Insulating a ceiling under a timber floor with R'BULL Pro

A timber floor is not a concrete slab

It is light, it lets air through between the boards, and it transmits impact noise without attenuating it. Insulating under a timber floor therefore answers three questions at once: heat, air and sound.

Airtightness, often the real problem

In an old house, air moves freely between floors through the gaps in the boarding. That movement carries away more energy than conduction through the timber, and continuous insulation removes it.

Why a reflector suits this configuration

It is fitted continuously across the whole area, joined to its neighbours by overlap and closed at the perimeter. It is that continuity, more than the thermal value of the product alone, that addresses the real problem.

What it brings against noise

A flexible layer under a timber floor reduces part of the airborne noise, but not impact noise, which travels through the structure. Dealing with footsteps means working above the floor, which is another job.

The space available

Between the joists, height is tight. A product thirteen millimetres thick fits where traditional insulation would mean dropping the ceiling by several tens of centimetres.

The finish below the insulation

Stretched fabric or plasterboard: the air gap between insulation and facing is part of the system and is kept. A facing pressed directly against the insulation cancels part of the expected benefit. It is the most common mistake on this kind of job, and it is never visible once the ceiling is finished.

Airtightness is set out on the dedicated page, and the fitting on the watertight insulation page.