Multifinish Vs. Board Finish

Hi all,

Just bared all walls in house to brick (as plaster was blown everywhere) and dot and dabbed soundboard to them.

I'll be skrim taping the weekend and prob by next week should be ready to start skimming.

Am new to 'plastering' but have just tried a fireplace and it turned out ok so think the technique is ok, but the reason for posting is that I want to guage peoples opinions on what to use.

Most plasterers tend to use Multifinsh, but would I be better with board finish bearing in mind I have boarded? Can you please give reasons for answer so I know the difference?

I have bought a bag of both for testing purposes so will find out in due course, but it would be nice for comments from you guys/gals as you have a lot of experience. Would one be more forgiving bearing in mind I'm learning?

Can't really pay a pro before it gets recommended as low on funds so will have to just learn quick.

Thanks in advance.

headworx said:

Just bared all walls in house to brick (as plaster was blown everywhere) and dot and dabbed soundboard to them.

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Hope they aren’t solid brick external walls youve D&D'd onto? Don’t let your LABC find out what you’ve done or you may get a nasty shock when they tell you they want the external walls upgraded to current insulation standards. Know as the 25% rule for changing a thermal element (the plaster); it has happened when BI’s call in to inspect other notifyable work.

headworx said:

Am new to 'plastering' but have just tried a fireplace and it turned out ok so think the technique is ok, but the reason for posting is that I want to guage peoples opinions on what to use.

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Are you using the fireplace for any sort of fire/stove? If so, Gypsum plaster or plasterboard (even Fireline) won’t stand more than 49C, it’ll crack & fall off! I have a lot of other info I can give you on that one.

headworx said:

Most plasterers tend to use Multifinsh, but would I be better with board finish bearing in mind I have boarded? Can you please give reasons for answer so I know the difference?

I have bought a bag of both for testing purposes so will find out in due course, but it would be nice for comments from you guys/gals as you have a lot of experience. Would one be more forgiving bearing in mind I'm learning?

Can't really pay a pro before it gets recommended as low on funds so will have to just learn quick.

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Its one thing to skim a small area such as fireplace, quiet a different matter to do a whole wall & ceilings are 3x more difficult. Plastering is time critical & one of the most difficult of trades to master, the larger the wall the more problems you will have & will almost certainly run out of time when you first start out. I’m self taught & have high standards so it is possible & you could be a natural like me but many go at it for years & are still NFG; you would not believe some of the attempts I’ve seen (even in my own home but that’s another story)+ the sob stories & pics we get on this forum. Your first attempts are likely to look like sheite until you understand the materials your using, get your speed up & master the techniques/little tricks of the trade. Two sucessive coats (ideally the same mix) is normaly accepted practice & will give you more time to finish off but you will have to be quick to get it on there (40-45 mins max really) & leave yourself enough time to finish off; dont go getting too hung up about it though, especially when skimming nice flat boards.

Most use Multi on everything as indeed I now do; some say Board finish gives a better off the trowel finish but I’ve not really noticed. Multi goes off slightly slower on boards so will give you a little more time which can be useful if your not experienced & you can slow it down a little more by PVAing the boards but it’s not normally done or required.

Never use out of date or badly stored plaster; B&Q trade is one of the best places to buy it IMO, it’s well stored (not in some damp BM’s tin shed with the doors open all day) & they sell so much of it it’s a quick turn around. Always thoroughly clean your tools between mixes or it will shorten the cure time of your next mix; don’t over mix or mix too quickly or, again, you shorten the cure time & aeration can be a problem. Don’t fall off your hop up (as I did once) or get it in your eyes or you could end up in hospital.

Just remembered the wiki;
//www.diynot.com/wiki/plastering_and_rendering

Hi Richard, cheers for your full response.

I found out about this 25% thing after I had bared all the walls - But to be fair every wall was blown anyways so would have needed to come off anyhow.

If I've read your post right, does the 25% thing only relate to external walls as I haven't done them yet?

With them I was going to put an internal render on, then dot and dab soundboard, then skim - Does this sound like it would meet the BC requirements?
The bathroom, I was going to internal render with waterproofer, then moistureboard it (aquapanel is a bit dear so opted against it).

As for the fireplace - No they will not be used, I'm planning on blocking them up and placing an air brick in to vent.


Thanks for the advice on the multi finish, will use that then to give me longer.
Getting it done by a pro isn't really an option as I have to blow what money I have left on getting the kitchen extension re done, so it's on the cheap.
I'll have to learn quick! I will though only attempt a wall at a time and start with the smaller ones to build my techniques up. Time isnt't too much of an issue, and I too am a bit of a perfectionist.

Hopefully I'll be able to post back soon with some pics of a triumph and not a disaster.

A Couple of quick questions:

I presume the angle ead stuff is only for external corners?
How thick should I be doing each coat of skim?

Thanks again. [/b]

With Part L I think you're supposed to get the U-value of external walls down to 0.28 W/m²/°C, which might require something like 70mm of PIR insulation (Kingspan or Celotex) on solid masonry walls.

headworx said:

If I've read your post right, does the 25% thing only relate to external walls as I haven't done them yet?

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Yes internal walls are not “thermal elements” as far as I’m aware.

headworx said:

With them I was going to put an internal render on, then dot and dab soundboard, then skim - Does this sound like it would meet the BC requirements?

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Unlikely I would think; I don’t know the exact requirements but see ajrobb’s post, take a look at Building Regs part L1B & Part L2B;
http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/approved
If your going to go down the submission route, you need to talk to your LABC to ensure you get it right or they won’t sign it off. Additionally you must be careful how you treat external solid walls; any render must be waterproof but that’s probably not the best way to go if adding additional insulation. D&D is not advised as it will create cold spots causing condensation & you will get all sorts of nasties growing behind the board; the best route is use a vapour barrier, insulation & board over or fix a proprietary insulation board such as Thermaline Plus;
http://www.british-gypsum.com/produ...es/gyproc_thermal/gyproc_thermaline_plus.aspx

headworx said:

The bathroom, I was going to internal render with waterproofer, then moistureboard it (aquapanel is a bit dear so opted against it).

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If this is an external wall then the above applies. If internal, don’t bother with the render it won’t give you any advantage. If by moistureboard you mean Moisture Resistant plasterboard, this is OK for "dry" areas but if you use it in "wet" areas, it should be tanked if you want it to last; when you factor in the cost of tanking, a waterproof tile backer board is the only way to go IMO. If your having 1/2 tiled/plastered walls, MR board must be primed before plastering

Please ensure you read the Tiling Forum sticky & Forum archive posts before you start or buy any materials, it could avoid you making potentially catastrophic & expensive mistakes.

headworx said:

As for the fireplace - No they will not be used, I'm planning on blocking them up and placing an air brick in to vent.

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Also fit rain caps to the pots.

headworx said:

Thanks for the advice on the multi finish, will use that then to give me longer.
Getting it done by a pro isn't really an option as I have to blow what money I have left on getting the kitchen extension re done, so it's on the cheap. I'll have to learn quick! I will though only attempt a wall at a time and start with the smaller ones to build my techniques up. Time isnt't too much of an issue, and I too am a bit of a perfectionist.

Hopefully I'll be able to post back soon with some pics of a triumph and not a disaster.

Click to expand...

Read the Plastering Forum archive posts, loads of information & guidance in there & post if you need further advice; good luck with it.

headworx said:

I presume the angle bead stuff is only for external corners?

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Yes

headworx said:

How thick should I be doing each coat of skim?

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Overall skim thickness is usually between 3-5mm; you won’t be able to go much thinner than 1.5mm due to the grit in the plaster.