Some opinions on this spec please

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DannyMac

DannyMac

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We're doing a pool house and the guy wants to soffit outside to look like a continuation of the plasterboard skimmed ceiling inside. It's been suggested that we use the green moisture boards, skim, oil based undercoat followed by a real good exterior paint.

In theory, sealing it completely from the weather. I know gypsum on the exterior is frowned upon but once it's totally sealed could it work on this area that doesn't receive direct sun or rain?

What other systems could be used to achieve a smooth flat surface like the inside?

There is also a 15mm gap that needs to be created around the entire perimeter of the soffit where a LED strip will sit.

Some pics...

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There'll also be a metal fascia that will lip under a few inches.

Thanks for looking.:-)
 
Weve done it before but it was only a small area. Could you not use the external (yellow?) Board then tape and joint
 
beddy said:
Weve done it before but it was only a small area. Could you not use the external (yellow?) Board then tape and joint
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That's a possibility, how much are those boards? We need about thirty.


The knauf green moisture boards state on them to use betonkontakt before skimming. I've never used a bonding agent on them before, has finish been failing on them?? I've not read anything on here like that.
 
All MR boards should be treated first. Think its say so on the bags of multi. Although I have never had any fall off.
 
DannyMac said:
That's a possibility, how much are those boards? We need about thirty.


The knauf green moisture boards state on them to use betonkontakt before skimming. I've never used a bonding agent on them before, has finish been failing on them?? I've not read anything on here like that.
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Same as, never ..
 
superspread said:
I think youll be mad to put m/r board outside . Asking for trouble IMOIMO
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Why do you think that, what would make aquapanel more suitable in this instance?

There shouldn't be any moisture from above or below once it's painted.

My doubts come from how the mr board will perform under freezing conditions?
 
Ive skimmed mr boards untreated before and never had a comeback but it was never outside. Not sure how much the yellow boards are. Ive never used them but seen one of the machine lads post a job he did with them a while back.

Another possibility. Could you aqua panel then thin coat. Rub it up and flatten with a trowel. @Runswithscissors
 
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DannyMac said:
Why do you think that, what would make aquapanel more suitable in this instance?

There shouldn't be any moisture from above or below once it's painted.

My doubts come from how the mr board will perform under freezing conditions?
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Youve answered your own question,cos its protected above and below means nothing,why not sand and cement?
 
superspread said:
Youve answered your own question,cos its protected above and below means nothing,why not sand and cement?
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Because it would be a massive ballache and I have to create a very straight 15mm channel, mid soffit, all the way around the building where a led light strip sits.
 
i dont think it would make that much of a diff job i was working on down cheltenham did all the car ports ceilings in soundblock and the bit under the building itself and just skimmed it they had no problems
 
we had a spec for a job that was soundbloc on the underside of some flats (on stilts) so you could walk under the building kind of similar we skimmed it and it was or still is fine........as far as i know:RpS_confused:
 
Hi Guys

I would not advise the use of Gypsum board in an external application, moisture will eventually get into the core (in the form of dew, or through joints or fixings) and make it heavy and soft...... especially a soffit, where it is likely to just fall down (gravity is a cruel master....)

Knauf Aquapanel Exterior with a thin coat basecoat and mesh, smoothed out, then painted up would be the best method (as @beddy said earlier).

Knauf Aquapanel Exterior is Freeze Thaw tested and is ideally suited for this application (we even do 1200 x 900 boards for soffits - lighter boards!)

Danny - give me a shout tomorrow if you want to discuss it further....
 
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I insisted that the edge which sits under the fascia is painted with an oil based undercoat before its fitted and advised him that it wasn't exactly a "by the book method".

He, with this information gave us the go ahead.
 
LOL

Not really recomended...... I bet they are up and finished as well..... LOL

Read what it says on the back of the boards... I am pritty sure you have to prime MR boards before skimming - for internal applications..... externally, do what you want - it is your problem... LOL

It should last until the cheque has cleared..... lol
 
ive given up telling builders green board needs to be primed prior to skimming they always ignore me.
i have seen it shell off before tile weight pulled it clean off the board the board was still clean as a whistle
 
sorry mate..... outside my expertise now......

if it is internal - Betokon...... Beterko...... what you said...... is the spec....

depends on what you planning on finishing it with..... with skim stick to SBR....?

I don't know.... not my area of expertise.... LOL
 
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