PREMIER DAMP PROOFING NI
We treat a wide range of building damp at Premier Damp Proofing NI. View our services below and contact us for more information and to get a free price quote.
OUR DAMP PROOFING SERVICES
Found in houses and buildings across the country, the symptoms of dampness usually appear to be much the same. But in reality, there are many different types of damp, ranging from simple condensation, rising and penetrating damp to internal and external efflorescence. Even though all damp seems similar in terms of water spots, discolouration and mould, it is very important to correctly identify the root cause so that the problem can be properly resolved.
Our damp specialist covers everything from walls to floors. Their job just isn’t confined to old buildings, it has a much wider reach. They’ll get rid of that awkward condensation before it turns into something much bigger. The chances are your damp problems have probably crept up on you so you won’t have noticed the warning signs right away.
RISING DAMP
Rising damp is the process of ground water travelling up through masonry and mortar by capillary action. A physical damp proof course (dpc) inserted whilst the building is under construction will stop rising damp from happening. Unfortunately, some older houses were built without a dpc and others the dpc has deteriorated or damaged over time causing damp. Sometimes rising damp can still occur even though a dpc is present, if the dpc has become bridged is a good example.
The water drawn up into the masonry from the soil contains salts which are mainly nitrates and chlorides. When the water evaporates it leaves behind these unsightly salts on the surface of the walls.
Signs of Rising Damp
- Damp walls causing peeling wallpaper or paint.
- Salt deposits visible on the wall surface.
- An unsightly tide line across the wall up to one meter high.
- Deteriorated plasterwork.
- A damp odour.
Identifying the difference between rising, hygroscopic, penetrating damp and plaster bridging is not straight forward so it is always recommended that a professional should carry out a survey and advise on any remedial works necessary.
Treatment
Strip the wall plaster off at least one meter high or 300mm above the last visible signs of damp, whatever is the greater.
Drill a 12mm hole, 90% through the brick joint at 100-120mm centres and 150mm above the external ground level. Inject the dpc cream as specified by the manufacturer into the predrilled holes. The cream will spread into the masonry creating a continuous water repellent barrier.
Replastering
All coats of the new sand cement will now be mixed with water incorporating a render proof mix (salt inhibitor and a water proofer). This will protect the new surface and finishes from moisture and salts during and after the drying out process.
Scud coat – Made up of 2 parts clean sharp plastering sand to 1 part of Portland cement mixed with water including the render mix and an sbr agent, this will aid the scud coat to adhere to the bare wall.
Scratch coat – Made up of 3 parts clean sharp plastering sand and 1 part Portland cement. This should be applied in coats of no more than 12mm at any one time and scratched before drying out. Further coats can be applied once the previous coat has set. Keep the mortar up 30mm from the finished floor.
Float coat- Made up of 4 parts clean sharp plastering sand and 1 part Portland cement applied no more than 12mm thick, kept up 30mm from the finished floor. Once harden a standard multi finish can be applied.
Gypsum Bonding and/ or galvanised angle beads should never be used at any stage when replastering after a damp proof course has been installed.
Wall Tie Replacement
The majority of homes built in the last hundred years consists of cavity wall construction. This means that there are inner and outer walls (known as leaves) linked together with wall ties. This method gives a warmer and drier home compared to the older solid brick construction.
However, unless the ties consist of stainless steel or very heavily galvanised, there is a tendency for the ties to rust and making the wall less secure. Mild steel wall ties have a shorter life span than the brickwork and my need replacing before major repair work is necessary. Houses built before 1980 may need an inspection to clarify the materials used and their present state of corrosion if any.
We are full accredited members of the Wall Tie Installers Federation, the representative trade organisation for the registered installers of remedial and replacement wall ties and related services in the UK with a unique 25 year insurance backed warranty scheme. If you are a house owner or considering buying a house and want to ascertain the condition of the wall ties, please contact us for a survey.
Signs of Wall Tie Failure:
- Horizontal cracking- usually very easy to spot on a rendered house, a pattern of horizonal cracks 900mm in height apart. As the wall ties rust, they expand and crack the render.
- Mortar Bed Separation- Long horizontal gabs appear where the mortar joint has come away from the brick.
- Lintel Drooping- If a lintel above a window or door begins to sag and looks off the level.
- Lifting of roof edges at gables.
- Damp penetration.
- Outer walls starting to bulge or buckle.
Replacing Wall Ties
The surveyor will ascertain what type and size of wall tie to be installed. A metal detector will locate the existing wall ties and the position marked on the wall with chalk.
New stainless steel wall ties will be fixed into position and in a different location from the existing wall tie. Tensile testing of the new ties at random locations and a report made and provided for the guarantee and a brick will be removed at the position of the old tie so the tie can be completely removed with the original brick being built back into position.
Dry Rot
What is Dry Rot?
Serpula Lacrymans is a fungus that will attack and destroy the timbers in our houses if given the correct conditions. This fungus thrives in the timber with a moisture content of 20-40%, it is more aggressive than the wet rots and will spread throughout the house even through masonry, feeding on timbers leaving them structurally unsafe. Penetrating or rising damp even poor ventilation could be attributed to the timber’s high moisture content.
