Fire ants in our porch roof

A fire ant colony has taken up residence in the roof of our second-storey porch, and are digging out bits of urethane insulation and dropping them onto the porch from where they blow into the bedroom.  To me this looks like a health hazard.  

Is there a permie solution to fire ants living in the house?

That absolutely sounds like a situation for diatomaceous earth. The roof will even keep it dry for maximum effectiveness.

I have some food grade diatomaceous earth - will that work?  How should I apply it?  That is, how do I get the ants to bring it to the nest?

Casie nailed this one. Diatomaceous earth is the answer. Hopefully the "worker ants" for lack of a better term (I'm sure they have a proper name) bring enough of the DE back into the nest for the queen to crawl across some and achieve a colony collapse.

How should I lure the ants to the DE?  We have a dog and cats, so I'm concerned about any kind of bait just getting eaten by the pets and not the ants.

I don't know if this is a good idea, but maybe mix a little powdered sugar in with the DE. Don't all ants like sugar? Maybe sprinkle some near the nest opening, or near/on a scent trail?

Food grade diatomaceous earth is very fine, like powdered sugar. Take a handful and blow a cloud of dust across everywhere you think the ants can be, particularly focus on corners so that it will settle in crevices. Just be careful not to breath it in during this process. You want the ants to walk through it.

It's a mechanical means of killing the insects by damaging the exoskelton rather than a chemical process that disruptions the biological functions. Think of it like microscopic caltrops. There's nothing about it that should attract animals or insects to it (though it won't harm any of your pets) but they'll not be carrying it back to the nest.

edit:

For horizontal surfaces we sometimes put it into a mesh kitchen strainer and use that to spread it. Particularly on an upper porch, the natural breezes may help carry this into crevices.

Thank you, that's very helpful, Casie.

google Dirt Doctor, whose name is Howard Garrett out of DFW and he has excellent ways of dealing with fire ants.  Thanks for reminding me why I left Texas.

Thanks!  Some helpful suggestions.  Ordinarily we don't have much trouble from them because we have a robust armadillo population and other critters who probably eat them.  We don't have huge numbers of mounds, but this time they got it in their tiny heads to move all the way up the house to the porch roof.  Just freaky weird.

I want to try the diatomaceous earth but my husband is insisting on trying poisons first.  I'm not thrilled with that.  I worry about other critters getting into the poison.

I'm wondering "why" they are up there. My guess would be moisture. Possibly there's a leak in the roof? Are the gutters full of leaves and thus holding moisture?

When I saw the title, I assumed it was carpenter ants.

Fire ants love heat, so I figured they moved up there because it's hot.

Vinegar will also kill them.  When we lived where we had fire ants I always kept my kitchen counters sprayed with vinegar.  Every so often I would find dead ant all over my counters.