Diagnosing Damp in a Chimney Breast Longridge
01254 878756
Preston
Diagnosing Damp in a Chimney Breast
Chimney Inspection
Check the following items from the ground (binoculars are useful) and from inside the roof (use boards for safety);- Chimney pots – are they open topped or capped, capped with or without ventilation, or with a metal cowl? Is the mortar at the base of each pot, where it enters the chimney, in good condition? Do you share chimneys with your neighbours? Are their’s in good condition?
- Flashing's and flaunchings – the lead, zinc or mortar between the chimney and the roof, around the chimney base. Are these areas in good condition with no crack? From inside can you see any signs of water marking around the chimney, staining or salt crystals?
- Ceilings upstairs – are there any water marks, stains or ‘salts’ showing on the ceilings?
- Chimney breasts – is the plaster damaged or stained, are there any ‘salts’ or variable damp patches?
Chimney Breast Indoor Walls
Damp in chimney breast is dealt with in much the same way as damp elsewhere except that, because of tar and other chemicals, the salts are sometimes a little harder to deal with. The recommendations for this are below. When working on chimney breast damp in the loft please be very careful to strengthen the floor before walking and plastering on it.
A quick summary checklist: a ' damp meter ' and surface thermometer are useful tools for this diagnosis - if not available use the back of your hand to assess the relative dampness of one affected area to another unaffected area..
Symptom:- White, fluffy salts, plaster possibly 'blowing' off the wall - 'efflorescence' - you have a water source which needs to be found and eliminated.
Answer:- Salt Neutralizer might work if you can find and stop the leak, or the plaster may be too damaged and need replacement to our Specification.
Symptom:- Damp patches on the ground floor (at low level, right down to the skirting board) that come and go - you have 'hygroscopic' salts that are attracting moisture from the air.
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--> Answer:- You may have Rising Dampness, or your damp proof course may be 'bridged' by high outside ground, plaster on the inside or debris in the cavity (cavity walls only). Rectify any defects and if necessary inject Quick Cream at the correct level to form a new Damp Proof Course. The plaster will need replacement to our Specification.
Symptom:- Damp patches on or around chimney breasts - sometimes showing yellow or brown stains in wallpaper or paint - you have 'hygroscopic' chimney salts that are attracting moisture from the air, which may include tars and other chemicals from burning wood or coal.
Answer:- These 'salts' are very difficult to hold back in the wall, even with the re plastering to our Specification carried out to perfection. We recommend using Mesh Membrane - a type of dry lining - to allow you to re plaster using normal, lightweight plaster, with no risk of further 'salting'.
Products mentioned above:
Salt Neutralizer:- a clear liquid used to neutralize 'salts' in render, plaster or masonry, either to attempt to save otherwise sound plaster or as a preparation prior to re-plastering to our Specification. Apply two coats, wetting in between with fresh water.
Mesh Membrane:- easy to install dimpled plastic 'air gap' dry lining membrane, supplied in rolls like wallpaper. Designed to cover damp or salty walls and provide a fresh surface for re plastering with a modern lightweight plaster (usually 'bonding').
Quick Cream:- new, easy to install, cream damp proofing product - no pump required, no mess, no smell - includes injection nozzle extension. Designed to gently diffuse into the wall to form a water repellent layer - a 'damp proof course' (DPC). It is approved by the British Board of Agreement - BBA Test Certificate No: 02/3961 - as used by the professionals. The BBA is a Government Approved organization which has been testing building materials for over 30 years. Note - not all damp proofing materials have passed these tests - beware of cheap imitations).
If you need any help with any type of Chimney damp problem or plaster repair, Property Repair Systems will be pleased to give you completely free, no obligation advice on 01626 331351.
