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Restoration & Refurbishment

Rendering an exterior wall

What temperature must it be for exterior render to dry..the day I plan it, it is 6 degrees dropping to 1 degree overnight. How long must it be warm for in terms of days or is this unnecessary? I have scaffold up but am worried... maybe I should leave it up till april for it to be warm enough to do this? But then it becomes a cost issue - the scaffold cost 1k in the first place. We are only filling exterior cracks and inserting helifix bars not rendering a whole wall. Also how much later can it be paint over with Weathershield? Is rain an issue its fairly shelted in alley with scaffolding. And finally what is a test I can do on it to see if it has adhered or not? If not whose fault would that be - mine asking builders to do this job now or the builders? Would it be covered by the renderers guaranteed? Using SE Ties. seem reputable. Anything I should look out for when they are here to check they are affixing the helifix bars well and doing the job well.

1 Answer from a MyBuilder Restoration & Refurb Specialist

Best Answer

As long as the temperature remains above freezing , sand / cement renders with modern additives should be fine providing that the additives instructions and ratio mix are properly followed ! Lime renders at this time of year are an absolute no go . It is up to the tradesman to determine that the substrate is sound for adherence and key , that is what we are paid for and any tradesman worth their salt should be guaranteeing their work without question ! The problem with this kind of work at this time of year is that any moisture is being trapped within the fabric of the walls and has to go somewhere . If the walls are cavity then no problem , but if solid the moisture can only go inwards if the outside is sealed up ! As for SE ties , these are mechanically cut into the brickwork and resin bonded usually bout a third or just beyond , the depth of the wall for general stitching ! As for painting , if the wall is not completely dry the paint will be trapping the moisture behind it , often resulting in blistering ! In short , this is completely the wrong time of year for this kind of work if you want the finish to last ! Hope this has helped ?


Answered 1st Feb 2015

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