Existing cable routes through joists etc

[rsmck]

As stated above, as this is your own house, only you will know what condition your joists are in and if you think drilling holes will be detrimental to the overall strength of your upper floor...

We found one of them with a 'notch' about 3/4 of the dept of the joist - apparently to accommodate a bathroom pipe... - that one has been appropriately attended to

The plumbers who installed the central heating added a fair few of their own too unfortunately, thankfully much shallower.

In general I'm sure the holes wouldn't be detrimental to the strength of the floor but since the notches are already there then reusing them with appropriate protection and clear markings is probably a good solution. I'm not talking about running them beside pipes or anything like that, these are old notches for electrical cables which helpfully allow me to bring the new cables down the same route as the old to the consumer unit.

 

[rsmck]

I thought the rules were holes only within 0.25 and 0.4 x of the clear span of the joist with the holes a maximum of 0.25x the depth of the joist, so 25mm for a 100mm joist and 44mm for an 175mm joist with adjacent holes no closer than 3x the maximum permissible diameter apart.

Oh, and no holes within 100mm of a notch...

Notches can be closer to the edge, but I can't remember off the top of my head how much closer.

But yes, in practice for many years builders, plumbers and dare I say electricians have just put holes in them wherever convenient in many many buildings and they're all still standing

 

[JD6400]

Sorry i was corrected !
Just bothered to find my IEE guide to the building regs and as usual i have just had another Senior moment , which is not good at just 35 !

 

[Des 56]

If you do a rewire and was to try and comply with building regs, you would be lifting boards up here there and everywhere
Real situations are better overcome by using our common sense,as said, how many houses have collapsed because of a few holes in the non stipulated zones

 

[Engineer54]

If you do a rewire and was to try and comply with building regs, you would be lifting boards up here there and everywhere
Real situations are better overcome by using our common sense,as said, how many houses have collapsed because of a few holes in the non stipulated zones

Totally Agree.... commonsense Rules!! ...lol!!

I often wonder who the hell dreams up all these meaningless dimensions. Had nothing like this in bygone years, doesn't seem to have done any lasting damage over all those years either!!!!

All the times i've brought up different things about structural requirements of various mediums, of wood, steel, concrete etc, over the years on numerous projects, with ''Real'' working Structural Engineers. Only to be told nothing to worry about. Seems that most of these calculations are based on very worst case scenarios that the real world rarely see's. Lapped up by various organisations, so that even more rules are banded about, along with all the scaremongery that goes with them....

There are many buildings in the UK, that are hundreds of years old, built without a fraction of today's building Reg's. ...How many with ALL of today's building Reg's will be around in a hundred years time, ....not very many at all is my guess!!!

 

[rsmck]

There are many buildings in the UK, that are hundreds of years old, built without a fraction of today's building Reg's. ...How many with ALL of today's building Reg's will be around in a hundred years time, ....not very many at all is my guess!!!

Case in point - the changes on equipotential bonding from 16th to 17th

But yes, my first flat was in a building over 200 years old. Nothing wrong with it to this day and built without todays modern mass-produced components (every nail a different shape, every door made by hand and a slightly different size) - the plasterwork is a dying art now, and yet even the most basic rooms in that building had huge ornate cornices - I imagine the builders were proud of what they produced back then.

I can't imagine many of the buildings springing up left right and centre today will still be standing in 200 years time... yet somehow I believe, and hope, that my first flat might