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I have used polyurethane foam to cover a 5 cm (2 inch) horizontal gap between a metal door and the ground. Polyurethane foam , as I know , needs to be covered with cement in order to withstand the corruption. In order for cement to apply I am going to use a metal frame. I am not sure how to try to stuck the metal frame to the foam in order to be able to use the cement then.

Below is a photo to get a better idea.

Foam + cement ground + frame

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2 Answers 2

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The best way is to embed (bent edges of) the wire mesh in the foam while the foam is wet, and let the foam harden around it. Since it's now too late for that, try large coarse screws, or bend a wire into a section of a circle and poke it into the surface, in a manner where the bent-circle aspect means it pops back out of the foam face elsewhere. Such tie wires could also be better done as embeds while the foam is wet, with a rod, nail or washer wrapped by the wire inside the foam to give them a better hold.

On the screw front, screw-in drywall anchors might give a better grab to your screws, since even the coarsest screw hasn't got much hold in foam. anchors - image from anchorco

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Many thanks for the idea. I will try an easier alternative for the moment. That is to use tile glue (cement based) and try to glue the frame to the foam to some points. –  Konstantinos Chertouras Jun 12 at 14:08
    
Used tile glue (Portland cement + resins) and the frame is secured. –  Konstantinos Chertouras Jun 13 at 13:32
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I would pull the foam out and fill the gap with concrete. Should be a fairly simple job. Just secure a 1x4 against the concrete while it dries. Some metal mesh embedded in the concrete will hold it together longer.

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In this case it was not possible to secure something (a piece of wood or something similar) from the inner side of the metal door to allow the concrete (sand based not cobble based) to dry and get a correct shape. Foam is easier but you have use plaster afterwards. I used tile glue (Portland cement plus resin glue) and I managed to attach the metal frame. Now it's time to create and apply the plaster! Thanks for your suggestions. –  Konstantinos Chertouras Jun 13 at 13:29
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