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?
Larry
Perhaps he could use 12" blocks until the last course, then use 8" blocks. That would allow you to simply rest your 2x8 ledger on the 12" blocks.
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.
CP
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
That's good advice. Although if they take the advice I gave, there's no connection to the house, just the foundation.
BTW, there's no such thing as dry rot. It's all wet. :-)
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 carport. 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.
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?
sheesh.
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 latter.
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 catastrophic failure.
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
I think you should go supervise just to be sure. :-p
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.
Right. Code dictates HOW a deck is to be attatched to the structure but does not REQUIRE it to be attached.
wrote
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 joisting. A pressure treated 2x6 or corresponding ledger to fit joist size is what is bolted on. 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.
johnloomis
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?
Larry
Some of that "plastic wood" actually has wood fibers in it. It can rot. I've a contractor friend here that has had to replace such decks...
...Kevin
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 anything.
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.
JP
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