Best hollow-wall fixings through tiles?

The grab rails have to withstand the full weight of a person, so I wouldn't fancy using spring toggles, which might break the plasterboard. You say the rails are a fixed length - are the ends bent round to the wall, with round flanges to take at least three screws?

Do the rails have to be horizontal, or can they be angled so that the fixings coincide with the wooden studs?

Or you could put thick pieces of plank behind the plasterboard to take normal screws and spread the load over a large area.

Under most circumstances the majority of the force would be directed downwards rather than at ninety degrees away fro the walls, but I take your point. Wouldn't the tiling offer extra resistance though?

Exactly so.

Horizontal is preferred.

That would involve some fairly drastic destruction on the non-shower sides of the walls, which would be pretty tricky in one case but could I agree be worth it for the extra strength.

Thanks.

But not all

circumstances the majority of the force would be directed

What if someone slips and grabs the rail on the way down?

Not a sound engineering principle!

You really can't fasten anything like that to plasterboard. I mean, chances are it would be OK, but it's a bit of a risk, and it isn't a risk you can legitimately take.

Bill

My experience of this is that the tiles alone are sufficiently good at spreading the load that there is no point in using anything other than a plastic rawlplug - but do use a proper diamond tipped core drill to make perfect holes on the tiles.

The surface are of the tile is far greater than any wall fixing could be and since it is a shower you will have proper waterproof tile adhesive so the chance of the tile pulling off the wall is extremely remote.

The only better solution would be to fit a noggin from the rear and attach to that - but really, it isn't necessary. All my bathrooms/toilets are done using core drill and rawlpug and in 20 years none have come loose..

Do they?

Mostly as I get older I find that I am not aping Tarzan and swinging off handles, but using them as a steady - they take a little lateral load only.

so I

In the end there are two issues of strength to understand. The first is the issue of the joint between handle and plasterboard, and the second is between plasterboard and stud.

As far as the first goes I can assure you that rawlplugs through

in 30 years of hollow wall DIY I have never found *any* 'hollow wall fixing' to be effective. Plasterboard itself is too weak to take point loads. but a tile spreads the load better than anything except a wooden plate .

With respect to the plasterboard itself - well unless you by pass it altogether and connect to a noggin attached to a stud, what fixing you use is irrelevant. The plasterboard is only as strong as it is.

IN the case of a grab handle that will only be experiencing very strong vertical loads, tiles are your friend. Think of them like a thin brick wall whose buckling is improved by attaching them to a nice stiffening wall.

Imagine standing on a tile propped up vertically. It will take your weight far better than a piece of plasterboard placed on edge.

So when you think of tiles *structurally*, stop thinking of them as a decorative layer and think of them as actually far stronger than the plasterboard wall - whose purpose is to stop them buckling under load.

Not really. Your least bad option is probably to put the rail holes towards the top of a tile so that if it were ever to be subject to full falling body dynamic stress the tile will act as a load spreader.

I wouldn't like to bet on it holding up under those circumstances. It would probably be OK for holding onto under normal conditions, but when you really needed it to save yourself from a fall it might fail.

Trouble is that three screw hole into the plasterboard weakens the bit in the middle - especially in a shower situation.

Had one heater in our VH lever itself off a lath and plaster wall during the winter as the cold and damp made the plaster slightly softer than in mid summer when they had been installed. It is now fixed with butterfly wing load spreaders which require a huge hole to go through the wall.

It was the top fixings that were pulled out by the cantilever load of the wall hung heater.

It might be the only realistic option to make it safe. If you are falling and grab a rail the forces are partly downwards and also away from the wall but with a huge dynamic torque as well trying to lever the thing off the wall. I'm not sure how well pasterboard will stand up to that particularly if as seems likely it may become damp as well.

If you *really* can't modify the grab rails to suit the (probably 400mm) stud spacing then I would go to plan B and find or make some grab rails the right length.

Many thanks for all the replies and the (very varied, as usual) advice.

I think as a preliminary move I'll drill a series of holes in the other (non-tiled) side of the two walls and try to determine the exact position of the vertical battens.

Do those electronic stud-locators have any value? I borrowed one many moons ago but the results were far from definite.

i use a series of very powerful neodymium magnets to locate the plasterboard screws/nails...... May not work well though with tiles increasing the gap between nail/screw heads and the neodymium magnet.

Or fit them vertically. Better than nothing and both ends would be secured to a stud.

Also handy for holding a collection of long drill bits and metal tools in my understairs workroom. Sticks to a ladderax upright and holds lots of things.

SH & Andrew, thanks for the idea of using a magnet (or more than one) to detect plasterboard nails or screws.

Apart from a defunct microwave oven, what would be a source for a suitably powerful magnet?

A defunct or unusably small hard-disk.

However, neodinium magnets are pretty cheap online - try Amazon, Ebay or the like.

Well, I have a few of those. More than a few, in fact. I'll get dismantling.

Thanks.

Watch your fingers, ye don't want ya flesh pinched.

and keep them away from ya nose, just in case ye feel the urge ...

I've removed one magnet from a dead drive but am having trouble parting it from its metal cradle. I might simply use a steel probe attached to the magnet but extending beyond the cradle - or will the complete strength of the magnet be reduced slightly through a separate piece of metal?

Thanks for the link. Dire warning noted.

Incidentally, this is the first time I've opened a hard drive; it's a tad terrifying to see just how small and frail the pick-up arms and heads (not the correct term, I imagine) are, given how much one relies on them.

I agree with all that, but I think there are too many uncertainties to be sure of the best option. Are they thin, 4 inch tiles or thick, 12 inch ones? The latter, provided they are well secured to the plasterboard, will be more secure. 12mm plasterboard will be better than

I'm with Dave; especially if it is a heavy person with a risk of falling heavily I'd be looking to provide more support from the back. For example a (roughly) square piece of 18mm ply between the studs and against the plasterboard.