DIY Doctor

Main navigation

New 1st Floor Bathroom - Reinforcement of Joists

Postby MJN » Sat Feb 16, 2008 12:14 am

Apologies if this has been asked before but I've looked everywhere and can't find an answer!

I'm installing a new bathroom on the 1st Floor of my house and I'm not sure how to overcome the problem of what I believe to be insufficient strength/size of the joists. :(

The joists are 170x47mm @ 350mm centres with a span of 4,200mm. The bathroom is 3,200x2,700mm (the 3,200mm is the distance along the 4,200mm length at which point there is a non load-bearing partition timber stud wall (which separates the proposed bathroom and a corridor).

The bathroom will include a 1,800x800mm acrylic jacuzzi bath located on the external wall (opposite side to the corridor), a shower (adjacent to the separating timber stud partition) and other standard fittings (WC, basin, units, etc).

My first question is whether the existing joists are sufficient (which I doubt). If not, do I need to double up the joists (same size as existing for between every joist or every other joist?

If I need to double up the joists I then have the problem of fitting them (4,200mm) due to the timber stud partition at 3,200mm. Don't think this is feasible but could I install two shorter lengths of joist at 2,100mm each with an overlapping wood joint and some fixing between them - I appreciate this gives a weakness in the joint but would this not help to reinforce the existing floor.

Sorry for all the questions but hopefully I given all the facts. With any luck somebody will tell me that the existing joists will suffice but maybe that's wishful thinking!

Look forward to hearing from anyone who can help as I'm now at a dead end.

Rank: Labourer
Progress to next rank:
Posts: 4
Joined: Fri Feb 15, 2008 11:41 pm

Postby welsh brickie » Mon Apr 14, 2008 7:24 pm

what about installing a beam under the joists??
If you can do it your cutting the strain on the joists by half.
But you will need to check with building control first.
They are there to help always ask first.
welsh brickie
Rank: Project Manager
Posts: 2611
Joined: Sat Apr 12, 2008 7:54 am

Postby rosebery » Tue Apr 15, 2008 12:17 am

You need proper structural calculations done to be absolutely certain.

Rank: Project Manager
Posts: 2021
Joined: Wed Sep 26, 2007 8:55 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics