# sinking decks which are attached to houses



## GettingBy (Aug 19, 2010)

In general:
How much sinkage over how long have y'all seen? An inch/yr?
What type of soil, what type of foundation?
How much sinkage does it take for the HO to be concerned?
Does sinkage happen soon or after many years?
Does it stop after a while?

In your opinion, how meaningful would an 800# load test for a few minutes be, where the depression due to loading for a one square foot plate in the subsoil is measured? This would be one corner of a car jacked up with the other wheels blocked.

These guys maybe use dynamite instead of weight.
http://www.testpile.com/PDF/Statnamic Testing Brief Overview for Web Site.pdf


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## Beanfacekilla (May 19, 2011)

Well, if a deck is attached to a house, it shouldn't sink at all (IMHO).

That is what footings are for. The idea is, the footings are below the frost line (42" for me), and they sit on undisturbed soil, so they can't sink. Also, the piers are designed in such a way, that the winter freeze can't lift them up. 

I don't think decks are supposed to sink at all, if built properly.

My $0.02


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## knucklehead (Mar 2, 2009)

I have never had one sink. I have fixed a couple that did from poor workmanship. That is hard to measure


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## Tom Struble (Mar 2, 2007)

problem is you really don't know the exact soil conditions for any particular post

maybe something like this is more better?...i don't know:whistling

http://www.technometalpostusa.com/us/techno-metal-post-dealers/techno-metal-post-usa/


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## fourcornerhome (Feb 19, 2008)

I hope you're talking about others work. I just fixed one that heaved up about 3" in the middle of the deck. footings were done poorly.


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## concretemasonry (Dec 1, 2006)

Differential settlement/heaving is a common problem with ledger attached decks and that is on the reasons not to go that route.


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## Beanfacekilla (May 19, 2011)

concretemasonry said:


> Differential settlement/heaving is a common problem with ledger attached decks and that is on the reasons not to go that route.


That is a good point. I prefer free-standing decks personally. A few more holes, but a better design IMHO.


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## kcremodeling (Nov 8, 2009)

A properly built deck should not settle at all except for rare circumstances. We only build freestanding decks if there is an issue attaching to the house. I like to go freestanding if it's an all stucco house or if the foundation is questionable.


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## CO762 (Feb 22, 2010)

Beanfacekilla said:


> That is a good point. I prefer free-standing decks personally. A few more holes, but a better design IMHO.


and part of that design is no house penetrations.


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## Beanfacekilla (May 19, 2011)

CO762 said:


> and part of that design is no house penetrations.


Yup. That's right.


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## Tdawg (Jul 24, 2011)

When you guys say "freestanding", I assume you are talking about ground level platform decks, right? I can't imagine that your local codes would allow you to build a second story deck that is not attached to the house.


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## woodchuck2 (Feb 27, 2008)

fourcornerhome said:


> I hope you're talking about others work. I just fixed one that heaved up about 3" in the middle of the deck. footings were done poorly.


X2, the one i repaired recently had hand poured piers shaped like upside down cones. Every yr the frost would heave up the piers/deck and the soil along side the pier would fall under holding it up. After several yrs the deck had heaved up over 1'. I would post pics but i never took any.


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## RobertCDF (Aug 18, 2005)

They should not sink (or heave) at all. If done poorly then freestanding deck will also sink/heave. It's more about doing things properly than anything else. You can take best ideas in construction and the best designs in construction and execute them poorly and it will fail.


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## Beanfacekilla (May 19, 2011)

Tdawg said:


> When you guys say "freestanding", I assume you are talking about ground level platform decks, right? I can't imagine that your local codes would allow you to build a second story deck that is not attached to the house.


 

I prefer to build decks that are not elevated as free-standing. I will avoid a ledger board if I can. This is just my opinion. 

However, if you don't build it properly, it will look like poo after a winter or two. 

Good point you make though... 

Peace.


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## Beanfacekilla (May 19, 2011)

woodchuck2 said:


> X2, the one i repaired recently had hand poured piers shaped like upside down cones. Every yr the frost would heave up the piers/deck and the soil along side the pier would fall under holding it up. After several yrs the deck had heaved up over 1'. I would post pics but i never took any.


Good grief! That is really bad.


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## GettingBy (Aug 19, 2010)

Thanks, all. This gives me something to think about. 

Sounds like properly made footings eliminate virtually all deck problems and my copy of the IRC has a lot of pages devoted to footings.


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## Tinstaafl (Jan 6, 2008)

Tdawg said:


> I can't imagine that your local codes would allow you to build a second story deck that is not attached to the house.


Why not? Properly supported and braced, it will be just as solid.

Waterside piers are built without being attached to houses. Stairs going down steep hillsides or cliffs are built without being attached to houses.


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## CO762 (Feb 22, 2010)

GettingBy said:


> Thanks, all. This gives me something to think about.
> 
> Sounds like properly made footings eliminate virtually all deck problems


Think about this....a house built right next to a house...with a slight space between. Both are 'structural'.


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## Tdawg (Jul 24, 2011)

Beanfacekilla said:


> I prefer to build decks that are not elevated as free-standing. I will avoid a ledger board if I can. This is just my opinion.
> 
> However, if you don't build it properly, it will look like poo after a winter or two.
> 
> ...


The point I was trying to make is that here in Ontario, any deck that is more than 24 inches above grade MUST be attached to the house. You can lag bolt into a poured concrete foundation. Attaching to anything above the foundation (brick, wood siding, etc.) must be through bolted. Are you guys saying that your local building codes don't require something along these lines? If so, that's freaking scary.


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## Tom Struble (Mar 2, 2007)

Tinstaafl said:


> Why not? Properly supported and braced, it will be just as solid.
> 
> Waterside piers are built without being attached to houses. Stairs going down steep hillsides or cliffs are built without being attached to houses.


houses are built without being attached to houses:thumbup:


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