Massive masonry outside walls get quickly wet due to driving rain

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Sami Roikonen
Posts: 15
Joined: Thu Jul 04, 2013 3:05 am -1100
Location: Finland

Massive masonry outside walls get quickly wet due to driving rain

Post by Sami Roikonen » Tue Jun 11, 2019 12:01 am -1100


I'm modeling a massive masonry outside wall (600 mm, uncoated) and whenever I have driving rain on, the whole brick layer gets wet rather quickly. This is odd, since I've never encountered abnormally high moisture contents in massive masonry outside walls. Should I add a surface condition with a small Sd-value to the outside surface? Could I even switch off the driving rain altogether? The facade is an old bare brick wall so I think switching off driving rain might be a bit irresponsible...

I've encountered this problem with multiple different bricks (Fraunhofer: Solid brick masonry, Solid brick historical).

When I'm simulating massive masonry outside walls with rendering I have the same issue. The results seem more accurate when driving rain is switched off and when some Sd value is used in the outside surface.

I've enclosed some screenshots.

Could this effect be happening because the brick layer in the model is homogenous and the actual structure may have air pockets, vents, cracks etc. in the brick wall? Is there any good way of simulating them? Other than putting air layers in the model of course.

Bump. I'm hoping this gets answered.
I've tried to research this topic, but the most relevant article I could find was only about physical simulations [1]. It had no mentions of actual measured data from actual structures...

1. [G.B.A. Coelho, F.M.A. Henriques, Influence of driving rain on the hygrothermal behavior of solid brick walls, Journal of Building Engineering (2016), pp. 121-132.]
Surface conditions.PNG
Surface conditions.PNG (31.06 KiB) Viewed 1156 times
Historical Brick.PNG
Historical Brick.PNG (67.29 KiB) Viewed 1156 times

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