Bricking in a bath - concrete floor

One of the tasks which I am unsure of in planning my bathroom reno is the bricking in of the bath.
Planning to have the bath sitting on a brick hob all around. ( not cut into the brick wall ) Is it necessary to leave an access to the underside of the bath or can it be enclosed and just vent the underside through the adjacent outside wall to help eliminate moisture underneath it.
Is the correct order of installation of the bath as follows;
Support bath at correct height
Fix waste outlet to bath
Remove bath and make a mud base for it
Reinstall bath and level
Brick up side of the bath leaving room for tiles under bath rim
Tile the bath

Does that sound right?
Any help appreciated as working to a budget
Cheers
Juan

I conpleted pretty much the same reno about 5 years ago.

My house is double brick and the concrete bathroom floor is above the garage.

I also blocked in a window ( with villaboard -saw your other post)

This bathroom was already tiled so I just went over the old tiles with a good adhesive on the tiles. though I dug up the floor tiles to keep the floor level. I could only see extra work removing them from the walls and then getting the walls smooth.

I put in a corner spa, I used an aluminium rectangular tube I had spare to fix to the corner walls to support the bath. I then built a brick front for the other sides of the spa.

I left some bricks out so I could check everything was Ok when I put in the bath. I had to move the drain hole position but I left the old one in the floor as it had a S bend to stop any problems still on it under the floor. I cut it off level with the floor in case the pipes from the spa ever leaked so the water would run away.

When I put the bath in I made the mistake of stepping into the bath when I bedded it into the cement I put under it. It flexed down a bit (fibreglass) and when the cement dried there was a small air space under the bath. As I had left a few of the bricks out I was able to not only see the problem but also fix it. I injected plaster into the space and it was bedded properly. Afte I was satisfied everything was OK I filled in the missing bricks

Don't know your exact circumstances but if its a cast iron bath it would take forever to rust through if water condensation got on the back of it even a pressed steel one would take years, but if it is steel/iron you could paint it underneath before you place it in the space.

I would think there are several ways to vent the area depending on what is under the floor or what rooms surround it. If there is nothing under the floor (rooms etc) you could leave the space around the drain pipe free to allow the area to vent. If you seal it off with a mesh it would stop problems with bugs etc. If the room wall is double brick a hole into the cavity would work,

As you mentioned about the window I should tell what I did.

My window is a two piece one, top opened bottom section fixed glass. The old design of the bathroom had a vanity with a shelf under the window which was low about bath height. I blocked off the lower section by putting a piece of villaboard in and then tiling straight across the wall. It has never looked like being a problem.

If the walls are brick which I think you stated they were I would think putting the batterns onto the brick and going over the whole wall would be a less satisfactory result than putting the villaboard onto the brick. Though why not just tile onto the bricks?

Thanks for your help Durwood. After talking to James Hardie Customer Support, I have decided to take the long road and brick up the openings and plaster the wall rather than using villaboard. Still a little unsure on on the bath though.
Regards
Juan

You don't have to remove the bath to mud underneath it, make sure it's level and connected to the outlet then make up a very dry mortar mix (just enough water to hold shape when you squeeze it in your hand).

Pack it in under the base of the bath till it is flush and supports the entire base, not too much directly under or the base my 'bubble' upward esp. if it is acrylic.

Then half fill the tub to bed it in the mortar evenly. Drain water out after after a couple of hours. Voila, perfect mud base.

Thanks Scotty