Plastering a wall.

[chrisauk]

Hi there. This may sound like a daft question but I am pretty basic with my DIY skills so thought I would ask for opinion first ...

We have a little space in our downstairs lav that we plan to utilise for a basin. Its actually the old chimney. Anyway, we have cleared it out, and are faced with bare walls. So, do I need to put slats on the walls, and then platerboard onto the slats, OR, as it is a brick wall, can I just get it plastered directly onto the brick?

As I say, fundamental question but, needed to kow before employing a plasterer.

 

[Penners]

You can certainly plaster direct on to the brick walls. As it's an old chimney, founded into the earth, your best bet is to have it plastered in lime. That way, any moisture that makes its way into the bricks - either upwards or downwards - can dissipate through the lime plaster. If your bricks do ever get damp, gypsum plaster will deteriorate pretty quickly.

If you employ an ordinary jobbing plasterer, he may not be experienced in using lime plaster. Be sure to find yourself one who is.

It sounds as though this is a very tiny room. It would be a good plan to ensure that it also has some form of ventilation. Ideally you should have an extractor fan vented to the exterior of the house. But if that's not possible, do arrange something - even if this is just a gap under the door and a grille in the wall above the door.

 

[biffvernon]

Yes, definately plaster with lime. It's actually much easier than gypsum for an amateur as there is no hurry. It does not go off in a few minutes so you can mess about with it for as long as you like.

 

[chrisauk]

ok, thanks. So, can I buy lime plaster in a 'just add water' format? And where can it be bought from?

 

[Mark]

As a small room it would be ideal for you to develop the skill of lime plastering. Plenty of topics on this if you do a read through the forum. I think Biff and Gervase have both posted good instructions. I think I do it too wet

 

[biffvernon]

ok, thanks. So, can I buy lime plaster in a 'just add water' format? And where can it be bought from?

You can buy it in ready mixed form where you don't even have to add the water. Google for "Lime Putty" gives several specialist suppliers.
Or you can get a bag of lime from any builders merchant and mix with sand in a ratio of about 3:1 sand:lime and add a little water to make a workable mix. Seach for 'lime' on this site and you will find hundreds of hours worth of reading!

 

[mark_j_k]

Just out of curiosity, what sand is best to use; regular building, sharp, or some other kind.

 

[BMcD]

mark_j_k wrote:

Just out of curiosity, what sand is best to use; regular building, sharp, or some other kind.

Well graded Sharp sand. Builders merchants will generally have a plastering sand in stock. This should have been passed through a 5mm mesh to extract the courseness out of the sand leaving a good proportion of partical size making it more workable (sand with larger particals are less workable and smaller particals are less durable). The angular (sharp) particals interlock, with the smaller ones filling voids and adding strength. It's a good idea if you mix up your hydrated lime into a putty a few weeks before you need it and keep it in an air tight container with some water covering the surface and use this to mix your coarse stuff (3:1 sand:lime) . This allows the lime to fatten up adding to the workability.

 

[BMcD]

chrisauk wrote:

can I just get it plastered directly onto the brick?

After just reading your new post and seeing the pictures I'd be inclined to say no. Soot is just plain nasty, even when you think it's all cleaned off you can't get anything to stick to it, it bleeds through your finished work and it stinks. I don't know if a parge would work, I've never tried it. I know it's used for lining flues but I don't know of anyone using it for going over soot. I'd be interested in hearing anyones thoughts on this but since it's made up of 4:1 lime putty:slurried cow dung I don't imagine it's very popular.