Drilling timber engineering joists

[Riley26]

Can timber engineering joists be drill if the pre knock out holes dont line up? Any one got any info on this?

 

[Belboz]

Maybe in BUILDING or ROOFING? This is PLUMBING and CENTRAL HEATING

 

[Riley26]

Yeah I wondered if plumbers had come across this when first fixing?

 

[nortonj]

Yes you can drill through them.

 

[Riley26]

Suppose there'll be areas you can and can't ?

 

[nortonj]

Just drill through centre of joist. What size holes we talking?
Whatever you do dont do this

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• nortonj
• 8 Jun 2015
• 1

something i came across a few weeks ago

 

[Riley26]

doesn't have to be 0.25-0.4 of the span?

 

[Nozzle]

The joists shown in the picture (rotate it!!!!!!) should not be cut AT ALL along the top or bottom sections. The OSB in the centre is just there to keep the top and bottom rungs away from each other and to stop them twisting. If you look up a manufacturers website for these things, they have application notes.

Nozzle

 

[Jackrae]

The joists shown in the picture (rotate it!!!!!!) should not be cut AT ALL along the top or bottom sections. The OSB in the centre is just there to keep the top and bottom rungs away from each other and to stop them twisting. If you look up a manufacturers website for these things, they have application notes.

Nozzle

Not quite right there.
A wooden manufactured joist is the equivalent to a rolled steel joist where the vertical plate depth is the predominant strength member.
Therefore the OSB plate is the strength member, by virtue of its second moment of inertia.
The top and bottom pieces (flanges) are to actually prevent the OSB from twisting, provide some extra strength and provide something for the ceiling and floor sheets to screw onto.
Only holes in centre of plate cause minimal weakness, anything else has a major structural effect unless extra material is added to compensate

 

[bernardgreen]

The majority of the strengh is due to the top "flange" being under compression and the bottom "flange" being under tension as the beam tries to bend under load. The vertical web has to keep them apart and thus can be peforated and still be as efective as if it were not perforated.

In some designs the perforated beam can carry more load as has les of its own weight to support.

In timber the compression and tension zones spread from top to bottom of the bean with a neutral, ( neither compression nor tension ) about the mid point between top and bottom.

 

[muggles]

Consult with the manufacturers of the particular TEJs you're using - they will have the answer

 

[nortonj]

The joists shown in the picture (rotate it!!!!!!) should not be cut AT ALL along the top or bottom sections. The OSB in the centre is just there to keep the top and bottom rungs away from each other and to stop them twisting. If you look up a manufacturers website for these things, they have application notes.

Nozzle

yes i know that i was showing an example of of something not to do.
i repaired this joist by glueing and screwing some ply either side.

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• nortonj
• 8 Jun 2015
• 1

Op if your drilling anything over 50mm i would consult manufacturer