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Community and Q&A

Where to buy polyiso in small quantities?

Trevor_Lambert | Posted in General Questions on

Two part question:
1)Where can I buy this stuff in Ontario? I’ve never seen it in a store. A web search shows it at, but as is typical with just about anything I am interested in buying, Home Depot in Canada doesn’t have it.
2)Would this be suitable for insulating a box containing a radiator? Having never seen the stuff, I’m not sure of its properties (e.g. rigidity, brittleness, tensile strength). Is it closer to XPS or EPS? I’ve already ruled out EPS as too flimsy.

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  1. GBA Editor
    Martin Holladay | | #1

    Here in Vermont, most building materials suppliers (lumberyards) sell polyisocyanurate. Some workers at these stores don't know the word "polyiso," however, and refer to what they sell by brand name.

    Try asking for "the rigid foam that is yellow with foil facing." You might be surprised to discover that everyone sells it.

  2. GBA Editor
    Martin Holladay | | #2

    Q. "Would this be suitable for insulating a box containing a radiator?"

    A. What kind of box? What kind of radiator?

    I'm thinking of an old-fashioned cast-iron radiator -- part of a steam heating system or a hydronic heating system. If you are building a box around that type of radiator, you don't want insulation -- you want some type of perforated metal screening. So I'm guessing that you are talking about a different kind of radiator.

  3. Trevor_Lambert | | #3

    So many of these words have so many meanings. I chose radiator because I thought it was less ambiguous than heat exchanger, but I was obviously wrong. Picture an automobile coolant radiator, but thicker.
    The box would ideally be folded from sheet aluminum, but given my limited access to sheet metal tooling, I'll probably make it out of 10mm baltic birch plywood and seal it with polyurethane.
    I've managed to find Polyiso at Rona. Thanks.

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