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. can create massive quantities of water vapour that progresses up the chimney stack, getting cooler as it moves upwards. If you don’t have a DPC around your chimney breast and water and moisture gets inside the stack and is allowed to sit at the base, or the ground beneath your chimney breast is damp, then this damp can rise up into the walls of your chimney breast (rising damp). Apply a mesh membrane to your wall to be sure that salts won’t reappear on your wall. If you have a DPC, then check the area for anything that could be bridging the DPC for example renders/ finishes possibly debris in cavity walls. In the case that you have debris and rubbish in the chimney breast void the only choice is to clean it out. You can then replace the bricks and redecorate. As mentioned replacement could be very expensive but to ensure a proper fix this is your best option (more information in our Chimney Flashing project). If your chimney is blocked up and is capped and sealed at the top, the lack of ventilation could be causing chimney condensation to build up in the void, meaning that when your house warms up, condensation collects and forms damp on the chimney breast surface. Signs include: These signs can be evident, downstairs around the breast, in the above room and the attic. Another typical indicator of hygroscopic salt contamination is the fact that the damp patches will in most cases be more apparent during wet weather or more humid conditions. Our two most popular solutions are below. 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. For a cheaper option, you can instead remove your pots and add a paving slab on top of the stack instead, raising it up on all sides by about 2-3 inches to provide ventilation. Typically lead is lapped and layered, soldered or sealed using silicone to create a continuous run, and over time these joints can become weak and split, or in fact the lead itself can become weak and crack. Reply Reply Author. Permagard is a leading manufacturer and supplier of basement waterproofing products, damp proofing membranes, and structural repair products. We can offer non-partial advice on the damp proofing products available. If there is debris in your chimney breast clear this at the same time as this may be causing DPC bridging. We regularly get questions here at Permagard about what’s causing damp patches around a chimney and how to stop it. Does your chimney breast have a DPC (Damp Proof Course – layer of slate or plastic between brick courses about 6 inches above ground level)? Have a good look inside your roof for possible leaks. This is absorbed into the brick to form a waterproof chemical layer in the brickwork. You can ventilate a blocked up fireplace by adding an airbrick or vent to the wall in front of the fireplace – this can be added to the wall about 300mm up from floor level or you can add it below your floor if there is an underfloor space to minimise draughts in your living area. Again, the way to remedy this is to replace your caps with either a chimney cowl on each of your chimney pots or a raised paving slab directly on top of your chimney … Lines Open: 9am - 5pm, Monday - Friday. If not then this could be causing condensation to build up in the chimney stack due to cold air being trapped in the void, meaning that when your house warms up, condensation then collects to form damp on the chimney breast surface. If not then this could be causing condensation to build up in the chimney stack due to cold air being trapped in the void, meaning that when your house warms up, condensation then collects to form damp on the chimney breast surface. Chimney cap prices: $25-$135 | Galvanized steel chimney cap; $40-$165 | Aluminum chimney cap; $45-$215 | Stainless steel chimney cap; $175-$650 or more | Copper chimney cap; $250-$600 | Decorative non-metal chimney cap; 20%-40% premium | Custom-sized caps in all materials; Supplies prices: $5-$15 | Screwdrivers and pliers; $4-8 | Tube of construction adhesive or RV caulk … For more information, read our guide on How to Clean a Gutter. Damp chimney breast issues are normally caused, diagnosed and fixed in a similar manner to ordinary damp issues, but with a few subtle differences and potential causes. Examine your roof for broken or missing tiles – remember to check your entire roof and not just the surrounding chimney stack area. Inspect your guttering for cracks and faults which could be exposing your walls to moisture and damp. Below you will find a list of items and areas to look at. You should also check inside your roof for any signs of water leakage or a build-up of a white salt-like substance (hygroscopic salts) as this could indicate flashing failure. Discussion in 'Building' started by Km32, 21 Jan 2011. Either hire a professional or, if you feel confident, use DIY flashing tape such as No Nonsense Flashing Tape to repair the damage. It may also help to introduce some room ventilation on the same side as the prevailing wind, helping to equalize the pressure at the top and bottom of chimneys. Chimney condensation. Damaged pointing allows water and moisture to enter the stack and will quickly cause damp in the chimney. Any capping, sealing or bricking up that a chimney has had should itself be ventilated. If penetrating damp has been diagnosed as the source of damp the chimney needs to be checked and repaired where necessary then to stop the further ingress of water we recommend the application of a masonry water repellent to the whole exposed chimney to prevent water ingress which will protect the area from the effects of weathering for a good period of time, if Microshield Ultra is used this could be 25 years upwards. All project content written and produced by Mike Edwards, founder of DIY Doctor and industry expert in building technology. We often get asked ‘can a blocked chimney cause damp’? The chimney should be vented at both the top and the bottom. As we all know fuels generally come from the ground (e.g. If the chimney is capped, damp appears and goes when is raining, and also damp dust is dropping down- so this have to be condensation ! ) If your chimney is blocked up and is capped and sealed at the top, the lack of ventilation could be causing chimney condensation to build up in the void, meaning that when your house warms up, condensation collects and forms damp on the chimney. Keep up to date with our DIY projects, tips and latest deals, © DIY Doctor Ltd 2021 All Rights Reserved. It's lined with what look like ceramic drain pipes. 