How to seal off heat from an attic?

Author: Prof. Raleigh Stracke Sr.  |  Last update: Sunday, June 1, 2025

Seal small gaps.
  1. Form an insulation dam. Form an insulation dam to prevent insulation from contacting the flue pipe. ...
  2. Find attic bypasses. Check for gaps in your attic that facilitate air movement by checking for dirty insulation. ...
  3. Fill holes with caulk. ...
  4. Stuff gaps with insulation.

How do I stop heat from coming through my attic?

Insulation in your attic is essential as it helps to reduce these heat flow processes, keeping the hot air from entering the living spaces below the attic. The choice of insulation material is crucial in managing heat transfer in the attic.

How to seal off an attic?

Use GE insulating foam to fill gaps around pipes and wires. For larger spaces, cut and fit rigid foam board to cover the openings, sealing the edges of the board with foam or caulk. This will prevent warm air from escaping and cold air from entering the attic.

Is air sealing an attic worth it?

A professionally air sealed attic makes your home more comfortable and lower your energy bills year-round, because your heating and cooling system will not need to work as hard to keep up with air leakages.

Is it bad for an attic to get too hot?

If your attic temperature is consistently hitting 130 degrees or hotter, damage to your home and a high utility bill is very likely. You can keep a thermometer in your attic to check – it doesn't have to be an expensive one and will give you a better idea of how hot things really are.

You Can Air Seal Your Attic

How do I make my attic not hot?

Ventilate The Attic Space

How else can you keep the attic cool? Remember the cool attic trifecta: radiant barrier, insulation, and attic ventilation. A complete ventilation system consists of exhaust vents, intake vents, and solar attic fans. Proper ventilation improves airflow and air circulation within your house.

Do radiant barriers work in attics?

A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic. A radiant barrier works best when it is perpendicular to the radiant energy striking it.

What is the best product to air seal an attic?

Acrylic latex is suitable for general sealing purposes in the attic. It works well for sealing gaps and cracks between insulation and framing, as well as around plumbing and electrical penetrations. It is paintable, dries relatively quickly, and is easy to work with.

How do I make my attic airtight?

Plug the big holes first.
  1. Create stuffed bags. ...
  2. Plug open stud cavities. ...
  3. Cover dropped soffits. ...
  4. Seal behind kneewalls. ...
  5. Cut aluminum flashing. ...
  6. Seal with silicone caulk. ...
  7. Form an insulation dam. ...
  8. Find attic bypasses.

How much does air sealing an attic cost?

Attic Air Sealing

The cost to seal an attic is $500 to $3,500. Many of the air leakage problems result from a problem with the attic, so it's a good idea to start your air leak sealing project from here. The contractor starts by filling in the larger gaps and moves towards the smaller ones.

Why would someone seal off an attic?

Besides keeping energy costs low, it'll mainly help to keep your home feeling comfortable long-term. Without a sealed attic, hot air can get inside the living space (heat gain) during warmer months and get outside (heat loss) during colder months.

Can I finish my attic myself?

You can still do a lot of the work yourself, but you'll have to do the work according to the latest building codes in your area and you'll have to have it inspected.

How do you push hot air out of an attic?

Install electric ventilators and attic fans, which remove hot air from an attic. They have thermostats that turn the fan on at a recommended preset temperature of 100-110 degrees. Alternatively, install passive vents such as gable, soffit and ridge vents, which are openings in the roof that allow hot air to escape.

Why is my finished attic so hot?

Heat rises to the top of the house and gets trapped under the roof. Roof windows also mean plenty of sun throughout the day. All this can cause an uncomfortable attic temperature, especially during hotter months.

How much heat do you lose through your attic?

Hot air rises, just like your energy bill will do if your attic is poorly insulated. A poorly insulated attic can result in 25% heat loss in fall and winter—that's 25 percent of your average heating costs going toward energy that won't even heat your home.

Can I use Flex Seal in my attic?

You can also use Flex Seal products inside an attic to help patch, seal, and repair problem areas.

Should an attic be sealed or vented?

In hot, humid locations, it may also be advisable to construct unvented rather than vented attics to help reduce the entry of moisture-laden air into the attic. In hot, humid locations, the outside air is likely to be more humid than the inside air.

Which is better, attic insulation blown or rolled?

Blown fiberglass insulation scores an R-value of 3.2 to 3.8, making it slightly less likely than rolled fiberglass to prevent the flow of heat into and out of your house. That being said, though, blown fiberglass insulation isn't meant to cover huge areas like rolled fiberglass insulation.

Should I remove old attic insulation before adding new?

Do I Have To Remove Old Insulation? Unless your insulation is wet, moldy or infested with pests, you don't need to remove it before adding insulation on top of it. ENERGY STAR® recommends that you inspect your insulation for signs of mold, mildew, moisture and pest infiltration before making this determination.

Can I put too much insulation in my attic?

It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers.

What are the downsides of radiant barriers?

When radiant barriers develop moisture problems, they can impact the efficiency of heat repellency. In addition, unchecked moisture can drop down onto other surfaces in the attic, causing water damage and mold. In order to prevent moisture issues, it's imperative to use perforated radiant barriers.

Can I install a radiant barrier myself?

Installation Summary:

Use a stick (1/4" furring strip with nail in the end works well) to help push the barrier into the tight spaces of your attic. Continue covering the attic floor by overlapping each section of radiant barrier already rolled out by 2" inches.

Where should attic vapor barrier be placed?

Tip 3: Determine the most vulnerable side – When installing insulation with a vapor barrier, the vapor barrier should usually be applied on the side of the insulation that's closest to where it will be exposed to the most warmth and moisture.

Previous article
Can I clean my oven racks with Easy Off oven cleaner?
Next article
How can I make my air cooler more effective?