Is there a reason for external render to be very roughly textured/wavy?

There is no reason whatsoever as to why the render could not have been a smooth finish except for the fact its quicker and cheaper to do a rough finish. To rectify you need the render chipped off then re render it. I like your idea that it may deflect sound as that made me smile today. Good luck Malcolm

Good day to you, There could be a number of explanations regarding the rendering finish on the exterior walls. Ideally it is always better to inspect such property, instead in trying to guess blind. However, let me share some of my thoughts on this subject as follows: 1. How old is this property, e.g. when it was originally built? 2. Is this a new structure (new extension) or part of a section of the property or it is applied to the complete exterior of the property? 3. Usually if the previous builder used instead of clay bricks used concrete blocks, this type of renter is applied (it is usually called different names around the world such as ''bag finish'' or ''bagging'' and some call it ''Spanish plaster'' among others etc) 4. In some cases, if the wall has a lot of small and large cracks, and the repairs are done purely, the builder, applies PVA to the surface and the render type and smears such finish on the complete surface to camouflage the imperfections. 5. Another way, is if that side of the building is facing North, thus it is not exposed to the Sun, therefore mildew is been build and penetrated in the previous render, then this new rendering is applied to again camouflage the finish under the surface. 6. Finally, if it is none of the above and simply was a Client's or Architect's chosen finish. If you do not like it, they are a number of other alternatives you can do to improve it. To give you a more accurate answer, an inspection of the premises would need to be undertaken. I hope this helps you a bit more with your query. Kind regards Gus Barbero

No reason its down to cost and personal choice.. , will hide more imperfections and is preferred by less talented renderers who cant achieve a nice flat finish.. main reason is Cost rendering is expensive especially if your builder will have to hack of solid render ...Most builders will run away if the render is in good condition!

Hi, the only reason for wavy dipped rendering is poor rendering skills . It's not easy to get large areas perfectly flat , but it's down to the plasterer