Where are the air leaks in your home?

[ create an image map from the EnergyStar site – image location and notes from Lets look around – Do We Have an Air Leakage Problem What we are defining here is called the envelope of your home and the air control barrier for your home where it makes sense to fight the war against air leaks. In most existing homes this is the inside sheetrock level. Air leaks at penetrations and joints and corners and against the floor… lets just explore some escape routes here.

Lets do a physical inventory for some air leaks

Lets start with the attic or rather the ceiling under the attic. We will actually explore the attic later. Why the ceiling first. Because there is so much ceiling and hot air floats on on top of cooler air. Many of the biggest air gaps in the house are hidden from view but go up through the ceiling. We will explore those later. [stextbox id=”info” caption=”Air Leaks Relate Closely to Moisture Problems ” shadow=”false” bwidth=”2″]Moisture is a huge issue with leaking air So heated air rising in the heating season works it way through gaps in our ceiling. This rising cools down and can reach dew point and condense on cold surfaces. High humidity and moist surfaces area a breeding ground for mold and mildew in the attic. The cooler air leaking in and replacing this hot rising air is very dry because it was dry cool air and as it warms up the humidity goes down.  Many people think this is a problem and have humidifiers running in the heating season to add moisture to the air. This dry air is a symptom of air leaks. Next summer the house will be too humid as warm and humid outside air comes in and cools down and raises the humidity level of the house.  We talk about all things related to moisture here. Understanding moisture is critical and how well your home handles air leaks and moisture determines how healthy your air is and how comfortable you are in the house.[/stextbox]

Ceilings by empirical study are the biggest problem in the typical home and provides the best return on investment to fix. This is why we add extra insulation in the ceiling. But we have to stop the air leaks first. Loose fill insulation and batt insulation do not stop air leaks. We deal with insulations issues here. LINK

Lets  walk around and inventory mechanical breaks in the ceiling against the attic.

Where are the duct vents?

Are there forced air supply duct vents in the ceiling? I am sure you have seen them. They look like this.

This is a view of the uninstalled supply grill where you can see the louvers. The air gap is between the cover flange of the grill and the uneven edge of the finished sheetrock cut in around the metal duct vent housing that this grill fits into.

This is a view of the uninstalled supply grill where you can see the louvers. The air gap is between the cover flange of the grill and the uneven edge of the finished sheetrock cut in around the metal duct vent housing that this grill fits into.

Or are they coming up from the floor? Take a minute to figure out where these are because they leak air into the structure wherever they are. In the ceiling, the grill is the easiest place to deal with the leak. Also in the floor. Remember the air control layer? We have to keep this where we can see and deal with it in an air leak retrofit. Once leaking air gets into the floor joist cavity- it has too many pathways to freedom outdoors. Duct vents are scruffily cut into the sheetrock and this scruffy cut is covered with the grill trim. They look lovely but this trim piece does not slow down those rowdy air molecules that you heated up with your heating bill, or stop those barbarian hot air molecules floating down through these gaps in summer when your cold air is finding a space to drift away on an air leak highway. These ducts need attention. They need a fitted gasket placed between the duct and the sheetrock to make it difficult for air too break out here. They have to be placed in carefully and the compression secured with proper screws. I have seen these screw up. The screws come loose and the gasket just pushes out and lets the air in- this is a maintenance issue with screws staying secured.

 Make sure we inspect the vent fans in the bathrooms.

Since we are mostly looking up at the ceiling, this is also a great time to mention fans in bathrooms. They same principle as the supply vent is in play here. The bathroom vents in your bathrooms either go through the ceiling or right out through the exterior wall. These again are rough cut through the interior sheetrock and then trimmed out with a little cover. These need a gasket too… or some repair more appropriate. It has to fit within the design of the duct housing. Bathrooms ducts have lots of issues. We deal with them and dryer vents and kitchen vents in a separate document. They have peculiarities that are more elaborate to describe here. LINK Do you have eyeball lamps in the ceiling? Recessed lighting? These often are recessed into a soffit or or up into the attic and these are a problem in multiple ways beyond being a big air leak source.

A brief diatribe about eyeball lights and recessed lighting.

Eyeball lamps traditionally are a light  source that misuses electricity to create more heat than light. They create so much heat that they have to be given proper clearance to keep other materials from getting dangerously hot or the light fixture itself from overheating. This creates some serious air leak passages. The leaking air zooming by recessed lighting- in an out of your attic- are not harmed by the wasted lighting heat but your wallet iends up bruised. Sealing up eyeball lights is a complexity not addressed here. Eyeball lights are costing you on your electric bill twice. They let air leak profusely, but they also add heat to your home in summer – heat that becomes part of your cooling load. Eyeball lights are absolutely mean about taking your money. They are even difficult and expensive to work with to stop air leakage.

 This would be a great time to consider some new lighting design.

