The CPSC estimates that between 2003 and 2007, there have been over eleven thousand injuries caused by structural failure or collapse of guardrails at outdoor decks.  It’s not tough to understand why – when people have parties in the summer, everyone hangs out on the deck.  Throw in a keg of Busch Light, a few (ahem) ‘people’ that make the rockin’ world go ’round, and a weak guardrail… boom.  Guardrail collapse.  Weak guardrails are one of the most common safety issues with decks.

The current requirement for new deck guardrails is that they withstand 200 lbs of pressure at any point along the top rail (Table R301.5).  Actually, this standard applies to all guardrails, both inside and outside the house, but decks are the place where it matters most.

My standard method for testing guardrails has always been to just push on them a little.  If they feel weak, I recommend having them reinforced or rebuilt.  Once a guardrail moves an inch or two without much pressure, I stop pushing; I don’t want to be the one to break it.  Home inspections are supposed to be visual, I know, I know… but I like to touch stuff.

I’ve never used any type of testing equipment, but I recently picked up a fancy-schmancy piece of highly specialized deck guardrail testing equipment to help get a better idea of what 200 lbs of pressure felt like.  Jealous much?

Ok, it’s just an $8 bathroom scale.  After some playing around, I’ve learned that 200 lbs is about the most pressure that I can personally apply to the top rail of a guardrail, just by standing on the ground.  In the photo below I’m applying about 150 lbs of pressure, and I’m straining to do it.

The weakest point in most guardrails is always going to be at the end, where it terminates next to the house.  All that typically supports the guardrail at this location is the 4×4 post, assuming posts were used to construct the guardrails.   In the photo above, I’m pushing on the guardrail at the end.   This guardrail actually performed fairly well – most guardrails won’t tolerate nearly that much pressure.

The surest way to construct a guardrail that will withstand 200 lbs pounds of pressure is to use metal brackets that are designed just for this purpose.   A couple manufacturers that make such brackets are DeckLok and Simpson Strong-Tie.   If special metal brackets aren’t going to be used, the support posts should be constructed with full size 4x4s (not notched at the bottom), attached with through-bolts, and extra blocking usually needs to be installed to help keep the guardrail secure.

In the photo below, the ovals show where extra blocking was added.  This blocking tremendously stiffens the joist that the guardrail is attached to, making it so the guardrail won’t budge even when a full 200 lbs of pressure is applied.

The bottom line is that weak guardrails are a safety hazard that should be corrected, especially on decks that are high above the ground.  For specific guardrail construction methods and rules, turn to page 15 of the  Prescriptive Residential Wood Deck Construction Guide.

May is Deck Safety Month – Related Post:

How to prevent your deck from collapsing: start by attaching it properly

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Deck Inspector

May is National Deck Safety Month, so I’m going to start off this month by writing about the most common cause of deck collapses – improper attachment to a building.  Most decks are supported on one side by the building, and on the opposite side by the earth.  The photo below shows a deck collapse that happened here in Minnesota, and this is exactly how most decks collapse.  The cause of collapse is quite obvious – it wasn’t attached properly.

Is your deck properly attached to the building?  It’s not always possible to know for sure, but today I’ll discuss a few different ways of attaching a deck to a building.  The piece of wood that connects a deck to a building is called the ledger, or ledger board.  I’ll be using this term repeatedly.

Lag Screws

Traditionally, lag screws have been the most common method of attaching decks to buildings.  To properly attach a deck ledger using 1/2″ lag screws, 5/16″ holes need to be pre-drilled through the ledger and rim joist.  After that, a 1/2″ hole should be drilled through the ledger only.   For specific spacing and installation instructions, you can turn to page 12 of the Prescriptive Residential Wood Deck Construction Guide.   There’s no way of knowing if all of these steps were followed just by looking at a deck, but if lag screws are visible, you can feel a little better about the deck attachment to the building.

One problem that I occasionally find with lag screws is that they’re not attached to anything substantial behind the ledger.  When a home is constructed with floor trusses and there is no rim joist for the deck to attach to, it’s important to figure out what the screws are going in to.  In the photos below, the lag screws at this Eden Prairie townhouse were only attached to the fiberboard wall sheathing, which is basically worthless.  You wouldn’t want to put too many people on that deck.

