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Porches, Decks, and Awnings (And
By George Porter
Well, this is going to get a little ugly but it needs to get
passed around so here goes. Every home has an installation manual
and every one I have read (that would be a bunch) says that, "anything
connected to a HUD Code must be self-supporting". This means
porches, decks, awnings, room additions, carports, and on and
on. The technical meaning of this is that no live load or dead
loads from the new structure can be transmitted to the original
structure (the home). This doesn't mean that you can't have them,
just that the home can't hold them up. These additions must hold
themselves up. An exception would be if a factory special builds
a home that was designed to hold up a certain structure like a
garage. Such homes can be made, but the regular products from
the factories do not come with this option.
The principle of "free standing" is that if the actual
connection between the adjacent structure and the home were disconnected
and the home were to be moved away, then the structure would be
able to stand by itself and support all of its designed roof load
The main reason why the manufacturers want this to be is that
the frame system under the home doesn't give any extra support
to the sidewalls of the home in sufficient quantity to hold another
structure. These homes will do what they must do to comply with
the HUD Code but will not support other buildings or, more specifically,
the weight of other buildings.
Here's the nasty part, we have all seen 10's of thousands of
them doing it!
I used to have a great side business putting up awnings on
people's homes in my area. Never gave it much thought, just did
it like everybody else, one side goes to the house and the other
side gets poles, simple. For years most of the time when the crew
put an awning on a home the screen door needed adjusting as soon
as they were finished. I figured someone on the crew was standing
on the screen door like it was a ladder and would mess it up.
I didn't want them to break the door but more importantly I didn't
want anyone to fall and hurt themselves. I would ask who was the
person doing this and they would all say, "Are you nuts?
You can't stand on a screen door!" This went on for a couple
of years then it mysteriously stopped. I figured the guy busted
his rear one day and quit doing it. So I never found out who was
doing the screen door thing until a few years ago. It was me!
By hanging a 14 x 40 aluminum awning on the side of a 14 wide
home I caused the ends of the floor joists to bend at the sidewall
and buggered the door. Ah, but, I remembered that this door trouble
stopped in the middle of all this awning sales thing, why would
that happen? It dawned on me that that was about the same time
that I decided to stop ordering 20-pound roof load homes and upgrade
to 30-pound roof load homes!! The new homes had a stronger floor
and roof! This was in the 70's and 80's and of course I never
blocked the doors unless they didn't work. I figured out that
some seemed to work better if you put some blocks under them,
but they all didn't seem to need it, well, not right away anyway.
Then we didn't know, now we do and we still make some of the
same mistakes with only little variations in them. The "rules"
are simple and we need to remember them. Two of the rules are:
1. No extra weight on the home and;
2. No water under the home.
OK, so if we can't hang stuff on the sides of the home then
how do we do it? Easy, we use a separate header at the home supported
properly somewhere along it's length. You can seal, attach, or
whatever the awning to the home all you want. You just need to
be sure that no extra weight comes with the attachment. This is
doable with porches but what about small window awnings that are
attached to nothing but the sidewall of the home? Well the rule
is you can't do it, BUT it has been done a million times with
little to no effect on the home! While I absolutely can't speak
for manufacturers and what they want concerning these little awnings,
I can tell you what I would do if it were my home.
These awnings over windows probably average less than 40 pounds.
The HUD Code requires that the floor of every home be capable
of supporting 40 pounds per square foot. Now that is every square
foot of the entire floor so I would make sure that somewhere close
to the window with the awning there was an always empty square
foot of floor. That oughta' do it. You might think this is a little
silly but the lawyers are always looking for some fresh meat,
so file this away. Truth is, the only real problem comes when
these awnings are in snow country. The awning may be pretty light
but the snow it holds can be several hundred pounds. "If
it were my home" I would put a few supports under the window
with the awning, wouldn't take much but they would have to be
frost heave protected.
Now for the real trouble! Have you ever seen a new home with
a built in porch and or a recessed entry with an open deck? You
know, treated lumber over the steel frame of the home? Sure you
have, hundreds in fact. Well, have you ever seen any of these
homes with a perimeter enclosure? Could be just skirting or it
could be masonry. Here's the question: "Where does the water
go that falls through the deck?" (I told you this was going
to get ugly)
I think we know and I think we better figure out how to get
rid of it and keep it from creating a high moisture condition
under the home. A few manufacturers say a barrier must be created
between the heated area of the home and the open deck under the
home, OK, how, and out of what? And, where/how do you attach it
under the home? Need a little help here and quick I think.
There are other issues as well, such as water around the footings
of porch posts and an entire end wall or whatever with no available
ventilation. These are fairly simple. You provide drainage under
the home and compensate for the lack of venting by increasing
it on the other three sides. But, making the barrier, that is
a challenge in most cases and we need to work on that. Good luck