Replacing Floor Joists

I am replacing a rotten floor joist , I have bought a treated joist to use so do i still have to put some wood preserver on the end that fits in the wall and do i wrap the end in polythene or something similar ?, also do you have to fill any gaps in with mortar ?.Its the first time i have done this so any advice would be very welcome . Thank you for your help .

Yes yes & yes its easy to carry these out at this stage even if regulations dont demand it. It will just add to the life of the timber and replacing it again will be a lot more expensive.

Preservative always a good idea and I might sit it on a small piece of roofing felt also make sure there are at east six inches of the joist sitting on the brick work.

If the joist you've removed was rotten then what sort of rot was it as dry rot will of spread into the surrounding brick work and floor boards, wet rot isn't that much of a problem.

Wallbuilder , the rot was caused by a hidden leak in the shower . The underfloor was full of rubbish and is a bit damp but there does not seem to be any damp anywhere else. thank you.

Nucad / Wallbuilder Can i pick your brains just a little more please ?.

I had to knock a brick out to lay the new joist and i have disturbed the original dpc (1930s) . I am going to put a new piece under the brick and new joist is this ok , cos when we have finished we are going to have a dpc done all round the house , i am not sure what they call it but it is the one where they drill holes, will this method improve the old one?.

and finally i am thinking of putting a paving stone down under the joists and building a brick tower to give it a bit of extra support , what do you advise ?.

You can get steel joist hangers that you just put into the wall to support the joist cant you ? wouldnt that have been a lot easier ?

I have used treated timber ,preservative , polythene on the ends , sat on DPC & I have used galv angle brackets for some extra support. So hopefully it wont need doing again in my lifetime !.Thank you all for your advise it was very helpful.