22mm Copper Pipe through joists

[Jupiter01]

Hi All,

The old chestnut I suspect...
I want to run F&R through my floor joists and have read up on the permissible hole sizes and where they should be located. I also have a joining room which has the joists running in the opposite direction to the room in question. This means that fortunately I can raise my pipes up in this room and then feed through the joists in the room in question. Hope that makes sense...

I was planning to drill a hole in the first joist, feed the pipe through, mark out where it hits the second joist, drill a hole there and so on... Does this seem sensible and/or is there a more appropriate way of doing this?

Finally, which bit/tool should I use for the whole and what size should I go for given the expansion of pipes.

Thanks in advance.

 

[Agile]

Why can you not notch it like everybody else?

 

[Jupiter01]

Hi Agile,

Thanks for replying.
I though notching wasn't the done thing any more and the recommendations suggest drilling a hole within the permitted zone of the joist? Also, the holes would be easier for me since I am taking the ceilings down.

 

[xr4x4]

Yeah sounds fine, just use a sharp bit.

You will have to make sure the holes are lined up and straight, 22 copper is very unforgiving.

Never use copper for hidden anymore, sad but true. Easier quicker.

 

[Jupiter01]

Thanks Paul. How big should the hole be and do I use a hole saw, spade bit or something else?

 

[xr4x4]

Spade bit or I use auger bits.

Can't remember the size, 25mm rings a bell, you will need to measure the od of the pipe.

 

[Agile]

The OD of 22 mm tube is, wait, 22 mm !

Most wood bits will drill slightly oversized but 24 mm would give a little extra for misalignment.

But I would still want to notch!

Or at least use plastic tube! I hate it but for putting through holes cannot be beaten.

 

[Jupiter01]

I have been pondering the copper v plastic decision for some time and would like to use copper if I can. I am using 10mm plastic for the drops to the rads though!
Is 24mm in your opinion sufficient to accommodate the expansion in pipe? I was thinking of 26-30mm...

 

[Agile]

I think you have an over optimistic expectation of pipe expansion.

Suppose it expanded lengthwise ???

 

[Jupiter01]

I'm happy to go with 24mm if that's sufficient. Was just checking that you've taken the expansion into account. Thanks for your help.

 

[polesapart]

I'd go for 28mm or so, auger, Forstner or sharp spade bit.

Experience has taught me to leave a bit of room for imprecision!

A little felt can be wrapped/tucked around the pipe where it passes through joists to avoid any creaks from longitudinal expansion.