DAMP PROOFING

Rising damp is not the most common form of dampness encountered in buildings; this is left to condensation. However, it is very likely that a high proportion of older buildings are affected by rising damp to some degree or another, and it does cause problems with positive identification, appropriate remedial action and ancillary works.

At DPR we know that many other surveyors for other companies and bank/building society surveyors fail to diagnose rising dampness correctly and therefore instigate a new damp proof course where one is not required thus unnecessary upheaval and expense to the home owner. DPR will only install a damp proof course where it is required.

Other dampness forms like condensation, lateral and penetrating damp will be diagnosed correctly and the necessary action put forward.


RISING DAMPNESS
Rising damp in buildings may be defined as the vertical flow of water up through a permeable wall structure, the water being derived from ground water. The water rises through the pores (capillaries) in the masonry by a process loosely termed ‘capillarity’. In other words the masonry acts like a wick.

The height to which the water will rise depends on several factors including pore structure and rate of evaporation. Masonry containing a high proportion of fine pores will allow the water to rise higher than a coarse pored material; basically the water is carried up the wall in the finer pores and not those of large diameter. The average size of pores in masonry gives a theoretical rise of around 1.5 meters but where evaporation is severely retarded, for example by the use of impervious membranes, moisture can sometimes rise in excess of 2 metres.

The major paths through which the water rises are the mortar beds; For water to rise through the bricks then it must cross a mortar bed. In effect the mortar beds form the only continuous pathways for water rising through the wall. If a house is built from impervious bricks then water can still rise through the mortar bed but if an impervious mortar is used then no water will rise even if the bricks are very porous. The mortar beds will form an important part in the chemical treatment for rising dampness.


GROUND WATER
Ground water also contains small amounts of soluble salts, the most significant of which are chlorides, nitrates and sulphates.

These pass with the water in solution up the wall and are left behind when the water evaporates. Over many years of active rising dampness large quantities of these salts accumulate within the masonry and decorative surface, most becoming concentrated in a general ‘salt band’ towards the maximum height of rise Frequently, the concentrations of these salts are very low towards the base of the wall.

Both chlorides and nitrates are usually hygroscopic, i.e.  they can absorb moisture from the surrounding environment and, in general, the greater the amount of salts the greater the absorption of moisture especially under humid conditions.

Thus, even though rising dampness may have been controlled by the insertion of a remedial damp-proof course these salts alone can cause the wall and any contaminated decorations to remain damp.


DAMP-PROOF COURSE
Therefore, to provide a ‘dry’ wall and a suitable surface to take new decorations the new damp proof course system (Dryzone or Tri-Gel) involves two fundamental processes:

1. The insertion of the chemical damp-proof course by DPR operatives.
2. Removal of old contaminated plasterwork/decorations by DPR operatives and replacing with specialist replastering to prevent the passage of any residual moisture and contaminant salts from passing to the new surfaces from the underlying masonry.

ROOFING

PROPERTY RENOVATION & STRUCTURAL SERVICES
DPR carries full public liability insurance for your protection should the unexpected happen.

DPR will agree dates with you and stick to them as far as we possibly can. The main uncertainty is the weather. Naturally you will not want your roof stripped off during heavy rain or high winds.

Our prime concern is the health and safety of yourself and our team. If bad weather delays work, we will talk to you and agree revised dates as soon as possible. Please be assured that, once we start work, your roof will be protected at all times. If we have stripped the roof covering but not finished the replacement, we will put fully weather-proof tarpaulins and other measures in place to prevent any leakage.

In a worst case scenario, such as a severe storm, we provide a 24-hour emergency call out service. We can generally give a start date within a few weeks.

Home owners and small businesses are DPRs main customers, so we will not have to 'fit you in' around other projects. We can do emergency remedial work very quickly if this is needed at a nominal charge.

Planning permission is not normally needed for roofing projects, unless you are in a conservation area or the property is a listed building.   Buildings regulations is now mandatory for re-roofing work.  Forms should be obtained from your local authority.

Guarantees for roof work vary. New roofs are guaranteed for ten years and will have a manufacturers twenty five year product guarantee also. Repairs are guaranteed for one year which is long enough to confirm the repair has been successful having gone through the very unpredictable British seasons.

Built up felt roofs (flat roofs) are guaranteed for five years but usually have a lifespan in excess of twenty years dependent on location and surroundings. Please note that naturally we can not be held liable for storm damage as this is obviously beyond our control. Your insurance company will assist in the event of storm damage requirements whereby DPR will correct the damage very quickly.

DPR also specialise in Structural Engineer assistance and can specify corrective measures to combat property movement. We can install the latest in structural strapping, lintels, wall re-building and stabilisation.

Typical new wall tie for domestic property use. Patented shear nut design means fast installation which keeps costs down for the client.