Insulating Walls for Comfort and Efficiency

Proper insulation keeps Florida homes cool and energy efficient, even during the hottest months.

While the exterior walls and ceilings of houses in Florida are usually insulated, the interior walls often remain completely hollow. Anyone who values sound insulation or additional thermal insulation in interior rooms must actively ask for it – and usually pay extra. Here we report from our own experience on what to look out for and which insulation measures make sense.

When we asked what was going between the timbers that make up the walls, our builder looked at us a little puzzled: “Nothing. The walls are sealed hollow, you can’t see them”. OK then, and what about the background noise from the neighboring rooms?

Without further ado, we decided to pay USD 580 for an upgrade and have these walls insulated. After all, we don’t necessarily want to hear everything that happens in the neighboring rooms. In retrospect, it is still very hard to hear. I can’t imagine what it would have been like if we hadn’t had the insulation.

The ceilings are insulated as standard, but the roof is generally not, although we will have this done later. As no reinforced concrete is used in the ceilings as in Germany, this insulation keeps the heat away from the roof truss.

Insulation of interior walls in Florida

Insulating interior walls is not standard in Florida – even in new construction. Generally, the spaces between the wood stud walls are simply left empty unless the builder specifically requests acoustic or thermal insulation. Typically, a simple glass wool (R-11 or R-13) is inserted in what is known as an “interior wall insulation upgrade”, usually purely for reasons of sound insulation. The effect is noticeable, but should not be compared with the sound insulation of European solid walls.

Bathroom walls or partition walls to utility rooms are also not insulated as standard, although noise from ventilation, washing machines or water pipes can occur there. Insulating these areas is also considered a costly upgrade – often in the range of USD 300 to 1,000, depending on the size and contractor.

Anyone who values a little more peace and quiet and privacy should therefore make specific inquiries during the planning phase as to which walls can be sensibly insulated – and how much it will cost. Installation at a later date is possible, but involves greater expense.

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Frequently Asked Questions

What is the best insulation for interior walls?

The best insulation for interior walls depends on the objective: glass wool (mineral fiber) is suitable for sound insulation as it is easy to process and offers good acoustic properties. For thermal insulation , calcium silicate, wood fiber or polyurethane (PUR/PIR) is more effective – especially where space is limited. In the USA, products such as glass wool (e.g. R-11 or R-13) are usually used.

What are the benefits of 2 cm of interior insulation?

A 2 cm insulation layer on one side of an interior wall only provides very little thermal insulation. The insulation performance is minimal and is at most sufficient as a solution against surface cold or for mold prevention in small problem areas. This thickness is too low for noticeable energy savings, acoustic effects or more living comfort.

What is the best way to insulate from the inside?

The best method for interior insulation is a suspended, rear-ventilated system with a vapor barrier, e.g. with calcium silicate boards, wood fiber insulation materials or PUR/PIR boards. Correct moisture protection is important, as internal insulation carries the risk of condensation and mold. In new buildings (e.g. Florida), glass wool is often simply clamped between the wooden studs – without a vapor barrier.

What is the best thermal insulation for indoors?

The best thermal insulation materials for interiors are calcium silicate, PUR/PIR rigid foam boards or wood fiber boards. They combine good insulation values with moisture compatibility. Important: The better the insulating effect, the more attention must be paid to correct processing in terms of building physics (e.g. vapor barrier).

What is the U value?

A U-value of 0.30 W/m²K means: 0.30 watts of heat are lost through 1 m² of wall surface for every degree of temperature difference. The lower the U-value, the better the insulation. A well-insulated building component (e.g. external wall/façade) should be below 0.20-0.30 W/m²K. Uninsulated interior walls often have U-values of over 1.0 W/m²K or more – depending on the material.
In Florida, the U-value for interior walls usually plays no role in energy requirements, but at most for comfort or sound insulation. For exterior walls, windows and roofs, however, it is part of the building regulations (Energy Code) and is therefore mandatory.