Interior wall affected by rising damp and leaks

System description

Introduction

Damp due to capillarity is one of the most common problems in our homes. This is not only associated with aesthetic problems, but also contributes to the accelerated deterioration of the building and people’s health. That is why we must act in an effective and lasting way.

Reason for the intervention

The reason for the intervention was the high level of deterioration of the entire perimeter of the ground floor of the building. It was affected by rising damp. In addition to the unpleasant appearance of the entrance, the high humidity caused odours, unhealthy conditions and energy losses in the building, and it was impossible to leave any item in the storage room, furniture, bicycles, etc. as they were easily damaged.

Challenges and constraints

The walls adjoin neighbouring buildings with no possibility of access, even underground. As is often the case, the damp is not always caused by a single cause, in this case it was capillary damp, but in the storage rooms there was also damp due to filtration, as they were underground, so they affected the whole length and height of the wall.

The added difficulty was therefore to effectively cut both rising damp and seepage damp.

Molins Solution

The proposal was to first prepare the substrate, i.e. to chop the old mortar down to the brick, combine the performance of the PROPAM® CREAM product, as a chemical water-repellent barrier against capillary humidity, with the waterproofing membrane capacity of the PROPAM® IMPE product with a thickness of only 2 mm, to finally regularise to the required thickness with a waterproofing mortar with a fine finish PROPAM® FINO.

Execution

The implementation was carried out as follows.

“1. Repair and restoration of the entire perimeter plinth of the entire interior entrance of the building up to its masonry base support. The salts and saltpetre coming from the ground and deposited in the mortar by capillary dampness cause some parts to be easily chipped. It is always advisable to repoint 50 cm above the stain left by capillary dampness.

“2. In the storage rooms, all the mortar in the wall affected by the leakage was repointed.

“3. Once the disintegrable particles had been removed, the first step was to cut the rising damp by capillary action. To do this, a series of holes were drilled at less than 10 cm between perforations and with a sufficient depth to be within 2 cm of penetrating the wall. These holes were filled with PROPAM® CREAM, a cream water repellent with a high capacity to be absorbed by the porosity of the substrate, which leaves a permanent barrier to capillary humidity.

“Once PROPAM® CREAM had been absorbed for 24-48 hours, the holes were covered with PROPAM® IMPE and then, in a fluid consistency, two crossed coats of this waterproofing product were applied, which also acts against hydrostatic pressure, being effective at a minimum thickness of 2 mm in the two coats. In the case of the storage rooms, this process was carried out on the entire affected wall.

” 5. The following day we proceeded to regularise to the desired thickness with water-repellent mortar with a fine finish. PROPAM® FINO is a mortar with high workability and adequate open time allowing any type of finish, in this case smooth for subsequent painting. It should be noted that PROPAM® IMPE waterproofing acts as a membrane, but allows any subsequent finish, whether ceramic, mortar, plaster or lime.

Technical note

Damp due to rising damp is one of the biggest problems in old and not so old buildings where the impediments were not put in place to prevent it from occurring. The fact is that the foundation is in direct contact with the water table. The water rises through the capillaries of the wall materials due to a liquid phenomenon called surface tension. The surface tension around the perimeter of these capillaries produces a force with a vertical component causing the water to rise within the capillary until the weight of the water column balances the vertical force generated by the surface tension.

The height reached by rising damp depends on several factors. The diameter of the capillaries and the evaporation that occurs on both sides of the wall. In principle, the stain “stops” as soon as the amount of water that is absorbed from the foundation equals the amount of water that the wall is able to evaporate. Therefore, the greater the evaporation capacity of the wall, and therefore of the mortar with which it is coated, the lower the height reached, for which macroporous mortars work very well outdoors.

The evaporation rate therefore depends on the ambient relative humidity, the temperature, the porosity and permeability of the materials used, etc.

Capillary water carries dissolved salts, which, when deposited on the surfaces of building elements, cause whitish stains, commonly known as efflorescence or saltpetre.

These deposits in the internal pores of the material can initiate expansive crystallisation processes, increasing its volume and creating strong tensions that cause the pore to open. The materials that suffer from it show important flaking, thus in plasters there is a generalised loss of resistance (sandblasting) and in bricks, layers of a few millimetres are easily detached.

When these salts are deposited inside the elements, they occupy the capillary network, giving rise to cryptoflorescences.

On exterior walls this can be solved with macroporous mortars such as PROPAM® CAL SEC that accelerate the evaporation of moisture, but on the inside we want to minimise those dampnesses that later end up in condensation in other parts of the rooms.

Molins, thanks to its R&D team, has managed to develop two products which, combined together, form a totally effective system against damp and filtrations in walls affected by capillarity and which act from inside the home.

Its main features are:

PROPAM® CREAM

“ Easy to apply and high penetration.
“ Permanent chemical barrier inside the wall.
“ Highly concentrated.
“ Eliminates the appearance of whitish stains and efflorescence.
“ Water-based, non-toxic.

PROPAM® IMPE

“ Waterproofs at low thickness (2 mm).
“ Works under both positive and negative pressure.
“ Can be applied by brush or trowel.
“ Compatible with any subsequent coating.

I also summarise its fields of application:

“ Walls affected by capillary rising.
“ Aggressive environments with capillary rising (SR).
“ Pre-treatment of walls with lime mortar finishes.
“ Any room or tank that will contain water or where water penetration is undesirable, see also
PROPAM® IMPE FLEX.