Btw the pipework had already been previously done by a plumber, it was there ready under the joists ready to be cut to length and have the trap fitted.
large notch in joist
- Thread starter warriorgal
- Start date
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There are options to look at tray waste layout on the internet. Most give accurate dimensions regarding waste location etc. This is how we select the correct tray or reject ones that are not suitable. I'm surprised that this was not discussed and explored further.
Has the plumber butchered any of the other joists with the waste pipe or does the pipe run freely between joists?
Has the plumber butchered any of the other joists with the waste pipe or does the pipe run freely between joists?
Thanks for replies.
the plumbing work, pipe runs etc, was done last year by the plumber and I had no concerns. Was the plasterer who did the large notch.
the plumbing work, pipe runs etc, was done last year by the plumber and I had no concerns. Was the plasterer who did the large notch.
Sorry if I'm being a bit thick here, but the waste pipe was already installed , just waiting for the trap, and this guy jumps in an notches the joist like that without even checking for it? That's reckless imo and he should pay for remedial work.
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Ditto.
Yes that's what happened. Shall keep you updated
If you want to do it properly, the timber would have to be re-graded under BS4978.
Yes, BS5268 and EC5 tell you how to calculate a notch for any grade, they don't tell you that any timber can be notched as calculated and still be in grade. If the beam is free of knots around the notch, then you could 'assume' the remaining section is still SS or C24, but the engineer may not know this or specify this (it happens), so you end up with it working in calculation, but failing due to knots near the notch meaning it isn't actually C24 any-more which the calculations are based upon.
This is not normally a problem with 'normal' notching as the limits are so small so as to not 'tip' a beam over from being SS grade to GS grade or fail.
In the OP's case, You can see knots within and around the notch, they are probably fine given their size and the position of the pith, but you can't see the other two faces, more knots on those faces and it probably won't pass grade.
Too many times engineers have skipped over that clause and just 'assumed' a notch is OK based upon calcs.
(None of this is of interest to the OP maybe, but I am Mr pedantic).
Granted if a piece of - say - 50 x 200 was cut down to two 50 x 100s, they would need regrading.
But considering a whole length of timber statistically, I wouldn't have thought that a short notch would affect the grading, regardless of the depth of the notch - though of course it would increase the stress on the timber around the notch.
If the notch was to be as deep as the timber, then you would end up with two lengths, and you could not say each of those lengths would potentially be of a lesser grade?
But I agree it's down to common sense when doing notches. and in the middle is not a good idea.
But considering a whole length of timber statistically, I wouldn't have thought that a short notch would affect the grading, regardless of the depth of the notch - though of course it would increase the stress on the timber around the notch.
If the notch was to be as deep as the timber, then you would end up with two lengths, and you could not say each of those lengths would potentially be of a lesser grade?
But I agree it's down to common sense when doing notches. and in the middle is not a good idea.
The following is a good read if you want help getting to sleep!
Grading timber is about assessing lots of features, but knot size and more importantly knot size in relation to its position within the cross section is primary.
When grading timber to GS or SS (the preclude to assigning C16 or C24 etc.) you assess the margin condition, which is if there is a % of knots on the two 1/4 edges.
If there is a margin condition, this reduces the allowable knot sizes or KAR (knot area ratio).
On SS grade (which is commonly C24), if there is a margin condition the knots are only allowed to be 1/5 of the cross section as a percentage (or 1/3 if there is no margin condition).
So if you notch near or around a knot, this is why it can badly affect the grade, particularly with a timber that had a margin condition, as you could significantly change the knot as a percentage of the allowable cross section, meaning your C24 timber may now be C16, or even fail.
This is why the codes provide no tolerance for knots around notches, though for 'normal' notching it isn't so much a risk because the grading rules do somewhat account for them.
(It is also why you are only allowed to plane of 5-10mm from structural timber, as this also changes the knot area ratio and therefore the grade).
Thanks for all your advices, update, Buildings regs took photos and said it needs bracing, so I shall get someone to sort it, and take it from there.
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