Sorry mate I ment finish stronger than the scratch,Hi Jamesdooley. isn't the scratch coat meant to be stronger than the finish coat. Napped in late November and scratched in October. Finish mix was 25 shovels sand to 4 shovels cement to 1.5 shovels lime and 150ml waterproofed...... Definitely didn't dry too fast. It was in by 9am and napping for 2pm. Wet down prior to coating aswell. I see this alot lately and I'm beginning to think it might be waterproofer reacting with the lime...or else dirty sand
sorry mate I ment finish stronger than the scratch coat, might be an idea to check your sand supply, can always do a simple field test to check for silt, put a sample of your sand in a clean jar, add a solution of teaspoons of salt and a litre of cold tap water, close the lid shake it up and leave for about half hour or so,if the layer of silt that settles on top is more than 1/10 the size of the sample , it has a high fines content so it will take more mixing water which will result in shrinkage, I haven’t used waterproofing in sand/cement since leaving Ireland bout 11years ago so not sure if that’s your problem to be honestHi Jamesdooley. isn't the scratch coat meant to be stronger than the finish coat. Napped in late November and scratched in October. Finish mix was 25 shovels sand to 4 shovels cement to 1.5 shovels lime and 150ml waterproofed...... Definitely didn't dry too fast. It was in by 9am and napping for 2pm. Wet down prior to coating aswell. I see this alot lately and I'm beginning to think it might be waterproofer reacting with the lime...or else dirty sand
Sorry mate I ment finish stronger than the scratch,
sorry mate I ment finish stronger than the scratch coat, might be an idea to check your sand supply, can always do a simple field test to check for silt, put a sample of your sand in a clean jar, add a solution of teaspoons of salt and a litre of cold tap water, close the lid shake it up and leave for about half hour or so,if the layer of silt that settles on top is more than 1/10 the size of the sample , it has a high fines content so it will take more mixing water which will result in shrinkage, I haven’t used waterproofing in sand/cement since leaving Ireland bout 11years ago so not sure if that’s your problem to be honest
Not here it isn't. 2bags to 40 shovels is top coat. 1 to 18 for bands and projective base or in slow drying conditons. 1-15/16 for scratch.Scratch coat is always done 40 shovels to 2 bags cement (opc)
I think he did it to be more visible on the pictureWants a hole drilled and a camera poked through to see inside cavity. Looks damp to me
Is it the whole wall like this?In ye're opinion why has this crazing happened. Napped finish about 2 years ago
Do you d spatter coat before the scratch?Just to say we must have 10-12 house's done last year with the exact same mixes for each house. I'd say of the 10-12 houses done iv seen this sort of crazing in maybe 3 of them. We usually scud and scratch with whatever sand is left from the blocklayers and order more when it's needed. I'd give the client 3/4 suppliers to get a plastering sand delivered from.
Depends how much sand your shovel holds, gauge it out for best resultsScratch coat is always done 40 shovels to 2 bags cement (opc)
Just to say we must have 10-12 house's done last year with the exact same mixes for each house. I'd say of the 10-12 houses done iv seen this sort of crazing in maybe 3 of them. We usually scud and scratch with whatever sand is left from the blocklayers and order more when it's needed. I'd give the client 3/4 suppliers to get a plastering sand delivered from.
Yes, it can work both ways. I have mentioned before that controlling suction is at the base of our trade. Not only drying quick, but too slow as well. Reading your post I assume it has gone the other way for you. If you say same mix, same method etc then you exclude the mix from the problem . What I think happened in this case is you hit the wall too earlier and caused dragging, respectfully friction between the two coats. If is too soft you don’t touch the top coat, leave it till bonds to the scratch and sets to be ready for sponge or float. I always compress the render with float to minimise this problem exactly. The difference between summer and winter cracking is the size, but I’ll leave that for another dayWas out for dinner Sunday at a restaurant we plastered 18 months ago. Sponged finished elevations on this place up on 80m2. Used the same mix as the house in this thread and the restaurant is fine. It was after raining aswell so crazing should have been evident..... 1 thing I didn't mention was that the owner of the house was drawing water in 5 gallon drums(about 15 of them) and keeping the 200gl water tank topped up. Water seemed to be OK to look at.....although we never tasted it.
VFR12 you mention significant temperature change. What do you mean by this. Temp change to frost or temp change to heat wave?
Running out of ideas so ..... f**k off!Cheers vfr12 but nah,it was fine to float(twice) and napped up OK. The plinth probably was a bit "soppy" due to it being layed on because after rulling off we had a barrow left over. Would frost create this effect....trying to remember if the nights were around freezing temps when done...
I rendered a house in December, mixed everything same as usual, only difference I used frostproofer in the mix, it had crazed to the extreme, when damp after rainfall but cracks not visible when dry. Thing is the client is blaming me. Although he told me at the time that he was going to paint the house this summer, he now seems to think the paint won’t hide the crazing
Without easy fill?Het him to paint it and see.... or offer to paint it....
Without easy fill?
The only problem would be if the crazing showed through the paint where would I be? I don’t think it will though as I see lots of crazing in unpainted render, and none in painted. Probably the best option for him would be acrylic itHet him to paint it and see.... or offer to paint it....