Before you can go about putting right any damage caused by the damp in your chimney you will first have to ensure that the source leak/moisture point is located and repaired. You can do this by drilling holes into your chimney breast about six inches up from ground level and injecting a chemical cream DPC into the holes. These are created when water in your damp wall evaporates on the surface of the wall, leaving behind salts. This can cause water to get inside the attic or house as it runs down the brickwork. If your chimney is open at the top but is not in use, rainwater can travel all the way down to the bottom of the chimney stack. Make sure you get your chimney inspected and swept regularly to be sure debris isn’t building up – this can also cause dangerous chimney fires. Damp patches on the chimney breast, brown or yellow marks on the walls and ceilings surrounding the chimney often point to damage caused by a water leak or building faults such as inadequate guttering, missing roof tiles, poor flashing details and absorbent masonry. The second option is to prime and reseal the area using our PermaSEAL damp proofing range. Once the membrane has been installed you can then either dot and dab or render directly over it. DIY Doctor have worked closely with PRS for a number of years and have found them to have a consistently high level of expertise in the treatment and prevention of damp in and on chimney breasts and associated areas. There is an irregular water mark stretching either side of my chimney breast on the ground floor - its definatley not rising damp as it only appears midway up the wall (about 30 cm from the ground) - we've had the place professionally dampcoursed, as did the people before us. Allow the wall to dry out thoroughly, giving it as much time as is required, in some case this can be several months. Wet and mouldy in capped chimney? It's lined with what look like ceramic drain pipes. For more information on how to replace a brick see our Replacing a Brick Project page. Also be aware that just because there is no evidence of a leak around the immediate chimney area, water or moisture may be getting in and running along to the chimney area to form damp so ensure that your checks are thorough! The best way to check that this is the problem is to remove a brick from the base of the chimney breast and access the inside to see if there is moisture present. Keep up to date with our DIY projects, tips and latest deals, © DIY Doctor Ltd 2021 All Rights Reserved. All project content written and produced by Mike Edwards, founder of DIY Doctor and industry expert in building technology. If you find that your lead is damaged then it will need either replacing or repairing. The visual signs of chimney damp can provide a good indication of where to start looking for the cause. In the event that you can’t find any evidence of water or moisture penetration then another damp problem inherent to chimneys and the areas around chimneys is the presence of hygroscopic salts (sometimes known as Chimney Salts). However, chimneys can experience some other additional potential damp causes. Another cause of your chimney damp could potentially be a bridged DPC in your chimney breast. Chimney damp is normally caused, diagnosed and fixed in a similar way to other damp issues. It is important that you do not seal your chimney at the top, whether the chimney is in use or not as you want to encourage air flow. How to seal a chimney. Some older properties in particular were built with no DPC around the chimney breast. Especially in windy areas, a chimney cap … All of these features help to prevent the penetration of water via wind pressure, gravity and also tension on a surface. coal, wood etc….). We thought condensation … If your chimney is open-topped you may notice that once there is heavy precipitation the rain will pour into your chimney. The best way to identify this problem is to speak to your neighbours. If you’re not able to get up onto your roof then borrow or hire a decent set of binoculars as these will allow you to view your chimney almost as well. It will all need to be removed and you will have to re-plaster from scratch. How to handle condensation in the chimney Originally published March 17, 2012 at 6:00 am Updated March 17, 2012 at 8:01 am You will need to protect the fireplace insert from moisture problems. However, condensation in your chimney could also be caused by a blockage. You can find out how to replace plastic guttering in our Replacing Plastic Guttering project page. Chimney condensation. When the materials are burnt these salts and minerals are released and settle on the inside of the chimney. Depending on how bad the damage to plaster, wallpaper etc is you may then need to remove it all and then replaster and redecorate. Using a torch, mobile phone, video camera etc…. Any staining caused on these patches, in most cases, is the result of soot and other particles that have also managed to creep through the wall over a period of years and this is also occasionally due to the type of room e.g. Condensation in a chimney: Vir Campestris: 1/19/16 1:59 PM: We've got an old chimney in our kitchen. If this is the case, the chimney stack and surrounding brickwork will need to be repointed before the damp issue can be resolved. Typically lead is used in flashing because it is very malleable (easy to shape), long lasting, low maintenance, good with extremes in temperature and is relatively wind resistant. If any of these symptoms are visible then simply removing them can stop the issue in its track then its a case of making good the effected areas. NOTE: Burning fuels produces fumes that can be potentially fatal if not removed from the property correctly or if there insufficient air within a room space. If you live in an area where rain is common then the sheer act of lots of water running down your walls can over time can cause also cause your chimney to become damp as water can be