Lag screws are fairly inexpensive, but they take special steps to install correctly.

Special Ledger Screws

Because of the tedious process involved in drilling several pilot holes in the wood to use lag screws, there are a few products available that are designed for the specific purpose of attaching a deck ledger to a building.  One such fastener is the FastenMaster LedgerLok®, which is pictured above.  Simpson Strong-Tie makes a similar fastener, called the Strong-Drive® SDS Screw.  These fasteners are designed to be installed without any pilot holes, and they already come with a washer attached to each head.

While these fasteners may cost a little more, they’re fast and easy to install, and they’re code approved to be used in place of 1/2″ lag screws.

Through-Bolts

Through-bolts can be used to attach a ledger to the house when the interior of the rim joist is accessible.  This is typically done using carriage bolts, pictured above.   When through-bolts are used, you’ll either see the head of the bolt or the end of the bolt at the ledger.  Lag bolts work in a similar manner.

All things being equal, a through bolt makes for the strongest connection per fastener.  Without all things being equal, there are certainly ways of installing through-bolts improperly.  In the examples below, taken at a townhouse in Edina, you can see the end of the bolt where a washer and nut were fastened.  The problem with this installation is that someone didn’t have long enough bolts, so they had to chisel out a bunch of holes in the ledger to sink the washers and nuts in to.

This is probably the least common method of deck attachment because it takes more time, and requires more running in and out of the building.

Nailed Ledgers

Nails are not an acceptable way of attaching a ledger to the building, because they can pull out.  I don’t have any statistics to quote, but this is probably the most common cause of deck collapses.  If you look at a deck ledger and all you can see are nails holding it in place, it should be addressed.  This is one of the most common deck problems that home inspectors find, and the repair is usually an easy fix.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Deck Inspector

There’s a show on HGTV called Holmes Inspection, which exposes problems with houses that were allegedly missed by other home inspectors.  Here’s the basic formula: John and Jane buy a house, have it inspected, no major problems.  Time passes, problems show up, Mike Holmes gets called in.  Mike inspects the house, agrees there’s a problem, tears everything open to show what was done wrong or could have been done better, and then says he’ll “make it right”.  In the end, the original home inspector gets blamed for missing defects with the house.

I’ve had countless clients ask me about the show, and I’ve heard a lot of discussion about the show from other home inspectors, so I finally took the time to watch an episode to see what all the talk was about.

Holmes Inspection makes for great TV.  I watched an episode titled Frigid Floor, wherein the homeowners complained about a cold floor at the addition of their house.  There were a couple of other miscellaneous issues, but the big one was the cold floor.  Mike Holmes doesn’t know exactly what the problem is, so he has his crew come in and cut out a huge section of the kitchen floor to get at the crawl space below.  There is no final diagnosis of what the problem is, but his crew spares no expense in making it right.

They tear out all of the cabinets, countertops, flooring, and subfloor to get at the crawl space.  They spend three days hand digging the crawl space to make it several feet deeper, install rigid foam on the floor, pour self-leveling concrete on the floor, then have the walls insulated with spray foam (I loved that part).  While they’re at it, they also beef up the floor structure.  They add access to the crawl space from inside the basement by cutting an opening through the foundation wall, and they add a heat register and a light.   They definitely ‘make it right’.

The original contractor who did the addition gets thrown under the bus; Mike says that this is how the job should have been done to start with.  While Mike’s work was far superior to that of the original contractor, I think it’s unfair to put down the original contractor.  The work was done for the previous owner, permits were pulled, and the work was inspected and approved.  We have no idea of what was agreed upon between the original contractor and the previous owners.  Maybe the original contractor gave the previous owners a bid to do exactly what Mike Holmes did, and the owners opted to save $10k by only doing the bare minimum.

If the previous owners got three different bids for the job, there’s a slim chance that the contractor who gave them a bid on a beautiful crawl space would actually get the job.

