Wondering what quality of foam you would end up with if it wasn’t in a mold. I see so many shows with people using the pour foam in an open air form, not a sealed mold. I’ve used the crap in a can used to seal windows in the past and it’s useless because it develops large bubbles, plus it is heavier than I expected.
I’m helping a frend on a project with an internal frame, and I’m cutting up pieces of EPS and XPS to fill it, but I’m wondering if it might be easier and quicker to use pour foam. We could make a simple plywood bottom piece then pour in the foam, and let it spill out. Large air bubbles would be a bummer when we cut away the excess, and I don’t want to bother with a heavy concrete mold.
It depends on the foam. You can buy the foam in a variety of densities. They range from very pourous 2 pound density to 16 pound density that is hard as a rock.
I used both the 2 and 8 lb. pour foam from Fiberglass Hawaii. I used it to fill compartments in boats, gluing EPS foam blocks together, creating a block with a EPS blank to mount boxes for foils. I also used it to glue in balsa or high density foam blocks in EPS blanks to mount fin boxes. It can melt EPS foam if poured too thick. I also use it to fill PVC pipes when I need to stiffed the pipes. I like the idea that it can be sanded and shaped while filling voids. Good stuff.
My experience is mostly void filling in boat work, where you need to be real careful about how much you put in, lest (these are mostly sealed voids) you blow it apart. Open- it varies, in general the warmer the faster it goes off, bigger bubbles and so on.
Having said that, another possibility: spray foam insulation, the commercial industrial kind where somebody comes in to insulate your house with the rig in a truck and a couple of long hoses to a gun the guy inside uses, blah blah blah. It comes in two flavors: the regular high expansion kind for new work and open bays on the inside walls and a lower expansion flavor for retrofits where they squirt it into walls that already have the insides on and finished. Low expansion 'cos blowing the plaster across the room doesn’t make the homeowner happy.
I’ve done house renovations where they had used spray foam and I’m here to tell you it most definitely sticks to whatever it was sprayed against. Easiest to sawzall out part of the wall and start over rather than trying to get the foam out.The wall gets what you might call monolithic- in post and beam work you don’t need diagonal bracing to keep the wall from wracking.
It’s a urethane foam, pale yellow-brown in color, works with polyester resins if that is an issue, the people who work with it are likely way more expert with it than you and I. The drawback being that they don’t do the small batches you’re looking for, for that matter they avoid small jobs. Basic setup and cleanup costs on every job, I imagine. But if there’s a company nearby that does spray foam insulation, you might be able to tag along or something when they do a bigger job.
Thank you everyone, I appreciate your responses. I’ll pass on the info and maybe try that for the next iteration. It would be a lot easier to pour the liquid into the voids than cut and fit the small pieces of foam. Hopefully it will be lighter than previous experiments. This came about because I showed some of my franken boards using pieces of foam glued together to make a board. Since I had experience and lots of pieces of foam, I thought I’d help out. One thing that might be an issue is redoing things. I’ve cut out part of the foam at least once to deal with things we didn’t think about. Pour foam may make that problematic.
Is there anything I could use to allow me to pull off the wood or whatever we use to hold the foam in? If not pour foam won’t work, or he’ll have to seal one side before pouring the foam.