Just watched a vid of the process and they only used a single screw at
each end of the bar.
On one hand, it makes sense:
- With two holes exactly centered on the stud,
the hole that is under the bar is inaccessible,
leaving only the "Outside" hole.
- Offsetting the holes enough that both a top
and bottom hole are accessible seems like it is
flirting with screwing into one or both
edges of the underlying stud.
On the other hand.... just 2 screws ????
Yeah, each screw is 2" long... but still...
Can somebody make me feel better about this?
Thanks.... They're pretty official-looking screws supplied by the grab
bar manufacturer, so I would trust they are sufficient.
Now that I am visualizing it, weight on the bar results in a levering
force over a 1.5" lever that is stopped by the 3" diameter mounting
plate bearing on the wall and transferred into trying to pull the screw
directly out of the wood.
'Cuz they snap a head off at the sign of anything hard you try to drive
'em into...and why? Because it's easy/cheap to make 'em hard if they
also don't have to be ductile.
They're designed for a very specific purpose, lateral load not being
And, the bulk of the load in OP's application is, _but_ --- if load the
bar by any vertical pull that fraction of the total load is in shear and
when pulling anywhere on the bar besides directly over the fastener
there is a least some bending moment. Can't avoid either, entirely.
On Tuesday, March 15, 2016 at 7:50:40 PM UTC-4, dpb wrote:
If the tension force times the coefficient of friction is sufficient to be greater than the vertical force, theoretically there is no shear load.
The bending moment - I dunno, might have to give you that, but..........if the screw tension is enough to prevent movement I think it would be small.
Not sure I'd give a lot of credit to the vertical friction force on a
(presumed) rock wall...
"In theory there is no difference between theory and practice. In
practice there is." Jan L. A. van de Snepscheut
Years ago, before I first knew how brittle they are, I built a roof
frame for a shed on the ground. It was a small 10X12 ft frame made from
2x4s. I screwed it all together. When it was all put together, I began
to lift it onto the walls. By the time it was halfway up, I had a few
broken apart pieces. I added more screws. Then I hoisted it up onto the
top of the walls and the whole frikking thing fell apart. After I
finished cussing, I had to take all the pieces and rebuild it all over.
This time I used 16d or 20d common nails. That time everything worked
I also bought a homemade wooden lawn chair at a garage sale. It looked
nice, was made from all oak. A few weeks after I got it, I sat in it,
and it partly collapsed. Sure enough, they used those goddamn drywall
screws. Fortunately no wood broke, so I just replaced every drywall
screw on the entire chair, with real wood screws. I still have the chair
after 10 or 12 years and it's never broken again.
Drywall screws are made for drywall, and nothing more. Yea, you might be
able to mount a piece of 1x4 trim around a window frame with them, but
dont use them for anything that will put any load on them.
I know they are brittle having broken a bunch by over tightening. Easy
to snap. I'd never use them for anything other that sheetrock or
similar non-critical application.
FWIW, Each of my showers has a horizontal bar in back, vertical bar in
the front side and they feel very secure with the single screw mount.
Check the specs. many have 500 pound rating, some are 250.
Back when people took pride in their work, and before everything was
made to get the most profit with the least amount and quality of
materials, and the least labor, they used to knotch the 2x4 studs and
put a horizontal 1" (3/4") thick board wherever there was to be anything
mounted, such as wall mounted sinks, towel and toilet paper bars, and so
on. That began in the 1940s maybe before that, and ended in the late
1960s or early 70s.
These days, unless you build your own home, you wont find any of that.
Homes are built as cheaply as possible and have a life expectency of 30
years (IF they are constantly repaired).
I expect that in 20 years all homes will be entirely made from molded
particle board. Just pour the liquid mixture of sawdust, shreaded
cardboard, and glue into forms, let it harden, and you have a home. But
if it ever leaks, kiss it goodbye in weeks....
On Thursday, March 17, 2016 at 7:14:00 AM UTC-4, email@example.com wrote:
Yes. Because the studs are notched, there is no shear stress on the connection of the board to the wall. There is only tension on those fasteners.
Of course there can still be shear stress on the connection of the sink to the board.
The one I put in for my mother had 2 at each end.
To be extra cautious, I didn't drill the holes big enough and I had a
heck of a problem getting the screws out after she died.
And it was a rented apartment, but they were very nice and didn't
complain about anything. I didnt' drill into the tile either, only
sheetrock. But I put switches on the bathroom fans, pull chains, so
she wouldn't have to listen to that infernal noise all the time. I
just left those.
And I kept renewing a month at a time while I tried to pack up all her
stuff and sell what my brother and I coudln't use, and one time I
forgot to renew and when I went to do so a day or two in advance,
they'd rented the apartment to someone! I didn't know what to say,
but they said, Don't worry. We'll tell them they have to take another
one. And they did.
On Tuesday, March 15, 2016 at 1:51:57 PM UTC-4, (PeteCresswell) wrote:
I use a minimum of two screws on each end of grab rail. I don't want a sin
gle point of failure. You can usually position them so you can get two to
bite on the same 2x4 if you figure out exactly where it is behind the wall
and angle the fasteners a little.
That's how the manufacturer made and rated it. The ones I have in my house
are three screws each end. I had to block out the finished wall to my
Look at stair handrails. Some of the ones I've seen look pretty sketchy but
I am no lightweight. I see your later posting that you are happy-good.
DAGS on Sheetrock screws and there has been much discussion here on their
durability (none). Work for their intended purpose. I would like to find a Z
bolt to fix my miscalculations.
On Tuesday, March 15, 2016 at 10:51:57 AM UTC-7, (PeteCresswell) wrote:
Rather OT but when my wife became disabled I installed hand grabs and long
bars everyplace I could. One was a vertical grab about waist high and at a
comfortable arems reach on the wall by the toilet. First time I used it I
wished I had done it 30 years earlier. I highly recommend one, makes gett
ing up, wiping, etc. a whole different job.
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