The original home inspector gets thrown under the bus as well.  Mike concludes the show by saying that if the original home inspector actually knew something about construction,  he would have warned the buyers that there was no crawl space.   That comment really bugged me.  The home did have a crawl space, it just didn’t have any access, and it was too small for most people to actually crawl in to; that doesn’t mean it’s not a crawl space.  I’d love to know what Mike would have said to the buyers if he had done the original home inspection.   Here are a few potential warnings:

• This home has no accessible crawl space.  So what?
• This home has no accessible crawl space, but it should.  I can’t inspect what I can’t see.  Before you buy this house, you should have the sellers make the crawl space accessible and have it inspected.  The home inspection was performed in warm weather, and there were no signs of any problems.  The work was done with permits and inspected, so what would actually happen if the buyers demanded the crawl space be made accessible for the inspection?  Do you think the sellers would agree to that?  My experience tells me absolutely not.
• This home has no accessible crawl space.  I know that permits were pulled for the addition and inspected by the city, but I don’t care.  If I can’t see it, it’s probably not right.  Don’t buy this house.  Ha!  Now I’m just being silly… I think.

Just for the sake of argument, let’s say the inspection was done during the winter, the floor was cold, and the crawl space was barely accessible.  What would the recommendation have been?  Gut the kitchen and make it right?  That suggestion would go over like a lead balloon.  Personally, I would have told the buyers that the floor was cold, and to fix it would probably be cost prohibitive.  This is what you’re getting, take it or leave it.

My conclusion

I’m not trying to be too critical of the show, but the repairs performed on this house were completely over-the-top and unrealistic.  Don’t get me wrong, it’s a very cool concept for a show – take a problem with a house that is cost prohibitive to repair and fix it any way you want with time and money being no object.   It would have been nice to do it this way from the start, sure… but I can’t imagine any sane person spending their own money gutting a kitchen just to make the floor warmer.  This is a fun show to watch as long as you remember that it’s just TV.  I think the main messages are good: hire an excellent home inspector and don’t skimp out on your remodel project.  You’ll save money in the long run by spending a little more up front.

I think I’ll start watching this show.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

One of the most common defects I find with asphalt shingles is improper nailing.  The manufacturers of asphalt shingles give specific instructions on how to fasten shingles, and they’re all pretty much the same.  Unfortunately, following those instructions seems to be a difficult thing to do for a lot of roofers in Minnesota.  The two most common nailing defects that I find with shingles are overdriven nails and improperly located nails.

Overdriven Nails

Most roofers use pneumatic nail guns to nail down shingles.  When the pressure is set too high, the nails get driven in to the shingles too far, plain and simple.  When the nails are overdriven, the heads of the nails punch right through the mat of the shingle.  This voids the shingle manufacturers warranty and greatly increases the potential for shingles to come loose and blow off, possibly in sheets.

The diagram below shows what proper and improperly driven nails look like.

The photos below show several examples of overdriven nails.

Improperly Located Nails

The other most common nailing defect that I find with asphalt shingles is improperly located nails; specifically, high nails.  When shingles are located too low on a shingle, it’s an obvious defect that anyone with a good eye can usually spot from the ground.  This is probably why I don’t find this defect all that often; it’s just too obvious of a defect for most roofers to leave uncovered.

The more common and problematic nailing problem is to have nails located too high on the shingle.  There is a fairly narrow strip on every shingle where it’s acceptable to place the nail.  When properly placed, the nail will actually catch the top edge of the shingle below it.  When nails are located too high on the shingle, they never catch the shingle below, which effectively cuts the amount of nails going in to each shingle in half.  Hopefully my diagram below will help to illustrate this; the blue dots are supposed to be nail heads.

The photos below show examples of high nailing.  Yes, I know what I did there.

When shingles are improperly fastened, they have a tendency to slide and rip out of the nails holes, and this won’t be covered by the manufacturers warranty.  When the entire roof covering is installed like this, there is no simple fix.  Either the new buyers need to accept the fact that their roof will be prone to having shingles blow off, or the roof covering will need to be repaired or replaced.

These installation defects can’t be seen from the ground, even with a very expensive pair of binoculars.  For this reason, you shouldn’t expect most municipal inspectors to identify these issues; it’s outside the scope of their inspection.  I wrote about this topic here – Who Inspected Your Roof?  If you want a thorough roof inspection, you would do well to hire a home inspector who will access the roof.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

I heard Adam Carolla mention this quick tip, and it really works.  I had to pass this along.  If you need to drill a hole in your wall and you don’t want to make a mess on the floor, just use a Post-it^® note.

