I might be building a deck for a woman, about 20' x 12'. I've seen pillow blocks do well but I've also seen them sink a bit. I don't want a call from her in a few years complaining that her deck is now horribly uneven.

Coincidentally, this month's Fine Homebuilding has an article about a more thorough foundation for a deck, involving sinking piers down a few feet and even doing it with a larger foot on the bottom, say 12" diameter and a smaller concrete post, maybe 6" diameter extending to the surface.

I'd rather use the pillow blocks -- there's not going to be a hot tub on this deck. One deck I did a few years ago was going to receive a hot tub so I poured a footing with a smaller square footing under where the tub was going to be.

Any thoughts?

__________________
Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

I would not use a pillow block -- but that depends on where you're located. Ice can really screw up a footing (or lack of).

I would tick with a traditional footing and concrete tube-fill. Figure your loads, etc. and then over-build a bit -- if you can. Nothing worse than seeing a deck jacked up by ice damage.

OTOH, if ice isn't a concern, then you have to deal with sinking, etc.

Good Luck,

Pete

Doesn't seem like you and she are considering pulling a building permit. To build anything without a permit, but especially a structural system, where a collapse could injure someone, is not a good idea.
regards,
Mark

Why pull a permit? You would only have to build to code and the added deck would be added to the property value thus increasing property taxes. It's much better to do things under the table, if it works for the Clintons it should work for Joann non-taxpayer.

Where did you guys read that he wasn't going to pull a permit?

The forum safety patrol strikes again. Thanks for keeping it real.

I was just espousing the benefits of not pulling a permit for everyone's general amusement. I wouldn't dare assume that anyone on this forum would do such a thing.

Perhaps I am confused also by what I read in the original post. So I ask the poster, even though it is not my business: are you planning to obtain a permit for the deck?
If you do, the building department, through either approval or rejection of your application, will answer your question about the foundation system for the deck.
regards,
Mark

I wasn't planning on pulling one. Not sure it's required, but it wouldn't hurt to find out. I believe you're allowed an outbuilding of up to 144 sq. ft. w/o a permit, so I could imagine a deck of this size, about 8 inches above the ground, would also be exempt.

Berkeley is a nice little town in many ways but the city gub-mint is a bit weird, all in all. Some real horror stories around permits and bldg. inspectors, but I guess that can happen anywhere.

Virtually no problem with freezing here. Some winters, it doesn't dip below at all. When it does, it's usually for a night or two around 25 F. It's a big story around here when the snow level dips to below 1,000 feet.

I'm fininshing an octagonal gazebo in a guy's backyard that someone else started, built on pillow blocks. Probably not the best idea. When I came onto it, it had the floor, the walls framed, and half the roof on, so changing it at that point would have been more costly than my client had in mind. Doesn't seem to be any problems around that, and it's been that way for more than 3 years (he keeps running out of money -- I'd just bail but I like the guy and the thing will look good in my scrapbook/resume).

With the deck, softness in the soil is my big concern. It's in the flatlands, probably gets pretty waterlogged in winter.

__________________
Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

It's 20 X 12--why go down a few feet? Why wouldn't traditional piers work, say 16" X 16" X 6" deep? Even throw in a little rebar square set up off the ground at 3" maybe. If you didn't want to wheel barrow the mud, I am sure you know a pump truck crew that could spare a couple yards on an over-figured job for cheap?

A foundation for anything built on top of the ground will settle over time. Check your local building code for the correct way.
Is the propsed deck attached to a house or another structure?
regards,
Mark

The way I have always built piers is by digging a hole and filling it with concrete. Never seen one above ground.

Edit: I see what you are referring to--the rebar goes in the hole (3" from the bottm), and is set on little wire hangers that place it in the middle of the pier.

I believe the depth of your footing is largely based upon where the frost line is in the ground. It sounds like you are aware of this already. Did you say the height of the deck is only eight inches? If that's the case, I can't imagine a collapse would be that catastropic, even if it did occur. Frost is noly an issue because it can cause the footing to move out of place and thus, to fail.

__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

This is about the least demanding deck I've ever encountered. It won't be attached to the house except for where it dovetails into the steps leading up to the porch. She has a small front yard with some good rose bushes next to the house she wants to preserve, so it will sit a couple of feet from the house.

I'm thinking maybe a narrower footing than you suggest, JD, might be sufficient. Maybe 8 - 10" wide, 5 1/2" deep, with a 2 foot deep post at each corner and in the middle on the two long sides. Connect the footing to the posts with a fair amount of rebar and the thing should be good way past the lifespans of me or my client.

The more I think about it, pillow blocks would put the whole thing about 12 inches off the ground which is awkward w/o a step. I can have the footing an inch off the ground, plus 2x6 treated framing and this 1" thick (5/4) stuff she found for the finished surface, the whole thing would be around 7 1/2" tall, about the height of one step. I imagine the 3 foot deep post and pier set-up like they have in Fine HmBld. would be overkill for a non deep freeze area like here.

__________________
Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K

The mention earlier of danger from a collapsing deck is well taken -- the one I'm building is non-hazordous -- but there have been at least a couple of disasterous collapses of 3rd story decks in the Bay Area in the last few years.

One involved a party where way too many people were dancing on a deck -- it fell -- one or two people were killed, many injured.

The other was really disgusting. A mid 20s woman was relaxing with a smoke on her 3rd floor deck, leaning against the railing -- it broke free -- she fell and is now a para-palegic. The damn thing was riddled with dry rot. Sweet girl was a ballet dancer and hot looking (would have been tragic even if she wasn't, of course) and at one point in the article I read, she lamented, "who will want me now?"

A cautionary tale to all: get to know your house -- rented or otherwise.

__________________
Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K