Green backed Plaster Boards

[wozza]

I have a new build in Buriram and the builder fitted green backed plaster (gyprock) boards under the eaves around the verandah that goes right around the house, problem is when the eves get water on the from gusty windy rain  the areas leave green marks, i demonstrated this by pointing a hose on a section and within an hour the green appeared , Is it the paint quality that does this or the preparation of the plaster, the areas that are exposed to rain has the paint peeling off. 

[eyecatcher]

A green backed plasterboard always represented a moisture resistant board, however that was usually for internal conditions such as a bathroom and kitchen.

They are not waterproof and really should not be used in an external position such as yours.

There are purpose made eaves boards for outside.

 

I think the green dye is the tip of the iceberg.

[SimpleMan555]

The 'Green Paperbacked Plaster Board' is only water resistant and designed for use in areas of periodic high humidity, and as a base for tiling, not for exterior wet areas. It will still absorb water and the staining is a result of the water pulling the green color to the surface. 
From your picture and text, I assume this is on a soffit area of the roof overhang? This area should not really be getting wet except under the most extreme of circumstances. The problem will persist unless you prevent the rain from hitting the surface or cover with waterproof material. 
 

Is it possible to install a wider Facia board with a drip edge that could help prevent wind-blown water from traveling across the soffit?
 

It might be possible to cover the plasterboard with soffit boards (designed for exterior areas), but if it were me, I would remove and then replace with the soffit material designed for a wet location. More pictures of the Soffit and the Facia would make it easier to understand. ????

Hope this helps, Cheers!

[wozza]

 

 

Thanks for your input

1 directly impacted by rain   

 

2  Large stained image caused by leaking roof tiles 

 

3 Eaves and Facia 

 

 

 

[David B in Thailand]

Green Plasterboard would not be my choice for soffit or eve areas. Conwood | Diamond Wood | Elephant Wood | Shera wood sheets or boards are specifically made in Thailand for soffit or eve areas. Every Home building center sells soffit boards and sheets. Soffit boards are easy to repair. Shera dealers employee well qualified technical advisors to assist your Buriram house builder in selecting the best outdoor ceiling soffit boards when you build a home or repair a home in Thailand. 

[Kwasaki]

2 hours ago, wozza said:

1 directly impacted by rain   

 

2  Large stained image caused by leaking roof tiles 

 

3 Eaves and Fascia 

1.  First things first are you able to withhold any money from builder if he specified the use of the wrong soffit material and any dispute sorted if possible.

 

2. Get your roof leaks fixed and see if the underlay has been installed correctly and leave everything as it is until a rain test.

 

3. Your 1st pix looks like rendered concrete and the fascia is of bad design it should be spacered off the wall to form a drip.

 

4. When everything is dried out go about replacing external plasterboard, you could do it section by section in the most exposed areas first.  

[wozza]

1.  First things first are you able to withhold any money from builder if he specified the use of the wrong soffit material and any dispute sorted if possible.

Finished 6 months ago and paid in full , The builder is a reasonable guy  I have had some minor issues and he has been here within 2 days to rectify 

 

2. Get your roof leaks fixed and see if the underlay has been installed correctly and leave everything as it is until a rain test.

He is coming back to fix the roof and he said he will take off all the tiles in that section and start again until its fixed

 

3. Your 1st pix looks like rendered concrete and the fascia is of bad design it should be spacered off the wall to form a drip.

No thats the green board again not concrete, but good suggestion re spacer

 

 

4. When everything is dried out go about replacing external plasterboard, you could do it section by section in the most exposed areas first.  

Yes and thanks for your reply and suggestions , again this builder stands by his build and far as Thai builders go has so far honoured any defects, early days we are still working something out for a fix. We have made recommendations since our completion and after showing our home to these people he has now 6 more projects on the go  , He knows we can send more projects his way or none , so i dont think there will be a problem.

 

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[canopy]

Everyone has said it already. Gypsum is not for outdoor use. It is the wrong material. Use a product such as SCG Smart Board. They have vented and screened types ideal for soffits, or wood look, or solid like yours. Just dozens of styles to choose from.  Or choose another company product line. Just don't use gypsum outdoors. The stuff you want is the same material as your fascia boards but comes in thinner panels.

 

[wozza]

Yes I understand now Gypsum is not the choice for outdoors and it will be replaced with smart board or similar  Thank you all for your help and suggestions