Lime Render Job best approach?

[JayJSF]

Need to re render a property which is currently sand/cement, solid walls and has damp internally.

I advised the customer that lime render would be best to let the building breath as the interior has also been tanked.

I'll be honest i've never used a lime mix so was wondering what the best approach is? Bagged premixed like k-lime or mixing ourselves with sand/lime?

Any info would be a great help! cheers

 

[flynnyman]

Why is it damp internally and have you go any pics?

 

[JayJSF]

Why is it damp internally and have you go any pics?

I don't have any pics at the moment but will get the customer to send some over. I put the damp internally down to no cavity with sand and cement on exterior, therefor holding moisture.

Whatever way I look at it it will need to be re rendered due to a few cracks and loads of patches over the years but would like to do it the correct way this time using a lime product to allow the walls to breath.

Apparently interior walls were tanked with bitumen about 10 years ago which has now failed so the problem has been going on for a while!

 

[vfr12]

No point using lime if the walls are tanked

 

[flynnyman]

@Bauwer

 

[JayJSF]

No point using lime if the walls are tanked

I didn't explain properly in the first post they were tanked internally about 10 years ago with bitumen which is now failed so I will probably end up re plastering the inside as the plasters damp but either way the render needs to be redone so rather than putting sand/cement back on I'm going to do it the correct way for damp walls without a cavity

 

[3kids1dog]

Knock off the existing render if you have time let the walls dry as much as you can .
l*m*-g***n , baumit , tellings, all do barrier mortar all lime based, use this on the damp areas as they will stop the salts coming through to the surface .
Then floating coat of lime render , I mix my own as pre bagged stuff is expensive.
Then lime skim! Again make your own if you can you will get twice as much if you can be bothered to mix it yourself . All done , happy days

 

[Bauwer]

@Bauwer

Unfortunately it is a common practise when modern construction methods are used in traditionally build properties. I agree with the comments, suggestions above eg. removing impermeable materials and allowing property to breath, as it was designed initially:

https://greenbuilding.co.uk/insulating-masonry-walls-of-old-stone-cottages-and-listed-buildings