3/8" hole in a 2x6

You make a couple of quick folds, paste the paper on the wall, then drill your hole.  All of the drywall dust or whatever you’re drilling in to will fall on to the paper.  Done and done.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

What’s the best temperature to set your water heater to?  There’s no single great answer.  The American Society of Sanitary Engineering Scald Awareness Task Group recently released a white paper on this topic, which essentially says that there is no perfect temperature to set you water heater to.

What’s a safe temperature for water?

On the side of most water heaters you’ll find a warning that says water temperatures of 125 degrees Fahrenheit can cause burns or death.  To be safe, the water coming out of the plumbing fixtures in a home shouldn’t be any hotter than 120 degrees.   The handy photo below (courtesy of Charles Buell)  shows how fast second and third degree burns can happen at temperatures that any new water heater is capable of producing.

Just turning down the temperature at your water heater until you’re at a safe 120 degrees isn’t enough to solve potential scald hazards because the thermostat on a water heater isn’t designed to keep the water at a constant temperature; it’s just designed to keep the water within a certain range of temperatures.  Seattle home inspector Charles Buell has posted a couple different blogs explaining how this works – one explaining how water heaters sometimes run out of hot water faster than they should, and another on the different temperatures that will be produced by a water heater during different stages of the heating cycle.

During a recent inspection of a large home that was heated with two high-efficiency water heaters, I found quite a range in temperatures.  When I first turned the hot water on at a fixture, the water temperature started out cool; this was because the water in the hot water pipe had cooled down to room temperature.  As the hot water from the top of the tank arrived at the plumbing fixtures, the water temperature rapidly jumped up to nearly 154 degrees – this was hot enough to cause first degree burns instantaneously, and second degree burns within one second.

The water only stayed at this temperature for a few seconds; it quickly dropped back down to about 135.  While there was a tempering valve installed to mix cold water in with the hot water right at the water heater outlet, it wasn’t enough to completely control the water temperature at the fixtures.

Minnesota has no requirements for residential water temperatures.  Anti-scald devices are required in all new or remodeled showers or shower-bath combos in Minnesota (4715.1380 Subp. 5), but this does nothing to address the final temperature of the water coming out of a fixture.   Anti-scald devices only help to prevent people from getting scalded by a sudden swing in temperature while taking a shower.  With old shower valves that didn’t have the anti-scald feature, if a toilet would flush while someone was taking a shower the pressure on the cold water line would drop, quickly increasing the water temperature at the shower.

Lower Temperatures Allow Bacteria Growth

It seems as though the solution to help prevent accidental scalding would be to turn down the temperature at the water heater to say, 115 degrees, but lower temperatures actually create other problems.

At temperatures below 135 to 140, Legionellae bacteria, which is responsible for Legionnaires’ Disease, can survive and even multiply in the water heater tank.  Estimates by LegionellaPrevention.org say that up to 600,000 cases of Legionnaires’ Disease are misdiagnosed as pnemonia each year, because this is something that isn’t tested for in hospitals.   The diagram below shows the time it takes to kill Legionellae Bacteria at different temperatures.

To help prevent bacteria growth, the ASSE recommends keeping the water in your water heater tank at about 135 – 140 degrees Fahrenheit.

Of course, this creates a scalding hazard.

So What’s the Answer?

To help prevent bacteria growth and to lower the risk of scalding, have a plumber install a tempering valve and crank up the temperature at your water heater to about 135 – 140, as ASSE recommends.  Last year I wrote about how I installed a tempering valve on the hot water outlet at my own house in order to get more water out of my water heater.  These valves would be a good thing to install in every home.  A tempering valve allows you to keep the water at a dangerously high, Legionellae-killing-temperature inside the water heater tank, yet it mixes cold water in with the hot water right at the outlet, making it so you don’t get this hot water at the rest of the fixtures in your home.

As I mentioned in my story about the recent inspection with dangerously hot water, a tempering valve won’t guarantee safe water temperatures, but it will get you a lot closer.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

Do you know what type of smoke alarms you have in your house?   There are two basic types of residential smoke alarms – ionization and photoelectric.  The vast majority of smoke alarms in use today are the ionization type, but they’re being questioned more and more as a valid detection method; today they’re no longer allowed as the only type of residential smoke alarms in Iowa, Vermont,  and Massachusetts.

