supporting walls

[Albert]

Hi,
Is it allowed to put in an outlet socket in a supporting wall, I mean if there is a beam (normally you will have 2) that support a RSJ, and a socket needed (this is the only place it can be installed) , it has to be flush, meaning that you will have to dig into the wall, what is the approach/rule or what people will do normally.
I did call the IEE and the NIC, but the reply was very vague.
I understand that this is a very general and vague question, so I need you , experts opinion/experience,
Thanks
Albert

 

[mrscalex]

I think you probably mean where piers (not beams) support an RSJ (that's the beam) is it okay to hack the pier?

You will defintely receive different answers to this. I am currently going through a nightmare where a builder has taken out a load bearing block partition and the council Building Control have said the piers he has left are too slender and unstable. Consequently I wouldn't dream of attaching anything to the piers, even if they were rebuilt in 70 Newton block because I am now paranoid.

You might choose to take the view, particularly if your work is pre-existing but non-original (and/or has never been opened for inspection to you) that your piers might also be flakey.

If you do justify going into them then I would use a proper box sinker to reduce vibration rather than hack out only with a chiesel.

This is just my view as a fellow DIY'er, it is not a professional one.

 

[Damocles]

I don't quite understand the layout you mean. If you really mean smashing a hole in the supporting wall immediately under where a beam rests on it, then this does not sound like a good idea. The further down from the point of support then the more the load is spread and the less problem there could be.

What is the wall mad of? Is it plastered, so some of the depth needed will just be in plaster which will not affect anything? Then what, brick, block, concrete?

If you are thinking of hacking into solid concrete beams, then I would think twice.

 

[ban-all-sheds]

I am currently going through a nightmare where a builder has taken out a load bearing block partition and the council Building Control have said the piers he has left are too slender and unstable. Consequently I wouldn't dream of attaching anything to the piers, even if they were rebuilt in 70 Newton block because I am now paranoid.

I wouldn't dream of even standing near the wall. I guess as you're a DIY-er it's your wall that the builder has potentially knackered. Get a structural engineer in, and if he agrees with BC, sue the arse off the builder.

This is just my view as a fellow DIY'er, it is not a professional one.

You too, Albert - get a structural engineer, that is. mrscalex has hit the nail on the head - you need a professional opinion. If you are concerned that cutting holes in something might reduce its structural integrity to a dangerously low level you must seek qualified advice.

 

[Albert]

I think you probably mean where piers (not beams) support an RSJ (that's the beam) is it okay to hack the pier?.

Firstly you got my question right, secondly as the reply from IEE & NIC is not clear any reply based on experience could be very helpful (just to tell you, because I had doughts I put the sockets on the surface), this issue interested me for practical reasons but as well as to know what the regs. (if any), say about that. As probably you know there are quiet clear instructions concerning cutting and drilling into Joists, so I thought what about piers?

I don't quite understand the layout you mean. If you really mean smashing a hole in the supporting wall immediately under where a beam rests on it, then this does not sound like a good idea. The further down from the point of support then the more the load is spread and the less problem there could be.

mrscalex got the question right, sorry for the messy description, I am not familiar with all the terminology. As an engineer in general mechanics i understand the importance of keeping the pier strong enough and that digging in to it might weaken it, but obviously in a way the Joists have the same problem, is there a written or thumb rule that will say how much you can dig in a certain size pier, it is sometimes quiet hard to know what is behind as it is plastered and painted, or may be the rule is 'DON'T TOUCH!!!'
Thanks
Albert

 

[mrscalex]

I wouldn't dream of even standing near the wall. I guess as you're a DIY-er it's your wall that the builder has potentially knackered. Get a structural engineer in, and if he agrees with BC, sue the arse off the builder.

For the record! I understood sufficient even before the work started that a structural engineer and Building Regs were required. The builder said, of course, 'don't worry - that's the only way to do it'. The truth is that I don't think the builder ever went to a Structural Engineer until after he did the work and was forced into a corner by BC. Now he is trying to get the calculations reverse-engineered. Unfortunately I let the builder convince me it was okay to retrospectively apply for Building Regs and of course that was where the flood gates were opened.

Suffice to say I now know more than my fair share of both the process and structural side of such work.

And if in doubt I would say this. By running a chase or sinking a box into a pier you are affecting it's mass and consequently it's load bearing ability, however minor, over what the structural engineer calculated. As part of his work, the structural engineer guarantees the design of the installation against future failure. Any reduction in mass or potential disturbance to the structure might legitimately invalidate this guarantee.

 

[Albert]

This one was modified

 

[Albert]

="ban-all-sheds You too, Albert - get a structural engineer, that is. mrscalex has hit the nail on the head - you need a professional opinion. If you are concerned that cutting holes in something might reduce its structural integrity to a dangerously low level you must seek qualified advice.

