So, many people have suggested over the years this should just be called the “old damp house forum”
So I thought I should start a basic guide to tackling damp in a period property that hopefully the learned members of this parish can add to, and we can then point others to in the future:
Broadly, no matter your house, the rules are the same. As a rule of thumb steps 1 & 2 are the cause of the majority of damp issues.
Stage 1 - External
1) Check and resolve any sources of external water ingress at the top (failed roof, gutters, gullets, roof valleys etc)
2) Check exterior vs interior ground levels and sort as far as possible (exterior should be lower, preferably at least 300mm but not always practical, but definitely below your DPC if you have one) and make sure all services, waste water, guttering down pipes etc are behaving and going where they should with no leaks
Pause
3) Address the walls themselves, remove any non breathable materials (masonry paint, cement render etc) and repair any damage to the walls then repoint (or render) with lime based mortar/render (either NHL or “fat” lime depending on your preference)
Pause
Wait, the feedback loop is slow as this stuff takes a long time to dry, there are various theories on here depending on construction, location and aspect, but between 1 and 3 months per inch of wall thickness will give you a good idea.
Stage 2 - Interior
If there are still problems then move on to tackle the inside
Floors:
If suspended are they properly ventilated? Are there service leaks in water/waste pipes underneath?
If solid, how are they constructed? Modern concrete floors may be forcing moisture into the walls, later coverings might be preventing earth or stone floors from breathing etc.
Walls:
Make sure that internal finishes are breathable - remove / replace gypsum or cement based plasters and vinyl paints where necessary
So I thought I should start a basic guide to tackling damp in a period property that hopefully the learned members of this parish can add to, and we can then point others to in the future:
Broadly, no matter your house, the rules are the same. As a rule of thumb steps 1 & 2 are the cause of the majority of damp issues.
Stage 1 - External
1) Check and resolve any sources of external water ingress at the top (failed roof, gutters, gullets, roof valleys etc)
2) Check exterior vs interior ground levels and sort as far as possible (exterior should be lower, preferably at least 300mm but not always practical, but definitely below your DPC if you have one) and make sure all services, waste water, guttering down pipes etc are behaving and going where they should with no leaks
Pause
3) Address the walls themselves, remove any non breathable materials (masonry paint, cement render etc) and repair any damage to the walls then repoint (or render) with lime based mortar/render (either NHL or “fat” lime depending on your preference)
Pause
Wait, the feedback loop is slow as this stuff takes a long time to dry, there are various theories on here depending on construction, location and aspect, but between 1 and 3 months per inch of wall thickness will give you a good idea.
Stage 2 - Interior
If there are still problems then move on to tackle the inside
Floors:
If suspended are they properly ventilated? Are there service leaks in water/waste pipes underneath?
If solid, how are they constructed? Modern concrete floors may be forcing moisture into the walls, later coverings might be preventing earth or stone floors from breathing etc.
Walls:
Make sure that internal finishes are breathable - remove / replace gypsum or cement based plasters and vinyl paints where necessary