Sound insulation for a dormer window

Dormer loft insulation
Sound insulation for a dormer window, or dormer loft, is in many cases necessary because the modern dormer loft is thermal insulated, but has almost little to no noise or sound insulation. This is due to the relative low mass of the building materials that are being used in constructing a dormer window, such as plywood. By adding mass to your dormer loft construction the sound insulation will be noticeably improved.

With Isomat KE you can make light materials more heavy, Isomat increases the acoustic insulation of the walls and ceiling of the dormer. As a result outside noises, such as traffic noise, will be less audible than before. Isomat is a mass loaded vinyl and isolates vibrations in plywood, underlayment or plasterboard. Isomat KE is also used to insulate wooden subfloors and lightweight doors.

Noise and thermal insulation dormer loft
If you are restoring an existing dormer loft you might want to improve on both noise and thermal insulation. To insulate against outside noises you can apply Isomat KE, we recommend the 14 kg/m² version, for the walls and ceiling of the dormer. Use a thin layer of Stauf glue on the jute fiber side of the Isomat. To keep the sheets in place you can use staples or short nails on the corners of the Isomat sheets. Next step is a layer of plywood to cover up and to fix the Isomat firmly in place on the surface of the dormer window walls and ceiling.

To improve the thermal insulating of the dormer loft you can fill hollow spaces, in the ceiling for example, with Acoustic Cotton Wool insulation. Make sure that condensation between hot and cold air is not a problem. On our tips page we have a step-by-step plan with more details and tips.

Below you will find the described products to insulate a dormer window

Sound Insulation for the Dormer Window