Kickout flashing might be one of the most important details to get right when it comes to preventing major water damage to a building.  Kickout flashing is a simple little piece of metal that directs water out and away from a building when a roof surface ends at a wall.  The illustration below, used with permission from the fine folks at CodeCheck, shows how this works.

Here’s an example of kickout flashing not installed, along with major water damage below the area where the kickout flashing was missing.

The rotted siding shown above is just the beginning; the real damage will be inside the wall.  Here’s another photo showing some more obvious damage.

Kickout flashing has been a requirement in Minnesota since 2007, when the 2006 IRC was adopted.  The 2006 IRC made no reference to kickout flashing, but the Minnesota State Building Code amended section R703.8, and this text was added on:

[Approved corrosion resistant flashing shall be installed at all of the following locations:]

9. Where the lower portion of a sloped roof stops within the plane of an intersecting wall cladding in such a manner as to divert or kick out water away from the assembly.

This is still the building code that is in force in Minnesota today.  My only beef with this language is that it’s not very specific, making cheesy installations like the type shown below ‘legal’.  Arguably.

I guess it’s better than nothing, but come on!  That’s just silly.  The only reason I find goofy installations like this is because of ignorance; it’s quite simple to make a perfectly effective piece of kickout flashing with a standard piece of step flashing.  If everyone knew how to do it, it would always be done right.  Here’s a short how-to video that I made, which shows how to easily bend up a piece of step flashing to create a kickout.

Post update 5/22/13:  Here are two more photos showing the bends in the flashing.  The first shows the bend I made in the video using a longnose pliers, and the second shows what I did with the vice in the video to make the bend flat.

Author: Reuben Saltzman, Structure Tech Home Inspections

One of the most common home inspection concerns for home buyers is ceiling stains. While it’s not always possible to determine exactly what caused a ceiling stain, the location of the stain will often give away what caused the stain.  For example, the photos below show an improperly flashed chimney at a home in Saint Paul, and a corresponding stain at the ceiling in the bedroom directly below.

The most obvious concern with ceiling stains is roof leakage. When a home inspector finds a suspicious ceiling stain, they’ll typically use a moisture meter to help determine whether it’s an active leak or not.  The video clip below shows me using the non-invasive feature of a moisture meter to confirm that the ceiling stain shown above was caused by active leaking.

If a stain is wet, most home inspectors will be able to trace down the source of the moisture and recommend a repair. When a stain is dry, it means the cause of the staining has been corrected or the conditions that caused the staining to occur are no longer present. In these cases, it’s a good idea to ask the seller about the history of the staining; specifically, what caused the staining and has the cause of the staining been corrected?

There are a number of other types of ceiling stains that are quite easily identified.

Stains below bathroom exhaust fans

This is one of the most common ceiling stains you’ll find in Minnesota, and it’s caused by condensation. When a bathroom exhaust fan is connected to an un-insulated duct that runs through the attic space and doesn’t make an airtight connection to a proper roof cap, the moisture that’s supposed to exhaust to the exterior is going to condense like crazy.

I know I’ve shared this photo below, but I have to share it again. The duct pictured below was completely filled with condensate in the attic. I set my flashlight behind the duct to take this photo showing how full of water it was.

As all of this moisture condenses inside the duct, it eventually drains down to the bottom of the duct and then leaks on the ceiling next to the fan. Boom. Ceiling stain.

The fix for this condition is to make sure the duct for the bathroom exhaust fan is properly installed; this means an insulated duct, a short run, and airtight connections.

Stains at outside wall/ceiling corners

When stains appear at the ceilings along outside walls at the corners, it’s typically the result of ice dam leakage. If the insulation in the attic is insufficient and there are attic air leaks, it’s very likely that ice dams caused the leaking.

In these cases, our recommendation is often to have the attic air leaks sealed and more insulation added to the attic. This is typically what it takes to prevent roof leakage from ice dams.

Random ceiling stains, no roof leaks

Condensation that occurs in the attic is a common cause of ceiling stains. When enough frost builds up in the attic, it can leave enough water when it melts to create stains in a bunch of random places.

To help determine if an attic experiences condensation problems, take a close look at the nail heads; if they’re rusty and there are stains on the roof sheathing around nail heads, it’s a condensation issue. The fix for this is to seal attic air leaks and reduce indoor humidity levels.

