I am in the planning phase of an extensive renovation of a house dating from the early 1800s (perhaps even the 1700s).
The house is 22x7.5 meters, with a basement (longitudinal hillside, where one short side is fully visible - with an exit to the garden - and where the other (left side) is completely underground).
Plans so far:
- Drain the basement (as there is extreme moisture pressure from the left side)
- Completely renovate the upper floor and replace the roof, as well as install a dormer.
- Replace all siding on the entire house.
- Renovate all windows and install energy glass.
- Install an FTX system.
I have had a structural engineer/inspector at home who has already answered a thousand questions, but one thing I haven't quite figured out is:
Should I install a vapor barrier on the upper floor when I redo/add insulation to everything?
Why/Why not?
The house is currently heated with geothermal energy (radiators in all rooms except the kitchen and one bathroom which have underfloor heating).
We also burn quite a bit in the stove in the living room.
The house is 22x7.5 meters, with a basement (longitudinal hillside, where one short side is fully visible - with an exit to the garden - and where the other (left side) is completely underground).
Plans so far:
- Drain the basement (as there is extreme moisture pressure from the left side)
- Completely renovate the upper floor and replace the roof, as well as install a dormer.
- Replace all siding on the entire house.
- Renovate all windows and install energy glass.
- Install an FTX system.
I have had a structural engineer/inspector at home who has already answered a thousand questions, but one thing I haven't quite figured out is:
Should I install a vapor barrier on the upper floor when I redo/add insulation to everything?
Why/Why not?
The house is currently heated with geothermal energy (radiators in all rooms except the kitchen and one bathroom which have underfloor heating).
We also burn quite a bit in the stove in the living room.
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My hobbyhorses collectively neigh: No.
An old house is built to "breathe." It is meant to let air in and out through intentional draftiness. If you start installing a vapor barrier somewhere, you increase moisture load somewhere else. In the worst-case scenario, damage.
Instead, you should use natural materials that can withstand a certain amount of moisture. Linen insulation or cellulose are examples of such materials.
An old house is built to "breathe." It is meant to let air in and out through intentional draftiness. If you start installing a vapor barrier somewhere, you increase moisture load somewhere else. In the worst-case scenario, damage.
Instead, you should use natural materials that can withstand a certain amount of moisture. Linen insulation or cellulose are examples of such materials.
Self-builder
· Stockholm
· 10 285 posts
Checked to see if there is any marking on the house or area?
I agree with ricebridge. Use hygroscopic natural insulation materials and you won't need any plastic film. You can use cardboard with limited vapor resistance, e.g., AC 150, on the inside of the insulation.
Cellulose - Check!
A quick Google search revealed that it is available both as a board and loose (for spraying).
I do like boards but... which would you recommend?
Is the price of cellulose roughly similar to mineral wool?
Could be good to know for an upcoming rough budget.
A quick Google search revealed that it is available both as a board and loose (for spraying).
I do like boards but... which would you recommend?
Is the price of cellulose roughly similar to mineral wool?
Could be good to know for an upcoming rough budget.
It completely depends on how it looks there. If you're going with loose-fill, have a company do it, and get a quote well in advance.C Chentin said:
What should be used instead of plastic between the insulation and the sparse paneling when intending to spray loose-fill insulation?
When replacing the outer panel: What do you think about placing a wind barrier inside the nail battens? That can't be wrong, regardless of what's inside, right?
When replacing the outer panel: What do you think about placing a wind barrier inside the nail battens? That can't be wrong, regardless of what's inside, right?
Insulation should always be surrounded by airtight layers. The one on the inside should be more vapor-tight than the one on the outside. Wind barrier, which is airtight but diffusion-open, is very suitable for the outside. On the inside, you can use asphalt paper type AC 150 or some similar material.
Does this apply to me as well? Should I use construction foil or something similar, or should I ignore it? See my thread:J justusandersson said:
https://www.byggahus.se/forum/threads/atgaerder-vid-borttag-av-kattvind.336233/#post-3215824
It is the choice of insulation material that determines how dense a vapor barrier you need. Materials that lack hygroscopic properties such as mineral wool require a dense vapor barrier of the plastic foil type. Hygroscopic insulation materials like sawdust, shavings, cellulose fibers, linen, etc., manage with significantly less vapor-tight layers. However, it is an old rule that the inner layer should be more vapor-tight than the outer one. One cannot overlook the construction year either. Older houses are significantly more drafty than newer ones.
I don't have any insulation in the ceiling other than some form of straw that I've understood, along with some cover out towards the sheathing that I've seen. 1940s house, plaster facade, with additional insulation on the outside and a framed vertical panel on the outermost part. So I essentially have two facades (not done by me). The additional insulation is regular insulation of mineral wool or glass wool type, I believe. But not in the sloped roof, nothing has been done there. The attic is wood chips and the roof is a parallel roof with, as mentioned, some form of straw or something. Half of the roof has this straw, and the part towards the attic only has the sheathing.J justusandersson said:
I don't agree with those who categorically say no. It depends on how you build. I have replaced the roof on my old house. The existing underlay was likely from the 1850s. Now I have a moisture barrier and external insulation.
If you (=eddiw) are not going to replace the insulation in the sloped roof, there is no reason to install a vapor barrier. The outer roof certainly lacks an air gap behind the sheathing, which is a prerequisite for using a vapor barrier.
How did you think now? If there's poor ventilation, it's even more important that indoor moisture doesn't get into the construction.
One should not enclose organic material between two vapor-tight layers (vapor barrier and underlayment felt). All 1.5 and 2.5 story houses built before about 1950 have sloped roofs with sawdust insulation or something similar, without an air gap. It is not an ideal construction, but providing it with a vapor barrier on the underside makes it catastrophic.