Reinforing Notched Floor Joist

[zand108]

Hi,

I am in the process of installing a new shower and while creating the run for the pipework was incorrectly advised by a friend that I could cut a 2" notch into the top of a 2x8" joist.

Untitled

• zand108
• 20 Sep 2008
• 2

Untitled

• zand108
• 20 Sep 2008
• 2

After accidently coming across other posts on this site I now realise that the maximum notch depth for an 8" joist is just 1".

The joist span is approx 3m and the notch is approx 50cm away from the end of the joist and is 7cm wide.

How do I go about reinforcing this joist (does it even need it?) I have plenty of 2"x4" (47x100mm) Sawn "Easy Edge" Timber from Selco lying around could I use this timber on either side of the joist beneath the notch to "brace" it I also have a box of 5x80 Turbogold screws can I use these to secure the "timber braces" to the joist.

Thanks.

[edit] This was also posted in the building forum as I wasn't sure where was the best place to post it. I hope this doesn't upset anybody.

 

[Deluks]

Don't worry, others have done worse. Bracing is about all you can do, extending at least 300mm each side, bolting would be preferable as the screws you have will only penetrate 30mm into the weakened joist.

 

[awbcm]

Check out this guide i produced.

 

[zand108]

Thanks for replying Deluks and so quickly too...

I have been looking at bolts. These will be long enough to sandwich the joist beween the timber braces. Would they be alright?

http://www.screwfix.com/prods/21613...eaded-Coach-Bolts-BZP-M12-x-180mm-Pack-of-10#

How many bolts would you recommend using and where would you locate them i.e. at the end of the braces, directly either side of the notch or directly underneath the notch?

Also... I will delete the post in the other forum.[/b]

 

[zand108]

Thank you Moderator and sorry for the inconvenience

 

[zand108]

Check out this guide i produced.[/url]

Thanks this is a really useful guide.

In the side view is the graphic saying to add a bolt every 100mm.

 

[awbcm]

Check out this guide i produced.

Thanks this is a really useful guide.

In the side view is the graphic saying to add a bolt every 100mm.

No

100mm maximum from the end of the lamination. Dimension X are all equal.

I have more guides that may be of help.

 

[zand108]

Ok, I see so what is a good distance for dimension X then?

 

[awbcm]

Ok, I see so what is a good distance for dimension X then?

If you have a space from the wall to start of the damage / notch the X is half this. X is a way of saying these dimensions are equal what ever dimensions you have.

Example

If the space between wall and damage is 150mm then X = 75mm

Please see disclaimer at the foot of the drawing

All my guides are designed to be adaptable to your individual requirements & is not tailored to any particular individual or circumstance

 

[zand108]

Hi,

I bought some 18mm OSB and these M10 x 130mm coach bolts (Threaded only at the end) from toolstation to use attach the OSB to the joist The packaging doesn't say what size pilot hole I should make can anybody help?

Also the guide I have been directed to doesn't specify them but should I be using any washers of any type???[/url]

 

[zand108]

Also, the place where I notched too deeply into the joist is exactly where I need the pipes to pass through it, once I have reinforced the joist is it better to notch again over the reinforced notch (making sure not to notch too deeply this time) or to drill through the centre of the joist underneath the reinforced notch instead?

Many Thanks!!

 

[awbcm]

It may be a good idea to contact member Big-all by PM

 

[zand108]

Tried to send Big-all a message but was told he is only accepting messages from friends.

 

[awbcm]

Tried to send Big-all a message but was told he is only accepting messages from friends.

I have sent the man an email so he should look in later.

 

[zand108]

Thank you I really appreciate it.

By the way what size pilot hole do you make for an M10 coach bolt and is there a special tool for making a square countersink for the bolt head???