How to drill through Styropor(stryfoam)insulation

Daily Life, Swiss News and General Topics
1
We have styrofoam insulation on the inside of a concrete wall that I want to drill into so I can hang something (a curtain rail). One side is concrete, this I can work with, but the styrofoam? This is new. Is this difficult? What materials should I use? (drill bit, etc), I have a decent Bosch drill.

I know it can be done as we had custom window screens made to fit our windows and they were installed on the outside of the house where we have similar insulation. The installer used a spiral shaped plastic plug.

Any tips/advice gratefully appreciated.

2
If the outer layer is concrete, I guess that it should be thick enough that you don't need to drill through into the insulation. In this situation most standard wall plugs should be suitable.

If the outer layer is a softer material such as plasterboard, you will need more specialist fixings such as in the pictures here. You should only need to drill through the outer board. The fixing should push into the foam quite easily. The third fixing would only be used if there is a hollow cavity behind the outer board.

Hope this helps.

3
You're McGyver in the real world aren't you Rod?

4
I had a similar problem on outside of my house - very thin shell, then around 6 inches of foam, then the brick/block. Here's what I did, from the best of my memory:

I had to look at house plan to ascertain thinkness of foam, then bought a special bolt. Essentially, a large rawl plug (similar to deep purple's left image) is fitted into the solid wall. But it is a special rawl plug with a bolt fitted. The wall must be drilled with a very long bit - so that the hole enters the solid wall, then the bolt inserted and the rawl plug on the end tapped into the brick hole (you just tap the bolt, with rawl plug attached to end). The bolt has a female end which, if you've done it right, protrudes just at the surface of your wall. An additional bolt or screw can then be attached. Sounds complicated, but it isn't. I had to ask around at a couple of decent hardware stores to find the bolts. Can't remember where you live, but if its close to me I'll loan you the long drill bit. Hope this helps!

Having just re-read your message (OP) I realize you are talking about the inside wall. The styrofoam should be easy to get through - using a regular masonry bit. What you use for the fitting would depend on how thick the styrofoam is - and on how much weight you wish to hang. If you are going to use a regular rawl plug (the obvious choice) and the load (to hang/attach) is quite big, then it would need to be long enough to enter the concrete - to give sufficient support. However, if the load is reasonably light you may be okay to use a smaller rawlplug (like DPs image - left) as long as it fits very tightly into the hole. For example, I have a guitar hanging from a screw attached by a rawl plug in plaster board.

5
Thanks for the replies.

Just to clarify, the styrofoam is on the inside of the wall. I have to look up the thickness as it was on the renovation specs. The garage is on the other side and we insulated this outside wall but from the inside.

What I want to hang is not heavy.

6
There must be some sort of skin on the inside of your wall, over the styrofoam .. either plasterboard, and/or render, if not concrete or brick. Do you know what the innermost surface is -- i.e. when you tap the wall inside the house, what are you touching?

7
The styrofoam insulation was installed directly over the brick wall on the inside. Then the plasterer finished off all the walls.

I saw them working. I didn't take any before photos but the room was unfinished, just concrete. It's a big room, over 30 m2, and we insulated the outside walls to preven heat loss since the room already had underfloor heating. We only insulated the outside walls before finishing the entire room, with a proper ceiling and flooring.

8
The fixings of your curtain rail(s) needs to be carried in the concrete, NOT in the foam. You may think they are light but foam doesnt carry much. Also it's not just going to sit there like a picture. They are going to be pulled open and closed, maybe pulled down if you have kids etc. every time you use them.

Believe me. We have a few fixings around the house where they were installed in the foam (externally) with these spiral plugs. They work loose and fall out with time, even if they look fine when first installed.

So you are going to need to drill through the foam into the concrete, insert long plugs /screws etc. You may also find that the size of screws needed to reach into the concrete will mean that they are too big to go through the holes in the fitting. So you might need say to mount a strip of wood or backing piece in which you screw the fitting.

Why not get someone who knows how to do it for you? OK you had bad experience with an EF'er but you know lots of people from your business don't you? Or try another EF'er that comes recommended. You could even watch and do it yourself the next time.

9
No small kids, and it is not curtains, just fabric wall panels on a track. Only one panel may be moved occassionally (to access a little used door). Yes, it is beginning to sound like I need a professional. I know lots of tradespeople, the trouble is the cost to have someone come for one small thing. I guess I have to find a few more projects.

I know there are reliable EF members, just no one local.

10
Oh. You said it was a curtain rail in your OP.

If you think it's really light just get some of those spiral plugs and try. Stick a spike/skewer through the insulation to measure how deep it is so you can get a plug taht isn't too long.

Worst thing is it falls off /works loose and you need to get a profi in. No real harm done - they can fill the holes...

11
To drill this is easy. Any normal drill bit will do, I'd actually use a wood/steel drill bit to cut the plater surface layer and styropore.

The bigger issue is fixing the curtain rail. Your best bet is to drill through the styropore to the concrete, then drill into the concrete to provide screw fixings for the rail. The issue here can be that the sytropore will compress when you tighten the screws.

As described above, there are fixing bolts that can provide a solid mounting on the concrete to the face of the styro pore, or there are large plastic fixings, simular to the metal one above on the left but much larger in diamter (ca. 2 or even a 5chf coin). These have a hole in the middle to take a standard screw.

Another option would be to just use long screws into the wall with rawplugs, combined with a metal tube cut the the thickness of the styropore. The diameter of the metal tube needs to be big enough for the screw to fit into it.

A final option would be to fit a wooden batten across the area to spread the load of the curtain rail.

12
We had to hang curtain rails in Italy and had a similar problem (not foam but a plaster cornice) where we couldn't use the wall. The solution was to hang the rail from the ceiling. This is simpler but your curtains need to run up closer to the ceiling to hide the fittings. Would this be an option in this situation?

F

13
I thought of that but the ceiling is acoustic tiles so no, that won't work.

14
The first thing to determine is the thickness of the plaster coat and the styrofoam. If the plaster coat is quite thin, there is a danger of cracking it. This is even more likely if the styrofoam is very thick or soft and compresses.

Fitting a wooden batten first may be the best idea. You may need spacers betwen this and the concrete wall to stop it compressing the plaster and styrofoam.

See rough sketch. Hope I have understood the layout