My son has asked me to help him erect an elevated deck on the new cabin he'
s having built. The cabin will be on a concrete block base, elevated a cou
ple feet above ground level. My instinct is to have the builder insert bol
ts in the concrete grout. The bolts would extend out a couple inches from
the base and we would drill corresponding holes in the 2x8 joist in order t
o bolt the joist to the dwelling.
Is this the correct procedure or is there an easier/better route?
Your son should get some expert advise from a reliable professional.
Bolting a ledger to the house without spacing is asking for dry rot on
the house ledger. Ask me how I know. Also bldg. codes require that a deck
be securely attached to the house. If he still wants to do this
himself, he should get a subscription to Journal Of Light Construction.
One of the latest issues has an article on this.
The deck CAN b a "free standing structure" - not fastened to the
building at all. This alleviates any settling ot heaving problems,
eliminates the possibility of foundation leakage at the bolt,
elimintes dry rot issues, and is generally simpler and more forgiving.
It DOES need to be properly cross-braced to prevent moving
As a general rule of good construction practice, wood should never
contact earth OR concrete. When placing a sill on a concrete
foundation, a "sill gasket" should ALWAYS be used. Heavy building felt
is commonly used, but there are other, possibly better options.
When setting a wooden post on a concrete piling, a galvanized steel
saddle (or equivalent) should ALWAYS be used. moisture from the
concrete piling continually absorbs into the end-grain of the post,
and in about 20 years there is nothing lest of the post. Perhaps 22 if
it is PT wood, or 23 if it is cedar. Friend's daughter just bought a
house about 2 years ago and the carport roof is sagging - just found
out there is no wood left inside the aluminum cladding of at least 2
of the 4 posts that are SUPPOSED to be holding up the end of the
Twenty some years ago I had the same problem with the post holding up
the corner of my front porch overhang. 4X4 wood sitting directly on
concrete "footing" - nothing but pulp for the bottom 8 inches or so.
On 9/12/14, 10:55 PM, email@example.com wrote:
I just assumed his builder would know to use a sill sealer of some kind.
I also assumed the deck would be made of pressure treated wood wich is
fine on concrete. Do we have to fu@k!ing spell it out in here or what?
"Playing is not something I do at night, it's my function in life"
National building code REQUIRES through bolting it to the foundation to keep
it from pulling out the bolts and collapsing, killing those standing on
decks that are well elevated. It has happened, many times.
There are charts on the spacing of the bolts that reference the length of
the deck extending away from the building. The bolts are to be heavy
galvanized, can't remember if it is 1/2" or 5/8" but I recall that it is the
This is one thing in the building code that I believe in. The spacing is a
little overkill, but lag bolts can, and do pull out. The result can be
Do this job right, whether it is inspected or not. The other choice is to
basically make it free standing by putting posts up next to the foundation,
which has already been mentioned.
Today's pressure treated lumber can still rot on concrete. And many
builders have obviously "forgotten" that standard lumber dhould never
contact concrete directlyere are MANY cases of this happening.
Do I have to spell it out???
I gave 2 experiences I have personally run into where it wasn't done
right - and I'm sure I could find another 10 if I walked through 2 or
3 neighbouthoods and shook the porch corner posts or carport supports.
Actually, while looking at houses recently I did find sI rejected out
of hand because one or more posts moved - and these were $300000 plus
homes, less than 40 years old.
on a 4 foot or higher deck I agree. On a 2 foot high deck, it is
overkill and it is becomming much more common to make it basically a
"patio" which sits on the ground. But made of lumber (and now even
steel) supported above ground
You should ping John Loomis, here on the wRec.
He builds a lot of decks.
That said, there are very specific code requirements for attaching a
deck to an existing structure. It pays off to build to building codes
for your area, as they should take into account regional climate
differences, and your project will last much longer.
I built a single level deck a few years ago that was almost 1000/sf, and
I built it freestanding (not attached to the existing structure), which
is, IMO, a good way to go for the height you mention, so give that
method some consideration.
No arguments with anything here. I would add that sometimes even a higher
deck can be made free standing and made practical.
I would add that the plastic wood is pretty cool to work with. I can't see
it ever rotting or getting tattered.
That is an excellent way to handle a deck ledger on a concrete wall.
I also place the bolts "off layout" so that they do not interfere with the
A pressure treated 2x6 or corresponding ledger to fit joist size is what is
The only problem is that the ledger and joist/decking need to be lower that
the 1" or so siding of the cabin.
so, there will be a slight elevation drop to the deck.
"Gramps' shop" wrote in message
My son has asked me to help him erect an elevated deck on the new cabin he's
having built. The cabin will be on a concrete block base, elevated a couple
feet above ground level. My instinct is to have the builder insert bolts in
the concrete grout. The bolts would extend out a couple inches from the
base and we would drill corresponding holes in the 2x8 joist in order to
bolt the joist to the dwelling.
Is this the correct procedure or is there an easier/better route?
Hopefully I'm not too late here, but what you're describing would be
absolutely the wrong way to do this, and has the potential to seriously
damage or destroy your foundation.
The most common accepted detail for this is to (expansion) bolt a
continuous pressure-treated 2x ledger board to the CMU wall. Depending
upon the situation and the actual cabin floor/joist construction, it's
often recommended that the ledger board be held away from the CMU wall
with small 2X spacers so that moisture can drain away. Then use
pre-engineered steel joist hangers fastened per manufacturer's
requirements to the ledger board. Set the deck joists into the hangers
and fasten them to the hangers. The connection through the hangers
allows a good deal of movement to occur without damaging or stressing
Contrary to what some others have posted, the national and international
building codes do not require that a deck be fastened directly to a
structure. If it is to be fastened, some codes do offer general guidance
on how this should be done, but they are by no means all-encompassing,
and intentionally allow latitude for many different methods and
materials to be used.
I would suggest that you take some photos of what you have already
constructed to a reputable architect or structural engineer (preferably
one who does design work on residential structures) and get some real
advice. Most all architects and structural engineers have detailed this
situation dozens of times, and will advise you for little to no cost;
and the peace of mind you'll have will be priceless.
This is my signature. Really. I'm not kidding. Stop reading now.
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