Notching and bracing joists

[pedro123]

Hi all, am after some advice. I have recently completed a project of coverting an old box room into my new kitchen.

I notched some of the 8" inch joist in my 1s floor flat by 1.5" deep to allow for a 1.5" drainage. This was to allow the drainage to go under floor.

I notched 7 joisted but braced them with large steel plates either side - 60cm wide x 1.2cm thick x 10cm high. 8 screws per plate.

Would you say that the joists will be ok?

Thanks Pedro

 

[Gasman1015]

Bit late now is'nt it.

 

[corgiman]

Bit late now is'nt it.

 

[esra_ptrap]

Not sure what you mean by braced or how many you have weakened, can you post a picture?

I would normally run waste pipes over joists and box in where necessary rather than let them into joists.

It's generally a good idea to ask before you do the work if you are unsure as it's a bit late now

 

[kevnurse]

Personally, I would bolt the plates together either side of the notch. I guess the joists are 2" thick.

 

[Agile]

There are rules of thumb about the permissible depth for notching.

A major factor is the total length of the joist and the distance of the notch from the end.

Generally you should only make any notches within the 25% distance from the support end.

The notch should not exceed 12.5% of the depth so you exceeded this guideline.

I doubt that it will collapse but if it did then your buildings insurance might not pay if they realised what you had done.

Tony

 

[pedro123]

Thanks folks,

Yes its far too late and its my fault. Have decided to get a structural engineers to assess the problem.

unforutnately, I didn;t read my plans correctly by my archietect and the plumber that did the work said that it was fine to do that.

Have learnt alot and am owing up to my error. The good news is that the joists have shown no movement and are plated both sides for more than a year.

http://good-times.webshots.com/photo/2478088310077805694OSAfhB.

Will gain structural approval or pay the price


[/img]

 

[Agile]

Thats probably a bit of overkill.

Joist thicknesses are usually specified for the widest span in the property. The same thickness is used in small rooms and that means the thichness is usually much greater than required for structural strength.

The plumber was probably an eager to please East European who had no formal training or the British equivalent.

That creates an interesting legal question relating to the many untrained people doing plumbing after a six week basic course. If they did that then you would have a legal right to have the joists replaced at their expense and that would cost several hundred pounds!

Something for the six week plumbers to think about!

Tony