Reuben's Home Inspection Blog

Inspecting Your Own Deck

May 3rd, 2011 | 9 comments

As I’m sure you already know, May is Deck Safety Month, so it’s a good time to talk about deck inspections.  Is your own deck safe?  Now is the time to check.  If you’re going to have a party or a large gathering, you better be sure.  The best way to be sure is to pack as many people on to your deck at one time as you possibly can, and have them bounce up and down all at once.  If your deck doesn’t collapse, it’s safe.

Collapsed Deck
Ok, that’s a joke.  Seriously, the best way to know about your deck is to have it professionally inspected. As I’ve said before, building a deck and replacing a water heater are two of the most common projects that get royally screwed up by DIYers on a regular basis.  If you’re not keen on hiring a home inspector or carpenter to check out your deck, there are still a few basic things that you can look for yourself.

Improper attachment to the house

The most common reason for deck collapses is improper attachment at the house.  That’s what happened with the deck pictured above.  If the deck is supported by the house, it should be attached with bolts, lag screws, SDS screws, or some other similar method.  The photo below shows proper attachment with lag screws, which I’ve circled in black.  This is the most common deck ledgerboard attachment method.  If you look at the deck attachment to your house and all you see are nails or small screws, you have a problem.  For a more in-depth discussion of different deck attachments methods, click here Deck Attachment Methods.

Lag Screws

Improper flashing at the house

There should always be flashing installed above the top of the ledgerboard – that piece of wood that attaches the deck to the house.  The purpose of the flashing is to keep water from leaking in behind the deck at the house and causing rot.  Here in Minnesota, painted galvanized steel is pretty much the standard way to flash the ledgerboard.

To determine if the ledgerboard is flashed, just take a peek underneath the deck.  If you can see a piece of metal sticking out over the edge of the ledgerboard from underneath, you know that flashing is present.  This doesn’t mean it was installed properly, but you should at least feel a little bit better knowing it’s there. If installed properly, this flashing will extend up underneath the siding.  The photo below shows what you should see if the flashing is properly installed; I drew a black rectangle around it.

Ledgerboard flashing

If there is no flashing present, there will be a much higher chance for water instrusion and rotting.

Improper joist hanger installation

Joist HangerJoist hangers are those metal brackets that attach the deck joists to the house and beams.  The manufacturers of joist hangers are very specific about how joist hangers should be installed; they specify exactly which nails should be installed, and exactly how much weight the joist hangers will support when installed properly.   Here are a few defects that I regularly find with joist hangers:

  • Missing nails.  Nails are supposed to be installed in every hole.
  • Improper joist hanger nails.  I find improper joist hanger nails on almost every deck.  If you can see a little “10” on the head of the nail, it’s probably the wrong nail.  Click the link above for more details on this defect.
  • Screws used instead of nails.  Screws don’t have nearly the shear strength of nails, and they’re not an acceptable substitute.  Well, there’s one screw I know of that’s an acceptable substitute, but I’ve never actually see it installed.  Joist hanger screw
  • Altered joist hangers.  Joist hangers shouldn’t be bent or cut.


Get a screwdriver and poke around your deck looking for rot.  The area that usually rots first is the place where two deck boards butt up against each other over a joist.  Pay special attention to that location.  If your deck doesn’t have the aforementioned ledgerboard flashing, you should also pay special attention to the place where the deck connects to the house.  The video below shows me inspecting a rotted deck in Minnesota last year.


Improper stairway attachment

The best way to attach a stairway stringer to a deck is to use a metal bracket that’s designed just for this purpose.  The photo below left shows a proper bracket for a stairway stringer.  This bracket isn’t the only way to properly attach a stairway stringer, but it’s probably the best way.  The photo below right shows an improper installation; they used a joist hanger bracket, and only managed to get a couple nails in the entire bracket.  Not cool, and not uncommon.

Stairway Stringer Bracket Improper stairway stringer attachment

Guardrail problems

Guardrails should be strong.  If you can push on the top of your guardrail and it moves a couple inches, it’s not strong enough; guardrails should be able to withstand 200 lbs of pressure along the top rail in any direction.  While this may seem like a lot, just think about a group of people leaning against a guardrail while heavyset guy who’s had three too many mint juleps falls against the guardrail.  If a guardrail is supported only with 2×2 balusters, it’s probably way too weak and should be reinforced.  You can read more about this topic at my blog about guardrail requirements.

Also, the current requirement for guardrails is that the balusters be spaced so that a 4″ sphere can’t pass through.  This is a requirement so little kids don’t get their heads stuck.  Common sense also tells you that you don’t want horizontal balusters that little kids can climb like a ladder, but there’s nothing in the building code that prohibits this design.

That makes up my list of the most common deck defects that you can look for yourself.  This isn’t a comprehensive list, but it’s a great starting point.  If you’d like a comprehensive but much less user-friendly list of things to look for while conducting your own deck inspection, you can download a deck inspection checklist from the North American Deck and Railing Association.

Reuben Saltzman, Structure Tech Home Inspections – EmailMinnesota Deck Inspections

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Common Deck Defects

May 16th, 2009 | 1 comment

May is the North American Deck and Railing Association’s Deck Safety Month.  This gives me a great opportunity to talk about what I look at when I inspect balconies and decks in Minnesota, and what the most common defects are.

It’s estimated that of the 40 million decks in the United States, only half are built to code.  As a side note, building to code means you’re doing the worst job you possibly can, while still being legal.  The building code is a minimum requirement, and building ‘to code’ is not something to brag about. From the thousands of home inspections that I’ve performed, I’d agree that at least half the decks I look at have issues.  Decks are a part of a house that many homeowners feel qualified to build themselves, permits are frequently not pulled for the work, and the work may never get inspected.


Deck with an improper load transfer

The most common cause of deck collapse / failure is lack of proper attachment to the house.  This is also one of the most common defects with decks that I find!  The deck rim (or ledger) needs to be bolted to the house to keep it from falling away, but is frequently just nailed.   A few of the other most common defects that I find are missing nails in joist hangers (brackets that support the floor structure), missing flashing at the rim (metal that keeps water from leaking in to the house), and improper load transfers.   The photo at right illustrates an improper load transfer – look closely at the top of the stairway and ask yourself, what is supporting the landing at the top of the stairway?  This deck needs repair by a professional contractor.

While many decks are improperly built and remain in tact for a long time, what leads to failure or collapse is typically a change in use, which happens when there is a change in ownership.  Grandma and Grandpa have had the deck for 10 years and haven’t had any problems, but when a new family buys a house and has their first housewarming party, it might be the first time the structure of the deck is really even tested.  This is why decks receive particular attention during home inspections.

I also happened to do a story on balcony and deck collapses last year with Fox 9 News, which you can view below.

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