Plasterboard finish?

Si_Clist

The chap who is adapting our bathroom has had to build a false wall of 4x2 and plasterboard. He seems to be assuming that he will fill the joins between the sheets, then we will simply paint the wall.

Is that right, or should it be skimmed with plaster?

FreeBear

I've always filled the joints between sheets of plasterboard with Knauf Fill & Finish, then apply scrim tape (mesh) while the F&F is still wet. Once dry, skim with two thin coats of plaster. Just filling the joints and slapping paint on sounds like bodgery to me….

In a bathroom, he needs to be using moisture resistant plasterboard (the green stuff). If in direct contact with water (e.g. around a bath or shower), then it should be a cement board or Marmox type material (finished appropriately).

WIAWSNB

Is it tapered-edge plasterboard? If so, it should be fine to tape and fill. The skim/fill is usually applied with a wide plastic blade to span the tapered section, so it all ends up at the p'board surface level. A light sanding should make it perfect.

sheenas

Either method works perfectly well. I don't partially like plasterboard in bathrooms and if it necessary I would consider tanking it, so it water proof.

stuart45

Tape and fill is an alternative to a skim coat of plaster. In the USA tape and fill has been standard in houses since WW2. In the UK it's been used more on new builds in recent years, although some people still prefer a skim coat. Time and motion studies in the USA found that you could tape and fill a new house in roughly 1/4 of the time it took to skim it.

As FreeBear said, the most important point in high humidity areas is to use a moisture resistant plasterboard.

clive0510

Surely if its in a bathroom, it needs to be plastered and then painted with bathroom paint. bathroom paint is moisture and mould resistant. the two things bathrooms are famous for.

stuart45

https://forums.moneysavingexpert.com/discussion/comment/82029974#Comment_82029974

Skimming the plasterboard doesn't make much difference to it.

FreeBear

https://forums.moneysavingexpert.com/discussion/comment/82029974#Comment_82029974

Better still, use a wall finish that is moisture resistant from the ground up. Lime plaster has been used since the Roman times in bath houses (there is also evidence that the Egyptians had been using it). In Morocco, lime plaster evolved in to Tadelakt which, done right, is waterproof.

stuart45

You might want to look at the cost of Tadelakt plaster before you book a tradesman.

FreeBear

https://forums.moneysavingexpert.com/discussion/comment/82030345#Comment_82030345

The materials are not hugely expensive unless you are buying premixed from someone like Kreidezeit. Just looked up the price from Mike Wye…. ~£200 for a 25Kg bag plus shipping.

Or you can mix your own from hydraulic lime, sand, crushed marble & marble flour, optionally, crushed chalk, a dash of pozzolan, and maybe a drop of a cellulose binder. Grain size of the aggregates needs to be limited to around 2mm, so everything should be sifted. The exact ratios are not critical as long as you are consistent across batches.

Timing of the final polishing stages is crucial, as is the use of olive soap which gives the plaster its waterproof properties. Plenty of videos on youtube demonstrating the techniques.

If you are paying someone to do the job, then yes, it gets very expensive. Not many craftsmen in the UK have the expertise or experience to do it.