Everything You Want to Know About Your Attic

Attic interior

How often do you think about your attic? Do you know how it works and how it affects the rest of your house?

Whether you want to finish an unfinished attic space, safely use it for storage, or update your home’s energy efficiency, there are some things you need to look for.

Use this guide to help you pinpoint trouble spots or answer basic questions before you call a contractor.

Attic Anatomy

There are two basic types of roof construction: rafters or roof trusses. The type of roof framing drastically impacts your attic’s space, whether it can bear any load – like storage containers – or whether it can be finished into a livable space.


Rafters are typically constructed from engineered lumber. They extend from the ridge board at the roof’s peak to the top plate of the exterior wall.

Rafters naturally “hang over” the eaves of the house. They are cut and installed one at a time – or one “stick” at a time – so a roof framed this way can be referred to as a ‘stick framed” roof.

The joists which make up the attic’s floor are placed first with this construction method, and they can bear weight like a standard floor.

Roof Trusses

Trusses are constructed using angled “webs” of lumber extending from the top chords to the bottom chord, similar to rafters. However, they aren’t the same.

Trusses do not leave large areas of open space in your attic. The bottom chords aren’t made to support heavy loads.

Your Home’s Envelope

Houses are made to contain either heated or cooled air in an “envelope” of insulation.

Depending on the type of roof framing you have and whether your attic is meant to be finished, your insulation may rest on your attic’s floor, or it may be installed between attic rafters.

Insulation on your attic floor means your home’s envelope doesn’t include your attic. If you want to finish your attic, you will need to move the insulation up to the rafters if it’s not already there.


Attic ventilation is important for a functioning roof system. If you have an unconditioned attic, adequate ventilation is essential to keeping moisture, mold, and rot from ruining your roof decking. In addition, you don’t want them getting down into your house.

You may consider installing an attic fan to aid in proper ventilation. If you are planning to finish your attic, the space will be enclosed in the house’s envelope. It doesn’t need the same type of ventilation, although building codes require ventilation for habitable space. 

Attic Energy Efficiency

Sealing air leakage in the central part of your house is critical for energy efficiency. For example, windows, doors, and vents are easy areas to close.

However, did you know there are many ways your attic can be inefficient?

Here are some places your attic could be contributing to your home’s inefficiency:

  • Recessed light fixtures
  • Gaps around the drop-down attic stairs
  • Clearance holes drilled for wiring 
  • Grilles connected to attic ductwork

Heat escapes through these cracks into your attic – which doesn’t need the warmth and which can contribute to ice dams on your roof. However, when heated air goes up, it creates a suction effect inside the house that can draw cold air from leakage points inside the lower part of your home.

It’s called the “stack effect.”  In a cold climate like Michigan, the stack effect can significantly negatively impact your energy bills. 

How to Combat the Stack Effect

To combat the stack effect, start by air-sealing your attic. Then, increase the attic’s insulation. It’s cost-effective and it will save you money in the short and long term. Moreover, it is the number one return-on-investment improvement when you go to sell your house. 

Here’s what else you can do to minimize the stack effect:

  • Seal potential leaks with spray foam 
  • Check your insulation levels even if you think you have enough. Recommendations have increased in the last few years.
  • Insulate any attic ductwork. You don’t want to be sending cooled air through hot vents or warm air through ice-cold vents. 
  • Cover duct joints with foil-faced tape designed for ducts (not duct tape).
  • Install a radiant barrier. Similar to the reflective sun shields for car windshields – to the bottom of your roof rafters for extra protection in hot climates. It can give you up to 15% savings on your cooling costs.

Bringing it Home

In conclusion, attics are dynamic and vital spaces for the overall health of your house. Do you live in Southeast Michigan? Please call with questions regarding your attic, insulation, or roof. Remember, we’re here whenever you need us!

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