Can you identify this external render?

[renov8r]

Hi all, new arrival to the forums here and just starting down the road of renovating a period property.

Would really appreciate any advice you could share and I hope to be able to post useful info about my experience over the next few months.

One of the first few things I am looking to improve are the external walls. The house is rendered in a material that I am not sure is breathable. I am considering adding a surface finish to protect and improve the appearance and was hoping someone would recognise what is on it at the moment. Knowing the type of render and it’s breathability will help decide the best finish for it.

I have taken pictures of the walls showing the appearance after a recent rain shower, and some close up shots of the window, ground level, a patched area, and two sides of a piece that has fallen off.

Any experience or advice you have on this is really welcome, thanks.

 

[Nigel Watts]

My guess is that it is a lime-based stucco. There is a good article on how to treat these finishes in the attached link (look for the Appendix).

http://www.lbhf.gov.uk/Images/GuidelinesonrepairsStPetersSq_tcm21-112603.pdf

The article recommends using a breathable silica paint. I chose to use limewash on my stucco.

 

[Flyfisher]

A common test is to introduce a small piece of the render to some sort of acid. If it fizzes then it is lime-based, if not then it must be cement. I'm not sure what sort of acids are needed for this, but I've used spirits of salts (40% hydrochloric acid) to clean the lime grouting from pamments and that certainly fizzed!

Of course, fizzing only reveals if there is lime in the mix - I suppose there could be cement as well.

 

[Zebra]

I've heard it said on here that vinegar will do, although I've not tried it.

 

[renov8r]

Thanks for all the helpful replies.

I will try and test the loose piece I have over the weekend and post the results.

Nigel - Thanks for the very useful link too - will be a great help in deciding the best finish.

 

[renov8r]

After a thorough search of the kitchen realised we were out of vinegar!

But I did find lemon juice (citric acid) so decided to give that a try. I could clearly see tiny bubbles forming and could hear the fizzing when I dropped some on the sample, so great to know I am dealing with a breathable lime render

Thanks again for the help.