How to get blocked over air vents reopened

Really depends on how old the building is, a lot of cavity built houses in the past had air vents high & low to vent the cavity with no internal vent this stop penetrating damp, older solid brick houses only generally had underfloor vents to to stop the floor getting damp & rotting as installing vents all the way through the wall creates nothing other than coldness, it was generally the materials used in its construction that allowed it to breathe and remain water tight.then more modern houses had small weep vents to allow moisture to escape so to answer your question &advice you on the best solution would require me to know what the house was constructed of how old it is. In this type of property it would have had a slate damp proof course installed at the time of construction ,it will be of solid brick( no cavity) the only reason for air bricks is to vent the underfloor void and prevent dampness in a wooden floor, according to the latest which survey rising damp is misdiagnosed in over 75% of cases rising to 95%in older property's most modern damp proof systems are designed to cover up the dampness rather than find the source of the water ingress and cure it, It really depends on what has been done to the property over the years as modern materials and old houses don't work well together as older material is designed to accept condensation and the weather &deal with it modern materials are designed to do the opposite, cement sucks in moisture to go off,lime mortar/plaster hold onto moisture allowing it to wick out the the building through the mortar joints when dry outside.y you need to read the rising damp myth or the heritage property web site to better understand how your building was constructed & how the material in its construction all worked together to keep it water tight, I can assure you having vents all the way through the wall unless to vent a suspended wooden floor will achieve nothing but a cold house. having a modern damp proof course will achieve long term the opposite of what you want regardless of any garauntee promised Also all chimneys pots should be capped at roof level with a breather cap &vented at room level to allow air flow in any un used fire places the size of the chimney will determine how many fires it is supporting leading to different rooms all these need vented both top & bottom to prevent dampness. Good luck Alex

if you live in an older house, and the brick/stone is layed and pointed in cement, this will stop your building from breathing, causing damp to rest in the walls with nowhere to go but in. if this is the case, a rake out and repoint with lime mortar will be the best solution. Newer houses shouldn't really have these issues, if so i'd get in touch with the building company rather then damp surveyors. Ben

Do not open air vents within rooms , they cause temperatures to drop in winter and condensation. Learn to ventilate the property properly through opening windows when necessary or mechanically. Don’t let anyone tell you you have rising damp .

Tbh they've probably just been bricked up and plastered over internally to stop draughts. Any builder, plasterer should be able to open them up and fit pvc air vents. It will be draughty after that which is probably the reason they were covered in the first place.