Welcome to Structure Tech

Inspecting Your Own Deck

By In Decks, Minnesota Deck Inspections On May 3, 2011


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.

Rot

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

Facebook Reuben's LinkedIn Page Follow StructureTech on Twitter ASHI Certified Home Inspector - Click To Verify Click to subscibe to Reuben's Blog

 

 

 

 


About the Author

Reuben

Reuben is a second generation home inspector with a passion for his work. He grew up remodeling homes and learning about carpentry since he was old enough to hold a hammer. Reuben has worked for Structure Tech since it was purchased by Neil in 1997, and is now co-owner of the company. Reuben’s favorite customers are the ones who have a lot of questions; he grew up thinking he was going to be a school teacher because he enjoyed teaching others so much. In a sense, that’s a lot of what home inspections are about, so Reuben truly does what he loves. Reuben has an A.A. degree in liberal arts and has attended most of the Building Inspection Technology classes at North Hennepin Community College. Reuben and his wife are the proud parents of two young childen, Cy Alexander and Lucy Nicole, and have a German Shepherd named Stanley. With two young children Reuben doesn’t have much free time, but he still tries to play disc golf as often as possible during the summer. Reuben lives in Maple Grove, MN. Professional Qualifications / Memberships: *ASHI Certified Inspector *President, ASHI Heartland Chapter *Member, Minnesota Society of Housing Inspectors (MSHI) *Licensed Minneapolis Truth-in-Sale of Housing Evaluator *Licensed Saint Paul Truth-in-Sale of Housing Evaluator *Licensed Maplewood Truth-in-Sale of Housing Evaluator *Licensed Hopkins Truth-in-Housing Evaluator *Licensed Robbinsdale Point of Sale Evaluator *Affiliate Member, Southern Twin Cities Association of Realtors

Related Posts

9 Comments

  • HomeMD Inspection Services 4 YEARS AGO

    Foundation failure is also one of the main factors. Foundation should be strong and durable as it is supposed to be.

    • Reuben Saltzman 4 YEARS AGO

      HomeMD - how would a homeowner inspect their deck's foundation? Or is this not really a home inspector leaving a comment, but someone hired to do web optimization by leaving comments that don't make any sense on other people's blogs?

  • John 4 YEARS AGO

    Is flashing required if the deck is attached to concrete?

    • Reuben Saltzman 4 YEARS AGO

      Yes, the flashing would still prevent water from getting in-between the ledgerboard and the concrete, where it could possibly just sit and eventually rot out the ledgerboard.