Stains below plumbing fixtures or radiators

These are both pretty obvious, right? When a home inspector finds a stain below a plumbing fixture, the next step is to use a moisture meter to see if there is active leaking. If the stain is dry, the plumbing fixture above should be thoroughly tested, and then the stain should be checked again.

This list makes up the vast majority of ceiling stains that we encounter during home inspections.  Stains on ceilings are definitely worth further investigation, but most of the time they’re only indicators of past leaks, many of which occured a long time ago.  Why?  Because active leaks will quickly destroy ceilings and they’re extremely difficult to hide.

Author: Reuben Saltzman, Structure Tech Home Inspections

Before turning on your air conditioner for the first time this year, there are three basic maintenance items to check on; the condensate line, the air filter, and the condensing coil.  According to Mark Jerde of RightMark, these three items make up a large portion of easily preventable equipment failures.

The Condensate Line

In Minnesota, about 99.2% of single family homes with AC have a split system.  This consists of a big box that sits on top of the furnace called an evaporator coil, which is connected to another box at the exterior that contains the compressor and condensing coil.  If you’re curious about how this system works, head on over to HowStuffWorks; they have some nice descriptions and illustrations.

An air conditioner ‘conditions’ the air by removing heat and moisture.  As warm, moist air gets passed over the evaporator coil (the thing that sits above the furnace or air handler), moisture condenses on the cold tubing.  This condensate drains down to a pan where it gets directed out.

Condensate needs to be directed to an appropriate location, which is typically a nearby floor drain. The drain material must consist of cast iron, galvanized steel, copper, PEX, polybutylene, polyethylene, ABS, CPVC, or PVC pipe or tubing.  The drain must also have an internal diameter of at least 3/4″.

When improper materials are used, the drain is undersized, or when the drain needs to wrap all over the basement to get to a floor drain, the condensate drain has an increased potential to get blocked up. If the condensate drain consists of a garden hose or clear plastic tubing, replace it. This will help to prevent a blocked condensate drain, which will help prevent unwanted leakage at the evaporator coil.

Before running your air conditioner for the first time during the summer, make sure the condensate drain is directed to an appropriate location.  When the AC condensate drain needs to run across the floor of a room, people often coil the drain up so it’s not in the way when the AC isn’t being used.

The Air Filter

The air filter, also known as the furnace filter, needs to be replaced regularly.  Usually every one to three months will do, depending on the type of filter that’s installed.  While most homeowners know about changing the filter during the winter, this still needs to happen during the summer when the AC is running.

If the home has a high-velocity system with an air handler in the attic, the filter will usually be located at the ceiling in an upper level hallway.

Restricted air flow = reduced efficiency.

The Condensing Coil

This is the one that gets forgotten about the most.  The compressor and condensing coil are the parts that sit outside the home, preferably in some out-of-the-way part of the yard.  To help dissipate the heat that gets removed from the home, a big fan pulls outdoor air over the condensing coils.

For the condensing coil to work properly, it needs plenty of air flow.  This means no trellis attached to it, no ivy, no plants, no walls, no boxes, and so on. Clearance requirements will vary from manufacturer to manufacturer, but a good rule of thumb is 24″ of clear space.  Keep vegetation trimmed away.

Condensing coils also need to be cleaned regularly. When they’re covered with dirt, dust, grass clippings, dryer lint, cottonwood seeds and other outdoor stuff, air flow can be severely hampered.  Take the time to inspect all sides of the unit and clean the coils off if necessary.  This can usually be done by spraying the unit down with a garden hose.  Don’t try a pressure washer; the fins will bend very easily.

If the unit has protective grills that prevent access to the coils, the grills will need to be removed first.  At that point, a little bit of dismantling is involved, and some homeowners might prefer to contact an HVAC tech to do the work.

Author: Reuben Saltzman, Structure Tech Home Inspections

This is a follow-up to last week’s post, which gave a home inspection checklist for the exterior of homes.  The goal of this checklist is to give potential home buyers a ‘heads-up’ for some potentially larger defects.  This is obviously not a complete or technical list, but it covers a lot of potential problems.

Foundation Problems

Look for cracks in the foundation walls.  Generally speaking, cracks larger than 1/4″ in concrete block walls and cracks larger than 1/8″ in poured concrete walls are reason for concern.

Cracks that are large enough to put your hand through shouldn’t be cause for concern.  They’re cause for repair.

