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DIY Forum >> Building Questions >> Spots appearing on plasterboard
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Message started by Overrunning Project on Dec 18th, 2016, 5:16pm

Title: Spots appearing on plasterboard
Post by Overrunning Project on Dec 18th, 2016, 5:16pm

Hi
We are towards the end of an extension project and the plasterboard has been up for almost a couple of weeks now.  In certain areas on the ground floor we are noticing spots appearing on the plasterboard (see photos).  They are also appearing around the plasterboard bordering of our newly installed bi fold windows.  Does anyone know what these are and if anything should be done about them?

[album]ijolly4&1482080697[/album]

Thanks

Title: Re: Spots appearing on plasterboard
Post by woodsmith on Dec 19th, 2016, 8:15am

Do you know how the wall is constructed? This looks like a new build rather than a conversion but round dots on plasterboard are normally caused by damp bridging from the outside wall through the dab of adhesive which is used to fix the plasterboard to the wall. Same round the window/door, you can get the same problem as a bead of adhesive is used all round the window to bond the plasterboard in place. This sort of problem would not normally happen with a new build though as the cavity wall protects the plasterboard, but I've seen it a few times in older houses with solid walls.

Perhaps the room has not had enough ventilation as it is drying out and this is where condensation is forming causing the mould to grow?

Title: Re: Spots appearing on plasterboard
Post by Overrunning Project on Dec 19th, 2016, 11:18am

Hi
Thanks for your reply.  The photos with the window are part of an extension to the rear of the property (pushed out about 1m) and I think the plasterboard is applied to the block work.  
The other photo is part of the original property that was stripped and had plaster board re-applied to brick to what would have been an inner wall to the original builds external side wall but we have extended around the side of the house as well so this now has another room on the other side.
There has been a large concrete infill on the ground floor that was done after some of the plaster board had been installed.  Further plaster board has been installed post concrete so there could be condensation that is causing the mould.
Is the mould a problem?

Thanks

Title: Re: Spots appearing on plasterboard
Post by woodsmith on Dec 20th, 2016, 8:31am

If the mould is caused by the building materials having been soaked, we've had some very wet weather of late, and lack of ventilation then once you get it dried out it should not cause you any further problems. I would look at hiring an industrial heater for a weekend and run it with the windows open but have a word with your builder first if you have any concerns.

Title: Re: Spots appearing on plasterboard
Post by londonman on Dec 20th, 2016, 5:39pm

Shouldn't there be some sort of cavity insulation in the blockwork? I'm not sure..just a thought.  If there isn't then that wall will always get cold surely and condensation form.

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