Efforecesence in concrete blocks and render?

[scotslad]

alright

 

Just wondering if I cold ask any builders/plasters/knowledgeable people on here.

 

Just finishing building a kennel block but some of the blocks have a lot of efforecense on them, in fact odd 1's are almost white. Got the blocks cheap a few years ago as miss sized and been sitting outside uncoverd until recently.

 

I'm planning to render it to waterproof it but will the efforecense affect the render and it bonding with blocks?

Should I treat the walls wit something or pwer wash the salt's off before rendering or put some special additive in the render.

 

I'll probably leave the worst of the white blocks out but there will stil be a few with runs down them.

I had a bit of a google online but nothing much about rendering on top/over it.

 

Cheers

[Red-dot]

Brickclean acid wash.

[rob-d]

acid is the only thing that will remove it!

if you are planning to waterproof it then clean the blocks down with acid then blackjack the exterior and the render it. salts stopped and waterproofed all in one.

[scotslad]

Cheers folks

 

So I take it the render won't stick to the salts then?

And probably a good idea not to use the worst of the blocks.

 

Never used brick acid before, I take it u just paint it on and wash it off?

With the black jack do u let it dry and render on top of it or are u better rendering on top of tacky black jack.

Only time i'v used it before was to tank my old garage/retaining wall and stick some heavy tar stuff to the back.

[rob-d]

follow the instructions on the container of acid, just make sure you have gloves and glasses on.

the black jack will take a couple of coats with the first one being watered down a bit to make sure it goes in all the holes. after applying the second coat and while its still wet flick some sand onto it this will help with the render sticking. or you could apply a thin scratch coat of render to the wall and then apply the black jack to that. there might be some videos on youtube?

Edited August 6, 2017 by rob-d

[TIGHTCHOKE]

Have a read through this;

 

https://www.marshalls.co.uk/homeowners/inspire-me/articles/how-to-treat-efflorescence-4197

[oldypigeonpopper]

Have a read through this;

 

https://www.marshalls.co.uk/homeowners/inspire-me/articles/how-to-treat-efflorescence-4197

hello tightchoke, you know all the good links

[TIGHTCHOKE]

Thanks, I am at work and have plenty of time to search for stuff.

[oldypigeonpopper]

hello, if that were me i would black jack internal and render external using PVA in the water, i did my sons front wall that way and using £ SHOP PVA and a nice smooth finish

Edited August 7, 2017 by oldypigeonpopper

[oldypigeonpopper]

Thanks, I am at work and have plenty of time to search for stuff.

hello, oh sounds a good job i have been searching for ever on a rifle part could i pm so you might be better than me at finding one. cheers

[TIGHTCHOKE]

Yes of course.

[millrace]

Ive said it before and will do so again.....pva is not for external use......read the jar!!!! The clue is pva is water soluable.....sbr or rend aid......

As for the blocks bin them and get some new ones cheaper than all the faffin about and no salts to worry about....

[Red-dot]

Call Banksy he will cover it?

[Twistedsanity]

As it's moisture that brings the salts out would a thick coat of render not stop the blocks from getting wet? House up the road tried allsorts on their brick wall including acids and it looks horrendous, I used a floor scrubbing brush to brush the dried salts off when they came out then a hosepipe, took a few goes but sorted it nicely