How to paint external wall?

ozez

Painting a new rendered retaining wall.  
1) Do I need a primer or is allweather external paint which includes a primer enough? 
2) One side of the wall (garden bed side) is pretty rough - anticipated putting in lawn and/or garden up to the top surface of the wall, but haven’t built it up quite to the top.  How would you suggest smoothing / finishing off that part of the wall? Chiselling the render / concrete dags? Priming / painting it almost to soil level following brush down? (Pressure spray will dislodge the soil there). Spray painting the lower part of the wall that reaches the lawn / soil bed? 
3) If I end up planting a hedge at the lower lawn point of the front wall, how much leeway should I give the plant next to the wall? Will a composite garden bed edge be enough to keep the buffalo grass from creeping back into the bed?  

thanks. 

MitchellMc

Welcome to the Bunnings Workshop community @ozez. It's sensational to have you join us, and many thanks for your question about painting a retaining wall.

You’re definitely on the right track with your prep and planning. Before anything else, it’s important to consider whether the rear (garden bed) side of the wall has been waterproofed. This is exceptionally important. If it hasn’t been properly waterproofed and you paint the exposed face, moisture from within the wall can push through and cause the paint to bubble, peel or fail prematurely. Assuming the wall has been adequately waterproofed, then using an all-weather exterior paint with built-in primer may be sufficient, provided the render has cured properly (typically 28 days). 

On the garden bed side, if the render is rough or has dags, it would be best to chisel or scrape those back for a neater finish. Follow that with a thorough brush down using a stiff broom to remove dust and loose particles — avoid pressure washing near the soil line, as it’s likely to dislodge soil or splash debris back onto the wall. Once cleaned, you can paint down close to the soil, just short of where it will be covered by turf or mulch. A brush or roller is best for this section rather than spray painting, which is less precise and can create overspray issues near the ground. If the roughness is too noticeable, consider applying a patching or skim coat compound to even it out.

Regarding the hedge and buffalo grass, it’s wise to allow a buffer space of at least 300mm between the hedge and the wall so the roots have room to grow and the plants don’t feel cramped. A composite garden edge can definitely help contain the buffalo grass, but it needs to be installed correctly — ideally buried at least 100mm deep to stop runners from sneaking under it, with a small lip above ground to stop lateral creep. Buffalo is aggressive, so even with edging, occasional maintenance will help keep your beds looking clean and defined. With these considerations addressed, you should end up with a durable painted wall and a well-structured, low-maintenance garden.

Please let me know if you have any questions.

Mitchell