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Plastering & Rendering

Outdoor newly rendered wall showing signs rustings on the edges

Anonymous user 23/02/2024 - 3.52 PM

Hi there As part of landscaping project, we had new raised plant beds built using grey blocks which were rendered using sand and cement with appropriate additives. We painted it once rendering completed.The edges of these beds where beads were put are now showing sign of rustings that are gradually appearing and growing through the whole length of the beads. There is no other pipes or any other iron equipments on these plant beds. The landscaper says it may be paint reacting and we can use stain blocker paint to prevent. Can you advise probable cause and potential remediations for the same please?

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4 Answers

Anonymous user

Rust stains on wall render can be caused by flue pipes, satellite dishes, mild steel fixings, overflow pipes, etc. And they can cause an otherwise sound property to look very unsightly. You can use stain block paint it’s fine…

Answered18 April 2023

Anonymous user

Hi there! Based on your description, it sounds like the rusting is most likely due to the use of steel beads that were not properly coated to prevent rust. The steel beads are used to provide a straight edge and a corner for the render to stop against. Over time, if the beads are not coated correctly or if the coating has worn off, rust can form and cause the render to crack and break away. One potential remediation would be to remove the affected areas of the render and replace the rusted steel beads with PVC or other non-corrosive alternatives. You can then reapply the render and paint over it once it has fully cured. Using a stain blocker paint may help to cover the rust stain but it will not address the underlying issue of the corroded steel beads. It is important to address the cause of the problem to prevent further damage from occurring. I would advise you to consult with a professional plasterer who can inspect the damage and provide you with a more accurate assessment of the issue and recommended remediation options.

Answered19 April 2023

Guarded Properties

Rating: 4.7 out of 5

High Wycombe

Did you use stainless steel or PVCu products for the external application? Galvanised steel beads should not have been used, which may rust. Here is helpful link to assist questions / solutions '' For rendering and plastering made simple, download the Simpson Strong-Tie 2020 catalogue at www.strongtie.co.uk/resources, which is packed with handy tips and installation guidance… and make sure you stay away from Rusty!''

Answered22 April 2023

T G plastering.

Rating: 5 out of 5

Spilsby

Hi. It seems galvanised corner beads have been used. These tend to rust which will bleach through your paint, and eventually will blow the corners. Stainless steel or plastic corners should have been used. A rust resistant paint will hold it back. Spray the effected areas with smooth hamerite once completely dry paint over with your preferred colour (exterior paint). Unfortunately may may not be a long term fix.

Answered24 April 2023