Maybe it is time to do some light remodeling and put some of the money you would have to spend to seal up the air leaks- to spend on your electric bill every moth- into just new lighting that gives you more lumens for less money…  and makes your home pretty and new looking. We look at lighting issues over here. LINK Recessed lighting can also be fluorescent tubes in a light bay and there is no heat problem here, but irregularities in the ceiling often create breaks and rifts in the air control layer and in insulation. These create busy work in the air leak retrofit. Any light fixture creating a hole in your ceiling- trailing an electrical wire or tied to an electrical box embedded into the ceiling is a problem which needs attention. And incandescent lighting uses a lot of electricity. You may have bulbs lately and found a lot of incandescent lights missing. It is national policy to discourage such lighting. You can save money and make things pretty and new by investing in lighting that saves energy. We look at lighting issues over here. LINK  Yes, so maybe it is time to look at lighting solutions that can save money. LINK

 Do you have a dropped ceiling or soffit for lighting or ducting?

Quite often these get ignored and forgotten and not built properly and provide avenues for air to leak in and out. Do you have soffits in your ceiling? These need checking and correcting.

 And do you have attic access with a ladder?

This is a huge hole in the ceiling. These are so notorious they get their own article. You might have seen one of these on an FBI poster for wanton stealing from citizen’s wallets. These guys arer so bad they need their own reality show. LINK

[stextbox id=”info” caption=”A peek at the math- detailing the impact of insulation and air leakage defects” shadow=”false” bwidth=”2″]The hole that makes up your attic access is a great example of a problem in homes where the best laid plans of mice and men and well intentioned people trying to save energy see their efforts undermined by serious defects which undercut the energy saving results seriously. We do a little math here to emphasize that the weakest link in a system can and has a huge impact on the results.  Understanding the Short Circuit principle in air leaks and insulation[/stextbox]

This brings us  around to the really big holes that are not in plain site but hidden behind the stud walls.

We need to introduce the concept of the chase.

No running involved here. Chases in this context are the transition areas between chimneys and framework, plumbing and framework, and even ducting and framework when major runs for return air and supply air transverse multiple stories.

Do you have a chimney on the premises? For a fireplace? for a furnace? do you have a fireplace? Fireplaces and Chimneys are a complex challenge when it comes to air leaks in the house. We have a whole other document to cover them LINK, but we iill mention one key area here. The chimney chase. This is a built in area of your house that is framed to keep the wood members from touching the stainless steel flue or your brick and mortar chimney. This chase provides a safe distance from a  fire and smoke conveying instrument. But within this gap created by the chase, is a huge air gap which allows air to escape from and into the conditioned part of the house. Chimney chases require a complex repair. We cover that briefly in the above document about chimneys and fireplaces…  If you have a fireplace of furnace with a stainless steel flue – check ithat out, otherwise you can just skip it. LINK Air leaks and Your Furnace or Your Fireplace

Plumbing chases and plumbing runs create air gaps.

As you survey the premises you are not going to see the plumbing vent pipes. You might have a plumbing chase our you might have individual plumbing runs running through top plates, or a combination of both. These are hidden away but little air moelcules are buzzing through these spaces like an Interstate highway.

Lets inventory all the stuff cut through the exterior walls or appliances which must vent to the exterior.

All kinds of stuff cuts through the exterior wall to make entry.

  • Dryer ducts to exhaust clothes dryers.
  • Bathroom vents or kitchen vents through an outside wall- or up through the ceiling through a chase type arrangement.
  • all the wire entries for telephone and communications- the TV cable- all these are added to your home by oblivious technicians that are thinking about lunch and beer and nary a thought about weatherization or controlling an entry point for air.

These must be individually repaired by the best method available by the unique challenges your home provides.

Electrical and gas service entrances fit well right here.

You certainly have an electrical service entrance and maybe  a natural gas service entrance too. These are not sealed well. Traditionally they are cut in and protected from weather- cross your fingers… but are not really sealed off. These need attention.

Lets look around and see what kind of air leaks are lurking in the interior walls.

Electrical outlets and switch plates are a big air entry and exit point. And this includes any other breaks in the sheetrock for thermostats, phone jacks, communication cabling…

The gaps around the sheetrock and the box allow air into the interior stud walls where they have free roam to find an outlet to the outside. – it is amazing how much air can pass through electrical outlets. These require a special foam barrier much like the duct grill covers- and these can require maintenance too. Screws loosen and the gasket pushes away…

Door frames leak air in several ways.

We will ignore the doors being open… but doors require special weather stripping against the door stop with a special sweep that you step across. The magnetic strips on a metal door work well, but foam stops along all door stop details work fine. The big battle is at the door sweep where the shoes do the walking. This is a maintenance zone, and ou need to give this regular attention. Proper weatherstripping plays a key role in keep air in its place.

Windows have several failing points when it  comes to energy.

The good news are that their are ways to solve these issues without tearing out the frames and putting in new windows. We discuss all things windows here- and it should be noted that you do not replace windows to save energy, you only replace windows if you heart is set on how beautiful they will make your home. Otherwise, your windows have to be really poor quality with no remedial options for repair… We talk windows here. LINK

Lets look for the gaps in the sheetrock behind stuff. Do you have baseboards?

