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BANGKOK 22 May 2019 11:43
The Deerhunter

Repainting concrete where paint has fallen off

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Had a house built 3 years ago and they refused to do the painting to the standard I wanted.  We only got one very thinned down coat of concrete primer round the edges of the plastered concrete block walls as they hated using a brush. "Roller or nothing and rollers are too had to use near edges." 

That and the lack of a dampcourse membane between foundation and blocks has (I presume) caused white powdery efflorescence and paint bubble off near the floor on the outside of the house.  I have done one section a year ago and it seems OK now but I need to do a lot more.  I intend to gently waterblast (pressure wash for you Americans) the damaged paint off and am wondering about pretreating the concrete surface before repriming it.  As the efforescence is likely alkaline in type how about I pre treat the exposed render with diluted white vinegar or similar.  Any ideas or advice?  Also, what is the best primer-sealer-undercoat to use in these circumstances that is available at Homepro or Thai Watsadu?

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14 minutes ago, Rimmer said:

Moved to DIY forum

That is where I thought I put it.  Sorry.

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I wouldnt use a pressure washer. Efflorescence is chrystalised salts that have been left on the surface after water has or is still trying to evapourate.

further use of water simply exxacerbates the problem.

Use a wire brush initially to clean the surface then continue to let the wall dry out for as long as youre happy.

If its ground water thats rising thro the concrete its too late to stop that but you can treat tge surface with a silicone wash first.

I dont like to do that as it just seals the walls and encourage damp to take another route.

If there is such a producr here ad a microporous breathable primer then start with that, and follow up with a similar topcoat.

Your typical tubs of mixed paints claiming 5,7,10years are crap and are no different to enamel paints in that when water gets behind them they can be peeled of in pieces.

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20 minutes ago, eyecatcher said:

I wouldnt use a pressure washer. Efflorescence is chrystalised salts that have been left on the surface after water has or is still trying to evapourate.

further use of water simply exxacerbates the problem.

Use a wire brush initially to clean the surface then continue to let the wall dry out for as long as youre happy.

If its ground water thats rising thro the concrete its too late to stop that but you can treat tge surface with a silicone wash first.

I dont like to do that as it just seals the walls and encourage damp to take another route.

If there is such a producr here ad a microporous breathable primer then start with that, and follow up with a similar topcoat.

Your typical tubs of mixed paints claiming 5,7,10years are crap and are no different to enamel paints in that when water gets behind them they can be peeled of in pieces.

all great suggestions, lime coming out of the concrete is normal here, the moisture just keeps dragging it out. Unfortunately I seriously doubt they will have the required material in Thailand, I have been trying to find certain paints here for years(it was my trade for over 30 years) to enable me to do certain work on our house but they simply dont stock them. Even if the walls were neutralized with an acid wash I doubt you would be able to stop the lime build up, rendered walls really need a block filler applied but due to the quality of the builders in Thailand and the lack of quality paints I doubt there is a lot that can be done about it, even with me doing the right thing here we have lime problems inside and outside our house on the bottom of the walls, moisture is just a part of thai life

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17 hours ago, seajae said:

all great suggestions, lime coming out of the concrete is normal here, the moisture just keeps dragging it out. Unfortunately I seriously doubt they will have the required material in Thailand, I have been trying to find certain paints here for years(it was my trade for over 30 years) to enable me to do certain work on our house but they simply dont stock them. Even if the walls were neutralized with an acid wash I doubt you would be able to stop the lime build up, rendered walls really need a block filler applied but due to the quality of the builders in Thailand and the lack of quality paints I doubt there is a lot that can be done about it, even with me doing the right thing here we have lime problems inside and outside our house on the bottom of the walls, moisture is just a part of thai life

Durn it!!!  You offer pretty disappointing news.  Also I was wrong about the repairs I did last year.  They are peeling off already. Pic x835 below is from last year's repair and it is showing bare concrete under a loose paint skin already.  Pic x849 is part of the 28 lineal metres that at least need current repair from the original paint job 2 or so years ago.   We are moving back to my home country to live soon so what I do not do in the next 8 weeks will not be done by me.  I am a fair bit older than my wife so it is likely she will come back to live here in a few (or not-so-few) years, and I was hoping the paint could be still on her retirement home when she got back after my eventual demise.  Is there nothing that will give a repair beyond a year or so?  I have had to use a low powered water blaster as 30 metrs with a wire brush on my hands and knees in this heat is beyond me and in our area labour is almost impossible to find.

