Vertical scratch

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bubbles65

bubbles65

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I passed a S & C rendering job earlier that had a vertical scratch coat on it and it just got me thinking, do any of you lads scratch it that way? Up here (West Cumbria) some lads call it the 'Isle of Man' scratch - cos there are a few that have worked over there and reckon they all scratch the base coat that way. Just wondering how common it is, and why that way?
 
i dont know why they do it that way bubbles was taught in college to scratch across not down because if you scratch down the next coat will slide off or wont bond as good and the couple of rendering jobs i have done i have always scratched across the way i was taught
 
maybe they built the house on its side and kept rolling it over to get at the high bits cos they couldnt afford a scaffold?
 
no mate, cant think of a reason why you'd do it that way? maybe the sand is so fine in the isle of man the render is that sticky they dont need a horizontal scratch and scratch it vertically so it gets rid of the water quicker?
 
Doing it sideways makes sense, like your haging the second coat off the scratches, if you like.

But I bet in reality it doesnt make any difference.
 
maybe they think that a vertical scratch will let the water out quicker from the top coat helping it to finish quicker , but it will weaken the tensile strengh of the over all job, there is a reason why bricks are layed the way they are layed and the vertical joints are stagered and you only eml straight vertical mortar joints ......
 
i seen it before i was told it was to let the water run off if it was going to rain so as not to wash the strach off as easey
 
The way I was shown was to horizontal scratch but in a wavey pattern to stop cracking of the top coat. But how deep do yoy scratch me about half way in.
 
horzontal in a wavey fashion,a wavey fashion to allow for any contraction,and as said to reduce cracking
 
Oh dear.............an old boy I worked with always said that a wavey scratch was the sign of a cowboy "Shouldn't have time to fuk about with waves, they'll be drawing mickey mouse pictures in it next". YEEEEHAAWWWW..........:RpS_laugh:
 
i was taught the wavey pattern was to stop water from staying in your scratch lines.

in florida they dont use scratchers but use a scratch brush,basically like a wallpaper brush with harder bristles,it worked well actually as it ki9nd of flattened it and you pretty much had a 100% scratch
 
henry said:
Funny you should say that bubbles my old boy name was roy roger's LOL.
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Thats alright roy.........err henry. I like to write my name with the scratch, usually near the peak on a gable:RpS_thumbup:
I'm off to the saloon now................
 
bubbles65 said:
Oh dear.............an old boy I worked with always said that a wavey scratch was the sign of a cowboy "Shouldn't have time to fuk about with waves, they'll be drawing mickey mouse pictures in it next". YEEEEHAAWWWW..........:RpS_laugh:
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thats what my old boss used to say. if uv got time to scratch it wavy ur not working hard enough. we did used to draw little boats in it tho :)
 
I do waves cause it looks pretty or it's cause I've got the shakes........ I've heard of people not liking it cause water can trap in the dips others like it cause you've got nearly twice the key
 
ive always one staight horizontal scratch & one wavey horizontal scratch then straight scratch then wavey it look nice & when i get bored draw fish in the waves being chased by a shark :RpS_laugh:
 
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The reason render cracks has nothing to do with how you scratch it, its because its topped to early, each coat should be left to cure for at least 2 weeks but these days they scratch coat one day and top a couple of days later
 
I thought the reason why we left it to dry is more to do with the suction back ground your rendering onto. If it was breeze why would I need to leave for 2 wks on a low suction back ground.
 
because the sand and cement still needs to cure/dry which can cause shrinkage. the longer you leave it the better
 
I was told to do wavey lines because its better on the eye than straight... if you do straight lines it can make the building look pissed....lol

Each to their own hey...lol
 
henry said:
I thought the reason why we left it to dry is more to do with the suction back ground your rendering onto. If it was breeze why would I need to leave for 2 wks on a low suction back ground.
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how long you been rendering, your reply answers it self.
 
if anything then boys....it shows how unsuitable s&c is in the modern world. Far too inefficient for this day and age(I do like a top notch fined down finish though still) No wonder mono is king of the building site....regardless of staining issues, nobody's prepared to wait for curing so any savings on materials of the trad stuff over the more expensive bagged renders are lost elsewhere on the build through knock-ons of delay.
 
iys alright leaving it for 2 weeks to cure but what if it were scratched in hot sunny weather south facing if you dont cure it properly with a spraying of water it means s**t .leavinfg it does not = curing
 
Yeah, needing to go back and soak it is a ball-ache, but necessary. Unless ya can get the punter to hose it for you:) And thats a good reason to scratch it horizontal to hold the water for longer, can't see any good reason for vertical lines...........
 
horizontal all the way about 4mm in just before you do this run a hard bristled broom in the same direction to increase the surface area of the key. never scratch in too early as 90% of the time you will key right back to the blockwork.
i always use waterproofer in scratch to reduce suction when top coating usually after 5 days of scratch curing.
 
maybe you dont pay any tax if you scratch it vertically? always thinkin outside the box me... :RpS_sleep:
 
rockhardsolidplastering said:
iys alright leaving it for 2 weeks to cure but what if it were scratched in hot sunny weather south facing if you dont cure it properly with a spraying of water it means s**t .leavinfg it does not = curing
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you right mate but that comes down to doing the job properly, yes you would have to cover with sacking and wet to hold damp in to cure it off or as you say, go there every couple of days and soak. its the same for lime work, the after care can cost an arm and leg . we all have to do things to times we are given, so the builders want things finished well before they should.
 
yeah and when they expect you to be working 7 days like its your duty or something......yeah right...see ya
 
Tried a wavy scratch on a huge garage i'm going to be roughcasting yesterday, never again, it looks shitt and tears the scratch coat more than a straight scratch and I think you should be shot if you do it.., I used to point and laugh at wavy scratches, anyway I started the garage like that so I had to finish it like that and when the owner came home I had to fill him with a lot of bullshit cos it's the first thing he asked me about...
 
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