Why all the bad press about ionization smoke alarms?

One of the major problems with ionization smoke alarms is that they give off too many false alarms – mostly from cooking and showers.  When a smoke alarm goes off every time someone cooks bacon, people remove the battery or take down the smoke alarm. Manufacturers require them to be installed away from kitchens and bathrooms, but there is no hard and fast rule for clearance requirements across different manufacturers.  Some cities, such as Minneapolis, have implemented even stricter requirements for ionization smoke alarms; they require smoke alarms that are within 20′ of a cooking appliance to either be of the photoelectric type, or to have a hush button.

Recent statistics show that in 24% of home fire deaths, smoke alarms were present but did not sound; in half of those cases, there was a missing or disconnected battery.  This is a common problem that I find all the time while doing Truth-In-Sale of Housing evaluations, and the reason people always give is that the smoke alarm goes off every time they cook or shower.

The other problem with ionization smoke alarms is that they take a long time to respond to a smoldering fire – they’re tens of minutes slower than photoelectric alarms (page 17).   Estimates show that at least one third of home fatal fires involve a significant smoldering period (page 14).   This is the major reason that there is such a push to replace ionization smoke alarms with photoelectric smoke alarms.  The diagram and text below comes from a handout published by the CPSC, showing how a photoelectric smoke alarm will give occupants much more time to escape in the event of a smoldering fire.

In the event of a smoldering fire, a photoelectric smoke alarm clearly outperforms the ionization type.  So why do we even have ionization alarms?  The main reason is cost.  Photoelectric smoke alarms typically cost about twice as much as the ionization type.  The other reason is that ionization smoke alarms will outperform photoelectric alarms in the event of a fast moving fire.  The faster reaction time can be measured in tens of seconds, but in the event of a fast moving fire, these are precious seconds.  The diagram below, again from the CPSC, helps to illustrate this.

Most Smoke Alarms are the Ionization Type

I’ve been hearing more and more about this push, but after recently listening to an impassioned speech on the benefits of photoelectric smoke alarms over ionization alarms, I started taking an informal inventory of the smoke alarms that are installed in Minnesota homes.  Over the past few weeks, I’ve taken a close look at every smoke alarm in every house I’ve inspected to get an idea of what’s the most common type used in Minnesota.  Out of the dozens of smoke alarms I’ve looked at, I found one dual-sensor smoke alarm, which employed both ionization and photoelectric technologies.  The rest of the smoke alarms were the ionization type only.  I didn’t come across a single photoelectric unit.

To know the difference between ionization and photoelectric alarms, you need to take the smoke alarm down and look at the back.  Ionization alarms all contain a trace amount of a radioactive material, Americium 241.  They’ll all have a warning about this on the back side.  Click on any of the thumbnails below to see a blowup of the text on the back side of a smoke alarm - I marked up the labeling that indicates these are ionization alarms in every photo.

Minnesota Requirements

Minnesota currently has no specific requirements when it comes to ionization vs photoelectric smoke detectors.  Smoke alarms are generally required in bedrooms and in common areas on every level of the home in Minnesota, and they need to be hardwired and interconnected when possible.  You can read the full requirements for smoke alarms in Minnesota here.

My Recommendation

I recommend installing both photoelectric and ionization smoke alarms, or smoke alarms that use both technologies called dual alarms.  Some people argue that these alarms shouldn’t be used because there could be more nuisance tripping due to the ionization sensor, which would cause the occupants to disable the smoke alarm.  While this is obviously a possibility, proper placement of smoke alarms and better education about how they operate is the best way to make a home safer.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

Chandeliers above bath tubs are apparently all the rage today.  A few weeks ago I somehow ended up inspecting three houses in a row that had chandeliers installed above the bath tubs – one in Chaska, one in Saint Paul, and one in Victoria.  They all look great, don’t they?

Shortly after I posted these photos on the Structure Tech Facebook Page, Debbie Nelson said she’s been seeing this trend for the last five years or so.  She even gave me a couple links to web sites promoting this look – houzz from almost a year ago, and HGTV from about five years ago.

