equipment and traingles. I would cut 4" wide strips of butcher paper or thick packing paper, and locate them in the intersections, taping them together. Cut the corners using a Stanley knife, keeping them accurate, but no measurements requited.


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## Toolman50 (Mar 22, 2015)

branimal said:


> Thanks toolman, but the manufacturer (schluter-kerdi) of the shower membrane wants a plywood floor. This floor has imperfections throughout.
> 
> 
> Sent from my iPhone using Tapatalk


In that case, I would lay the plywood on top of the existing floor.


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## branimal (Mar 29, 2017)

Some great ideas here guys. Thanks

I am leaning toward removing the subfloor as well so I replace the shower flange. And possibly the ptrap as well. 

Steve why do you suggest cutting the replacement before I demo the oak?


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## Steve Neul (Sep 2, 2011)

I recommended cutting the replacement before you demo the floor because with the floor there it would be a lot easier to measure and lay out the angles. If you look at the picture one corner is exactly in line with the seem between the fourth and fifth row of flooring. If you measure from the left side to the seam that gives you the measurement to that corner.


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## Larry42 (Jan 10, 2014)

Using two squares and a steel rule will get you a nearly perfect set of corner marks.


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## firehawkmph (Apr 26, 2008)

I would be able to lay out the new piece with a square and tape measure. However, do like the linoleum guys used to do. Take a piece of roofing felt, fit it in the space and cut it about a 1/2" smaller all the way around. Cut out a few triangles in the felt so you can tape it to the floor. Use a 1" blade from a combination square and place it up against the wall, and with a ball point pen, draw a line on the other edge of the blade. Go all around the opening like this. Carefully take up your felt and place it on the plywood. Using the same blade, place it on the ballpoint pen line you drew, and this time draw a line on the outer edge of the blade onto the plywood with a pencil. Now you've gained back the inch you lost when making the template. You'll get an exact fit. Very easy to do.
Mike Hawkins


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## Steve Neul (Sep 2, 2011)

In this situation the floor doesn't necessarily have to be cut out 100% perfect. Once installed if there is a miss cut you can fill the gap with caulk or great stuff. When the sheetrock is put back it will cover 1/2" all the way around. Filling the gap is only good to keep air and bugs from coming through there.


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## _Ogre (Feb 1, 2013)

tick stick method

http://www.finehomebuilding.com/2006/10/20/measuring-odd-shapes

https://www.boatdesign.net/threads/using-tick-sticks-to-scribe-odd-shaped-areas.46255/


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## VirginiaHart (Dec 25, 2020)

_Ogre said:


> tick stick method
> 
> Measuring Odd Shapes - Fine Homebuilding
> 
> Using tick sticks to scribe odd shaped areas


One of the oldest and most reliable methods. Old school!


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## ColeSMTH (Apr 28, 2021)

Our craft is a very complex business. It is a pity that society does not seem to understand this and underestimates us. After all, it is only thanks to our craft that people can do what they do at home. Our children all as one strive to the IT sphere, thinking that good money is spinning only there. None of them even wonders how to become a plumber. I believe that it is necessary to change the approach to such things and physical labor. We are real workers, not the wealthy of Wall Street. It would be better if our government was doing this!


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## fareastern (Sep 19, 2014)

A few three inch strips of doorskin ply and a hot melt glue gun will allow for a simple pattern to be made in there.Alternatively you cold buy a book on boatbuilding and research spiling.


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## DrRobert (Apr 27, 2015)

You need to make a template. Basically the way fareastern ^ described but I’ll be more specific. Rough cut cardboard or thick paper to fit inside. Secure with tape. Using a spacer block & trace outline.

Transfer shape using the same spacer. Give yourself 1/8” all around. Easiest way cut 1/8 off the spacer.

It will fit perfectly!


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## woodnthings (Jan 24, 2009)

Old post resurrected .....
Use 3" or 4" strips of thin cardboard to place all the way around the perimeter and hot glue them or tape them together. Just make the intersections overlap, but as accurate as possible. Then, "bridge them all together using more strips into one shape that's got the perimeter outlined. Lay that on your plywood and cut it out. 
NO MEASURING!


woodnthings said:


> *I don't like measuring!*
> I would never be able to layout that shape by measuring, even with all my drafting experience, equipment and tri-angles. I would cut 4" wide strips of butcher paper or thick packing paper, and locate them in the intersections, taping them together. Cut the corners using a Stanley knife, keeping them accurate, but no measurements requited.





fareastern said:


> A few three inch strips of doorskin ply and a hot melt glue gun will allow for a simple pattern to be made in there. Alternatively you cold buy a book on boatbuilding and research spiling.


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## branimal (Mar 29, 2017)

I ended up buying drywall shims and hot glueing them around the edges of the shower. Worked perfectly.

Now when I want to template larger spaces I cut 3/16 strips off of 2x lumber and hot glue them. Process works like a charm.

Used it to template a small quartz kitchen countertop.


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## kwoodhands (May 1, 2020)

Countertop installers use narrow strips of 1/4" luan plywood and just cut to rough length . Then hot glue the strips over lapping the joints.
mike


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