4 ms·

One note of caution, he describes removing the lath and plaster and inserting eps insulation. It didn’t mention if he did this, he might have done, but it’s imp

One note of caution, he describes removing the lath and plaster and inserting eps insulation. It didn’t mention if he did this, he might have done, but it’s important to have a continuous taped vapour barrier on the warm side of the insulation to prevent water vapour from passing through, condensing on the timber structure and causing it to rot. Also ventilate the cold side of the insulation or a least have a gap to form a capillary break with the cold outside wall. I’ve seen a few badly done insulation jobs in timber buildings that have needed floor joists and studs cut out and replaced. It only takes about 15-20 years.

OJFord 4y ago
Lath & plaster does not form a vapour barrier; deliberately not in most cases (there was perhaps some crossover when more moderm building techniques were still using lath and plaster) - old houses need to 'breathe' as they say, moisture needs to be allowed to move between inside and out. They can be warm & dry, but the way to achieve it is (paradoxically) porous materials.
- ArchitectAnon 4y ago
  Yes of course, but I was thinking more in terms of DIYers jamming a lot of non-breathable eps into old houses. Probably better to say consult someone who knows what they’re talking about before you internally insulate your old house.
  - bombcar 4y ago
    Yeah insulation that is a vapor barrier shouldn’t replace insulation that wasn’t without considering the effects. You can use something like rock wool (in batts or panels) to get insulation that is still vapor permeable and water resistant.
forgetfreeman 4y ago
I'm glad someone addressed this as I cringed visibly when I got to this part of the post. I'm very much hoping someone with actual experience with controlling moisture stopped this person before they completed this installation. If not, that house is the residential equivalent of a dead man walking.
bombcar 4y ago
Be careful with an impermeable vapor barrier especially if adding one. It may work perfectly for keeping water out of the wall cavity in winter, but become the condensation layer in summer - on the wall side! You can use smart vapor control layers (such as Intello) to counteract this - but be sure you’ve discussed how the wall can dry out if it gets wet. And the worst of all is if you end up with two vapor barriers - one on the inside and one on the outside - you’ll end up with a “dirty diaper” effect. https://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers https://www.buildingscience.com/documents/digests/bsd-106-un...
- ArchitectAnon 4y ago
  Good point, in a hot climate with air conditioning, everything works in reverse in summer. My perspective is Northern Europe; consult a local expert.
- Freestyler_3 4y ago
  What about one way barriers?
  - knodi123 4y ago
    those exist??
waingake 4y ago
Under my house ( 1920's wooden home ) I see EPS pushed up against the wooden floor boards. This was done by the previous owner. The EPS itself is exposed. Is this safe ?
phpisthebest 4y ago
> continuous taped vapour barrier on the warm side of the insulation so what do you do when it is 100 degrees outside and 70 degrees inside during the summer, and 30 degrees outside and 70 degress inside during the winder? Move the vapour barrier?

OJFord 4y ago

Lath & plaster does not form a vapour barrier; deliberately not in most cases (there was perhaps some crossover when more moderm building techniques were still using lath and plaster) - old houses need to 'breathe' as they say, moisture needs to be allowed to move between inside and out. They can be warm & dry, but the way to achieve it is (paradoxically) porous materials.

ArchitectAnon 4y ago
Yes of course, but I was thinking more in terms of DIYers jamming a lot of non-breathable eps into old houses. Probably better to say consult someone who knows what they’re talking about before you internally insulate your old house.
- bombcar 4y ago
  Yeah insulation that is a vapor barrier shouldn’t replace insulation that wasn’t without considering the effects. You can use something like rock wool (in batts or panels) to get insulation that is still vapor permeable and water resistant.

forgetfreeman 4y ago

I'm glad someone addressed this as I cringed visibly when I got to this part of the post. I'm very much hoping someone with actual experience with controlling moisture stopped this person before they completed this installation. If not, that house is the residential equivalent of a dead man walking.

bombcar 4y ago

Be careful with an impermeable vapor barrier especially if adding one. It may work perfectly for keeping water out of the wall cavity in winter, but become the condensation layer in summer - on the wall side! You can use smart vapor control layers (such as Intello) to counteract this - but be sure you’ve discussed how the wall can dry out if it gets wet. And the worst of all is if you end up with two vapor barriers - one on the inside and one on the outside - you’ll end up with a “dirty diaper” effect. https://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers https://www.buildingscience.com/documents/digests/bsd-106-un...

ArchitectAnon 4y ago
Good point, in a hot climate with air conditioning, everything works in reverse in summer. My perspective is Northern Europe; consult a local expert.
Freestyler_3 4y ago
What about one way barriers?
- knodi123 4y ago
  those exist??

waingake 4y ago

Under my house ( 1920's wooden home ) I see EPS pushed up against the wooden floor boards. This was done by the previous owner. The EPS itself is exposed. Is this safe ?

phpisthebest 4y ago

> continuous taped vapour barrier on the warm side of the insulation so what do you do when it is 100 degrees outside and 70 degrees inside during the summer, and 30 degrees outside and 70 degress inside during the winder? Move the vapour barrier?