Blown-in insulation: what it costs and whether it's worth it
How much does it cost? Is it worth it? We look at real prices, materials and experiences of blown-in insulation compared to SATE external wall insulation.
English · Original discussion in Spanish · Published
Blown-in insulation: quick fix or expensive patch?
For a brick house of less than 60 m³, blowing rock wool into the cavity wall costs between €1,000 and €1,300. The promise: feel the difference in winter and summer for less than the price of a SATE facade. But the details matter.
Materials under scrutiny
Three options dominate the market: cellulose, rock wool and cork. Cellulose (recycled paper) is cheap but produces dust that seeps through sockets, forcing you to seal them. Rock wool, the most recommended, performs well and causes no dust problems if installed correctly. Cork, a natural option, is gaining fans but is less common. Polyurethane foam, according to industry sources, should be avoided: some installers use it unscrupulously and its insulating properties when injected are questionable.
Real costs and savings
Prices vary: €1,200 for cellulose five years ago, €1,300 for rock wool for 90 m² seven years ago, and under €1,000 for a detached house a year ago. The key question is whether the energy savings justify the investment. Testimonials point to a noticeable improvement: in winter the house heats up faster and in summer the ceiling stops being an oven. However, if the house has thermal bridges in floor slabs or corners, blown-in insulation won't fix them.
Blown-in, SATE or both
The temptation to combine blown-in insulation now and SATE later is understandable on a budget. But experts warn: SATE (external insulation) is more complete, though it costs around €80/m². A whole facade can exceed €7,000. Compared to the €1,000-1,300 of blown-in insulation, the difference is enormous. The question nobody answers well is whether it's really worth doing both. Blown-in insulation is a good complement if SATE is added later, but if the facade is only re-rendered without insulating, the initial investment will be lost.
The tacit consensus: blown-in insulation is for flats where you can't insulate from the outside. For a detached house, SATE is the complete solution. Blown-in insulation remains a temporary fix. Quality or price? The data says that €1,000 can improve comfort, but true energy efficiency costs at least five times more.
Related debates in the forum
For a brick house of less than 60 m³, blowing rock wool into the cavity wall costs between €1,000 and €1,300. The promise: feel the difference in winter and summer for less than the price of a SATE facade. But the details matter.
Materials under scrutiny
Three options dominate the market: cellulose, rock wool and cork. Cellulose (recycled paper) is cheap but produces dust that seeps through sockets, forcing you to seal them. Rock wool, the most recommended, performs well and causes no dust problems if installed correctly. Cork, a natural option, is gaining fans but is less common. Polyurethane foam, according to industry sources, should be avoided: some installers use it unscrupulously and its insulating properties when injected are questionable.
Real costs and savings
Prices vary: €1,200 for cellulose five years ago, €1,300 for rock wool for 90 m² seven years ago, and under €1,000 for a detached house a year ago. The key question is whether the energy savings justify the investment. Testimonials point to a noticeable improvement: in winter the house heats up faster and in summer the ceiling stops being an oven. However, if the house has thermal bridges in floor slabs or corners, blown-in insulation won't fix them.
Blown-in, SATE or both
The temptation to combine blown-in insulation now and SATE later is understandable on a budget. But experts warn: SATE (external insulation) is more complete, though it costs around €80/m². A whole facade can exceed €7,000. Compared to the €1,000-1,300 of blown-in insulation, the difference is enormous. The question nobody answers well is whether it's really worth doing both. Blown-in insulation is a good complement if SATE is added later, but if the facade is only re-rendered without insulating, the initial investment will be lost.
The tacit consensus: blown-in insulation is for flats where you can't insulate from the outside. For a detached house, SATE is the complete solution. Blown-in insulation remains a temporary fix. Quality or price? The data says that €1,000 can improve comfort, but true energy efficiency costs at least five times more.
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Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (29 replies).
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