20190313_174835.jpg

20190313_174849.jpg

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18 hours ago, eyecatcher said:

I wouldnt use a pressure washer. Efflorescence is chrystalised salts that have been left on the surface after water has or is still trying to evapourate.

further use of water simply exxacerbates the problem.

Use a wire brush initially to clean the surface then continue to let the wall dry out for as long as youre happy.

If its ground water thats rising thro the concrete its too late to stop that but you can treat tge surface with a silicone wash first.

I dont like to do that as it just seals the walls and encourage damp to take another route.

If there is such a producr here ad a microporous breathable primer then start with that, and follow up with a similar topcoat.

Your typical tubs of mixed paints claiming 5,7,10years are crap and are no different to enamel paints in that when water gets behind them they can be peeled of in pieces.

Please see also my most recent post on this disappointing matter.  

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On 3/14/2019 at 1:46 PM, The Deerhunter said:

Please see also my most recent post on this disappointing matter.  

The wall needs to dry out.....again now that you have soaked it!

Dont use water on a building again, water is the biggest cause of damage in buildings.

 

I surmise that as typical proceedure here, render the wall then paint three days later and piss off before the paint falls off.

Because its hot and sunny everyone assumes a wall is dry in 24hrs its not.

i reckon the dry line at the bottom is the original cocrete ring beam then the problem startrs with the block or brick which would have been hosepiped before rndering. Most of the water will have collected in the bottom course.

 

I would think after drying out you can repaint it again, the problem isnt happening higher up.

 

Other checks to make.

1.make sure you dont have a water pipe running along that wall internally that could be leaking.

2. Try to minimise rain splashback from that concrete area that is potentiaally keeping that plinth area wet.

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Posted (edited)
On 3/16/2019 at 7:10 PM, eyecatcher said:

The wall needs to dry out.....again now that you have soaked it!

Dont use water on a building again, water is the biggest cause of damage in buildings.

 

I surmise that as typical proceedure here, render the wall then paint three days later and piss off before the paint falls off.

Because its hot and sunny everyone assumes a wall is dry in 24hrs its not.

i reckon the dry line at the bottom is the original cocrete ring beam then the problem startrs with the block or brick which would have been hosepiped before rndering. Most of the water will have collected in the bottom course.

 

I would think after drying out you can repaint it again, the problem isnt happening higher up.

 

Other checks to make.

1.make sure you dont have a water pipe running along that wall internally that could be leaking.

2. Try to minimise rain splashback from that concrete area that is potentiaally keeping that plinth area wet.

I have nearly completed my waterblasting of the affected areas, some for the second time.  Waterblasting was essential as wire brushing this area would have been nigh on impossible and if done with machinery, even more destructive that water blasting with the weakest machine Karcher make.  The house has extreme overhang of over 1.5 metres and wide surrounding walkway with a second foundation in the perimeter to protect the main wall foundations in heavy rain.  It is on a slope and we get lots of water rushing through in rainy season,.  There are no water pipes in the walls to be leaking and I am sure the main problem is a result of the lack of a dampcourse membrane.   After a week or two of drying (and the lower edges of the house walls get lots of direct sun), I will tidy up with sandpaper and a hand wire brush.  Lacking advice for suitable products available here I am using the two products shown below.  Sealer first perhaps several coats after wife translates the directions, then a different brand primer that used originally or last time.  We leave LOS in May to live overseas and I am trying to keep the property reasonable for when she may want to return after I shuffle off.  I do not expect it to be a 100% success but hope for better than the one, two or three years as we have now seen.  Also the water table even in wet season is over 5 metres deep so I was surprised at the amount of water uptake in the walls.  Hope for the best and will be somewhere else in 2 months, anyway.

