Central Heating Pipes - Joists

[thebadger7]

Hi all

I need to get hot/cold 15mm CH pipes from one side of a room to the other, and the moist direct through is through the joists. How bad is this? Would have to go through every joist.

1st floor room. Alternative is to run them around perimeter on skirting boards.

Thanks

 

[Stevers]

Ours go round the edge of the room in notches cut in the top of the joists. A bit old felt lagging in each notch is supposed to reduce noise. Keeping the notches tight and near the ends of the joists minimises the potential reduction in load capacity.

 

[Cubist]

A different opinion here. If you can, then route each of the pipes through a minimum 20mm hole in each joist while trying to keep the hole centres at least 60-75mm from any surface someone might try to drive a nail from - for obvious reasons. You can also leave enough room to mount pipe insulators cut to fit over the pipe runs between the joists.

 

[montyjohn]

Going through the middle of the joist (vertically) is best. This will have next to zero impact on the joist strength. Avoid notching top or bottom if possible as this has the most impact on bending strength. If you must notch it, avoid the middle (horizontally).

 

[Stevers]

Going through the middle of the joist (vertically) is best.

Appreciate the theory behind this approach, but how practical is it to run long lengths of copper pipe through holes on the centrelines of joists?

Not worked with plastic pipe, but that might have the flexibility to manage it.

 

[montyjohn]

Plastic is definitely flexible enough.

When I ran a shower drain I had to cut it into about 8 smaller lengths. It was a bit of a faff.

Not faced this with copper but I doubt I would bother.

 

[a twig]

If you have the access it’s easy enough with either - but yep if access is tricky then plastic is the way to go - you can just pull it straight off the reel and feed it through.

 

[larry]

For underfloor pipe runs I've definitely found the bendability of plastic pipe to be very helpful! The JG speed fit stuff either comes as straight lengths of PEX (which does bend to some extent) or PEX on a roll (much bendier).

Just buy the same brand fittings and make sure you use inserts on the pipe.

I second the point about lower depth to miss nails/screws... Found that out the hard way once with a CH pipe. Though I didn't find out it had a screw in it until I removed it and water started spraying about above the kitchen ceiling ....

 

[Lacan07]

Hi all

I need to get hot/cold 15mm CH pipes from one side of a room to the other, and the moist direct through is through the joists. How bad is this? Would have to go through every joist.

1st floor room. Alternative is to run them around perimeter on skirting boards.

Thanks

View attachment 18331

Can you not notch the joists?

Running copper through the centre of a joist is considered bad form, people use plastic for that now. If you do just make sure you use a known brand.

 

[paulc]

Notching of joists is generally acceptable if the joists are deep enough. This page gives some guidance: https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists

Whilst drilling holes on the centre line does not compromise the structural integrity of a joist as much as notching, unless you have a right angle head on the drill, it is next to impossible to make a hole.
If you didn't want to notch or drill joists, and don't want ugly pipes on view running round the room, it is possible to box them in behind the skirting.

 

[Stevers]

I second the point about lower depth to miss nails/screws...

Notches should run down the middle of a board with the board screwed down each side for future access. When you put the boards down, you will know exactly where the pipes are. After that never ever fasten into any more that the 20mm or so of floorboard without being very sure of what you are doing!