ᐅ Insulating an Interior Timber Frame Wall and Building Up the Layer Thickness
Created on: 27 Feb 2019 01:06
M
Maik MohrM
Maik Mohr27 Feb 2019 01:06Hello community,
we recently bought a house, but unfortunately, we now have to fix the poor workmanship of the previous owner: In one room there was a musty smell that was not noticeable before due to the commercial use. On the interior side of the half-timbered exterior wall (exposed to weather and facing north), panels were installed, underneath were 20mm (1 inch) polystyrene boards with significant mold growth behind them.
I then removed all the wallpaper and plaster down to the masonry/half-timber structure. Unfortunately, the infill panels are not aligned with the beams – they sit about 20-30mm (1 inch) deeper. Previously, this gap was filled with mortar and overlapped with interlocking tiles, but I no longer wanted to do it that way, especially as I don’t have matching roof tiles to use.
My idea now is to plaster the infills properly and then glue wood fiberboards onto the plaster. I would either place these flush with the beams or about 10-15mm (0.5 inch) in front of the beams and then bring the beams up to flush level with straw and clay plaster. Finally, I would screw an additional 20-30mm (1-1.5 inch) layer of wood fiberboard on the outside, primarily to close gaps and provide basic insulation. Over that, a clay or lime plaster would be applied.
What do you think? Is this a viable approach in terms of being vapor permeable, or is it a no-go?
If this idea is not good, please suggest something. I am far from an expert in this field, and this measure was unfortunately not planned in the budget. I also don’t want to fully coat the infills with clay mortar as that would probably take weeks to dry completely.
Regarding the pictures: The beams are quite gnawed but stable at their core (good oak). The damage is from woodworm on the damp side. This will be repaired as well.
Best regards – Maik
we recently bought a house, but unfortunately, we now have to fix the poor workmanship of the previous owner: In one room there was a musty smell that was not noticeable before due to the commercial use. On the interior side of the half-timbered exterior wall (exposed to weather and facing north), panels were installed, underneath were 20mm (1 inch) polystyrene boards with significant mold growth behind them.
I then removed all the wallpaper and plaster down to the masonry/half-timber structure. Unfortunately, the infill panels are not aligned with the beams – they sit about 20-30mm (1 inch) deeper. Previously, this gap was filled with mortar and overlapped with interlocking tiles, but I no longer wanted to do it that way, especially as I don’t have matching roof tiles to use.
My idea now is to plaster the infills properly and then glue wood fiberboards onto the plaster. I would either place these flush with the beams or about 10-15mm (0.5 inch) in front of the beams and then bring the beams up to flush level with straw and clay plaster. Finally, I would screw an additional 20-30mm (1-1.5 inch) layer of wood fiberboard on the outside, primarily to close gaps and provide basic insulation. Over that, a clay or lime plaster would be applied.
What do you think? Is this a viable approach in terms of being vapor permeable, or is it a no-go?
If this idea is not good, please suggest something. I am far from an expert in this field, and this measure was unfortunately not planned in the budget. I also don’t want to fully coat the infills with clay mortar as that would probably take weeks to dry completely.
Regarding the pictures: The beams are quite gnawed but stable at their core (good oak). The damage is from woodworm on the damp side. This will be repaired as well.
Best regards – Maik
No, that won’t work.
Insulating a half-timbered wall from the inside is quite demanding. If you have the necessary budget, have a professional company do it, or at least work together with one.
Here are a few brief notes on what would be necessary:
- Ceilings and floors also need to be exposed
- Ceilings and floors must be prepared so that a continuous vapor barrier can be installed across rooms and floors
- The masonry must first be sealed on the outside to be waterproof but vapor-permeable
- For the insulation, there are various options; a proven method is a complete stud framework on all exterior walls with insulation boards or blown-in insulation
- The interior side must then be sealed without gaps with a vapor barrier, followed by, for example, drywall
If you’ve never done something like this before, you won’t be able to manage it.
Your idea leads to exactly the problems you have already encountered.
Simpler, more cost-effective, and safer is exterior insulation.
Insulating a half-timbered wall from the inside is quite demanding. If you have the necessary budget, have a professional company do it, or at least work together with one.
Here are a few brief notes on what would be necessary:
- Ceilings and floors also need to be exposed
- Ceilings and floors must be prepared so that a continuous vapor barrier can be installed across rooms and floors
- The masonry must first be sealed on the outside to be waterproof but vapor-permeable
- For the insulation, there are various options; a proven method is a complete stud framework on all exterior walls with insulation boards or blown-in insulation
- The interior side must then be sealed without gaps with a vapor barrier, followed by, for example, drywall
If you’ve never done something like this before, you won’t be able to manage it.
Your idea leads to exactly the problems you have already encountered.
Simpler, more cost-effective, and safer is exterior insulation.
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