Cracks that have been patched and have opened up again are reason for concern, as they typically indicate ongoing movement.  Horizontal cracks are more concerning than vertical cracks.

Offsets in the foundation walls are cause for concern as well.  The house shown below ended up being demolished.

Wet Finished Basements

It’s usually quite easy to figure out if a finished basement has moisture problems if you’re willing to do just a little bit of digging.  Walk around the exterior of the home first, and look for any areas without good water management; for the most part, this means negative grade and missing downspout extensions.  When downspouts discharge next to the house, there’s a good chance that there will be a water intrusion issue at about the same place inside the basement.

Basement water intrusion staining always starts at the base of the foundation walls.  Pay special attention to inside corners for signs of water intrusion.  Loose for stains at the baseboard trim, and stained or patched wall areas.  Look behind furniture, and look underneath carpet if possible.

The photos below shows stained wood paneling and black, wet carpet tack strips in the same place.

The photos below, from the same house, show black staining (mold?) at the drywall in one of the inside corners, as well as staining at the baseboard trim.

If there are in-floor ducts, try to look inside the ducts at every floor register.  If water has entered this ductwork, it’s a serious problem.

Plumbing – Galvanized Steel Pipes

Galvanized steel water pipes were used on older houses up until about 1950.  The problem with galvanized pipes is that they rust on the inside, making the pipe diameter smaller and smaller over time.  This leads to less and less water flow at the plumbing fixtures.  Galvanized pipes are also more prone to leakage, typically at the joints.

To test water flow at older houses, turn on the laundry sink faucet all the way and then check water flow at the other plumbing fixtures throughout the house. On houses with galvanized pipes, we’ll frequently find no water flow at the second floor plumbing fixtures when performing this test.  Once it gets to that point, it’s time to think about new pipes.

The photo below shows a first floor kitchen sink faucet turned on all the way; if you look carefully, you can see a few water droplets in the air.  The repair for this condition is to have a plumber replace the old galvanized steel pipes.

The pipe coming from the street to the house is called the supply pipe; when this pipe is galvanized, there’s a good chance that water flow throughout the house will be minimal.  The fix for this is expensive; it means digging up the yard and replacing the pipe out to the street.

On older houses, check below the water meter in the basement to verify the supply pipe is something other than galvanized steel.  The photo below shows an example of a galvanized water supply pipe.

As with galvanized steel water pipes, galvanized steel drain pipes also rust on the inside.  This accumulation of rust reduces the pipe diameter and can lead to clogged drains and leaks.

Galvanized steel plumbing vents also rust out; sometimes they may completely rust through and allow sewer gas in to the home, but the vents are typically concealed.

The eventual fix for this is replacement of the old steel drains and vents with new ABS or PVC pipes.  The first drain to get clogged will always be the kitchen sink drain.  Run water down the kitchen sink for about ten minutes to make sure it drains properly.

Neglected Furnaces / Boilers

Watch out for excessive rust, debris, and especially black soot or scorching at the furnace or boiler.  These typically indicate then need for service or replacement.

Electric Hazards

FPE Stab-Lok electric panels are a latent fire hazard.  These panels can be easily identified by a label on the panel that says “Stab-Lok”.  We always recommend replacement of these panels.

In houses built from 1965-1974, look for aluminum wiring, or more specifically, aluminum branch circuit conductors.  These are a larger concern that can involve expensive repairs.  It’s not always possible to identify aluminum wiring without opening the electric panel, but if aluminum conductors are used with NM cables (aka ‘Romex’), it will say “aluminum” right on the cable sheathing.  Look for this in the garage or basement.

Fuse panels under 100 amps are typically inadequate for today’s houses.

To help determine the size of the electric service, look on the door of the electric panel.  Most old fuse panels will either be 60 amp or 100 amp.

Knob & Tube wiring is an obsolete two-wire system typically found in pre-1930′s homes, and is easily identified by the porcelain knobs & tubes that are used to hold and protect the wires.    When present, knob & tube wires will usually be visible in attics and unfinished basements. The photo below shows an example of exposed knob & tube wiring at the ceiling in a basement.

At best, the remaining knob and tube wiring is in good condition and most of it has been replaced.  Be aware, however, that many home insurance companies charge a premium or refuse to insure homes with knob & tube wiring, even if it’s still in pristine condition.