I think this is a great look, but as a home inspector I’m going to be a wet rag and say these are all improper installations.  The diagram below comes from Code Check Electrical 6th Edition.  This book is based on the 2011 National Electric Code (NEC), which prohibits any part of a chandelier from being within the shaded region shown below.  This comes from section 410.10(D) of the NEC.  The idea is that you’re not supposed to be able to stand in a wet tub and change a light bulb at the same time.

This doesn’t mean you shouldn’t install a chandelier above your bath tub… but you’re supposed to have a very tall ceiling to do it, and even then, the light should be rated for a wet or damp location.  The image below shows a chandelier rated for a damp location – you’ll notice that the bulbs are completely enclosed.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

For about the last twenty years or so in Minnesota, it’s been standard practice to seal up attic bypassses; little passageways for conditioned household air to leak in to the attic.  Attic bypasses are also known as attic air leaks.  It’s important to seal all of the bypasses in an attic, because air leaking in to an attic has a far greater effect on attic warming and heat loss than just missing insulation.

I’ve been doing a lot of new-construction inspections or one-year warranty inspections on new construction houses, and I’ve started to notice a new attic bypass that seems to be completely ignored by some builders and insulation contractors.  At a recent new construction inspection in Woodbury, I actually had a good suspicion that I would find this defect as soon as I pulled up to the house and looked at the frost covered roof.

That dark spot on the roof shows a warm spot where the frost never accumulated.  Click on the photo for a larger version.

This localized warm spot on the roof is the result of a tube that was fed in to the attic as a chaseway for future wires, such as satellite cables or antenna cables.  The other end of this tube is located in the basement utility room, near the data cable box - they call this a data tube or a tech tube, and I think it’s a great idea.  What better way to get low voltage wires from the basement to the attic?  The only problem is that some installers seem to forget that this is another attic bypass that will leak warm air in to the attic.

Just as every little hole and crack that allows air in to the attic needs to be sealed off, so does this relatively large opening.  Thankfully, the fix for this situation is very simple; just cap the end of the pipe.  This can be done pretty much any way you see fit – I’ve seen it done with both electrical tape and duct tape, and it works fine.  If you have a newer home, this is just one more reason to break the seal on your attic access panel.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector

If you see black stuff covering or growing on the roof sheathing in your attic, it’s probably mold.  It’s never fun to find out that your house has mold, but the fix for mold in the attic is usually quite straightforward, and doesn’t involve the services of any ‘mold remediation experts’.

There are a lot of folks in the real estate industry, including home inspectors, who get very excited when the word ‘mold’ comes up.  I actually sat through a seminar where we were told to never even use the word mold, because “you never know what something is without testing it.”  I couldn’t help pointing out that by that logic, we should no longer call houses ‘wood framed’ houses unless we test the material to verify that it’s actually wood.

What causes mold in an attic

When mold grows in an attic, it’s caused by a moisture problem.  Period.  Some moisture sources are obvious and have a huge impact – bathroom exhaust fans, kitchen exhaust fans, clothes dryers… they all pump moisture out of the house, and they should never be vented in to the attic.   Everyone knows that, right?

The less obvious moisture sources are attic bypasses; air leaks that allow relatively warm, moist air from the house to get in to the attic.  To reduce the amount of moisture getting in to an attic, the attic air leaks need to be sealed off.  Covering these air leaks with traditional insulation doesn’t stop the air movement; there needs to be some type of air barrier installed, such as foam insulation or caulk.  These attic bypasses show up quite clearly with an infrared camera, but any well-trained insulation contractor will already know exactly where to look for these.

Photos of Attic Bypasses / Attic Air Leaks

I’ve accumulated about a bazilli0n photos of attic bypasses over the years, so included below are a few of the most common places you’ll find attic bypasses in just about every Minnesota house built before 1991.  In all of the photos below, I’ve pulled the insulation away to reveal the bypasses; you won’t find any of these in your attic without moving insulation around.  For the record, home inspection standards of practice don’t require the home inspector to move insulation… so don’t be surprised if your home inspector didn’t mention any of this stuff.

Any time small cables or wires pass through the top plates of walls in to the attic, the holes for the wires should be sealed up.  When they’re not sealed, they leak air.  Do you see how some of the insulation in the photo below has been darkened?  It’s not mold.  This is the result of years and years of air leaking through the insulation; the insulation acts like a filter, and traps all the dust in the air, turning it black.  Even though these tiny holes don’t seem like a big deal, having them all over your attic can have a huge effect.  Sealing these gaps can be easily accomplished with a can of foam insulation.