physically sucked into it (by capillary action). Check that your chimney flashing is in good condition. Once dry you can then redecorate again but beware this may be a short lived fix. Be as amicable as possible as there is huge potential for disagreements, especially where money is concerned. This cream soaks into the brick and the chemicals in it join up with one another to form a waterproof layer in the brickwork – your new DPC. Burning coal and wood releases tars and salts that then settle into the chimneys of older homes. To check this access the area around the chimney breast from inside and outside if possible – the DPC should be visible. Applying a DPM directly over the area isolates the salty background from the new finish. Use a salt neutraliser to stop salts from appearing in your wall. The addition of air bricks and vents is a little easier than adding ventilation to your chimney top. In the case of open or damaged chimney pots, add a chimney cowl or cap to protect the stack from letting in moisture. After checking the chimney itself, the next port of call is to assess the surrounding area. You should only use ladders in situations where it is safe to do so and you have the necessary training to safely complete the job. Finally, skim over with Multi Finish Plaster. In the event that they have carried out some work on the chimney and it looks like this may be the cause of your damp issues you will have to come to an agreement on how it is fixed. Fix – Once you have resolved the cause of the damp (and either fixed the leak source or established that it’s down to a salt issue) remove all the damaged plaster from the chimney area and any affected surrounding areas (if any) and allow to dry thoroughly for as long as needed. If you are experiencing a severe level of plaster damage then this is most likely down to a water leak so you will have to use the checks listed above to trace and find the leak and fix it. After removing one or two bricks (do not remove any more than two bricks without the express permission of a reliable surveyor or builder). As moisture travels from wet to dry areas, the source of the chimney damp doesn’t necessarily need to be on the stack itself. The problem we have is that on the top floor, we have condensation forming on the chimney … The best way to resolve this problem is by inserting a chemical DPC into the base of your chimney. You can do this by adding an airbrick roughly 300mm above the level of your floor. If you have a white, salt-like staining present on plastered surfaces or even on bare brick or block surfaces then the damp you are seeing could be down to an extreme case of Hygroscopic  Salts as mentioned above, so also be aware of this if you are unable to find any leaks. In the case that you have debris and rubbish in the chimney breast void the only choice is to clean it out. Once the Damp Proof Course has been added to your chimney breast you will have to allow the area to dry out thoroughly for as long as needed. Apply a mesh membrane to your wall to be sure that salts won’t reappear on your wall. Add a vented cap or cowl to your chimney pot to increase ventilation. Fix – There are several ways to remedy this problem with varying degrees of difficulty. Issue – If you have yellow or brown stains or marks that are appearing on ceilings that join to your chimney breast and spreading outwards then you may have a water leak. We know that tackling the problem of chimney damp can be tricky. If you have stains and damp marks around the base of the chimney breast, no more than 1.5m high and salt tidemark, then this could suggest rising damp caused by a bridged damp proof course (DPC) or lack of DPC. If you can see cracks then there is the chance that water or moisture is entering through here and either running down the inside of the stack causing damp in the chimney stack itself or then running out of mortar cracks inside your property and causing damp issues on your chimney breast this way. In the room below, it is necessary to have chimney vent installed just below ceiling height. Don't fancy doing this project yourself? Examine your roof for broken or missing tiles – remember to check your entire roof and not just the surrounding chimney stack area. If you have a wood burning or gas stove in use you have to ensure that the chimney is correctly lined. Other visual signs can be a damp chimney breast and ceiling, damp walls either side of your chimney breast, damp in your loft or attic space around the chimney area or even damp halfway up a chimney breast. A chimney cap had been added to the chimney above the furnace flue when the roofing had been done to complement the existing cap above the fireplace flue. If due to the cost this is not an option, you can buy "Flashing Tape" from most builders’ merchants or your local DIY store. of course if not, since I am working in building industry I never had a condensation problem on the chimney breast- this is nonsense ! If you share a chimney with your neighbour it is possible that recent home renovations, such as the installation of a wood burner may be causing damp in your home due to poor chimney flue installation or inadequate ventilation. JavaScript seems to be disabled in your browser. Discussion. It is important that unused chimneys are vented at both the top and the bottom, to allow a constant flow of air. If you suspect rising damp explore the possible causes below. (i.e. They might have fitted a word burner without inserting the correct flue or they may have blocked up internal ventilation. Chimney damp will often occur if your chimney is unused and boarded up. Fix – If you have found that you do not in fact have a Damp Proof Course in your chimney breast then it is a good idea to add one. A picture in picture thermal image showing the dampness, note … bristolbaron. Check that your chimney breast has a DPC – if not it’s a good idea to insert one. 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