At worst, the knob & tube wiring has been exposed to high temperatures for long periods of time, causing the insulation on the wires to fall apart, leaving exposed conductors that create a shock and fire hazard. Examples of hazardous knob & tube wires are shown below.  Yes, these wires were live at the time of the inspection.

Interior Stains

Stains at the base of patio doors typically indicates water intrusion and rot.  Step on the floor next to patio doors to make sure the wood is solid.  The photo below shows major rotting at the floor by the patio door.

Water stains on windows are usually caused by condensation, which isn’t a major concern, but stains that are caused by exterior water intrusion are a larger concern.  To help determine the difference, click this link on window stains.  The photo below comes from that post, showing an example of window staining caused by water leakage from the exterior.

Hopefully these items will give potential home buyers a good starting point.  As mentioned last week, here’s a one-page Home Inspection Checklist in pdf format that may be helpful.

Author: Reuben Saltzman, Structure Tech Home Inspections

For home buyers interested in conducting their own home inspection, here’s a list of larger items to look out for while viewing houses.  This is a cursory overview of some of the larger problems that are frequently identified during home inspections.  Of course, this is no substitute for a professional home inspection, but it’s a great start.

Roof Problems

While many roof problems can only be identified by actually walking the roof or leaning a ladder up against the eaves, some defects can be easily seen from the ground.  Be sure to view all sides of the roof.  In older neighborhoods with tall houses that are close to each other, it may be necessary to walk a fair distance down an alley to get a good look at the roof.

Look for any irregularities with the roof: shingles that look curled from the ground indicate an old roof.  This type of curling almost always happens on the south side first, so pay special attention to that side.  The photos below show examples of some particularly nasty roofs.

Look out for cracks in shingles as well.  These typically won’t be visible on second story roofs, but it’s sometimes possible to spot these on single-story roofs.

Mis-matched or patched shingles, missing shingles, and shingles sliding out of place typically indicates an improper installation.  The photo below shows a horrible patch job. A ‘new’ roof doesn’t mean a ‘good’ roof.

Always look for loose shingles in valleys.

A large section of the roof below had been patched. Why was the roof patched to begin with? A patched roof is often the result of an improper installation that has led to shingles coming loose.

Shingles without neat rows may have been installed that way, but it may also mean that shingles are beginning to slide down.  Closer inspection of this roof revealed that the shingles were improperly nailed, causing the shingles to slide down.

Here’s a more extreme example of sliding shingles.

Don’t forget to view all sides of the roof.  This next roof was too high to be safely inspected with a 28′ extension ladder, but a walk down the alley revealed considerable, obvious damage.

Chimney Problems

Chimney repairs can be another large expense.  When buying an older house with a masonry chimney, take a close look at it.  Missing mortar between the bricks typically won’t be a major repair, but missing bricks and large cracks in the walls can sometimes mean the upper portion of the chimney needs to be re-built.

As with roofs, be sure to look at every side of every chimney.  The chimney shown below had been redone to look good from the street, but didn’t look so great from the back yard.

Problems with the chimney flashing, crown, and interior flues are difficult to identify from the ground.

Siding

Hardboard siding begins to swell and then literally fall apart when it rots. Deteriorated hardboard siding is usually quite easy for anyone to spot. Check the north sides, areas not protected by soffits (overhangs), and the areas closest to the ground first; these will be the first areas to rot. If unsure about an area, push on it with your finger, but not too hard.  When hardboard siding is badly rotted, it gets mushy.

Defects with newer stucco siding are difficult to identify from the exterior, but stains below windows are an obvious warning sign that there may be hidden damage.

Problems with others types of siding usually aren’t as easy to spot without a trained eye.

Windows

Rotted wood windows that have been patched may look fine from a distance, but it’s usually easy to spot damaged areas when up close.  Give the windows a little poke with your finger when rot is suspected.  Sometimes the patchwork will be paper-thin, so don’t poke too hard.

Aluminum clad wood windows can completely rot apart on the inside, yet leave no visible evidence at the exterior.  These windows can be pushed on or squeezed to help determine if there is internal rotting.  The windows that will rot first are the ones that aren’t protected by soffits (overhangs).

In the photo below, we pulled some of the cladding back to show severely rotted wood inside the sash.

Cranking windows open and looking at them from underneath can sometimes reveal water damage.

Decks

Always take a look underneath decks.  Sometimes decks will have a fresh coat of paint that conceals severe rotting, which may be quite visible from below.

