# Can a pressure treated deck joist rest on concrete? stoop?



## 4lane (May 20, 2020)

I'm building a deck over the top of a 3-step concrete stair. The joist edge will rest directly on top of the concrete landing but I'm wondering if I should notch the joist and put something (some kind of Simpson bracket) between the joist and concrete to prevent rot. Or is it fine as is since it's pressure treated?


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## johnedp34 (Jun 30, 2016)

I would just put some stout plastic at the contact to act as a damp course.
johnep


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## GeorgeC (Jul 30, 2008)

Treated wood is treated to provide protection against insects and rot. Treated wood is very often placed on top of or in the ground. Do you provide any barrier when used this way? Concrete is certainly going to be a more benign environment than direct ground contact.


George


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## Dylan JC Buffum (Jun 9, 2019)

Yes, it will last a long time. If you want, you could coat the end grain in some kind of tar or silicone, just for a bit more protection. But that’s probably unnecessary.


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## Tony B (Jul 30, 2008)

STOOP?????????????????????

Haven't heard that term since i left Brooklyn.
Ever play Stoop Ball?


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## JIMMIEM (Oct 12, 2014)

Maybe check with your building inspector to see if you need to attach the deck to its supports. Attachment would be for avoiding wind lift.


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## GeorgeC (Jul 30, 2008)

Tony B said:


> STOOP?????????????????????
> 
> Haven't heard that term since i left Brooklyn.
> Ever play Stoop Ball?



Yes, I did. Also stick ball. In 1948 my mother and I visited her sister in Brooklyn for 6 weeks. I was 12 at the time and the neighborhood had many the same age for me to play with.


George


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## John Smith_inFL (Jul 4, 2018)

I am not advocating right, wrong or indifferent.
but, when I was decking over a concrete patio poured by the 
previous home owner in 1988, my father-in-law was visiting
and he was watching how I was shimming the vertical 2x8 to be level.
and he said "if you cut a whole bunch of 1x2 P/T pieces for spacers;
rain, leaves and other debris won't accumulate as easily than if the lumber
just sits on the concrete and the vertical 2x8s can breathe easier".
this had nothing to do with how the concrete would affect the lumber.
it was more geared towards easier to clean out when needed and offer
more ventilation for the whole deck.
I removed the deck about 10 years later, all the wood under the top deck 
looked like new and they went to a neighbor to live another life.
the concrete patio (stoop) was about 6x10 feet. the new P/T deck was 12x24ft.









.


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## FrankC (Aug 24, 2012)

A strip of closed-cell foam can be installed between the concrete and the pressure treated wood for additional protection, your choice.


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## kwoodhands (May 1, 2020)

You do not need anything under the joists if the lumber is pressure treated. Last week I pulled 4 PT 4x4 posts out of the ground that I installed 10 years ago. When I pulled the posts and scraped off any soil the posts looked new.
mike


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## 4lane (May 20, 2020)

There are three joists that will go over the steps, they are 2x8's that will need 3" notched out since the top of the step landing is less than 8" from the door threshold, so I suppose I'll just coat the notches with some preservative and give it a go. I would put spacers under if I had the room, but that's not possible.


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## GCTony (Apr 5, 2018)

GeorgeC said:


> Yes, I did. Also stick ball. In 1948 my mother and I visited her sister in Brooklyn for 6 weeks. I was 12 at the time and the neighborhood had many the same age for me to play with.
> 
> 
> George


How about Kick the Can?


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## GCTony (Apr 5, 2018)

4lane said:


> There are three joists that will go over the steps, they are 2x8's that will need 3" notched out since the top of the step landing is less than 8" from the door threshold, so I suppose I'll just coat the notches with some preservative and give it a go. I would put spacers under if I had the room, but that's not possible.


Notching 3" out of a 2x8 only leaves 4". That takes a lot of strength out of about 1/3 the span of the joist. Depending on the grain, those joist could split the entire length. Butt the 2x8 to the stoop, (ledger and joist hangers) build up the stoop with 4" of independent lumber. 

In new house construction, a PT wood sill plate sits on top and bolted to a concrete foundation. However code requires a vapor barrier between the two, most times it's foam "sill seal". It keep moister from wicking from out of the concrete and into the wood.


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## GeorgeC (Jul 30, 2008)

GCTony said:


> How about Kick the Can?



Yeah, but that was not in Brooklyn.


George


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## Tony B (Jul 30, 2008)

GCTony said:


> How about Kick the Can?


Oh yes, I remember kick the can too in Brooklyn.

How 'bout playing marbles, pitching pennies and the numerous games with baseball cards?


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## woodnthings (Jan 24, 2009)

4lane said:


> I'm building a deck over the top of a 3-step concrete stair. The joist edge will rest directly on top of the concrete landing but I'm wondering if I should notch the joist and put something (some kind of Simpson bracket) between the joist and concrete to prevent rot. Or is it fine as is since it's pressure treated?


There are 2 types of pressure treated wood, above grade and ground contact. The ground contact has 2X the strength of preservatives:





Types of Pressure-Treated Wood


Learn the types of pressure-treated wood for outdoor projects like fences, decking, handrails and more. Read on to find which high-quality pressure-treated wood is best for your building and renovation projects.



www.homedepot.com





Also ground or soil has fungus, fungii? and other bacteria in contact with the woodwhich would encourage rot.
Concrete may have some acidic properties after it cures, ? ...but it can be sealed with special sealants.
I have used this one:








Diamond Clear - Concrete Sealer


DIAMOND CLEAR is a state-of-the-art curing and sealing compound, specially designed to provide a quality cure and seal while assuring total resistance to yellowing from ultraviolet exposure. DIAMOND CLEAR is particularly well suited for exterior architectural concrete where membrane yellowing is...




www.concreteandcurbingsource.com





Having a protective pad or strip will certainly insure a greater life span.
Many basement stairs stringers have been built to rest right on the concrete only to find out they rot out faster in damp conditions and are not typically pressure treated.
Having built many a deck and set many fence posts, I often spray the first 6" of the post with automotive undercoating as a preservative, two coats works well and it dries very quickly.


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## Steve Neul (Sep 2, 2011)

4lane said:


> I'm building a deck over the top of a 3-step concrete stair. The joist edge will rest directly on top of the concrete landing but I'm wondering if I should notch the joist and put something (some kind of Simpson bracket) between the joist and concrete to prevent rot. Or is it fine as is since it's pressure treated?


If the pressure treated is rated for ground contact it wouldn't hurt a thing sitting on concrete.


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## mouniawc (8 mo ago)

Honestly, I'm not a master at all of this. Since school, I haven't been very good at building different things. And that's why I recommend everyone to turn to a specialist in such situations when they have different questions or do not know what the next step is. I wouldn't even do it on my own. I needed to install some stairs in my yard, and I know that many can do it on their own, but I couldn't, and the specialists at almightyconstructionnw helped me get it over with. So I recommend you ask a specialist with experience in the field of construction.


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