ᐅ Insulation of a Detached Semi-Detached House – Experiences?
Created on: 8 Jul 2018 20:59
M
MoeTavern
Hello everyone,
I am interested in purchasing a currently detached house that is planned as a semi-detached property. The shell construction is already in place. My concern is the insulation of the house wall facing the yet-to-be-built neighboring house, given that it is completely uncertain whether the second semi-detached unit will ever be built.
The developer plans to insulate and plaster the wall in question with the soundproofing insulation typically used between two semi-detached houses, which is part of the house’s KfW55 energy efficiency rating. However, this insulation is only 6cm (2.4 inches) thick. The insulation on all other walls is 16cm (6.3 inches) thick. I am not a professional, but I assume that in this way I would have significantly poorer insulation, and in my understanding, the house would no longer comply with KfW55 standards. Using 16cm (6.3 inches) insulation here would lead to building violations. The neighbor had originally agreed to sell the land for the second unit to the developer but later withdrew, as they did not want to reduce their garden so much.
I am now uncertain because a) I don’t know what I should negotiate regarding the insulation, and b) I have no certainty whether a house—and if so, what type and quality—will ever be built directly next to my potential home.
I would appreciate any advice. I am happy to provide more information if needed.
Best regards,
Moe
I am interested in purchasing a currently detached house that is planned as a semi-detached property. The shell construction is already in place. My concern is the insulation of the house wall facing the yet-to-be-built neighboring house, given that it is completely uncertain whether the second semi-detached unit will ever be built.
The developer plans to insulate and plaster the wall in question with the soundproofing insulation typically used between two semi-detached houses, which is part of the house’s KfW55 energy efficiency rating. However, this insulation is only 6cm (2.4 inches) thick. The insulation on all other walls is 16cm (6.3 inches) thick. I am not a professional, but I assume that in this way I would have significantly poorer insulation, and in my understanding, the house would no longer comply with KfW55 standards. Using 16cm (6.3 inches) insulation here would lead to building violations. The neighbor had originally agreed to sell the land for the second unit to the developer but later withdrew, as they did not want to reduce their garden so much.
I am now uncertain because a) I don’t know what I should negotiate regarding the insulation, and b) I have no certainty whether a house—and if so, what type and quality—will ever be built directly next to my potential home.
I would appreciate any advice. I am happy to provide more information if needed.
Best regards,
Moe
M
MoeTavern11 Jul 2018 17:18Addendum:
In the meantime, I asked the builder to provide a comparative calculation showing the difference in insulation performance when the affected wall is insulated with only 6cm (2.4 inches) instead of 16cm (6.3 inches), possibly using a higher-quality insulation material.
The response was rather brief:
The building meets the standard of the Energy Saving Ordinance (Energieeinsparverordnung 2016 DIN 4109).
According to the building specifications, the relevant wall is planned to have 6cm (2.4 inches) insulation with a thermal conductivity of WLG 035.
Contrary to the Energy Saving Ordinance (60mm (2.4 inches) insulation board WLG 035), a 60mm (2.4 inches) insulation board with WLG 022 can be installed.
This would mean an insulation value of about 60% can be achieved.
####
Are you familiar with these insulation material designations? Is the figure of 60% a realistic estimate? I interpret an insulation performance of only 60% as an indication that I will definitely face significantly higher costs.
How would you proceed from here?
Thank you.
In the meantime, I asked the builder to provide a comparative calculation showing the difference in insulation performance when the affected wall is insulated with only 6cm (2.4 inches) instead of 16cm (6.3 inches), possibly using a higher-quality insulation material.
The response was rather brief:
The building meets the standard of the Energy Saving Ordinance (Energieeinsparverordnung 2016 DIN 4109).
According to the building specifications, the relevant wall is planned to have 6cm (2.4 inches) insulation with a thermal conductivity of WLG 035.
Contrary to the Energy Saving Ordinance (60mm (2.4 inches) insulation board WLG 035), a 60mm (2.4 inches) insulation board with WLG 022 can be installed.
This would mean an insulation value of about 60% can be achieved.
####
Are you familiar with these insulation material designations? Is the figure of 60% a realistic estimate? I interpret an insulation performance of only 60% as an indication that I will definitely face significantly higher costs.
How would you proceed from here?
Thank you.
K
Knallkörper12 Jul 2018 09:23MoeTavern schrieb:
Do you recognize the names of the insulation materials? Is the 60% figure realistic?Mathematically speaking: 6 cm (2.4 inches) of insulation with a thermal conductivity of 0.022 W/mK achieves 59.66% of the insulating effect of 16 cm (6.3 inches) of insulation with 0.035 W/mK [(6 cm : 0.022 W/mK) : (16 cm : 0.035 W/mK)].
The questions are more about what this means, firstly, for the overall energy demand of the house—which is probably minimal. Secondly, whether it could cause moisture problems on the corresponding interior walls due to lower temperatures. I don’t know. It also depends on the type of masonry material.
M
MoeTavern12 Jul 2018 09:40Thank you. So at least the 60% is correct. The affected wall, like all other exterior walls, is made of sand-lime brick.
MoeTavern schrieb:
But I assume the owner does not want to sell. I agree. The owner is unlikely to make their building plot unusable by selling off 1m, 3m, or 3.5m.
MoeTavern schrieb:
I think my best chance is to negotiate a right of first refusal with the owner. There is even the option of a registered right of first refusal, where the purchase priority is entered in the land registry. Why would the neighbor agree to that, unless they are handsomely paid? And if they want to sell to a close acquaintance anyway, they could just agree on an unusually high sale price that you would politely refuse. Besides, this does not solve the insulation problem.
MoeTavern schrieb:
If I insulate now with 16cm (6.3 inches), I exceed the limit that requires a building encumbrance, which I would have to remove at my own expense if the neighbor eventually sells and I have no right of first refusal. You have a building permit for a boundary wall. Once everything is completed as approved, you can insulate the remaining 10cm (4 inches) without needing further approval according to §65 (2) 2. Building Code NRW. You should regulate the use of the 2m² (22 sq ft) of the neighbor’s property contractually with the neighbor, including a commitment to remove the extension if the neighbor builds there. This way, you avoid a building encumbrance and land registry entry. The costs for removal will almost certainly be lower than those for a subdivision or a right of first refusal.
Similar topics