Also, take a step back from the deck and look for sagging, which may indicate a structural problem with the construction of the deck.  The deck shown below had a very noticeable sag in the middle which wasn’t obvious from up close.

Click this link for more info on deck inspections.

Water Management

This one is huge.  Make sure water is properly directed away from the house.  Look for proper gutters, downspouts, and downspout extensions.  They’re not required, but they certainly help.  Also, check to make sure the earth slopes away from the house.  Water draining toward a house can lead to big water problems in the basement or crawl space, as well as foundation problems.

Look at roof lines as well; if water gets concentrated against the house, the potential for water intrusion goes up.  The photo below shows a good example of several roof surfaces concentrating water in to a small area right up against the house.

Next week I’ll have a home inspection checklist for the interior, along with a one-page pdf checklist of all the interior and exterior items.

Author: Reuben Saltzman, Structure Tech Home Inspections

Many older houses in Minneapolis and Saint Paul have an old style of plumbing trap called a drum trap, which is no longer allowed in Minnesota except in special circumstances.  The photo below shows an example of a relatively small drum trap found below the bath tub at a recent home inspection in Hopkins.

Drum traps come in all different types of shapes, sizes, and configurations.  The crude diagrams below show a few examples of different types of drum traps I’ve come across, as well as one type of setup that wouldn’t create a water seal trap, shown at the bottom right.

As mentioned in previous posts, the purpose of a plumbing trap is to prevent sewer gases from coming in to a building.  A drum trap does the same thing, but instead of just having a dip in the pipe to create a P-trap, a drum trap consists of an enlarged ‘vessle’  that holds a large volume of water.  In the Twin Cities, drum traps were commonly used at bath tubs and occasionally at laundry sinks.

Why they used to be popular

In my posts about s-traps and plumbing vents, I explained how proper plumbing vents prevent water from getting siphoned out of traps and why it matters.  Water can be siphoned out of a drum trap in the same way it can be siphoned out of a p-trap or s-trap, but drum traps hold so much water that it’s pretty much impossible to have enough water siphon out to allow sewer gas in to the home.

Drum traps were also supposed to be easier to open up for cleaning and retrieving lost items, but it didn’t always work that way.  I’ll come back to this.

Why they’re no longer allowed*

One of the basic plumbing principals of the Minnesota State Plumbing Code  (4715.0200, “s”) says that “Each fixture shall be provided with a separate, accessible, self-scouring, reliable trap placed as near to the fixture as possible.”  If you take apart any properly installed p-trap, you’ll probably find that it’s nice and clean inside; this is because it’s self-scouring.  The water drains through the trap in such a manner as to pull solid materials out of the trap along with the water.

The main problem with drum traps is that they’re not self-scouring.  A drum trap holds so much water that the water and solids coming in to the trap will not be pulled directly through, which can allow for the accumulation of solids in the bottom of the trap.  This makes drum traps more prone to getting clogged.

Another problem with drum traps is that they can be difficult to clean out.  Most drum traps have a removable cover, but drum traps are usually located right below the floor, making the lid extremely difficult to access without cutting out the floor.  At my last house in Minneapolis, there was a removable panel in the floor created just for accessing the drum trap.

Even when the cover is accessible, it can be difficult or impossible to remove the cover because the threads are rusted shut.  One Minneapolis home-improvement blogger recently wrote about how he was able to saw the top of his drum trap off, and then covered it over with a rubber test cap.  While the test cap is only supposed to be used temporarily, I suppose I wouldn’t hesitate to do the same thing if I had a problematic drum trap.

When the cover for a drum trap is accessible and easy to remove, it’s important to make sure that it makes a tight seal.  It has the potential to allow sewer gas in to the home or leak if not sealed properly.

What to do about them

If you have an old drum trap in your house or you’re buying an old house with a drum trap, there’s no need to get whipped up.  Drum traps usually work just fine, but they’re more prone to getting clogged, and can be difficult to service.     Wait until a plumber is out doing other work to have your drum trap replaced.

On a personal note, I had a drum trap at my last house in Minneapolis.  It clogged shortly after I moved in, so I removed the cover and cleaned it out.  I put the cover back on, and never had a problem with it for the next seven years that I lived there.  It was installed in such a way that replacing it would have required making a nasty hole in one of my floor joists, so I just left it alone.

