Easy way to find joists above a lath and plaster ceiling?

[dom]

I'm putting up timber stud partitions, and need to screw several top plates into the loft joists in a lath and plaster ceiling (working around various exposed features).

For a bunch of reasons, access from above is not so easy (not impossible, just awkward).

My stud detector just bleeps everywhere (because of the laths and nails).

The only thing I can think off is to drill a few test holes with a fine drill (e.g 3mm) until I hit a loft joist. I reckon I could end up doing a few of those for each fixing point, as the loft joists are not very accurately spaced (Victorian building).

Anyone have any tips to make the job easier?

Where I have to fix top plates parallel to the loft joists (and no doubt not directly underneath one) - I'm thinking to fix noggins above (fortunately these will be in a more accessible area), and then use

120-130mm screws to be sure to bite into the loft joists.

Any other recommended solutions?

[Cash]

Tap the ceiling with a hammer until you hear a 'solid' sound - and that's where the joist will be!

Screws are really not essential here - simply cut the noggins between the ceiling joists (a snug fit) and then use 4" nails to fix them through the rafter or 3" nails if you are going to do 'skew' nail fixings.

Cash

[meow2222]

If tapping doesnt do it, tiny holes + coathanger to roughly locate them. With 2 points you can pencil lines on. Once you've got a few you can interpolate others.

its a brave man that will slam a large number of 4" nails into L&P :)

NT

[Anna Kettle]

Yes thats the way to do it. Just be glad that you have some access above so you can get an idea of the spacing and direction of the joists. I once worked on an old building with no access above and where the joist direction changed midway across the room. It took me ages to realise what was going on

Its worth putting a skirt around the drill bit so the chuck doesnt get bunged up with mortar

When you have finished fill the holes with polyfilla

Anna

-- Anna Kettle Lime plaster repair and conservation Freehand modelling in lime: overmantels, pargeting etc Tel:    (+44)  01359 230642 Mob:   (+44)  07976 649862 Please look at my website for examples of my work at:

 

[dom]

I was hoping you were going to answer Anna, thank you. I tried the tapping others have suggested - slightly better than the stud detector, but still very hit and miss - the fine drillings worked best.

No need to fill the holes, as they're directly above the timber plate (I already have a laser line to follow, it's just finding the intersections with loft joists that's the trouble!)

Thanks to all for your suggestions.

[BigWallop]

Do you know which way the joist are running? Those old ceilings have latte (lathe) batons across the joists, running at 90 degrees from the joists. When you try to find the joists with a detector, all you get is the points where the lattes are nailed to the cross batons, which is almost everywhere on the ceiling.

Where you are erecting your stud wall, punch a hole through enough to stick a hand in and feel exactly where you are with the joists. Use your tape measure to get an idea of where the rest of the joists are.

The hole you make is easily covered by the top plate of the stud you're building.

[Tonia]

replying to BigWallop, Tonia wrote: I?m just wondering, is your basement ceiling exposed at all?

If so, does the studs run the same way downstairs as up?

[Tonia]

replying to BigWallop, Tonia wrote: I?m just wondering, is your basement ceiling exposed at all?

If so, does the studs run the same way downstairs as up?

[tabbypurr]

I'm wondering why you hoh people keep replying to posts a decade old. Bigwa llop hasn't been seen here in a long time. Come here via a sane usenet port al & you won't have that problem.

NT

[Brian Gaff]

Oh yes they will seeing as I can see the posting date on that post on that portal, so why cannot they? I suspect this is due to that server ignoring years even though it adds them, it seems to treat all years the same way regurgitating posts over and over. Brian

[Rob Morley]

That's the difference between visually available information and perceived/processed information - if the stupid web page presents a post there's a tendency to think it's recent/relevant and not look for the date. In our nice Usenet clients we can sort messages by date and not have ancient posts put next to recent ones. The website also doesn't offer any sort of "hide read messages" option.

[Tim Watts]

As the orig "posted on November 8, 2008, 4:47 pm"

*sigh*

[Nathan]

Use a strong magnet to location the screws.

[Roger Mills]

Use a thermal imaging camera?

[Brian Gaff]

Does not work on Brass screws though. Brian

[Davidm]

a small repair job. Nailing is much faster.

[alan_m]

And the magnet method can fail if the old type plaster over the laths is and inch or more thick.

[John Rumm]

How many plasterboard ceilings have you fitted with brass screws?

[Roger Mills]

Who mentioned plasterboard - this is about lathe and plaster ceilings?!

Even less likely for the laths to be screwed rather than nailed.

[John Rumm]

True, my bad.

The point still stands though - how many laths have you seen fixed with brass screws?