United Kingdom

We live in an old house with cob walls. I grow 3 bright red Hydrangeas against the front wall (facing North) and they have been there 5 years or more. They are quite open bushes and they dont actually contact the wall but lean away from it. (They are about 18" away from the wall at the root) Should we be concerned about the affect these bushes may have on the fabric of the house either in terms of root damage or the possibility that they may trigger damp penetration through the wall at these points? (The wall is ,unusually, surfaced with cement and not lime morter) There are damp problems with the house but not where the plants are and not to a significant degree nor is there algae on the external wall.
The Hydrangeas look very effective growing against the white painted house and I'm reluctant to dig them out unless opinion is against them.

• 12 Oct, 2012