Lime Render Exterior Wall

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PlasterV

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Hi I want to lime render my soft red exterior bricks. I have got the lime, I would like to know what the mix is ? and any tips on applying it.
 
Mix for NHL tends to be 1:3/1:2.5 Lime to Sand. You want a washed sharp sand. Pit dug, dredged tend to contain salt which you don't want. If your using a bell mixer then remember to allow it to mix for at least 20 mins. Most common problem is over wetting the mix and not letting it mix thoroughly.
 
Oddly enough I have never done lime render,is it best to buy ready mix as in just add water or buy the NHL and make your own ,is it normally 3 coats with a week in between , first coat 3/1 second 4/1 ?
 
johniosaif said:
Oddly enough I have never done lime render,is it best to buy ready mix as in just add water or buy the NHL and make your own ,is it normally 3 coats with a week in between , first coat 3/1 second 4/1 ?
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when i have done it , we bought the lime bagged and added the sand and hair and water and mixed it through a mixer on site , but you can get it premixed (dry ) and add the water, we done 3 coat work with nhl 5 mixed with sharp sand then 3.5 mixed with a sharp and soft mixed then topped with nhl 2 mixed with soft , not much difference really between it with s&c , apart from you finish it with a float no sponge .
 
And yes a week in between coats and you stratch it more vertically in a daimond pattern rather than a the wavey horizontal way you do on s&c , the idea being you want the water to drain away downwards on lime to finish it and in s&c your holding the water in the stratch hope that makes sense :confused:
 
You would need a good price for it,if you were doing it on its own,what ratios did you use with first second and third, do you always use NHL 5 for first ..
 
Use NHL 3.5 for all coats. You don't need to make the mix any weaker as you come through the coats. The same mix is fine for all coats. You can get premixed wet or dry. Hair already added just cut bags open and knock up. Still works out cheaper plus you don't have to guage anything other than maybe add some water. About a week between coats but depends on environment. Suction control is most important thing and making sure it doesn't dry out too quickly. To test each coat it should be hard enough you can't indent it with your thumb but can still indent it with your nail. With NHL this could be a couple of days but could be longer if damper conditions.
 
johniosaif said:
You would need a good price for it,if you were doing it on its own,what ratios did you use with first second and third, do you always use NHL 5 for first ..
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it is slow , expensive, heavy, a good earner, but enjoyable. you use different nhl for different jobs.
 
bodders13 said:
Use NHL 3.5 for all coats. You don't need to make the mix any weaker as you come through the coats. The same mix is fine for all coats. You can get premixed wet or dry. Hair already added just cut bags open and knock up. Still works out cheaper plus you don't have to guage anything other than maybe add some water. About a week between coats but depends on environment. Suction control is most important thing and making sure it doesn't dry out too quickly. To test each coat it should be hard enough you can't indent it with your thumb but can still indent it with your nail. With NHL this could be a couple of days but could be longer if damper conditions.
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So you would use sharp or fine sharp and some soft for finish ? All at 3/1 ?
 
Ideally you want sharp at 4/5mm down. Preferably an angular sand rather than rounded but if you use fibres in it that would get over the use of rounded and help with shrinkage.
 
Thanks for the tips everyone. Much appreciated.
Also is hair required in the exterior lime render? Slightly confused there.
 
PlasterV said:
Thanks for the tips everyone. Much appreciated.
Also is hair required in the exterior lime render? Slightly confused there.
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If you use fibres you can use these in both the scratch and float coat. Helps with resistance to cracking and shrinkage.

If you want to use hair or have to use use hair then only do so in your scratch but not the float as hair may stick through.
 
bodders13 said:
If you use fibres you can use these in both the scratch and float coat. Helps with resistance to cracking and shrinkage.

If you want to use hair or have to use use hair then only do so in your scratch but not the float as hair may stick through.
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Thanks a lot. Much appreciated help.
 
bodders13 said:
Tbh no I don't do void tests. Rule of thumb is 1:3 but with NHL you can go 1:2.5 as you won't get as creamy a mix as you do if using putty.
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Thanks Bodders, I've gone as much as 1:2 with grit sand for dubbing out, that's alright isn't it? (3.5 NHL)
 
We have been doing lots of lime work, love it.

Latest job is 100m2 of Eco Cork. Consolidation harling coat, dubbed out with 3:1 hydraulic no hair, eco cork scratch fully meshed, leave a few days then top.

Eco Cork is lovely gear to use, did a 50m2 gable on Tuesday and had loads of time to float it, and no cracks the next day :)

We don't use hair, no need for it with hydraulic lime.
 
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