# Forum Home Renovation Brickwork  Block Retaining Wall  - what to use for waterproofing?

## scoobysteve

hi Guys, 
i'm nearing (75%) completion of my masonry block retaining wall. I need to waterproof/seal the back of the wall.  
Anyone know what product i should use? I've read in previous post that people use bitumen paint? I have no idea what that is. 
I ducked into Bunnings yesterday to see what they got, and i'm not sure what to use as there is so many differents types -- is it a sealer I buy? or a water proofer? the naming is all different on the products. Are there different ones for external use and internal use? 
any suggestions on brands and where to get them would be great. thanks.

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## Bros

I had a block wall to seal and I used a mixture of bondcrete, cement powder and water and I painted it on.  
From memory the proportions were on the bondcrete tin.

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## Blocker

"Gripset 51" is a water based ,easy to use ,reliable product for this type of job.
Generally available everywhere. 
Regards,
Blocker :2thumbsup:

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## scoobysteve

thanks guys... gonna duck into bunnings this arvo or tomorrow morning and see if they've got it.. 
i know they've got bondcrete just not sure about Gripset 51.

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## cherub65

we use gripset 51 its quick and easy to apply, but if the wall totally needs to be waterproof either use a vertical plastic drain or coreflue directly against the wall, then backfill

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## GrahamC

I bought Duromastic BLW from Wrimco in Leichhardt. I'm finding it very easy to use. I also put on a 1 pack expoxy primer underneath. It takes me a whole day to do one coat (60 sqm) - I'm doing it by brush because the space I am working in is so narrow and deep.

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## scoobysteve

hi guys, 
Ok.. just bought a 20L of Gripset 51.. it cost me $165.. that really shocked me but then again, if it works, it worth it... Also, is it necessary to put a primer on? if so, would i mix the primer as per the application description? Then would i just apply the waterproofer without mixing with water? 
I'm thinking of using a stiff brush to put it on as its pretty tight in some space.. let me know if you think otherwise.

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## scoobysteve

anyone? sorry for such a dumb question but i'm intending to apply this stuff today. 
the instructions says: 
Priming: 
"Gripset 51 is self priming: porous surfaces diluted @ 1:3 with water; non porous surfaces diluted @ 1:1 with water" 
Application: 
"For waterproofing applications, product is to be applied in a minimum of 2 coats at a total minimum coverage of 1.5L/m2, forming a dried film thickness of approximately 1.2mm".  
Can anyone confirm if when applying (not  the primer coat), i just apply gripset without it being diluted? I'm getting confused on the part where it says "self priming" as i thought self priming meant that the product includes primer already and should be able to be applied without being diluted - unless the dilution ratio is the application ratio. 
any thoughts would be great. thanks so much in advance.

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## Blocker

Steve,
Second coat should be full strength straight from can.
Regards,
Blocker :2thumbsup:

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## scoobysteve

thanks Blocker... that clears things up..

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