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    • Norfolk_Jim
    • By Norfolk_Jim 11th Jan 09, 10:58 AM
    • 1,176Posts
    • 1,109Thanks
    cracks in rendering
    • #1
    • 11th Jan 09, 10:58 AM
    cracks in rendering 11th Jan 09 at 10:58 AM
    I've got longstanding cracks in my exterior rendering, the kind you see under windows on older houses. I want to cover them up as they spoil the appearance of my house - but I don't know whats involved.

    Can rendering be skimmed over in the way plaster can? Is this a DIY job or will I need a specialist? If a DIY job, what materials do I need to buy for the job? If a contractor job, who am I looking at? Local builder? Specialist?

    I regularly coat my walls with exterior masonry paint but the cracks always reappear through it, though they never get any bigger and are not subsidence.

    Anyone else had this problem and sorted it out? Its purely so the house looks good.
    Last edited by Norfolk_Jim; 11-01-2009 at 10:59 AM. Reason: typo
Page 1
  • dandare
    • #2
    • 11th Jan 09, 11:52 AM
    • #2
    • 11th Jan 09, 11:52 AM
    is it a stone built house ye have? if so a lime render would be better as it allow the building to breathe out moisture and allow for movement of the stone.
    if it's not you could probably fill the gaps depending how bad yerself but it'd be the trying to match the colour. ye could fill the cracks yerself then give the whole building a paint.
    • Norfolk_Jim
    • By Norfolk_Jim 11th Jan 09, 1:07 PM
    • 1,176 Posts
    • 1,109 Thanks
    • #3
    • 11th Jan 09, 1:07 PM
    • #3
    • 11th Jan 09, 1:07 PM
    Some walls are brick & flint rendered over while out at the back its breeze block. the cracks are very hairline 1 < 2mm but reappear after painting. I've tried exterior polyfilla for want of anything more suitable but its visible and I was really hoping for a clean relatively flawless surface. I wish it was flint fronted like the rest of my row but its covered over. I think it would be a massive job to get it back to flint.
  • Unstoppable
    • #4
    • 11th Jan 09, 2:04 PM
    • #4
    • 11th Jan 09, 2:04 PM
    If you get a contractor in, it'll cost a fair few bob and H&S legislation say they now have to use scaffolding towers.
    • MX5huggy
    • By MX5huggy 11th Jan 09, 2:48 PM
    • 4,061 Posts
    • 2,653 Thanks
    • #5
    • 11th Jan 09, 2:48 PM
    • #5
    • 11th Jan 09, 2:48 PM
    The only way to get a "relatively flawless surface" is to hack the render off and re-render maybe with a lime render depends on the house. You could probably do the hacking off but by your questions you would need a pro to do rendering job. I would try to forget about the small cracks, maybe fill them with mortar.
    • savemoney
    • By savemoney 11th Jan 09, 2:58 PM
    • 12,806 Posts
    • 11,425 Thanks
    • #6
    • 11th Jan 09, 2:58 PM
    • #6
    • 11th Jan 09, 2:58 PM
    I had a couple of cracks very noticeable on street on some cement rendering on our house when we first moved in 2 years ago

    The paint on rendering was bad too and almost none existent on the brick window sills

    What I did was get some waterproofed polyfilla that you mix with water its designed for outside use, I filled the cracks in and sanded down so it blends in, applied some pva glue watered down and repainted with two coats of Dulux weathershield. So far no wear at all anywhere on the house

    Quite pelased with the finish never painted a house before

    I also used the polyfilla at back on house on bricks that were damaged (chipped) and were previously painted. Applied the filler to make it roughly back to how the brick original looked and then sanded down and repainted, it looks good as new
    Last edited by savemoney; 11-01-2009 at 3:00 PM.
    • Lorian
    • By Lorian 12th Jan 09, 8:17 AM
    • 4,086 Posts
    • 2,223 Thanks
    • #7
    • 12th Jan 09, 8:17 AM
    • #7
    • 12th Jan 09, 8:17 AM
    I used acryllic based filler only for small jobs, and "mix yourself" exterior pollyfilla or render repair motar for bigger jobs.

    If you use the acryillic filler you have to scrape out the crack lightly, then fill. then leave 48 hours and fill again as it shrinks. You have to use a straight edge to get the finish pretty perfect then because it's not so easy to sand flat when set.

    If you use the exteria pollyfilla it needs to be the mix-yourself kind in a box, I find the ready mix in tubes and tubs nowhere near as easy to work with. The cracks need to be opened wider and preferably with clean edges. Then paint the inside of the crack with diluted pva and wait till its mostly dry. The pollyfilla needs to be made up to a mixture like thick butter and spread in slightly raised. then you sand this flat after 12 hours (using rough sandpaper, must use a block) but definitely before 48 hours. During this period it's easy to sand, afterwards its very hard. Only downside is it can sometimes chip while sanding it when its green, so you have to re-fill a bit here and there (when completely dry).

    The exteria polyfilla is quite dark until sanded properly, when it goes to light grey making it much easier to overpaint with just a couple of coats of the water-based exteria finish I use.

    When you are cleaning the cracks if you see any green in them that might indicate some moisture in the wall, and I would open the crack slightly and leave to air well during the summer on some dry days, then fill.

    After quite a lot of practice (I'm not a professional) I find Its possible to fill cracks in flat or bagged finished render so that you can't see it. Always needs at least two coasts of paint feathered in around the filled/sanded crack and then at least one coat all-over (pref 2) after all the cracks are done.
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