Damp Rising in Old Buildings

[Riz]

I am looking for technical information/experience to share on how to tackle damp rising in old historic buildings. Construction of walls in stones held together with mud and lime mixed mortar. During rainy periods water table is almost above foundation level.

Existing building has neither damp proof membrane in the floor nor damp proof course in the walls. The building is a 2 storey structure about 80 years old.

I have used a combination of French drain to lower the water table and applied a low viscosity epoxy pressure injection resin (Sika Product) to the walls for forming a barrier against infiltration of ground water. The mortar for plastering walls had waterproofing admixture. The plastered walls were than treated with a water dispersed epoxy resin coating. The ground floor slab was touched with new screed having a waterproofing admixture. This has helped considerably.

 

[Ron]

Riz,
Sounds like you've done about all one could reasonably do with this. If you have no limitations on floor slab penetrations, you could inject a barrier under the floor slab, depending upon soil conditions, that would impede the upward rise. A silicate gel would typically be used for this. Another approach for the floor slab would be to let moisture come through and dehumidify mechanically.

Be sure that you do not install a barrier covering on the floor as blistering is likely.

There are a couple of companies in the US that have created cementitious barrier overlays for prevention of vapor migration in floor slabs. They typically offer a 10 year warranty on them. You might consider this approach if you intend to place tile or other barrier coverings on the floor. One of the companies is "Floor Seal Technologies", but I can't recall the name of the other.

Good luck.

Ron

 

[daveross]

There are some companies who manufacture special ceramic inserts for providing damp proofing in old buildings. I can't remember their names, but you might find on the internet. As far as I recall, you drill holes in the walls at recommended intervals and insert the ceramic. If I find any more info I'll let you know.

Regards,

david.

 

[ADT]

As I understand it you've treated the INSIDES ONLY of the walls, which is fine. I would add that the mortar joints throughout might need replacement in order to prevent some continuing damp damage and in order to give you a better final result than leaving the old lime mortar in place, would provide better external protection and structural integrity.

I've done a couple of jobs like this (lived in one of them) and it can be done piece by piece by a good mason; it can also provide a substantial improvement in appearance, colour, texture etc. On no account would you waterproof the external wall face as well.

You seem to have already done a good job. Hope this may help as well.
Anthony Tugwell
Project Director & Consulting Engineer - just relocated to Australia