Where are my ceiling joists and noggins?

[myheadisonbackwards]

Hi everyone.

Last year, I made a ceiling, after loads of great advice from people on this group. Then I had it plastered, then painted it, now looks lovely.

Some months passed, and then I realised I should not leave the light fittings dangling forever, and I should screw them to the ceiling. But I cannot find the wood to screw them to!

The problem is that the plasterboard is below Kingspan insulation, and this insulation is below the woodwork. Kingspan is faced with metal foil. This metal foil interferes with my stud-detector. And I cannot find lines of screws with a metal detector, because it just detects the foil. Here is a word-picture of the layers:

Roof Void Woodwork Kingspan Plasterboard Plaster Paint

Of course, I know roughly where the joists and noggins are, because the lighting cables come down from where I attached them - but I do not know well enough to start drilling.

The only thing I can think of is to start drilling small holes until I find the right place, then patch up the test holes that missed the woodwork when I have finished. Not ideal.

Is there a better way?

Thanks, David P.

[myheadisonbackwards]

To answer my own question: I could perhaps glue the ceiling rose to the ceiling with No More Nails or caulking or something like that. The back of the ceiling rose is shiny plastic that looks like it would not take glue very well. And I have a funny feeling that this would not be electrically safe....

What do you think?

Thanks, David P.

[Stephen Dawson]

"myheadisonbackwards" wrote in message news: [e-mail]...

Don't do the glue thing, because when you want to change the light youwont beable to, and you will probably end up replastering the ceiling when the plaster gives way, because of the ornate lamp shade SWMBO has requested.

I have the Bosch Stud detector and it is excellent, but expensive failing that you a small screwdriver knocked in to find the joist.

-- Rgds

Steve

[Cicero]

=============================== Use a strong magnet in a circular motion around the light fitting to find the screws / nails holding the plasterboard. A bit tedious but should work.

Cic.

[Lurch]

On 17 Feb 2007 10:32:58 -0800, "myheadisonbackwards" mused:

Plasterboard fixings.

[<me9]

Unless you are going to swing on the light, any of the standard plasterboard fixings suitable for the load should suffice.

[myheadisonbackwards]

Thanks everyone, for your advice yesterday.

I think plasterboard fixings are the best way to do this. I had thought of this already, but had a weird mental block on it for some reason - like this was giving up, and I should stick with my original method. Daft of course, and plasterboard fixings it is.

As for the magnet idea - I cannot find one at the moment, but I tried moving a compass around close to the ceiling, and the needle did deflect as I did so. But not strongly enough to identify the position of anything.

Thanks again, David P.

[Duracell Bunny]

Did you try the low-tech method of sounding it out with a hammer or any solid object? The sound will change when you hit (gently of course) over a joist.

[myheadisonbackwards]

Yes, thanks Karen.

Unfortunately, the thick layer of insulation sort of acoustically disconnects the joints from the plasterboard.

Regards, David P.

[Weatherlawyer]

Poke up something exactly where you want the fittings to hang. Remove what light fittings you have placed on the wires.

Take some timber, some gripfill and a saw with you. Squares of 3/4 ply with an hole pre-drilled in each, will do. Climb into the void and drill holes in the ceiling where your markers popped through.

Pop a square of ply over each hole and feed the wire back down that. Make sure the glue has adhered to both surfaces, if not apply more to the surface that failed and replace ply.

When the glue has set, the patresses will now be ready to accept screws for the light fittings.

It would have been better to put the noggins in situ to take these fittings before you started closing the ceiling. Next time check further afield for the right advice.

Or remember to include the detail in the original post. But I suppose had you remembered to ask, you would not have needed the advice in the first place.

[myheadisonbackwards]

Absolutely right. Lack of experience led me to mess this up, and if I ever do it again I will not make this mistake (unless I forget).

Anyway, I have fixed it now. Plastic wall plugs with caulk down the holes are strong enough for these lightweight lights.

Thanks everyone, David P.