*The exception

Section 4715.0960 of the Minnesota State Plumbing Code says that “Drum traps shall be installed only when permitted by the administrative authority for special conditions (laboratory tables, dental chairs, etc.). ”  Drum traps are allowed in these locations because they’re not self-scouring.  If someone’s gold filling falls down the drain, a drum trap will allow it to just sit in the bottom for retrieval.

A few photos, just for fun

The photo below shows a crown-vented lead drum trap with the cleanout at the bottom.  The bath tub drain was also leaking.

This next one shows a relatively new PVC drum trap.

The drum trap shown below leaked profusely when we filled the bath tub with water and then drained it.

Here’s a drum trap at a laundry sink.

The drum trap at this next laundry sink had a severely corroded cap.

This next one shows a drum trap installed on its side, along with a bunch of those rubber clamp connectors that aren’t supposed to be used.

Below is one of my favorite photos of all time, which I’ve shared before.  This drum trap had probably rusted apart or someone had to cut the bottom off to clean it out, so MacGyver  fixed it with the bottom of a coffee can, glue, tape, and string.  Spray painting the bottom red was also a nice touch.

Author: Reuben Saltzman, Structure Tech Home Inspections

Two of my recent blog posts have been about the need for combustion air ducts and common problems with combustion air ducts, but I never covered the topic of connecting a combustion air duct directly to the plenum on a furnace.  This actually used to be standard practice for a long time; the crude diagram below shows how this worked.

When the combustion air duct is connected directly to the return plenum for a furnace, the blower fan on the furnace pulls outdoor air in to the return plenum.  To supply this air to the furnace room, a supply register is added at the ductwork in the same room, typically right above the furnace.  This is an undesirable setup, for a number of reasons.

Waste of Energy

During the winter, this setup pulls cold outdoor air in to the house, directly in to the return plenum for the furnace.  While a combustion air duct that terminates at the floor will allow cold air to come in to the house, it’s not nearly as much air compared to the duct connected to the furnace return plenum.  When it’s very cold outside outside, that’s a ridiculous amount of cold air being pumped in to the house, but because it gets tempered by the furnace, nobody feels it.  This is a big waste of energy.

During the summer, the opposite happens.  This setup pulls warm, moist outdoor air in to the house just before the air conditioner’s evaporator coil, as shown below.  Again, this is a waste of energy.

Pressurizes the House

When a combustion air duct is connected directly to the return plenum on a furnace, the house becomes pressurized when the furnace blower fan starts running.  How does this air leave the house?  Any way it can; plenty of these household air leaks were covered in this post about why houses need combustion air ducts.

The air leaks that really cause problems are the air leaks found in the attic.  Attic air leaks lead to frost in the attic as well as ice dams, and the effect is magnified when a combustion air duct is connected to a furnace return plenum.

Code Violation

As a home inspector I don’t get hung up on code requirements, but as long as I’m blogging about this topic, it’s worth mentioning that the Minnesota State Mechanical Code no longer allows the combustion air duct to be connected to the return plenum.  Section 708.1, #3 says:

[Combustion air ducts shall:] Terminate in an unobstructed space allowing free movement of combustion air to the appliances.

Frequently Disabled

While it’s common for home inspectors to find combustion air ducts stuffed shut with clothing inside the house, it’s actually even more common for the combustion air duct to be disabled when it’s connected to the return plenum.

Remember, that register above the furnace is what supplies combustion air to the furnace room.  Because this register is located right above the furnace, it’s also the most powerful register in the house, which makes the furnace room very warm during the winter.  When well-intentioned homeowners don’t understand how their combustion air is connected, they assume that the register above the furnace is only there to supply heat to the room, so they block it off to get more heat to the areas that matter.  This prevents combustion air from getting to the appliances that need it.

Note the cardboard blocking this opening in the photo below, despite the stern warning from the HVAC contractor.

What To Do

If the connection from the combustion air duct to the return plenum is visible inside the house, the fix for this situation is simple: have the combustion air duct disconnected from the furnace return plenum, and have the duct dropped down in to the room.  Also, have the old hole in the return plenum blocked off.

Any HVAC contractor should be able to help make this simple change, which is something we’ve recommended to countless home inspection clients.