Signs of Dry Rot
- Mushroom like smell.
- Spore Dust- a fine brown/red dust covering localised surfaces.
- Shrinking or distortion of timbers
- Mycelium- A white cotton like substance called Mycelium on the surface of the timber.
- Fruiting Body- A sudden appearance of an orange pancake shaped object.
Identifying the difference between dry rot and wet rot is not always easy, so it is always recommended that a professional should survey the timbers and recommend any action if needed. As dry rot is the most serious of fungi decay it is imperative that identification and treatment starts quickly.
Treatment
The first step is always to identify and stop the source of the moisture causing the outbreak.
Dry out quickly the surrounding area.
Cut away at least 600mm beyond any decayed wood and remove this from the site.
Determine the full extent of the outbreak including stripping off plaster or render.
Masonry surfaces should be sterilised with a masonry fungicidal biocide.
Replace the timber with pre-treated timber and treat surrounding timbers with a dual-purpose solution to prevent future outbreaks.
Wet Rot
What is Wet Rot?
Wet rot is the most common form of fungal decay found in the timbers used in the construction of our houses. There are many variations of this fungus, but they are either white or brown in colour. The most common among wet rots is the Cellar Fungus Coniophora Puteana.
The wet rot fungus thrives within timber that has a continual high moisture content of over 50% usually caused by a plumbing leak, roof defect or penetrating damp ect. The Fungi feeds on the moisture and nutrients from the timber which overtime will weaken and destroy the structural integrity of the timber.
Signs of Wet Rot
- A damp musty smell.
- Soft and spongy timber.
- Darken or Lighten timber- the affected timber will appear discoloured compared to the neighbouring timber.
- Cuboidal cracking of the timber.
Identifying the difference between wet and dry rot is not always easy, so it is recommended that a professional should examine the timbers and recommend any remedial action.
Treatment
The first step is to identify and stop the source of the moisture causing the outbreak.
Dry out quickly the surrounding area.
Cut out and replace any weakened timbers with pre-treated wood.
A hardening gel can be applied to any remaining vulnerable timbers.
Wood-boring Insects
Northern Ireland has two main wood-boring insects, the common furniture beetle, and the wood-boring weevil. Both are attracted to untreated soft and hard woods with a high moisture content which makes it easier to eat and digest.
Common Furniture Beetle- Anobium Punctatum
This is a small beetle 3-5mm long which will not only attack furniture but joists, floorboards, and other timbers in your house. Between the months of May to September the mature beetle will exit its host timber to fly away and mate before depositing upto 60 eggs in another timber member. Once the eggs have hatched the larva about 6mm long will continually tunnel the timber for up to 5 years before exiting to mate, lay eggs and die. Due to the high numbers in an infestation, if left untreated you could see structural failure of the timber.
Signs of the Common Furniture Beetle
- Exit or flight holes 1.5mm-2mm in diameter.
- Bore dust around the exit holes.
- Dead beetles on floors or on window cills.
Treatment-
Spray all localised timbers with a water based insecticidal timber fluid.
Wood Boring Weevil- Pentarthrum Huttoni
This is a small beetle 2.5-5mm long which loves wet timber often compromised by wet or dry rot. Found in timbers around leaking water pipes, sinks and bathrooms ect, they will attack both soft and hardwoods.
Signs of the Wood Boring Weevil
- 1mm exit or flight holes with a ragged edge.
- Oval-shaped tunnels travelling along the grain and sometimes breaking through the surface of the timber.
- Coarse bore dust that feels gritty.
Treatment-
Treating the fungal decay that is allowing the weevil to attack the timber is foremost. By removing the affected timbers and stopping the water ingress the beetle infestation will be eradicated.
It is recommended that a professional should investigate the affected timbers, looking at the exit holes and frass to determine which beetle is causing the infestation, before advising on any remedial works.
Other Forms of Damp
Condensation
Condensation forms when warm moist air encounters a cold surface. This temperature change reduces the ability of the air to contain its moisture, so the access is released as water droplets on the cold surface. Mould spores will be attracted to this damp surface and will quickly multiply causing unsightly black patches.
Hygroscopic Damp
When a wall has become wet usually by another form of dampness it can bring with it soluble salts which remain after the wall has dried out. These salts are susceptible to drawing in and absorbing the moisture in and around your house causing unsightly damp patches.
Interstitial Damp
Interstitial damp happens when warm moist air passes into a floor void or roof void with poor ventilation or inadequate insulation. Due to the high moisture content this dampness can cause both wet, dry rot and attract wood boring insects.
DPC Bridging
The three main reasons for damp caused by bridging of the damp proof course:
- External ground level is above the damp proof course.
- Internal wall plaster has been taken down below the damp proof course or is in contact with a solid floor.
- Rubble in the cavity.
Penetrating Damp
This is the term given to rainwater that has penetrated through the outer fabric of your house because of an external defect.
The main causes are:
- Roof- broken or missing roof tiles or slates.
- Gutters- broken, leaking or full of debris.
- Chimney- No lead tray, defective pointing, no ventilated cap on disused flues.
- Walls- Cracked or boast render, defective pointing to brickwork, rusted wall ties.
- Windows and doors- Defective silicone sealant or cement pointing around frames.