can I skim direct onto brick wall?

[garyo]

One of the walls I need to plaster is a new brick wall. The pointing is flush with the bricks, so the surface of the wall is pretty much flat.

What is the purpose of a bonding layer, or dot'n'dab in this situation? To stop the skim later cracking in a pretty brick work pattern?

Cheers

Gary

 

[noseall]

try skimming a bare brick wall and see how it turns out!

it will end up cracking and what you have left will probably either fall off or get knocked off.

or is this a wind-up, 'cause it sure seems like one.

backing plaster (browning, bonding,cement render) or dabbed plasterboard is an ideal substrate to which you can skim successfully.

 

[garyo]

No - not a wind up, just wondering why things are done the way they are!

 

[MrTeeny]

Finish plaster is hard and wouldn't flex with any movement in the brick so would just crack along the brick lines with any movement. Bonding plaster or sand/cement render is more forgiving and acts as a floating coat to absord any movement therefore stopping the finsih coat cracking

 

[noseall]

finishing plaster is a very dense powder and holds relatively little water per volume. therefore, when applied to a dry substrate, it will dry out quickly and shrink. and crack.

finishing plaster must be applied to a low-moderate suction medium. if the backing plaster has completely dried out then it must be wetted prior to skimming.