I am not very good at this adding pictures thing.image.thumb.png.4374652423c96a5a4421cd888953e69f.pngimage.thumb.png.a151f45186d3d479f6d57d15a6df7837.png

Edited by The Deerhunter

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The OP might check with DR Fixit line of repair solutions in Thailand. The MD of this building materials company attended High School and University in Texas. He told me that they will soon have a cost effective line of floor coating for grow rooms in Buriram Thailand. His focus is to provide solutions to construction challenges in Thailand. The woman I buy Dr. FixIt wall and floor coatings from in Buriram speaks Thai German and English. Dr. Fix it has catalogs in English as well as Thai language. Global House, Hardware House and independent builders merchants stock this brand which offers solutions to problems as outlined by the OP. 

Buriram Home Builder Expo 2019.jpg

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21 minutes ago, kamalabob2 said:

The OP might check with DR Fixit line of repair solutions in Thailand. The MD of this building materials company attended High School and University in Texas. He told me that they will soon have a cost effective line of floor coating for grow rooms in Buriram Thailand. His focus is to provide solutions to construction challenges in Thailand. The woman I buy Dr. FixIt wall and floor coatings from in Buriram speaks Thai German and English. Dr. Fix it has catalogs in English as well as Thai language. Global House, Hardware House and independent builders merchants stock this brand which offers solutions to problems as outlined by the OP. 

Buriram Home Builder Expo 2019.jpg

Thanks but job done now.

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when you have a rendered wall to paint normally you let it dry completely then block it to remove all the loose surface then apply the correct coats of paint, this simply doesnt happen here  as they want everything done straight away. The peeling paint is at the bottom of the wall which is the natural place for moisture to travel in the cement render taking all the lime with it which in turn caused the paint to bubble then peel. Moisture guard is designed for exterior walls to stop water penetrating the walls not coming out of the wall, you need to allow the rendered walls to dry fully then clean them off to stop the lime problem

 

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when you have a rendered wall to paint normally you let it dry completely then block it to remove all the loose surface then apply the correct coats of paint, this simply doesnt happen here  as they want everything done straight away. The peeling paint is at the bottom of the wall which is the natural place for moisture to travel in the cement render taking all the lime with it which in turn caused the paint to bubble then peel. Moisture guard is designed for exterior walls to stop water penetrating the walls not coming out of the wall, you need to allow the rendered walls to dry fully then clean them off to stop the lime problem
 

So, are you saying that after removing all the loose peeling paint the surface can be simply repainted using paint only ?
The reason I’m asking is my house was last painted 2 to 2 1/2 years ago , I moved in just short of 2 years ago, and in many places lower down the paint has bubbled and peeled off. It’s all protected from rain now and has been for around 1 1/2 years and am getting ready to repaint.

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On 4/5/2019 at 5:37 PM, seajae said:

when you have a rendered wall to paint normally you let it dry completely then block it to remove all the loose surface then apply the correct coats of paint, this simply doesnt happen here  as they want everything done straight away. The peeling paint is at the bottom of the wall which is the natural place for moisture to travel in the cement render taking all the lime with it which in turn caused the paint to bubble then peel. Moisture guard is designed for exterior walls to stop water penetrating the walls not coming out of the wall, you need to allow the rendered walls to dry fully then clean them off to stop the lime problem

 

If what you are saying is correct then I should be alright except for water still coming up from the concrete path.  It did dry out properly before painting.  Direct Thai sun for  a number of days before sealing and painting.

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2 hours ago, The Deerhunter said:

If what you are saying is correct then I should be alright except for water still coming up from the concrete path.  It did dry out properly before painting.  Direct Thai sun for  a number of days before sealing and painting.

A number of days won't dry it out, it needs weeks.

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