Building Reg., how have they changed?

  jack 17:21 16 Sep 2010

Such as floor joist spacings?
My 52 years old house was fitted on completion with a 5ft florescent strip light.
Over time the batten/power pack died and it was replaced[say 20 years ago] replacing was a breeze-
disconnect the wiring ,slacken off the screws in the keyhole slots shift the unit to one side and down it came.
Its replacement had similar keyhole slots- no need to remove the screws- offered it up thread the cable tighten screws.
That was then.
Last week that one died.
I at first simply went looking for a new tube and starter - only to find we now have the new energy efficient type slim type and the whole unit needed to be replaced.
So I did - only to find that now the pre drilled holes in the casing no way matched the existing holes in the ceiling in the joists- indeed they fell nowhere near joists.
Thus a back stretching neck cricking half an hour trying to mark the casing to drill new holes to match the joists.{ OK after a bit and much grunting and stretching it dawned on me to lay old casing on top of new top and mark through.]
So what has changed?
Joist spacings are different now?
If so why not allow for older spacings- perhaps as one wag suggested in the land where the item was probably made the holes match to the rafters in straw huts.

  Forum Editor 17:33 16 Sep 2010

The spacing interval is largely dictated by two things:-

1. The depth and thickness of the joist.

2. The span between the bearings at either end.

As the span increases for a given joist depth the spacing interval will reduce, but as a general rule in domestic properties you will space joists at 450mm centres. There's not the space here for a full list of spans and depths, and in any case there's no need.

Fluorescent light fittings are not usually very heavy, and lots of them are fixed straight to the ceiling with cavity fixings, rather than bothering with finding joists. In any case, if a casing is to be fitted parallel to the joists it may not be possible or convenient.

  jack 18:42 16 Sep 2010

Its true the pack contained a bag of 2 screws and plugs- but no way 'cavity type'
I would not care to trust this item- as you say fairly light weight -to cavity plugs through plaster board. But nuff said - job done now

  Pineman100 19:07 16 Sep 2010

In addition to FE's comments above, given that there's just as much chance that a fluorescent batten will aligned to run along a joist, instead of bridging across joists, I doubt whether the manufacturers pay a great deal of attention to the likely joist spacings in a house.

They probably just locate the fixing holes where (a) they can be accessed without too much obstruction from the components inside the casing, and (b) where it's easiest for the production machinery.

  Dragon_Heart 22:21 16 Sep 2010

I was informed a few months back you can now vent a WC into the cavity ..... nice !

With a 50+ year old property the use of cavity type plugs into 'plastboard' may be a slight risk ( if it is plasterboard ). The answer could have been to fit a cross batten between the joists adjacent the fixing point at plasterboard level.

  Forum Editor 22:32 16 Sep 2010

"I was informed a few months back you can now vent a WC into the cavity"

I don't know who told you that, but it's incorrect. You can terminate a soil pipe in a loft, provided it's fitted with an Air Admittance valve. If you do that you should ensure that the valve has a polystyrene cap on it - one is usually provided in the box by the manufacturers.

Venting into a wall cavity is absolutely not on however. In any case it would be impossible in anything built these days as the building regulations require you to install cavity wall insulation panels during the build. The cavity is completely filled, and you should not attempt to vent anything into it.

  BT 07:53 17 Sep 2010

At the risk of being pedantic, surely its then no longer a 'cavity' any more. Perhaps we should have a new name for it.

  sunnystaines 07:59 17 Sep 2010

a few bits come in recently as from oct new windows need argon gas between the panes, another one is electric fuse boxes if you have an older one its ok but any electrical work done on the mains must include an updated fuse box.

these are recent tips i have had recently when have tradesmen round for quotes.

  Pineman100 13:13 17 Sep 2010

I would be a bit sceptical about that quotation of the regulations by tradesmen. The one stating that "you have to have a new consumer unit (ie: fuse box)" is not infrequently used to drum up a bit of business.

To the best of my (inexpert) knowledge, there's no specific requirement under Part P of the regulations for you to have a new consumer unit, just because some work is being on your mains circuit.

  jimv7 15:55 17 Sep 2010

Have building regs changed that much,
"you will space joists at 450mm centres"

My newest tape is still marked for 16" centres and standard plasterboard sheets are still measured as 8'x4' (2400x1200mm), at 450mm centres the plasterboard would fall a bit short.

  Pineman100 16:16 17 Sep 2010

I thought the usual standard was flooring joists at 450mm and studs at 600mm.

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