Larger penetrations in to the attic, such as plumbing vents, also need to be sealed.  Again, foam in a can works well.

The first place I always check for attic air leaks is around the furnace vent; if there is air leaking in to the attic around this chaseway, there will surely be air leaking everywhere else.  In this first photo, the darkened insulation is a dead giveaway that there is a lot of air leaking through here.  Foam insulation wouldn’t be an appropriate repair for this location – the vent is supposed to have at least one inch of clearance to anything combustible.  In the photo below, installing a small block of wood to fill the gap at the bottom (maintaining a one inch clearance to the vent) and then sealing the entire assembly with high-temperature caulk would be a good fix.

Here’s another furnace vent – this one is completely missing the sheet-metal collar.  I could see right down in to the walls after pulling the insulation away.  This is very common.

Here’s a huge bypass around a furnace vent; the chaseway that leads down to the basement was large enough for a person to fit through, and it was basically wide open at the attic; they just had a piece of fiberglass insulation covering the top.  You can clearly see the basement ceiling from inside the attic.

The space around masonry chimneys will often be a source of air leakage.  If the chimney is being used for a wood burning fireplace, there needs to be a two-inch gap to combustible materials.  Sealing these air leaks will require the use of high temperature caulk and sheet metal.

As I mentioned in my blog about evil recessed lights, they can be a huge source of attic air leakage.  Notice all the light pouring through this fixture; the light equates to a lot of air leakage.

When additions are put on, the transitions between the new and old portions of the house are often sources of air leakage.

Whole-house attic fans can be a major source of air leakage in to attics.  These are fans that are designed to be run in the summer only.  The photo below shows light leaking through the attic fan, which means a lot of air is leaking through as well.

Probably the largest attic bypass that I commonly find is the one above the stairway to the basement on old ramblers.  All of the wall cavities are wide open to this space, and nothing above it is sealed off.  This is a bypass that’s large enough to fit a small family in to.  Other areas where ceilings drop down in older houses will be areas to look for bypasses – especially over bath tubs and kitchen soffits.

Finally, the space below the knee walls in old one-and-one-half story houses can be a major source of air leakage.  The way to repair this is to have solid blocking installed underneath every joist cavity, and have it made completely airtight.

This is certainly not an all-inclusive list of the places to find attic air leaks, but it should be enough to help you understand what an attic bypass is.  This is how air leaks in to the attic.  When all of these air leaks are perfectly sealed and a vapor barrier is properly installed in the attic, the attic interior will stay dry.

What if the air leaks can’t all be sealed?  Sealing off all of the attic air leaks is nearly impossible to do without completely removing all of the existing insulation. I’ve actually recommended doing this many times, but before starting with such a drastic measure, it’s a good idea to check the obvious stuff in the house first.  If the house is too humid, fix it.  A large percentage of attic moisture problems are caused by whole house humidifiers.  This fix for this situation is a no-brainer; turn the humidifier off.

Does adding more ventilation fix the problem?  Attic ventilation is required by the building code, but it’s not a magic elixir.  Air moving through an attic will help to remove moisture, but this isn’t the cure for a moldy attic.  I’ve heard many people conclude that an attic mold or moisture problem was caused by lack of ventilation, but that’s a little like saying a hangover was caused by not taking enough Advil before going to bed.  Adding more ventilation to an attic is just a way of dealing with the symptoms, and it doesn’t always work.

So what needs to be done about the existing mold?  It depends on who you ask.  If you talk to someone who has a financial interest in cleaning up the mold, they’ll tell you it needs remediation.  If you ask someone who could get sued for not recommending professional remediation, odds are they’ll tell you to have professional remediation.  Other people might argue that once the air leaks between the house and attic have been sealed off, it won’t matter what’s in the attic.  As long as the roof sheathing isn’t rotted, I tend to agree.

For the record, sealing off attic bypasses is also one of the most effective ways of preventing ice dams and preventing frost accumulation in the attic.  The Minnesota Department of Commerce has an excellent guide to finding and repairing attic bypasses, which gives more detailed information on how to find all of these bypasses and how to fix them.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector