How to fix rising damp on external wall?

[colinweiren]

Hi guys, We’re having some trouble with the paint on our external wall peeling and deteriorating—possibly due to rising damp (or maybe the rainwater without the cover). Please see the attached photos

(1)  What’s the best way to deal with rising damp? Ideally without having to remove the existing render on the wall.

(2)  Would adding a rain cover, awning, or canopy help? Thinking it might stop some of the water hitting the wall directly.

(3)  What’s the best type of plaster or filler to use to fix the damaged render before repainting?

Thanks

Colin

[EricL]

Hello @colinweiren 

This appears to be a very extensive rising damp issue. I propose engaging the services of a leak detection specialist so that the point of water entry can be pinpointed. Sealing the wall without addressing where the water is coming from will not solve the issue and you'll never be able to paint the wall properly as it will just keep peeling off. I recommend having a look at this discussion - What paint to use for rising damp? by @KatM.

Once the source of the water has been addressed and the wall has been fixed and treated, you can then paint the surface using ordinary exterior paint. Ordinary mortar patch can be used to repair the render Dingo 10kg Mortar Mix. 

If you need further assistance, please let us know.

Eric

[colinweiren]

Hi Eric,

Thanks again for your advice. I believe the dampness is caused by rainwater accumulating at the base of the wall due to poor drainage. I’m planning to re-lay the pavers to create enough elevation to direct water away from the house.

I also had a couple of follow-up questions:

1. What’s the best product to use to fill the gap between the pavers and the wall—would silicone be appropriate, or would some type of mortar be better?

2. Before laying the pavers, should I apply a waterproofing paint or membrane to the base of the wall for added protection?

Appreciate your guidance!

[JacobZ]

Hi @colinweiren,

With a gap like this, you need to use a flexible sealant, as there will be slight movement between the surfaces that would crack anything rigid, like mortar. I'd suggest using Sikaflex 11FC Purform, which is a flexible sealant that is often used in concrete expansion joints and situations like yours.

Considering the pooling issue, it would certainly be worthwhile applying a waterproofing membrane such as this Crommelin 1L Exterior Grade Brushable Waterproofer, which can be painted over once dry.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob