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Insulation - Cantilevers

This new construction townhome has a bump out (cantilever) on the front of the home. The floor joists run beyond the
foundation wall making it exposed underneath (overhang). If not insulated correctly, it can be the cause of high bills and cold/hot spots.

Typical Upper Floor Cantilever

Cantilever air sealing and insulation Maryland

A common type of cantilever is an upper floor bump that usually extends between one to three feet adding quite a bit of overall square footage to the living space.

Insulating Cantilevers

Take note of the soffit areas around your home and consider what they are connected to before you do any work to the area.  Strong consideration should be given to adding or improving insulation to the cantilever cavity prior to adding any soffit product so that once the soffit work is done, it is not necessary to take it down to treat the cantilever with insulation.

Cantilevers around Maryland homes are classic thermal bypasses.  A thermal bypass is the movement of heat around or through insulation.  A thermal bypass typically occurs due to missing air barriers or because of gaps between the air barrier and the insulation.

A poorly insulated cantilever can create hot and cold spots around a home in certain circumstances.  Cantilever insulation work requires a company that understands three trades in order to complete the project correctly.  Carpentry, siding and insulation techniques must all be in order. A contractor should be able to do the following:

1. Carefully remove the existing soffit material without damaging any of the siding or trim.
2. Properly remove the old insulation in order to block the cavity for insulation.
3. Properly insulate the cantilever so that once it is back in place, the work is done.
4. Reinstall the wood or vinyl soffit paneling to close up the area and seal it from the elements.

Air Sealed-Insulated Cantilever

*The process of insulating a cantilever requires two steps

1. Blocking is first so that insulation has a cavity to fill
2. Insulation is second to air seal and insulate to a minimum of R-25

Why are Cantilevers an Issue?

Why are Cantilevers an Issue?

Missing Air Barrier

At first look, this cantilever appears to be well insulated, but it is not. Fiberglass insulation does not stop the flow of air.  As a result this cantilever is not insulated properly and it can create comfort issues as well as higher energy bills.

Cantilever insulation Maryland

A closer look at a rear upper floor cantilever that can be seen on Maryland houses.

Watch Cantilever Insulation Videos

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