I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?
What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.
Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?
Thanks,
Simon.

sm_jamieson wrote:
I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?

You will not weaken the joist - in fact, if you really stop and think -
you are in fact reinforcing it!

What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.
Or drilling a countersink for the screw ?

When you thing plumbers, electricians, carpenters and all and sundry, drill
through joists for there relevant bits of pipe, cables etc to go through
(and usually in the centre or top third) then how are small pilots going to
affect the strength of the thing?

I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.

He's go more intelligence and experience to say that.

Should I devise another fixing method ?

Yes, *skyhooks*

Ah well.

"sm_jamieson" wrote

I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?
What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.
Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?
Thanks,
Simon.

If you are simply fitting noggins, then the usual way is to screw or nail at
an angle through the side/end of the noggin then into the joist. Not screw
through the full thickness of the joist into the noggin end. At time of
house build, nailing noggins in place is OK. If you have ceiling/wall
attached, then hammering will cause nail heads to pop out and all-sorts. So
best pre-drill noggins and pilot into joists for screws.

HTH

Phil

sm_jamieson wrote:
I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?

If you screw near the centre line of the joist then it is fine. The
worst place to do it is near the underside when the wood is in tension.

What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.

Don't do that!

Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?

Skew fix the noggings into place - screwing/nailing diagonally through
the end of the nogging into the side of the joist.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 28 May, 11:45, sm_jamieson wrote:
I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?
What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.
Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?
Thanks,
Simon.

Dear Simon
It all depends where you put the screw!
If it is in the top half of a beam then you are not weakening it
If it is in the bottom half then there is a weakening effect but only
so much as the shear stress parting the longitudinal fibres in the
bottom tension zone which is likely to be very little. The nearer the
bottom you get the worse the effect. You can ignore the top 75 % of a
beam for all practical purposes as being at risk should you put screws
in.
What do you mean by roof supporting joists?? I assume ceiling joists
and if so and you are concerned use full length noggins and fix in the
middle (neutral axis) or if you want to be anal use joist hangers (a
silly over reaction to a non-problem but theoretically an answer)

Chris

On 28 May, 15:19, John Rumm wrote:
sm_jamieson wrote:
I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?

If you screw near the centre line of the joist then it is fine. The
worst place to do it is near the underside when the wood is in tension.

What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.

Don't do that!

Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?

Skew fix the noggings into place - screwing/nailing diagonally through
the end of the nogging into the side of the joist.

--

So is there any recommendation for how far into the joist to screw ?
I have to fix the noggins near the bottom, but I don't want to fix
them below since this would reduce head height.
I guess it may be the best idea to use a fixing that hangs the
noggins, so the screws are in the centre line of the joist, e.g. joist
hangers or a timber block.
Cheers,
Simon.

coughed up some electrons that declared:


So is there any recommendation for how far into the joist to screw ?
I have to fix the noggins near the bottom, but I don't want to fix
them below since this would reduce head height.
I guess it may be the best idea to use a fixing that hangs the
noggins, so the screws are in the centre line of the joist, e.g. joist
hangers or a timber block.
Cheers,
Simon.

I can highly recommend 5x80 or 5x100 ScrewTites. Upon a previous
recommendation here, I used a load of 5x80's to do some studwork, very
successfully (beat nails hands down, times lots).

Needed to fix some 44x94 (2x4") to some ceiling rafters and I found that the
ScrewTites worked just as well there. No pilot hole, easy drive, good pull
together and good grip, and head self countersinks. This may not work if
your joists are oak!

Anyway, as my upstairs floor is a bit of a disaster area, I'll be adding
some noggins for cross-bracing to stiffen up the dodgey areas. I plan to
stick some 2x4" in as noggins, level with the top of the joist in my case
(bottom area fouled with random wood). For the fixing I would just screw a
couple of ScrewTites in horizontally into the end of the noggin from the
opposite side of the joist. They hold fine in the end grain and without a
pilot hole, they form a pretty effective peg.

Unless anyone tells me that's wrong... But having used them, it seems like a
reasonable idea. I'm relying on these to add structural stiffness. For your
application, they will definately be a suitable fixing method without any
doubt. No vibration either

These are the item:

http://www.screwfix.com/prods/93282/...mm-Pack-of-100

You'll need a power screwdriver, but a small one like the little Bosch will
suffice - they are lubricated and drive very easily.

HTH

Tim

sm_jamieson wrote:
I know it sounds silly, but how much does it weaken a joist to screw
sideways right through it ?

Almost not at all.


? If I fitted noggins (extra support for
plasterboard) between joists but flush with the bottom of the joists,
by screwing right through the 3 inch joists and into the noggin ends,
how much would it weaken the joist ?

Use nails. Quicker and actually better if the structure can take the
impact loads.

What about drilling small holes near the bottom of a joist - say for a
screw pilot hole.
Or drilling a countersink for the screw ?
I want to make sure the BCO doesn't turn up and say I've wrecked my
roof supporting joists.
Should I devise another fixing method ?

Nail em on, and herringbone bracing too. Makes a huge difference to 'bounce'

Thanks,
Simon.

The Natural Philosopher coughed up some electrons that declared:


Use nails. Quicker and actually better if the structure can take the
impact loads.

I would debate "quicker". A ScrewTite pops in in a few seconds in one easy
motion. Certainly no slower than nailing.

I reckon it's equally as sound as a nail for lateral support (it's the same
size with no hole slop so it should be, and way better able to resist
pulling forces.

Bloody things have me sounding like Dribble now.

Tim S wrote:
The Natural Philosopher coughed up some electrons that declared:


Use nails. Quicker and actually better if the structure can take the
impact loads.

I would debate "quicker". A ScrewTite pops in in a few seconds in one easy
motion. Certainly no slower than nailing.

I will give you a race - as long as I can use my framing nailer ;-)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm coughed up some electrons that declared:

Tim S wrote:
The Natural Philosopher coughed up some electrons that declared:


Use nails. Quicker and actually better if the structure can take the
impact loads.

I would debate "quicker". A ScrewTite pops in in a few seconds in one
easy motion. Certainly no slower than nailing.

I will give you a race - as long as I can use my framing nailer ;-)


I suppose that's quid pro quo - bah! ;-