Kreg Owners' Community

Hello everyone

I am new to this forum and I begin to say thank you for any help.

I have completed building a woodworking shop in my garage to do the hobby I love! Someone told be about using a 4X8 sheet on insulation as a table top that can be put on horses to lay a 4X8 sheet of ply wood to cut on. It stores easily when I breakdown my shop for my wife's car to get into the garage. I bought the insulation at a Home Depot.

it worked great until it started to warp. I noticed on one of the Kreg videos sheets were being cut on some sort of insulation and so I am wondering two things:

1. Does anyone know what the builder was using on the video of using the Greg rip guide?

2. Does anyone have any ideas to make the insulation not warp if I buy a new sheet or another way of having a easily moveable table top

thanks in advanced for your time!

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When the insulation board is in the horizontal position, the underside needs to be supported, to prevent sagging/fracturing.

I use 2" thick rigid foam board insulation, place it on a solid foundation, such as a concrete floor or driveway---

lay the plywood sheet material, that is to be cut, on the insulation board and cut it out.

I only do this when I'm cutting sheet goods with a circular saw.

NOTE: Set the depth of cut on your circular saw, so the blade is about 1/8" of the blade teeth protrude below the plywood sheet.


a.  for easier handling of the insulation board, I cut it in half---so that I have (2) 4ft x 4ft pieces.

when cutting full size plywood sheet I butt the two sections together.

When cutting smaller size wood pieces, I use only 1 of the two insulation boards.

Placing the insulation board on a concrete floor, deck or the like, and then cutting the plywood, make it easier when kneeling down vs standing upright when having reach a long distance across the board, like when ripping a 4ft wide sheet in half, or the like.

b. This method can also be used for other cutting tasks---not only plywood sheets.

Ex: ripping long boards, making layouts, patterns, and the like.

c.  When the insulation boards get damaged, after making lots of cuts, I just replace the insulation board with a new section.


Wow! Never thought of cutting it in half! That is a great idea! I thank you for your time.

I do put it on saw horses because it is easier to cut a piece for me while I am standing. Do you think that is why it is warping or is it that I bought a cheep piece from Home Depot? Maybe I should get something like you mentions 2" thick and "rigid insulation"

Hi Dom,

The 2" material will be better---it's thicker and more rigid, for such purposes.

As previously noted, I put my insulation board on the concrete shop floor, driveway, patio or deck---

then lay the material, I plan to cut, on top of the insulation board.

This works well the ripping and cross-cutting sheet goods.

I find this works better for me, to be in the kneeling position, vs standing upright---it's easier to manuver the sheet goods while cutting.

On some builds, I ripped a lot of sheet goods, from 1/4" to 3/4" plywood, as well and paneling.

When ripping the sheet goods, I use an edge guide---either buy or make your own.

If it's just a rough cut, I just snap a chaulk line, and rip away.

I use a variety of different circular hand saws---

Worm-drive, conventional types, compact styles---

corded and battery powered.

If using the thinner material, I'd suggest placing  sheet of 1/2" plywood underneath, if you plan to use it on sawhorses, or place the insulation board on several 2x4, or the like, to rigidize the thin insulation board.


Prior to using the thicker insulation board, before it became available on the market, 

I'd just place 2x4's, at various intervals, and placed the sheet goods on the 2x4's to support the sheet goods off the floor or deck.

When the insulation board gets a lot of saw cuts, just flip it over and use the back-side.

When it gets to a point when it's unusable, just purchase a new board.

You'll get lots of use out of it for only spending $25.

BTW---it's more cost effective just to buy the 2" thick insulation board, vs the thin insulation board and 2x4's.


Actually  I just saw a commercial for a company locally that sells rigid insulation. I am going to giver them a call to get a piece.

Interesting that you bring up that you use a variety of circular saws.  I have a corded one and I am thinking about getting a new one. Thinking about the Festool or maybe a battery operated one so I don't have to worry about the cord. What I cut is 3/4" birch for the tables I make. I rip using a guide that I have made 24X28. I then do the rest of the work on my table saw.

Any suggestions on a good battery operated one or the Festool?

Again I thank you Ken for your time!

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