Author: Reuben Saltzman, Structure Tech Home Inspections

The newest version of the Minnesota State Plumbing Code, published electronically on November 13, 2012, now requires a safety device to be installed on bath tub faucets to help reduce the potential for serious scalding injury.  Here’s the exact text, which comes from section 4715.1240 of the Minnesota State Plumbing Code:

Subp. 4. Hot water temperature control device for tubs. Bathtubs and whirlpool tubs must be provided with water temperature limiting devices set at a maximum water temperature of 120 degrees Fahrenheit to reduce the risk of scalding, according to ASSE Standard 1070.

This means that the water coming out of a bath tub faucet needs to be tempered so that the hottest water that can come out of the faucet is 120 degrees F.

So how is this done?  I asked Mark Jerde of RightMark Plumbing how he achieves compliance with this new requirement.  He installs thermostatic mixing valves conforming to ASSE 1070 at the supply lines to bath tub faucets.  One such mixing valve is the Watts MMV series, pictured at right.  Just don’t look for these types of valves at big box home improvement stores; they don’t sell them.  Maybe this will change soon.

For more info on this new standard, click here: ASSE 1070

Author: Reuben Saltzman, Structure Tech Home Inspections

Last week I wrote about what combustion air ducts are and why houses need them. This week I’m going to follow up with some of the most common problems and solutions related to combustion air duct installation and maintenance.

By far, the most common problem that occurs with combustion air ducts is that they get blocked.  When a combustion air duct is blocked, air needs to ‘leak’ in to the house through many different undesirable pathways.  I’ve done a number of home inspections where the windows were completely iced shut throughout the house, and in every case there was a blocked combustion air duct.

Problem: Intentional, ignorant blockage

A combustion air duct brings in fresh outdoor air, which usually means cold outdoor air in Minnesota.  This can create a cold floor where the duct terminates, as well as a cold draft.  I was going to make a nice little drawing of this cold air coming in to the basement around my own combustion air duct, but then I remembered I have an IR camera.  Duh.  Check out the two images below for a nice visual of how the combustion air duct is making my basement floor cold.

 To prevent this cold air from dumping in to their home, people sometimes stuff clothes or towels in to the combustion air duct, or the block the intake at the exterior of the home.

Solution: Remove any obstructions.  If you want to help cut down on the amount of cold air that just ‘dumps’ down in to the basement, try creating a trap at the bottom of the combustion air duct.  Make the air have to rise back up again before coming in to the home.  I don’t have any hardcore proof that this makes a big difference, but I’ve convinced myself that it helps, and it’s easy enough to do. The two most common ways of creating a trap are to either make a “J” at the bottom of the duct, or to put a bucket  or box underneath the duct.  With either of these methods, the air will need to rise up before coming in to the home.

Just make sure that the bucket or box you use isn’t so small that it restricts air flow.  I’ve always just eyeballed this, but if you’re super anal, you could make your sixth grade math pay off by measuring the inside diameter of the bucket and the outside diameter of the duct, then calculate the surface areas (Πr²) and make sure the bucket’s is at least twice that of the duct’s.

Also, make sure the duct isn’t so long that the opening sits flat on the floor, effectively blocking it.

Problem: Lack of maintenance

The opening at the exterior for the combustion air duct will bring air in to the home, and with that comes dust, dirt, insects, leaves, etc.   I’ve found that the closer the combustion air duct is located to the ground, the more likely it’s going to get blocked with debris.

Solution: take a peek underneath your combustion air duct every year to make sure it stays clean.  If you do this during the summer or fall, watch out for wasps.  They love to make nests in this opening.  If the opening is dirty, vacuum it off.  If you have an HRV, check the HRV intake at the same time.

Problem: Small Mesh at the Exterior

The opening at the exterior of the home needs to be covered with a steel mesh having openings not less than 1/4″, and not more than 1/2″.   When standard window screen is used here, it will get dirty very quickly.  Click on the photo below for a larger view; you’ll see the opening is actually covered with a window screen, which should be removed.

Solution: Remove any restrictive mesh or material, and replace it with 1/4″ hardware cloth or something similar if it’s not already present.

Problem: Unintentional, ignorant blockage

Every so often, vinyl siding installers will forget which opening was meant for the combustion air intake, and they’ll install a damper at this opening instead of a screen.  These dampers allow air out, not in.

Solution: Replace the exterior terminal with a type that is designed for a combustion air intake, or remove the damper and cover the opening with 1/4″ hardware cloth.

Problem: Inlet installed too close to the ground

The inlet for the combustion air duct needs to be installed at least 12″ above grade.  When it’s too close to the ground, it can get dirty very quickly, and can get blocked over with snow.

