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Joists rotted in bathroom, advice please

Postby happyhero » Fri Apr 10, 2009 12:30 pm

Hi I am helping my friend sort out his bathroom (I am ex-building services so broad-ish skills). He cannot afford much, but wants to sort things out. He lives on the 1st floor in a flat which is actually built like a fairly typical house ie floorboards, lath and plaster ceilings, cavity wall etc, so presumably it was once a house and is now converted into flats.

Anyway his bath was fitted with a gap at the outside wall end (this is also the tap and waste end), this gap was filled with a batten and siliconed and leaked. This was done because there was a pipe in the way going up the wall. The result was that there was damage to the flat below and apparently this has been going on for a while.

I had a look at it all and found he has 2"x7" joists, one of which is badly rotted in the bottom inch or so for about a foot and that bit goes into the inner wall, plus another joist next to this one is not too great so could do with some attention. A few of the floorboards are rotten in this area with the result I can crumble them in my hand and one bath leg is actually floating in mid air with no floor under it, where the boards are so bad. The bath is one of those pressed steel ones ( hope I have that right, its metal cheap type basically).

He has also got some new taps to fit and due to it being a very small bathroom and the toilet being in the way, I think it best to remove the bath and repair the floor properly first, and this will enable us to connect the taps more easily too. Then we could deal with the pipe up the wall so its in the wall and we can fit the bath right up to the wall withoput a batten to leak etc, ie a much neater job.

Question is how would you go about this repair, ie joist is rotten into wall (which looks like brick as far as I can tell so far), would you join another one to it and channel the wall so it goes into the wall for support or how would you do it?

If I did this splint type job, what would be the correct method to join the joists, ie big screws, coach bolts or nut and bolt etc?

Rather than channel into the wall is there a bracket I should consider using (only problem with this idea depending how it fixes is the damaged joist is right under the bit of wall that has all the wastes going out of it), got any ideas here?

Lastly if I channeled the wall, how would I insure the joist was supporting the floor and that the channel was not too big, my guess is you make it bigger and then put cement in and rest it on that, is that right and if so could I use quick setting cement etc?

Any help appreciated, as I say my friend does not have too much money but wants to do it well.
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Postby Worldlife » Wed Nov 26, 2014 3:39 am

Similar problem in our kitchen.
Contractor has coachbolted an extension to a joist resting in mid-air in the corner where the floor was beginning to collapse. The end of an adjoining joist was in damp building materials and decayed. That section was cut out and a new section of treated timber attached.

The ends of each joist entering a potentially damp support structure were fully enclosed in damp proof membrane.
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