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. If you suspect rising damp explore the possible causes below. The first thing to identify is whether your chimney pots are open-topped or capped. For more information one this have a look at our project on injecting a damp proof course for larger jobs and also our project on smaller chemical DPC jobs. Once you have added the salt neutralizer (and membrane if required) and allowed it to dry (following manufacturers guidelines) you can then go ahead and plaster and redecorate your chimney area. Discussion. Broken roof tiles can allow damp into your roof timbers, Ventilation (capped or sealed chimneys and bricked up fireplaces). The ventilation for a blocked up fireplace can usually be found on the wall in front of the fireplace itself at ground level somewhere around 300mm up from the floor (occasionally in properties with an under-floor void, the vent will be under the floor as this helps to reduce draughts). These can erupt through your plaster, blowing it off the wall. The tell-tale signs of this are damp around the base of the chimney breast, as the moisture rises up from the inside. Dans un tuyau en acier inoxydable lisse, le liquide s’écoule vers le bas et dans les tuyaux à surface intérieure rugueuse (par exemple, en brique), le liquide pénètre dans les murs. Especially in windy areas, a chimney cap … Replacing a tile can be a bit of a tricky job so it may be best to bite the bullet and call in a roofer. Home Improvement: We had our chimney capped a couple of months ago (the next-door semi were having theirs done, so we said “yes” to their contractor doing ours at the same time). If they are open-topped and your chimney is not in use there is the chance that moisture is entering through here and travelling to the base of your stack, causing damp in your chimney. Be as amicable as possible as there is huge potential for disagreements, especially where money is concerned. If you think that this may be the cause of your damp chimney breast, you will have to insert a chemical DPC into the base of your chimney. If you cap the chimney in its entirety, you may give rise to condensation. 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. To do this you will need to remove a brick or bricks from the chimney breast or bricked up fireplace and insert an air brick in its place to increase ventilation within the chimney void (a link to our Removing a brick project can be found above) This should help minimise any damp in your chimney breast that has been caused by poor ventilation. If your fireplace is bricked up and you haven’t got any ventilation on the wall area directly in front of the fireplace, you’ll need to introduce this. Here are the most common methods used by builders and other tradesman: A simple cap – usually a patio … If after examining the damp in your chimney area following the guidelines above you are still unsure about the cause of the damp and how to fix it give Property Repair Systems a call on 01626 872 650. Your checks will have to be thorough as in some situations it can be a little hard to spot. 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). Even if this is not the root cause of your issue, it’s certainly not helping so will need repointing to prevent future problems. 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. If you can’t find the information that you need to help find the cause or fix your damp problem, we are more than happy to discuss your issues and find a solution so you can enjoy a damp-free home. After removing one or two bricks (do not remove any more than two bricks without the express permission of a reliable surveyor or builder). If, on the other hand, the top of the chimney is capped, but it isn’t ventilated, moisture can build up on the inside of the chimney … Condensation in a chimney: Vir Campestris: 1/19/16 1:59 PM: We've got an old chimney in our kitchen. If the top of the chimney is capped with building slabs, as is often the case rather than flaunched, or fitted with a concrete cast top, it risks leaks down a flue where slabs have been joined together. If you have a broken gutter, in heavy downpours water can run down the face of a wall and seep into any splits or cracks in mortar, presenting as damp in your chimney breast. get some images of inside the breast. As always, the cause of the chimney damp needs to be addressed before damp proofing can begin. The chimney runs up along the exterior wall. Make sure that any debris has been removed to make sure this isn’t causing the damp problem. We know that tackling the problem of chimney damp can be tricky. Firstly prime the area with PermaSEAL Salt Inhibitor then, whilst damp, apply two coats of PermaSEAL Tanking to the area as per the data sheet then apply a minimum 10mm coat of PermaSEAL Renovating Plaster over the surface to form a salt-resistant barrier. You can find out how to replace plastic guttering in our Replacing Plastic Guttering project page. JavaScript seems to be disabled in your browser. If you have both capped chimney pots and sufficient ventilation, next check for any cracks in the pointing of the chimney stack. Are quite a few available on the capped chimney condensation damp to touch of to. 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