This was a small job and I did not have a problem to convince the customer to put the socket on the surface.
Please read my reply to mrscalex, where I explained my question. It can be very costly if I need to ask a structural engineer to come in for a job of £100, (I don'd disagree about the importance of the strength of the pier/supporting wall), but there must be a something that will give you some idea.. or not...?
Thanks
Albert

 

[pipme]

Albert ... Found this info here :- Deputy PM's place

2C30 Chases:

a. vertical chases should not be deeper than 1/3 of the wall thickness or, in cavity walls, 1/3 of the thickness of the leaf.

b. horizontal chases should not be deeper than 1/6 of the thickness of the leaf of the wall.

c. chases should not be so positioned as to impair the stability of the wall, particularly where hollow blocks are used

CSA (Cross Sectional Area) of the support column is important here, vertical chase would have less effect than horizontal chase of same dimensions.
Does that mean that a 'double box' cut out being oblong, is seen as a 'short horizontal chase' ?? not much depth allowance on 3" leaf wall then !!

(c) Suggests, as already posted, expert opinion required.


[url]http://www.odpm.gov.uk/stelle...ntentservertemplate/odpm_index.hcst?n=244&l=3[/url]

I wonder about changes which may have occurred between the older and 2004 editions of Structure Doc. (A) Building Regs etc ? Not in Albert's case, but in the situation of mrscalex. That is to say ..was the builder up to date on specs ? Would his work pass under the old rules ? Was it totally bad workmanship or did he work to out of date regs ?

P

 

[Albert]

Albert ... Found this info here :- Deputy PM's place

2C30 Chases:

Thanks,
Albert

 

[Damocles]

I don't think you can consider a concrete beam the same as a wall. They might be just concrete, but very likely have steelwork buried inside. So depending on where you attacked it, you might affect it differently. Just skimming an inch of concrete off the surface of an enclosed rsj might have virtually no effect on its strength. Or it might form a breech in its fire protection (in case anyonw is planning to crash an aeroplane into the buiding, and melt the steelwork). Or it might be all concrete with a few steel bars.might have unforseen consequences by introducing cracks.

I doubt a hole for a box is the same as a chase. A horizontal chase would be long.

 

[chappers]

Lets get this in perspective boys he wants to sink a socket in a pier supporting a beam and maybe chase a wire to it.Just cut it out even if it were a single skin 4" wall and he took a whole brick out what do you think is going to happen?


Yep thats right absolutely nothing unless this pier is just a series of bricks piled singley on top of each other, and if it is it 'aint doing nothing to support the beam.

When was the last time you saw an electrician call in a structural engineer before he sank a socket box.

 

[Damocles]

Well it kinda depends on the situation. I can think of one where a concrete cased RSJ was sitting on a single leaf standard hollow brick wall. Holding up all the weight of the centre of the house. Came to my addention because the bricks under the beam were cracking from the weight.

Now if they had not cracked already, and someone had come along and insisted on smashing a hole for a socket, could have been very nasty.

Like I said earlier and I think you would agree. Depends where you put the hole. Lower down and I agree, it would not have made so much difference because the load would have been spread across the wall. But also, from one side you can't tell exactly what is behind.

 

[dingbat]

The builder said, of course, 'don't worry - that's the only way to do it'. The truth is that I don't think the builder ever went to a Structural Engineer until after he did the work and was forced into a corner by BC. Now he is trying to get the calculations reverse-engineered.

I did some work recently in a house where the lounge and dining room had been knocked into one some years ago, with no permissions, of course. The ceilings were flush, which meant the joist used was about six inches deep (the depth of the floor joists) over a twelve-foot span. It was a timber joist and over the years it had flexed and the ceiling had cracked.

Builders were in, replacing the joist with a steel one. In conversation I discovered that the builder had originally calculated that a beam of 200mm depth was required, but as this would mean interrupting the run of the ceiling the owners didn't want it. So, he swapped it for a beam of the same width of flange and thickness of web... just shallower. No new calculations, no third party consultation and (I asked him) no planning permission or building control permission. He'd reasoned that as they were re-doing a job that had already been done then none was required and if he was replacing six inches of timber with six inches of steel then it had to be better, right?

Oh, and by the way, the wall directly above the beam is solid brick - the remaining second storey of the original full height brick wall!

I advised the owners that they might want to telephone the building control office and check because I'm pretty damned sure that structural alterations require at least building control approval.

 

[pipme]

I don't think you can consider a concrete beam the same as a wall. They might be just concrete, but very likely have steelwork buried inside. So depending on where you attacked it, you might affect it differently. Just skimming an inch of concrete off the surface of an enclosed rsj might have virtually no effect on its strength. Or it might form a breech in its fire protection (in case anyonw is planning to crash an aeroplane into the buiding, and melt the steelwork). Or it might be all concrete with a few steel bars.might have unforseen consequences by introducing cracks.

I doubt a hole for a box is the same as a chase. A horizontal chase would be long.

No steel reinforcing ! No load bearing beam !!
The steel should take care of tension hence larger rods near bottom face of beam ... the concrete being poor in tension (pulling apart) is very strong in compression toward the upper beam face. I don't think we were talking about cutting into the beam (complete no,no I imagine), more into the pier, pillar or column.
Spent two summers ages ago on the 'Kango hammer' cutting chases brick and concrete ... nothing which was 'on the edge' in a structural sense .. but then, to take care of 'interpretation' I'll bet there is a fair margin of error involved ... How much of that is eaten into by the finger in the air brigade ?

P