XPS coolroom foam, how should I cut it?

Scored three lengths of XPS fo from a mate working in the coolroom biz. 2.4 x .6 x .15 roughly…wondering do I glue em together then cut a rocker slice so and then join two halves together? Ie. so the joins are running parallel to the rails?

or glue and use the 600 as the width of the board? Just want to use the foam the most efficienty. Attached is a pic 

The whiter piece looks like EPS. I can see beads.

If you have enough thickness you could hack out a shape from a single slab. I’ve made boards using a single sheet of 3 inch thick XPS, they have very low rocker. For boards with more rocker, I cut rocker slices, then I add a piece along the perimetter for a nice rail. I make these boards stringerless.

Sharkcountry and his brother are masters at this stuff.  As always, cool stuff by Sharkcountry!

I’d just like to point out that there are ways to tweak rocker in the glassing process… hooks/weights, rocker table/vacuum, etc.  After glassing there is some springback but you can overshoot a bit when tweaking and end up with what you want.  With compsand/vacuum bag it stays closer to what you want. 

Some guys cut their blank profiles with straight rocker and tweak rocker to get more blanks from a block of foam. 

I’ve placed a shaped blank with the tail end positioned at the nose end of my rocker table to get a more pronounced tail rocker boost.

I’d think you’re pretty safe cutting multiple rocker/thickness profiles and sandwiching them together with vertical gluelines.  Horizontal gluelines are arguably more difficult to shape cleanly. 


goriila glue and better sumo glue or roo-glue are expanding type glues that fill in the gaps but also end up brittle in the long term.

They are eay to cut through later while shaping than epoxy but epoxy is stronger with both surfaces roughed out

you can cut eps/xps with a drywall saw or even a carpet knife using multiple passes if you don’t have electricity

also razor knives and/or hot wires or hot knives(you can get these at hobby stores) don’t create the foam bubble mess which blows and contaminates everywhere the wind blows.

The right piece looks like EPS the left looks like the stuff Fiberglass Hawaii used to sell in place of the old corecell. It’s high density fire insulation material. I used to use it for fin boxess and rails/stringers inplace of Corecel which is more expensive.

If I where building it I would put the lighter EPS in the center and build outward with the heavier density stuff on the outside of the eps or a center stringer of the heavier density foam followed by the EPS and the the heavier density foam closer to the rails to give you a little more structural support with the blank. Also the heavier density stuff is easier when you are final shaping your rails with screens.

as always the main thing is to just have fun and not over think it

Yeah that is EPS. Should’ve said. The other stuff is XPS tho. This stuff to be exact:


Cheers for the info!!

Yeah this is what I’m thinking. Hotwire yeah? So glue them up as thy are stacked (plus or minus the EPS)

and then glue two or three pieces of that together depending on width of board.

Yeah should’ve said that, three XPS, one EPS. The XPS has tongue in groove

At 1.88 pcf and 43 psi min. compressive strength, your XPS should be decent surfboard foam.

I did one board where I used a single piece of 3" thick XPS then I added a little more nose rocker with weight. Had several good sessions with that one.

I prefer making rocker slices over doubling up layers to get thickness. I don’t like shaping over a scarf line. The only exception is when we bend EPS sheets on a rocker table. We usually add a permeter rail on the layered EPS to hold the rocker and also make shaping rails better.

I use foaming PU glue with EPS and XPS, it seems to have the best hold and it shapes reasonably well.


I like what you’re doing in your shaping room, as well as what you’re doing in the water.     Geev’em!

Thanks Bill.


I shaped a board from construction XPS that came out beautiful. Because the blocks were only 60x120 cm (ruffly 2x4 feet) I had to join them together somehow. First though was to simply glue them together making a 2x8 foot blank. I descided that a diagonal glue joint would probably be a little bit stronger and also not as prone to creating a ridge while sanding due to the harder glue joint. So this is what I did and it worked out great. I had made a little bit oversized stringer that I glued in the center so I had a guide while ruffing out the rocker with the planer. There was a 4" layer of foam dust covering the entire shaping bay floor when this was done. 


I used high quality PU glue called Duracol 65 from Nordcoll.



The XPS i used (100 mm thick):


The board is going on 10 years now and probably over 200 sessions. Very strong board with almost no preassure dings after all these years. Weight is 7.6 lb with wood glass on twin fins and footpad.

Since the foam block used was 4" thick and quite soft to begin with I created a “new skin” after the shape was finished by squeeged a layer of tinted epoxy (swirls) on the blank and let that fully cure before glassing. I glassed with two layers of 4 oz on the deck and then either 1 or 2 layers on the bottom, can’t remember now.

The glue joint was not noticeable while shaping and is almost invisible after glassing.

I’ve also heard of people “baking” their construction XPS in a sauna or in a black “hot box” (if you have that type of climate) meaning that you put the block between two stands at either end and place a weight in the middle making the blank slowly bend in to a rockered shape. Then you just leave it like that for… some time. In a hot sauna I think over night was sufficient to get a nice rocker. I read some guidelines on times and temperature somewhere (must have been here on swaylocks…) Not sure on spring back but I suspect it’s not a big deal if you get it hot enough and leave it alone long enough.

This is what I can find from the shaping process. On one of the pictures the diagonal glue joint can be seen over the bottom.

I make almost all of my boards from pieces of foam glued together. Some boards are made from long strips, but lately I’ve been using small pieces. I do all my shaping by hand, sometimes roughing out the board from an ugly mess. About 75 percent of these boards are stringerless. You can make a surfboard from anything, but the materials you use will dictate how much work and how hard it is to get good results.

As far as XPS versus EPS, I like the way EPS foam feels under my feet, XPS seems a less lively. EPS has issues with the beads tearing out, but XPS shapes really nice. Funny thing is that for EPS you end up sealing it, but with XPS you want it rougher. Best part of using XPS is that the foam will not suck water, worse part is that it is heat sensitive and will blister or delam. The EPS I’ve been using lately is 1lb or less, so I add a thin balsa veneer on the deck to make it more dent proof.

Wow!  You killin’ me brudda!  Pretty amazing.

Thanks Lowell. Sways has been the primary source of my board making education. That, combined with trial and error got me to where I am today. People like you who pass along little jems of knowledge are what makes Swaylocks great. The criticism can be hard sometimes, but it’s an important thing that can make us better.

Hope you have an enjoyable holiday season.


Sharkcountry I´m always amazed how you sculpt those beautiful boards out of glued up pieces of foam.

Great stuff. Thanks for sharing the pictures.


Thanks! Just using up what I have laying around and enjoying the process.

That is inspiring! Thank you for showing that!