ᐅ We are planning to build a house. Is what has been offered to us acceptable?
Created on: 15 Apr 2015 19:47
L
LittleWulf
Hello, we would like to start building our own home this year with a general contractor, a complete package.
Since I am not very knowledgeable about this topic despite a lot of research and cannot properly assess such matters, I wanted to ask what you think about the offer we have received. We are currently strongly leaning towards this provider.
We are curious whether this is more or less "standard" or if it is rather on the lower end. Also, what could possibly be improved without immediately having to pay several thousand more.
First of all, many items are listed as “insulated,” such as the lowered ceiling in the bay window, the roller shutter boxes, or the solid knee wall.
Floor:
Reinforced concrete slab foundation including frost protection edge strip and waterproofing against rising damp instead of strip footings. Thickness about 20cm (8 inches) and concrete quality C 20/25.
Steel reinforcement and slab thickness according to the assumed ground pressure as per the homeowner’s specification sheet (I can provide that if needed). A foil is laid under the slab as a clean layer.
Walls:
The exterior walls are executed with a total thickness of about 44.5cm (17.5 inches) as follows:
1.5cm (0.6 inches) fine plaster
17.5cm (7 inches) masonry of porous, fired clay brick
14cm (5.5 inches) cavity insulation, thermal conductivity class (WLG) 035
approx. 11.5cm (4.5 inches) facing brickwork
Interior walls on ground and attic floors are constructed with brick (Poroton).
(Now the addition for KfW 70)
The piping for the warm water underfloor heating is designed for a supply temperature of 35°C (95°F) by installing the pipes closer together.
Extension of roof insulation to 26cm (10 inches) with WLG 035
(Credit of 4,216,- if omitted)
[Is that reasonable for slightly better insulation and closer pipe spacing?]
For an upgrade to KfW 55 (20k-21k):
Different heating system with more solar input.
Ventilation system.
8cm (3 inches) insulation with WLG 035 under the slab.
Exterior walls then apparently no longer face brick but rendered, consisting of:
1.5cm (0.6 inches) fine plaster
17.5cm (7 inches) masonry of porous, fired clay brick
20cm (8 inches) external thermal insulation composite system (ETICS) with WLG 032 including silicate facade plaster.
Now my question is: since I would like a ventilation system, should I improve the insulation somehow even if I do not aim for KfW 55? And isn’t the masonry thickness of 17.5cm (7 inches) rather thin?
I skimmed a forum where this exact wall build-up (by the same contractor) was heavily criticized.
Since I am not very knowledgeable about this topic despite a lot of research and cannot properly assess such matters, I wanted to ask what you think about the offer we have received. We are currently strongly leaning towards this provider.
We are curious whether this is more or less "standard" or if it is rather on the lower end. Also, what could possibly be improved without immediately having to pay several thousand more.
First of all, many items are listed as “insulated,” such as the lowered ceiling in the bay window, the roller shutter boxes, or the solid knee wall.
Floor:
Reinforced concrete slab foundation including frost protection edge strip and waterproofing against rising damp instead of strip footings. Thickness about 20cm (8 inches) and concrete quality C 20/25.
Steel reinforcement and slab thickness according to the assumed ground pressure as per the homeowner’s specification sheet (I can provide that if needed). A foil is laid under the slab as a clean layer.
Walls:
The exterior walls are executed with a total thickness of about 44.5cm (17.5 inches) as follows:
1.5cm (0.6 inches) fine plaster
17.5cm (7 inches) masonry of porous, fired clay brick
14cm (5.5 inches) cavity insulation, thermal conductivity class (WLG) 035
approx. 11.5cm (4.5 inches) facing brickwork
Interior walls on ground and attic floors are constructed with brick (Poroton).
(Now the addition for KfW 70)
The piping for the warm water underfloor heating is designed for a supply temperature of 35°C (95°F) by installing the pipes closer together.
Extension of roof insulation to 26cm (10 inches) with WLG 035
(Credit of 4,216,- if omitted)
[Is that reasonable for slightly better insulation and closer pipe spacing?]
For an upgrade to KfW 55 (20k-21k):
Different heating system with more solar input.
Ventilation system.
8cm (3 inches) insulation with WLG 035 under the slab.
Exterior walls then apparently no longer face brick but rendered, consisting of:
1.5cm (0.6 inches) fine plaster
17.5cm (7 inches) masonry of porous, fired clay brick
20cm (8 inches) external thermal insulation composite system (ETICS) with WLG 032 including silicate facade plaster.
Now my question is: since I would like a ventilation system, should I improve the insulation somehow even if I do not aim for KfW 55? And isn’t the masonry thickness of 17.5cm (7 inches) rather thin?
I skimmed a forum where this exact wall build-up (by the same contractor) was heavily criticized.
Freely adapted from Uncle Wiki: "For insulation in new construction, solid materials such as rigid polyurethane foam (PUR/PIR), stone wool or mineral wool, extruded polystyrene foam (XPS), expanded polystyrene foam (EPS), or loose fill can be used. For retrofitting cavity insulation, options include polyurethane spray foam, stone wool or glass wool, expanded polystyrene granulate (EPS), silicate lightweight foam granulate (SLS20), expanded perlite, and aerogel. The insulation materials must be permanently water-repellent (hydrophobic) and comply with the standardized application according to DIN 4108-10 (WZ = insulation of double-shell walls, cavity insulation)."
For me, this means: Insulation materials without this certification probably require ventilation behind them (that’s my assumption).
For me, this means: Insulation materials without this certification probably require ventilation behind them (that’s my assumption).
B
Bauexperte17 Apr 2015 23:55LittleWulf schrieb:
What is correct now? Is air space between insulation and masonry required by DIN? Or is it only necessary depending on the type of insulation used?According to DIN 1053, an air gap at least 4 cm (1.6 inches) thick must be maintained.Regards, Bauexperte
L
LittleWulf18 Apr 2015 00:01Does that mean cavity insulation contradicts the DIN standard? Or is cavity insulation not applicable alongside the DIN standard at the same time?
B
Bauexperte18 Apr 2015 00:19LittleWulf schrieb:
Does this mean that cavity insulation contradicts the DIN standards? Or is cavity insulation not simultaneously applicable with the DIN? Some suppliers/architects believe that with cavity insulation they can omit the air gap because there is an approval from the Institute for Building Technology; I seem to recall, however, that this only applies when using mineral wool. On the other hand, this method contradicts the recognized rules of technology and therefore also the DIN standards.
Best regards, Bauexperte
Similar topics