Notching joists
Discussion
Notches and holes in simply supported floor and ceiling joists should be within the following limits:
Notches should be not deeper than 0.125 times the depth of a joist and should not be cut closer to the support than 0.07 of the span, nor further away than 0.25 times the span.
Holes should have a diameter not greater than 0.25 times the depth of a joist and should be drilled at the joist centreline. They should be not less than 3 diameters (centre to centre) apart and should be located between 0.25 and 0.4 times the span from the support.
Notches should be not deeper than 0.125 times the depth of a joist and should not be cut closer to the support than 0.07 of the span, nor further away than 0.25 times the span.
Holes should have a diameter not greater than 0.25 times the depth of a joist and should be drilled at the joist centreline. They should be not less than 3 diameters (centre to centre) apart and should be located between 0.25 and 0.4 times the span from the support.
For what it's worth when we had a new boiler fitted in our Loft, the plumbers went to town on our joists, with zero regard for regulations.
Does make me concerned about selling in future & someone lifting up the loft floorboards and seeing 6-8 joists each with 3 notches cut out to comfortably routing the 22mm pipes (feed, return & gas) - some 1/3 of the way through the joist.
Didn't realise until 18months later when I was laying extra insulation up there and wanted to route some CAT6 cable under said board.
''Professionals....''![frown](/inc/images/frown.gif)
Does make me concerned about selling in future & someone lifting up the loft floorboards and seeing 6-8 joists each with 3 notches cut out to comfortably routing the 22mm pipes (feed, return & gas) - some 1/3 of the way through the joist.
Didn't realise until 18months later when I was laying extra insulation up there and wanted to route some CAT6 cable under said board.
''Professionals....''
![frown](/inc/images/frown.gif)
Edited by Andehh on Tuesday 31st January 11:43
Andehh said:
For what it's worth when we had a new boiler fitted in our Loft, the plumbers went to town on our joists, with zero regard for regulations.
Does make me concerned about selling in future & someone lifting up the loft floorboards and seeing 6-8 joists each with 3 notches cut out to comfortably routing the 22mm pipes (feed, return & gas) - some 1/3 of the way through the joist.
Didn't realise until 18months later when I was laying extra insulation up there and wanted to route some CAT6 cable under said board.
''Professionals....''![frown](/inc/images/frown.gif)
Thats standard practice for most plumbers!Does make me concerned about selling in future & someone lifting up the loft floorboards and seeing 6-8 joists each with 3 notches cut out to comfortably routing the 22mm pipes (feed, return & gas) - some 1/3 of the way through the joist.
Didn't realise until 18months later when I was laying extra insulation up there and wanted to route some CAT6 cable under said board.
''Professionals....''
![frown](/inc/images/frown.gif)
Edited by Andehh on Tuesday 31st January 11:43
andy43 said:
18mm ply strips full length either side of the joists works well too, bolted or screwed.
Always check your plumbers toolbox for woodworms. Big buggers, usually with 25mm teeth...
Lol. Always check your plumbers toolbox for woodworms. Big buggers, usually with 25mm teeth...
I can't believe it, it turns out there was already a 50mm deep notch right where I needed it. Silly me.....
Relocating the shower waste is not an option nor is drilling the joist, because the pipe will run uphill to the stack. Raising the shower tray means the enclosure touches the ceiling as it's in a dormer. Notching & supporting the notch appears to be the only way without major expense and disruption to other rooms.
bernhund said:
Relocating the shower waste is not an option nor is drilling the joist, because the pipe will run uphill to the stack. Raising the shower tray means the enclosure touches the ceiling as it's in a dormer. Notching & supporting the notch appears to be the only way without major expense and disruption to other rooms.
Good luck with that. Hope you don't need to get NHBC, building controls or a surveyor to ever look at it.Get a different shower screen and raise the shower tray or drop the ceiling/box in in the room below.
Edited by Ahbefive on Wednesday 1st February 21:38
Ahbefive said:
bernhund said:
Relocating the shower waste is not an option nor is drilling the joist, because the pipe will run uphill to the stack. Raising the shower tray means the enclosure touches the ceiling as it's in a dormer. Notching & supporting the notch appears to be the only way without major expense and disruption to other rooms.
Good luck with that. Hooe you don't need to get NHBC, building controls or a surveyor to ever look at it.Get a different shower screen and raise the shower tray or drop the ceiling/box in in the room below.
bernhund said:
Our house is a grade 2 old stone school circa.1820. There's a central section with 3 rooms upstairs, the 2 wings are single level.
As it's listed,
As it's listed,
Ahbefive said:
I wouldn't think about notching 50mm out of a joist. Find another solution.
Have you worked out the effective point loading required to snap an 8" x 3" joist that's been notched down to 6"? It's not going to snap! It might be against regs, but it's not going to snap or flex appreciably. If the floor is well screwed to the joists then they will allow some transfer of load around the weakness as well.paulrockliffe said:
Ahbefive said:
I wouldn't think about notching 50mm out of a joist. Find another solution.
Have you worked out the effective point loading required to snap an 8" x 3" joist that's been notched down to 6"? It's not going to snap! It might be against regs, but it's not going to snap or flex appreciably. If the floor is well screwed to the joists then they will allow some transfer of load around the weakness as well.It may never cause an issue, it could ens up with minor issues with tiles/grout cracking or it could in time cause a big issue. If it were me I'd look for an alternative solution.
Ahbefive said:
paulrockliffe said:
Ahbefive said:
I wouldn't think about notching 50mm out of a joist. Find another solution.
Have you worked out the effective point loading required to snap an 8" x 3" joist that's been notched down to 6"? It's not going to snap! It might be against regs, but it's not going to snap or flex appreciably. If the floor is well screwed to the joists then they will allow some transfer of load around the weakness as well.It may never cause an issue, it could ens up with minor issues with tiles/grout cracking or it could in time cause a big issue. If it were me I'd look for an alternative solution.
All those things you list are heavy, but not on a per unit area basis. The regs are designed to take into account all possible use of the room, so there's enough contingency for you to use the room as a storage room for heavy stuff. They also make allowance for dynamic loading, ie someone jumping up and down or whatever. The maximum loading for the use of a bathroom is inevitably much lower than that.
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