I know you're worried about how the top coat/finish will look but you should consider what's underneath that, first. Plaster is rarely one coat, almost always two, or even better, three. Each applied separately and left to dry before the next is applied. The different coats are made of slightly different materials as they have different purposes, too. But the first thing to think about is the lath. I assume you are talking about wood lath? You said you have bonding stuff, but that's not going to be sufficient to stick the plaster to the lath. It's really intended to stick plaster to plaster, at the edges of the repair, which except in really small repairs isn't enough to secure the plaster to the wall. Plaster works largely because it is mechanically held to the wall when some of the first (deepest-in) coat is squeezed through the openings in the lath and blobs of it form behind it within the wall cavity. When you tore the old plaaster out, you no doubt saw the plaster material behind the lath, that wasan't sloppy work, it was an essential part of the plaster. Through a chemical curing process as the plaster dries the material on the room side of the lath and the blobs behind are permanently bonded together around and through the lath. Subsequent layers of the plaster are bonded to the deepest layer (and to each other when there are multiple coats) by a reactivation of the chemical reaction as they are applied and then dry. But the strength of the wall is based completely on the integrity of the first coat's attachment to what's behind it. The blobs are called "keys" and in a mechanical way they "lock" the first coat plaster tight to the lath. The strength of this layer comes because a chemical reaction occurs when the plaster dries (cures) slowly enough to become rock-hard and tightly stuck to the rough surface of the lath. Originally the wood lath (like all new wood) had enough intrinsic moisture content that it did not suck the moisture out of the drying plaster prematurely which would interfere with the vital curing process,thereby weakening the plaster. However when you are dealing with old lath (that was original to the wall), which is now almost tinder dry, you can have a problem. One solution is to try and re-wet the lath by spraying it to the run-off point repeatedly over several days just before starting the repair. You can also strengthen the repaired-section's adhesion to the lath and to the wall by attaching over the wood lath a section of expanded metal lath. Cut it to roughly fit the space and screw it to the wall studs. (Don't tighten the screws down so much that the metal lath is distorted and pulled down into the spaces between the lath strips. You want it to be a flat, secure plane lying just on top of the lath.) Do not use nails which can cause additional plaster pieces nearby to crack and come off. Very small repairs (6-8" holes) can get by with just attaching (withwires, or careful stapling) the expanded metal lath to the wooden lath itself, but anything larger needs the metal lath attached to studs. Your first coat of plaster is a rough coat and its pupose is to get good adhesion of the plaster to the wall so it gets troweled onto (and through) the lath pretty firmly. It should remain completely below the surface of the finished wall and there's no need to make it more than nominally flat. It is usually a much coarser mix and slitght roughness on its surface helps subsequent layers stick to it. Only scrape off big lumps which would interfere when the next layers are smoothed on. The first layer is allowed to dry and another one or two coats are added on top to fill the remaining space and bring the repair up to the same plane as the wall. Each will be slightly different in composition; the final one being more fine, and/or in your case more textured. As recommended above I would definitely try as many trials of your finished texturing as necessary before doing your wall. You needn't used multiple coats while you are practising the top coat texturing. Just try the finish samples on scraps of sheet rock over and over until you've got the technique for the final coat down to a satisfactory match. Top coat plaster sets up quite quickly and you want to be able to apply it, work the texture and be done before that happens. Before starting this job I recommend doing some more research on working with plaster. There are instructions in books on old house repair and from time to time in magazines that deal with old houses. You should also know that depending on the age of your house modern plaster available for repairs and orginal plaster are not the same thing. However for a small repair I think I would use modern materials rather than trying to source and work with older formulas. HTH L.

We are remodeling our 1930s kitchen. The plaster is cracked and crumbly in some good-sized areas (2' by 4' and 3' x 5' approx). Our trusted electrician insists that the kitchen contractors should demo the plaster and replace it with drywall in the worst areas. The kitchen contractors (whom we've never used before) do not believe this is necessary, and that patching the plaster will be sufficiently strong. They say that if we apply drywall to the old plaster, the new cabinets will not fit, and it seems to me that the extra weight of drywall on already-cracked plaster will only worsen the problem. They caution against doing a complete plaster removal due to the expense and amount of dust. (2 people in our household have asthma, so this is an issue). One wall is exterior brick with no studs beneath the plaster. Another is terra cotta block, also without studs. Metal mesh lathe is used throughout. Because there are no studs, how can they anchor the new 42" solid cherry wall cabinets with either scenario? Without studs, will the brick-plaster or brick-terra cotta systems hold up? (Our previous cabinets were 32" metal). Chat room advice is as varied as my contractors'. I don't know whom to believe!

BS. It looks like it's not in the wettest part of the shower. You seem to have broken the cement board behind. You could try to patch in a piece of cement board, after cutting out the bad stuff. Then scrape and apply some new mortar. On the other hand, I would be tempted to use mortar and a roll of mesh to replicate the cement board, removing loose chunks of cement board, but leaving the mesh in place. Either way, you'll have to pay attention to making a flattish surface for the final application of mortar and tile.

Try to find some old house forums and/or local people who do plaster repair. Beware that people whose skill set is drywall are going to tell you that it all needs to come out. Very rarely does all plaster have to come out unless its been neglected or water damaged over a period of time. It may be you use a range of different techniques depending on what kind of damage. You may find that some walls have only minor cracks that can be simpy filled ,while some walls may have major bowing and large loose areas. arger damaged areas can either be re-done using old methods OR.... just attach drywall patches and fill in gaps with plaster (using bonding agent to get old plaster to adhere to new plaster). Whatever you do, please dont do the thing of putting drywall OVER the old plaster and butting it up against the baseboard and window and door trim. Thats just plain ugly Ceilings might be the one surface you decide to have drywalled - looks like we are seeing ceilings in your pics? Gravity has greater effect on ceilings, so damage can be a lot worse than walls. And, since theres no trim to contend with up there, its a lot easier. If you want to start a thread and post some pics over on the old house forum, I think youd find a lot of us could advise in more detail.