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[mainline]

Sorry don’t understand your question. I was just suggesting cutting an access hole into the plasterboard.

It was related to cutting a hole across a joist, a hole saw is difficult to start the cut without some sort of pilot.

 

[123]

Tumble drier, washing machine, dish washer that’ll be ok I’m sure……
Larger cable is feeding a double socket with wm td on and the smaller flex is for the dishwasher…..

As with shower pullcords, it's always the neutral that fails

 

[brianmoooore]

Cut a hole in a piece of plywood, throw away the circular piece you cut out, then hold the plywood against the ceiling, and use the hole as a guide for the hole saw.

It was related to cutting a hole across a joist, a hole saw is difficult to start the cut without some sort of pilot.

Second quote should be first!

 

[mainline]

This is what I usually do too, where lifting boards in the room above isn't possible/feasible. I find the joists with a magnet, measure 120mm to the side and cut the hole centred there. I cut them all so I can see any cables/pipes, then drill the joists using a dewalt 90deg attachment for the drill.

I'm going to buy a 5 or 6" holesaw for it, as while 4" works, it is just a little on the tight side as you need to get your hand in to apply pressure as you drill the joist.

If you replace the correct p-board circle to it's respective hole, in the correct orientation (mark before cutting), they go back in perfectly. Easifill and then sand, no need for reskimming!

In my experience they never fit perfectly you have to peel at least one layer of the backing off the plaster board otherwise it's proud, ideally you want the infill paper thin below the surface makes it a doddle to skim over.

Orientation of the infill shouldn't matter as they should all be the same, not that it would matter with such small gap tolerances that's going to be filled anyway.

I'm of course assuming that you baton across the hole and screw the infill into that ? If so, then either side of the baton has to be screwed through the ceiling into the baton either side of the hole.

Notching the joist from below is far easier and much quicker, with far less damage to the ceiling.

If using 1mm then the notch is hardly anything.

Drilling the joist is the better job, but far more work.

 

[brianmoooore]

Notch the underside of the joists? Sounds a bit " mind your spurs don't damage the furniture" to me. The only place cables should be passing through joists is through a drilled hole on the neutral axis.

 

[mainline]

Notch the underside of the joists? Sounds a bit " mind your spurs don't damage the furniture" to me. The only place cables should be passing through joists is through a drilled hole on the neutral axis.

It's far less likely to get hit with a nail than a cable that's notched above the joist.

 

[Pretty Mouth]

In my experience they never fit perfectly you have to peel at least one layer of the backing off the plaster board otherwise it's proud, ideally you want the infill paper thin below the surface makes it a doddle to skim over.

Orientation of the infill shouldn't matter as they should all be the same, not that it would matter with such small gap tolerances that's going to be filled anyway.

I'm of course assuming that you baton across the hole and screw the infill into that ? If so, then either side of the baton has to be screwed through the ceiling into the baton either side of the hole.

Notching the joist from below is far easier and much quicker, with far less damage to the ceiling.

If using 1mm then the notch is hardly anything.

Drilling the joist is the better job, but far more work.

I have found that by returning the correct disc to the correct hole, and keeping the original orientation, the discs go back perfectly pretty much every time. You wouldn't expect it to make a difference, but it seems to. Give it a go!

Yes, I batten across the hole. , 18mm ply is best IMO, with woodscrews rather than plasterboard screws.

Notching the underside of joists? I dunno @mainline , it's a little bit non compliant dont you think? What do you think Delroy would say if he found out you get up to this sort of thing?

 

[Baddegg]

As a wood butcher I can assure you you don’t want to notch the underside of joists

 

[mainline]

I have found that by returning the correct disc to the correct hole, and keeping the original orientation, the discs go back perfectly pretty much every time. You wouldn't expect it to make a difference, but it seems to. Give it a go!

Yes, I batten across the hole. , 18mm ply is best IMO, with woodscrews rather than plasterboard screws.

Notching the underside of joists? I dunno @mainline , it's a little bit non compliant dont you think? What do you think Delroy would say if he found out you get up to this sort of thing?

In certain situations needs must, I work in very old properties lots are open beam so no void at all and a nightmare to hide cables.

Others are mostly lath plaster, which sometimes doesn't take kindly to vibration.

 

[mainline]

As a wood butcher I can assure you you don’t want to notch the underside of joists

Why ?

 

[littlespark]

Why ?

I’m sure it’s something to do with removing material from a length of wood, from the bottom, decreasing the cross sectional area and introducing a weak spot.

Same idea as drilling too many holes too close together through a joist.

 

[brianmoooore]

Building regs prescribe both the location limits and size limits for both holes and notches.

 

[mainline]

I’m sure it’s something to do with removing material from a length of wood, from the bottom, decreasing the cross sectional area and introducing a weak spot.

Same idea as drilling too many holes too close together through a joist.

Building regs prescribe both the location limits and size limits for both holes and notches.

You're allowed to notch the top or the bottom.

 

[brianmoooore]

You're allowed to notch the top or the bottom.

But only in certain places along the joist's length. Different places for holes.

 

[nicebutdim]

You're allowed to notch the top or the bottom.

Where did you learn that?

 

[brianmoooore]

Where did you learn that?

Building regs.

 

[nicebutdim]

Building regs.

Notching the underside of joists?

Thinking more about this, is it permitted within certain locations provided no notches have been cut in the top?

 

[mainline]

I’m sure it’s something to do with removing material from a length of wood, from the bottom, decreasing the cross sectional area and introducing a weak spot.

Same idea as drilling too many holes too close together through a joist.

Obviously, removing wood from a joist is going to weaken it.

 

[mainline]

Where did you learn that?

As Brian said

 

[mainline]

Notching the underside of joists?

Thinking more about this, is it permitted within certain locations provided no notches have been cut in the top?

How to get it right: Notches & holes in solid timber joists | LABC

When installing pipework or cabling, floor or ceiling joists may need to be notched or drilled. But this could weaken the floor to such an extent that it becomes structurally unsound. To find out if this might be the case, you can find guidance on notches and holes in solid timber joists for use...

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