These are notorious for not being finished off behind the baseboard. Sheetrock cut short not sealed against the sole  plate. We move onto wall construction soon, but baseboards can hid a lot of mischief.

On the subject of not being finished behind… many homes have unfinished sheetrock on stud walls and these are the open road for air leaks. How about behind the tub or shower surround? How about behind built-in cabinets? These need to be found and fixed.

How do you even find some of these problems? Well, there are powerful tools that the pros have and use to identify problems and they can look behind stuff… that you cannot see with your limited human vision. Yes, super powers are available. We  pick that up later when we move on to an actual course of action and getting work done on stopping leaks.

We have already described the problem with interior walls. Lets go into a little more detail.

There are so many wood to wood connections. These do not fit tight enough to corral in air molecules. If you are sneaky, if you can stalk the wild game, you just might find a wiley wild draft around a crack in the sheet rook, or around a hole in the sheetrook, or right out through the outlet box. There would be even more wiley wild air molecules on a windy day. Just just the back of your hand as a draft detector.

Interior walls are major culprits for air leaks. There have been many techniques for wood framing homes.For decades balloon framing was cool. Balloon framing was popular into the mid 50s but fire codes pushed this very open style out of the building code. This open style makes balloon framing a particular chore to create a good air control layer. But whatever the framing method, wood  to wood does not make a good airtight connection. They always need help.

The interior walls are connected to the floor joists and the floor joists are connected to the rim joist and the rim joist are connected to the interior walls, and the stud wall stud plates end up in the attic… all these venues for air molecules to roam must be fenced in at the most appropriate location. That  is the job of the professional leak stopper and the professional leak stopping specification writer…  We will address this area of work spec when we talk about what is the plan  for taking action.

Lets explore a few more leaky wood to wood connections.

If you can see light you know it is not tight- this is the giveaway for so many porous door slide weather stripping attempts. But if you cannot see light- iit still might not be tight.

Wood paneling does not make a tight fit anywhere- and this is especially a problem in cathedral ceiling because- you know- rising air. The crack between the baseboard and the wood floor deck is not tight, nor is the fit between the sole plate the bottom board of a stud wall tight to the wood or concrete slab. This is also a clear issue with existing windows. Lots of wood to wood connections that are not sealed and the whole in the wall and all the cut corners makes it particularly susceptible… but but but this problem is not automatically solved by new windows. The battle is is the work performance not the quality of the window. So therefore do not think that replacing windows is necessary to cut down drafts through windows or that new window poorly installed with cut down on the airleaks. I hope that makes sense. Never rely on supposition and trust.  Always trust but verify.

The most active leaks in the house- where the pressure gradients are greatest is in the high parts of the building and the low parts. In winter the hot air rises with a rush to escape floating on waifs of cooler air. In summer cooler air is slipping out the cracks in the lower part of the home- cold air is sinking out of the air conditioned house and the hottest air in the house- in the unconditioned attic  is filling in behind as the coolest air drains out. Not good.

We also need to mention wood to concrete connections.

Here is Texas, so many homes are on a slab with a footing around the perimeter of the slab. Some also have a foundation wall and a crawlspace. Either of these has a sill plate making the connection to the concrete. the sill is bolted on and the the studs are nailed and strapped to the sill plate.

In most homes- new green homes are an exception- new construction styles are making home much more airtight from the ground up- there is no seal between the concrete and the sill- no seal bewtween the butt joints of the sill. No air barrier is placed between the interconnection between wood and masonry, and these gaps are big enough to see light through… if you could get your eye down there for proper perspective.

Lets pick up a few miscellaneous air leak villains.

Do you have a wall mounted or window mounted air conditioner? This leaks air so bad… Depending on how you use this particular space you need to do some conjuring on what to do here. It portends bigger problems, that wasted energy and your money…  So you need to itemize these because they will need further investigation.

And what do we do when we have a good idea as to what need to be done and what to do next… well we will get to that but we have one large exploration adventure left. Actually entering the attic. Now we left this adventure to last, because there are many things beyond air leaks that need to be analyzed and inspected while you are here. Getting up into the attic is an adventure- there are some caveats, many suggestion and that how story is here.

OK, we have saved one expedition until last and that is the traipse through the attic. We waited to last because when you go into the attic, you need to be well prepared for the journey and when you go there you need to be prepared to evaluate a long list of items not just a jaunt to look for light leaking through air leaks in the ceiling. We have prepared a separate document for exploring the attic. LINK

Now we are ready to address your options. What to do next.

Well we need to return  to the top article to continue this conversation. You can skip down through the reasons why air leaks are such a serious issue in your home- and skip the link to this page- which was just a wide scope look around for the typical leaks in a North Texas home…  here is the link back to the top page on air leaks. 

Feel free to add your comments below. Have a question or a comment add it below.




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