pipe runs through RSJ.....graft!

[brumylad]

cutting holes in an RSJ for pipe runs. Anyone cracked this nut ?

I've done it using the drill lots of overlaping holes method; using a jisaw with metal blade on horizontal cut; and 4" angle grinder with carbarundum metal cutting disc (4 cutts).

the latest job needed 4 holes cutting so after spending so long lying on my belly nursing various overheating power tools I'm motivated to ask for ideas from others right now! My own thoughts are these.

Has anyone tried drilling a 18mm or larger hole with a hand held HSS drill

Can it be done with a bimetal hole saw

I'm not keen on the idea of using an oxyacetyline torch in somebodies house, besides I've only ever used a pinpoint flame for lead welding

 

[Agile]

I am also concerned that the structural engineer who designed the support characteristics of the steel beam might not have allowed for your "modifications" !

Tony

 

[corgiman]

gotta agree with tony

no way would i do that unless the architect on the site gave written approval

 

[Nige F]

Starett Holesaw Quality

 

[corgiman]

nige ytou are a devil you are

the devil may care but nige certainly dont

 

[jobloggs]

In a simple beam uniformly loaded the biggest bending action occurs at the midspan. This gives rise to high stress levels at the top and bottom of the beam. compression at top and tension at the bottom.

When drilling horizontal holes in any beam (timber or RSJ) you should drill at mid depth as there is no bending stress there even at the midspan.

If you want to drill vertical holes through a flange on a RSJ you should only do this close to the supports and keep these as small as possible.

Similarly notches should only be cut in timber joists close to the support and kept as small as possible. Even so there is a risk of shear failure in timber joists (greatest at the supports) if the notch reduces the depth by too great an amount, the joists were light to start with and there is heavy loads placed close to the wall.

By the way the professional you really want to check calculations is a structural engineer not an architect.

 

[corgiman]

like the man in orthopeadic shoes I stand corrected

 

[brumylad]

thanx Nige F for the holesaw tip, I'll go and buy a starett the next time I see an RSJ. Maybe some cooling fluid and a wetn'dry vac too.

Thankyou jobloggs for your reasuring post, I can confirm the rectangular cut-outs were less than 0.25 the depth of the RSJ (infact only 0.125) and were introduced at the mid-depth.

These 8" deep RSJ's span the centre of a wide (18') ceiling in a domestic property, 2 separate RSJ's are used lying side by side with 8" x 1 1/2" wooden joists coming off perpendicular. The 8" RSJ looks over specified but I'm guessing. I've seen RSJ's cut through by installers like this before.

It's a good point about the structural engineer of course, if the joist had been part of a wall I would have hesitated before mauling it.