I've got my foundation almost done but I ran into another question. I have 2" XPS under my Delta MS dimple sheild and I have the sheild hanging from the termination strips. I bought the little orange plugs for the fasteners to go through but I can't figure out how to fasten it through all the layers. I bought a box of 3 1/4" Tapcons thinking I could drill and then screw them in but it's not easy finding the holes. Would I be better using a Ramset with 3" fasteners, do they even come that long???? Thanks, Sean

I say it's worth a try. If you don't already have a Ram Set gun you can get a cheaper version that uses a hammer to fire it. Probably not as convenient but should be OK for one job. Or you can probably rent one from HD or elsewhere. I'm pretty sure you can get anchors long enough. There may be a problem with them penetrating to various depths depending on the local hardness of the concrete, and they may want to bend since there is no support the entire length of the anchor as it goes through the foam. You'll have to experiment to find which load of shot works best. If you have a problem with them puncturing through the dimple plastic you could try using something like large fender washers, or cut some plates from aluminum sheet to distribute the holding force of the head over a larger area. A pain, but a doable solution, I think.

Thanks for the reply. I rented one from HD and got 5 shots in and the gun broke. Went back to the store and they gave me another, 10 shots worked great with 3 1/4" nails then gun broke again. Now I'm thinking I might have to pay for both. I guess with nothing to stop the piston except the foam it tries to fire it right out and breaks the stop. I guess I'll have to use the tapcons or something. Sean

Maybe so, but I have a hard believing that's the case. Were the guns sized for that long a nail? If not the piston could be bottoming out before the nail stops in the concrete. You sure you used a low enough power shot? In usage such as pinning 2 x 4s to concrete the wood isn't going to offer much resistance. The way I see it has to be the concrete that provides the stopping resistance. Did you push the nail through the foam and bottom it out on the concrete before firing? If not maybe that's where the difference with wood is, the nail just flies through the foam and abruptly stops when it hits the concrete. With wood there's some resistance to its travel as soon as it leaves the gun.

I suggest you try a nail without the washer but put it through a fender washer. Push it through the foam until it rests on the concrete, then fire the gun. I think that would work. With as many fasteners as you need to put in it's worth another try, IMO!!!