Dot & Dab or or 2 coat plaster

[macadonald]

Hi guys,

Live in a 1930's terraced house and taken all my plaster off down to brickwork in a few rooms (got carried away after finding a few blown sections). After hearing various opinions, my question is:

Do I apply a traditional scratch coat and skim coat or make it easy and dot & dab plaster board onto the brickwork and skim?

I get the feeling either will work, but there's a proper way and shortcut way?

I'm guessing I will get supporters of both methods.

 

[Richard C]

Firstly be aware that if you strip more than 24% of the plaster from external walls, it’s considered as changing a thermal element & Building Regs. require that you upgrade the insulation on these walls to current standards. Now no one will ever know unless you tell them but if you’re having any other work done in the house that requires BI visits you could come unstuck if they spot it; just be warned as it’s happened!

As for the plaster; base coat & finish skim would be the “proper” job, base coat can be either a base plaster or render float & set.

12mm Dot & dab boards is a quick & dirty fix; much cheaper & quicker but not so hard wearing, doesn’t take fixings well unless you go through them & will sound hollow if you don’t close board.

Do you have cavity or solid brick walls? If solid brick then dot & dab method not a good idea unless you insulate as it can lead to problems with cold spots & condensation. You may also want to consider upgrading the insulation on external walls at the same time. Are you considering DIY plastering, if so have you done any plastering before?

 

[macadonald]

Cheers for that Rich,

Regarding the Building Regs, I think I'll just keep things hush hush. It is a double skin brick house, but with no cavity, so I don't think dot n dab is a good idea.

To be honest I think I now know that 2 coat plaster is the proper way and think I will do it this way. I have recently done 2 coat render on an outside retaining wall and it was a big learnign curve, but think it turned out damn well IMO.

I don't plan on doing the finishing skim coat myself, but had planned to do the scratch coat myself to save money.

Sorry for my ignorance, but what's the difference between 'base plaster or render float &set'? I think I did the latter before which involved setting metal 10mm trim guides, applying a 4:1 sand cement mix and then ruling this off. What is base plaster?

Cheers

 

[roughcaster]

Base coat (undercoat) plaster could be Hardwall, Bonding Coat or even Browning, ( less favoured nowadays, than the other two) Render float and set would be a cement render float coat, (ie render base coat) as opposed to an plaster base coat. The render float coat would then be finished (set) with multi finish,, the same finish you would use on any base coat plaster.