Fix Damp Patch On Wall
Is the most common kind of damp. It is caused by moist warm air condensing on cool walls, particularly in rooms that naturally generate a lot of air moisture, such as kitchens and bathrooms. It's mainly, but not always, a winter problem, as walls tend to be colder than the air inside.Condensation can be exacerbated by central heating that gets very warm and then cools down again, as this creates warm, damp air that can then condense, causing condensation.A lack of ventilation can also make the problem worse. This can be particularly apparent in old homes, which were designed to be naturally 'breathable' and allow damp air to evaporate out of the house. The removal of existing chimneys and energy-saving measures, such as fitting air-tight double glazing, can reduce ventilation in old homes, and create a condensation problem.
Is caused by ground water moving up through a wall or floor. It's natural for walls and floors to allow a little water in, but it’s usually stopped from causing damage by a barrier called a damp-proof course or damp-proof membrane (see image below). A damp-proof course is a waterproof horizontal strip, usually made of plastic or bitumen felt, built into the wall at a height of at least 15cm above ground level. A damp-proof membrane is a sheet of material that's impervious to water, which is laid underneath the floor. This should be connected to the damp-proof course so that the house is effectively sealed and protected from ground water. Newer houses will have both, as they are a requirement of building regulations (Part C for England and Wales). Older buildings (particularly those built before regulations came into force in 1875) may not, or they may have worn or been damaged over time.
If this is the case, your walls or floor may suffer from rising damp.Rising damp can also happen when there's a lack of drainage, or the level of the ground outside your home is higher than your damp-proof course, allowing water to get above it. Symptoms of rising damp.
Damaged skirting boards or plaster. Peeling paint and wallpaper, often with wet patches.
A white, powder-like substance on the wall, left by soluble salts dissolved in the water. Tide marks rising up the wall. If the problem is coming up from the floor, you may notice floor coverings lifting up.Read our guide to find out how to treat issues with rising damp, and whether you need to call in a professional to deal with it. If you do, our page will give you an idea of how much you need to spend. Penetrating damp. Is caused by water leaking through walls. This type of damp may expand across your walls or ceiling, but this will move horizontally, rather than by travelling up walls (as is the case with rising damp).Penetrating damp is usually caused by structural problems in a building, such as faulty guttering or roofing, or cracks in the walls, which let water in when walls or roofs are soaked with water during heavy rainfall.
It can also be caused by internal leaks, such as leaky pipes underneath the sink or bath.You’re more likely to get penetrating damp if you live in an older building with solid walls, as newer cavity walls provide some protection. Symptoms of penetrating damp. Damp patches on walls or ceilings, which may darken when it rains.Now you know more about penetrating damp, visit our page on how to get rid of penetrating damp, and find out how much repairs can costs on our page.
In this project we’ll go through the various different causes of damp patches and condensation on your internal walls, as well as explaining how to definitively stop damp entering your walls in the first place. Damp patches on internal walls of your home can be a real pain, not only due to the fact you get ugly looking marks on your walls but also the fact that moisture and damp patches on walls can also produce mould. This can in turn be detrimental to your health, as mould spores have been linked to quite a few issues such as asthma and allergies – so it’s not just your home that will suffer in terms of damage.If you require some additional assistance after reading this project guide please contact Property Repair Systems on 01626 872 650 for further advice free of charge.
How To Find the Cause of Your Internal Damp and How To Fix it What Causes Penetrating Damp?Cracks in walls and Mortar or Render – Whether this is the cause of your internal damp issue or not, this is still a problem!! If you have cracked mortar in your walls or chimney stack then water and moisture has the potential to enter your property and cause untold damp and rot damage.Mortar joints missing from a brick wall can allow water to get in and make internal walls dampIf it is allowed to sit on timber such as roof timbers, floor joists etc. Then these can rot out and cost a small fortune to put right.Check all of your outside walls (using a decent pair of binoculars for the higher areas – these can be hired if necessary) for cracks in the mortar joints of your brickwork, chimney pots and chimney stack.If you do find any cracks or faults in your mortar then they will need repairing. Rake out the joints using a plugging chisel or small bolster to a depth of around 10 – 15mm. Using a suitable mortar mix re-point the damaged mortar joints with new mortar.In the case of broken/cracked mortar around chimney stacks and pots this will also need to be replaced. Carefully chisel off the damaged areas and replace with the aforementioned mortar mix, using the Mortar Mixes project above for more information.If you have cracks in your render then this can be a little trickier. In the case of large cracks these will need plugging asap!!