Solution: When the combustion air inlet is installed this close to the ground, it’s usually done because that’s where the rim joist was located, so making a higher hole in the side of the house isn’t an option.  The solution is to install what Milind calls a ‘snorkel’.  I laughed the first time I heard this, but I like this term.  I think the photo below is pretty self-explanatory.

That concludes my list of the most common installation and maintenance defects with combustion air ducts.  If I think of any more, I’ll add them to this list in the future.

Author: Reuben Saltzman, Structure Tech Home Inspections

Quick links in this post: Blocked duct at interior, dirty intake at exterior, small mesh at exterior, blocked intake at exterior, intake installed too low, cut down on cold air coming in.

Have you ever noticed a big insulated tube dropping down next to the floor near your furnace or boiler in the basement?

If you trace this duct down, you’ll find that it connects to an opening at the exterior of the building.  This is essentially just a hole in the side of the building that brings in fresh outdoor air.  Homeowners, builders, and insulation contractors spend lots of  time trying to seal up every little air leak in to a house, but then the building code requires this big hole that allows cold air to just dump in to the basement.  Silly, right?

I’ll try to help make some sense of this.

Houses need air

This opening is a passive intake that provides needed air to the home.  There are several items in a home that remove air – here’s a partial list of common items found in Minnesota homes that remove air from the house:

• Furnaces and boilers that are not direct vent / sealed combustion type
• Water heaters that are not direct vent / sealed combustion type (at least 99%)
• Bathroom exhaust fans
• Kitchen exhaust fans
• Clothes dryers
• Wood burning fireplaces

The stack effect in a home, wind, and radon mitigation fans may also remove air.  The most common and obvious problem with too much air being removed from a house is a backdrafting water heater, but there’s a lot more to it than just this.

Houses leak

When air is removed from a house, it has to be replaced.  If a house is not built tight, the air will get replaced from every little hole in the envelope in the house; the photos below show a few examples.  These are the things that get corrected to make houses “tighter”.   The first photo below shows an outlet box at an exterior wall that hadn’t yet been sealed.  Those openings get sealed in new houses today, but this never used to happen.

The photo below shows the furnace vents going through the rim joist.  Daylight is visible around these penetrations, which means air leakage.

The opening around the faucet is obvious.

Of course, windows and doors are also a huge source of air leakage.  Daylight showing through is a dead giveaway.

Unsealed openings in the exterior walls equates to uncontrolled air leakage.  Every time the wind blows, air will leak in or out through these openings.  Even without any air moving at the exterior, the stack effect in a home will cause air to leak in through the lower openings in the envelope of a home, and back out through the upper openings, such as attic bypasses.  The image below, used with permission © 2013 E Source, gives a visual example of the stack effect.

The line of neutral pressure plane will be different in every home.  Some of the factors that affect this are differences in indoor / outdoor temperatures, wind, the height of the home, and how much air is leaking.  For the upper ‘positive pressure’ leaks, one of the most obvious that can be viewed from inside the house is a loose-fitting attic access panel.

Other attic air leaks, most of which can only be seen from inside the attic, are also major contributors.  These include leaks around furnace vents, electrical cables, plumbing vents, chimneys, etc.

When air is allowed to leak through the house uncontrolled like this, the amount of air leakage and energy loss is typically much more than it needs to be, and it doesn’t happen where, when, or how it should.  This can lead to condensation and frost at windows, in the attic, and even inside the walls.

The Combustion Air Duct

To help reduce the effects of uncontrolled air leakage, houses get sealed up as tight as possible and a single hole is created to bring outdoor air in to the basement, usually right next to the furnace.  This is the combustion air duct I showed at the beginning of this post.

When a combustion air duct is properly installed, it will help prevent the house from getting depressurized.  The air is allowed to come in to the house as needed through a large opening, and all of those other holes in the walls can be sealed up.  To see how well this works in a new house, try running all of the exhaust fans for about 5 minutes, then put your hand over the end of the combustion air duct; if it’s working properly, you’ll feel plenty of air pumping in to the house.  Beautiful.

I’ll have a follow-up post next week discussing the most common installation and maintenance problems with combustion air ducts, and well as the solutions.  Of course, I’ll have photos of everything.

Special thanks to Steve Schirber at Cocoon Insulation for helping to write this post.

Author: Reuben Saltzman, Structure Tech Home Inspections