If moisture is allowed to sit behind a rendered surface then it will gradually erode the inner surface away and create further cracks and eventually render will start falling off, creating a larger and more expensive repair job.Cracks in your render can allow water to enter your walls, creating damp patchesIn the majority of cases render repair can be quite a time consuming job so for an interim fix you can seal over the crack with a silicone based sealer. This is also the case for larger cracks where you can seal the crack void and surrounding area with a silicone sealer.Once you have some time to correctly repair the crack you can simply remove the silicone filler and proceed with the repair.In respect to the correct repair method, any cracks should be filled with a render mix of the same grade and consistency as the current render on the wall (premixed render or render patching compound can be purchased for this job. Products include K-Rend and Euromix. We have never used these products so cannot confirm how competent they are). Fill any cracks with your mortar or pre-mixed mortar and allow to dry for the required time.
To ensure that no moisture is allowed to penetrate your repaired area it’s also worth considering covering the area with a sealer or waterproofing agent.If you have coloured render then this is another element that needs to be considered. You will have to try and create a matching colour to patch any cracks. As you can imagine this can be really tricky so be prepared for the fact that the repaired area is going to stand out. One possible solution for this is to then paint your property using a suitable exterior render paint or cement based paint. Use ourRoof Tiles and Flashing – As with the above, broken or ineffective flashing (the lead sheeting that covers the joint between your roof and wall and chimney stack and roof etc.) can cause water ingress which results in damp patches on your internal walls. Using a decent pair of binoculars (either borrow or hire) check all the flashings around your roof and chimney stack for cracks and separation from the adjoining surface. In the case that you find any flashing faults then this will need to be repaired.
Ideally any cracked flashings need to be replaced with new flashings. Lead is very expensive and this can be a pricy job, but ultimately flashing replacement is the best course of action.Check lead flashing for and splits and cracks allowing water to penetrateIn the case that you don’t have the funds to do a replacement right away then there are alternatives available. Flashing Tape is a fairly good short term fix for sealing cracks.
It’s effectively a waterproof tape with an adhesive underside that you can stick over the crack, sealing it over. We have used a few of these in the past and found Sylglas to be one of the better ones.
Damp Proofing Internal Walls
For more information on this.In the case of cracked and broken tiles these will also need to be replaced as any cracks present can allow water to penetrate into your roof area, run down rafters and down into cavities and cause all manner of damp problems on internal walls.Changing your broken roof tiles immediately can ensure that water doesn’t enter your propertyThe type of tile (clay, slate, concrete etc.) will dictate how this is done. In most cases the tile will be nailed to the roofing battens below and, sometimes on old properties, fixed in place with mortar so you will need to break the nail off using a suitable slate ripper or hacksaw blade to cut the nail off or chip off the mortar with a suitable hammer and chisel. With the nail(s) removed slide the tile out and replace with a new tile.Once replaced fix the tile in place, or in the case of slates, instead of nailing back in (as you will be unable to access suitable nailing points) cut a suitable length lead strip (about an inch longer than the length of the tile when positioned in place) and nail to the roofing timber. Lead strip or galvanised metal is better to ensure that it does not rust.Push the tile up into place and ensure that it is sitting flush with the surrounding tiles. Now bend the protruding edge of the piece of metal back over the top of the tile so that it now holds the tile in place. In most cases the chemical DPC comes in tubes similar to those used for silicone or decorators caulk. You can also get chemical DPC injection machines.
These are similar to pumps that then pump the chemical agent into the wall. The applicator guns are a little easier to use if you are not experienced in using the injection machines.In respect to chemical damp proof courses there are quite a few on the market and as with most products some are better than others. Examples of products available include Permaguard, Twistfix etc. As we have found this to be about the best and it’s BBA ( British Board of Agrement) approved.
Cold Spots Giving Rise to Condensation and SaltsThese issues are arguably one of the most common causes of damp on walls. Condensation forms when warm moist air within a room touches a cold internal wall or surface.
Fix Damp Patch On Wall Shelf
It then cools rapidly and then condenses back into water. This condensation then sits on the internal wall’s surface and creates damp patches on the wall.Now that we know how the condensation forms we have to find what is causing the cold spots that are causing the condensation to appear. This can be caused by several defects. Firstly, are there any cracks in the mortar on the external wall around the area where the damp is appearing?
This could be letting draughts into the cavity and cooling the associated area on the internal wall, stopping it from warming up with the rest of the room. If there are cracks in any mortar then this will need repairing using the methods outlined above.Is the condensation appearing on a chimney breast? If so then this example of condensation could be caused by a poorly ventilated chimney breast. If you have bricked up fireplaces or a capped chimney stack then this may be preventing any cold air that is trapped in the chimney void from escaping and thus keeping the area at a consistently cooler temperature than the surrounding air. In this case, again, moisture can then condense on the chimney breast surface and cause damp on your wall.In this case, the ventilation provided by the open fireplaces and the act of fires drawing air up the chimney stack is no longer present and air can become static so we will have to introduce some new ventilation in order to get the air flowing again and the air warmed up.
Air bricks can be inserted on the ground level around 300mm above floor level and also towards the top of the chimney breast on the external wall. This will then introduce an air flow and prevent static cold air sitting within the void and keeping the chimney area cold.Keep chimney pots vented and allow air to circulate to prevent damp by using chimney cowlsThe wall around your chimney can also be prone to suffering from Hygroscopic Chimney Salts. Salts and minerals released from fuels burnt on a fire can settle on the inside of the chimney breast and over time seep into and through a wall onto the internal wall surface.
Tars and deposits that are also present on the inside of a chimney breast can also be drawn through along with the salts. The salts themselves appear as a white salt-like build up while stains from tars and deposits appear as a yellow/brown stain.You may be thinking the salts are damp and make the affected area damp when they are present, this is not the case. The salts themselves are hygroscopic in nature which means that they attract moisture from the internal air.
This moisture then settles and creates damp on the internal walls.In terms of a fix – the likelihood that any plastered surfaces have survived this are pretty slim. If it can be caught in the very early stages and dried out then there is the chance that you can simply treat the area with a salt neutraliser, allow it to dry and then redecorate but in all honesty the correct fix would be to remove all of the plaster from the damaged areas right back to the walls surface and then to treat the wall itself with salt neutraliser to prevent any further salt ingress. You can then replaster and redecorate with confidence knowing that future damage has been prevented.You can apply salt neutraliser to your walls to stop salts penetrating the internal surface of your wallThe salt neutraliser is a substance removes the salts and then prevents any further salt formation. There are quite a few different salt neutralisers available online or in your local DIY store but as we have found this to be the best of the bunch – some of the other brands produce inconsistent results.In some instances salt deposits can be very heavy and to provide even more protection and further minimise the chances of salts forming and causing damp to appear on your internal walls you may want to add a membrane to your wall before replastering. After you have treated the walls surface with salt neutraliser you can then fix a membrane over the area. The membranes themselves usually come on a roll (similar to wallpaper) and feature a dimpled surface.Fit a mesh membrane before replastering to prevent salts returning and causing damp on your internal wallsIf you need any help finding the causes of condensation and damp patches on your internal walls and would like further information on how to stop your walls getting damp please contact Property Repair Systems on 01626 872 650.
We have worked with them on many projects over the years and they are experts in this field. If you’d like more information on how to insert a new Damp Proof Course.