Patio Cover and footings

[tbz]

Good afternoon all....

We are installing a new patio cover to replace one that came down during the snow this past winter.

The existing aluminum cover was installed on top of this raised cement patio.

Now the current slab is poured over a second slab over stone.

We are looking to just cut out the 2 corners and one center point to dig and set (3) footings for (3) 3" columns that will hold up a aluminum I-beam.

Once we install the beam and columns we are going to install the screening between the columns and the house.

Here are my questions and see photo's below.

1.) With the slab over slab, over stone do you see the footings required?

2.) Do you see any issues with just the (3) columns being installed with the screening between.

3.) I an looking for a picture of a finished room and will post that pic when I find it.

But the questions is, for a patio cover do you feel we need to dig footings here?

 

[mjesse]

Ick.

Footings required to frost depth for anything attached to the house here.

If not, cover will move seasonally causing problems with the connection at the house.

Will your footing and hold-downs take wind uplift into account?

 

[mark handler]

Replace with what? metal? Wood?

Spans between columns?

 

[Francis Vineyard]

IRC appendix H

 

[mark handler]

IRC appendix H

If adopted

 

[mtlogcabin]

Build it free standing and use IBC 1809 or submit under alternate materials and methods and reference appendix H and/or IBC 1809.5

The plain concrete will easily support the aluminum patio, wind up lift would be the main concern if the new footings are not large/heavy enough to resist the up lift.

The slab appears to have been there for quite some time and if there is no history of it heaving or moving then I would not be concerned about the cover being attached to the structure.

 

[fatboy]

I'm with mjesse.......

 

[tbz]

Replace with what? metal? Wood?Spans between columns?

I should know better for got in a rush.

Aluminum EPS foam core like this

The only difference we would be enclosing the area with a screen room.

 

[tbz]

We are looking at (3) columns along the front with a single I-beam

We are looking at 96inch projection

20ft width on the raised slab

Building it free standing is not an option we have to tie it to the house.

 

[JCraver]

I'm with mjesse.......

Me too. I would require footings here.

 

[mtlogcabin]

Are you using a "C" channel attached to the fascia? If so design the channel so the fastener holes are slotted on the top of the channel and will allow the panel to move if frost heave is a concern. Similar to slotted track for stud walls in a building that allows for the roof deflection in snow areas. Flash the top for weather resistance There are plenty of flexible materials on the market you can use

If the slab heaves 6 inches on your 96 inch span that is about a 3/4 inch movement you would need to account for. Unless you have some clay issues I seriously doubt that in your climate you would have much movement due to frost if your soils are well drain-able and the water runoff from your patio roof drains away from the slab

 

[tbz]

Are you using a "C" channel attached to the fascia? If so design the channel so the fastener holes are slotted on the top of the channel and will allow the panel to move if frost heave is a concern. Similar to slotted track for stud walls in a building that allows for the roof deflection in snow areas. Flash the top for weather resistance There are plenty of flexible materials on the market you can useIf the slab heaves 6 inches on your 96 inch span that is about a 3/4 inch movement you would need to account for. Unless you have some clay issues I seriously doubt that in your climate you would have much movement due to frost if your soils are well drain-able and the water runoff from your patio roof drains away from the slab

MT,

The wall mounting unit is a pivot mounting C unit.

The mount to the wall allows for about 7deg rotation we mount them in the center so we have 3deg +/- rotation.

So frost is not a problem we have ever had.

The patio structure is almost 50 years old. My father built the first aluminum awning cover with screen room for this client in the mid 60's, the roof and screen room were just lag down to the slab.

No movement in 50 years seems to be a pretty good indication of stability to me.

This past winter the main roof of the house built up snow pretty high and when it started to melt about 2/3 of the roof slid on to the awning, you can imagine the result of a structure with 0.030 aluminum sheets with 1.125 x 3.5 x 0.035 rafters 16" on center held up on that.

It folded in the center and dropped about 3ft in the middle.

When we cut through the slabs we are going to hit bedrock, which the slabs are poured over. Seems like a lot of work for nothing when we have drilled 1/2" holes down 20" to confirm rock under double slab.

 

[mtlogcabin]

When we cut through the slabs we are going to hit bedrock, which the slabs are poured over

It is a lot of work and totally unnecessary for this project.

R403.1.4.1 Frost protection.

Except where otherwise protected from frost, foundation walls, piers and other permanent supports of buildings and structures shall be protected from frost by one or more of the following methods:

1. Extended below the frost line specified in Table R301.2.(1);

2. Constructing in accordance with Section R403.3;

3. Constructing in accordance with ASCE 32; or

4. Erected on solid rock.

I suggest you install snow brakes on the roof to reduce the snow slide and eliminate a re-peat failure in the future.

http://snowbrakes.com/

 

[mjesse]

When we cut through the slabs we are going to hit bedrock, which the slabs are poured over.

Important point not clearly described in OP

"slab over stone" to me, means a stone/gravel sub-base. Solid rock is is a different story as MT points out.

Still need to consider wind uplift.

 

[mtlogcabin]

We do a lot of concrete labs or 6 inches of washed 3/4 gravel and have no problems with frost heave

I believe the uplift loads are easily addressed by the connect to the original slab

 

[mjesse]

We do a lot of concrete labs or 6 inches of washed 3/4 gravel and have no problems with frost heaveI believe the uplift loads are easily addressed by the connect to the original slab

Not being argumentative, just clarifying my thoughts...

1- Slabs here are similarly constructed. The slab itself may have no "problems" per se due to frost heave, but they do move based on soil conditions.

The problem begins when the patio cover attached to the slab hinges against the house due to movement. Haven't seen the pivoting mount mentioned above, then we don't have many of the types of units pictured in my municipality.

2- Uplift MAY be addressed by the weight of the slab, but it may take more than a 1-1/2" tapcon at each column to make it work.

The only thing worse than a jacked patio cover against your house, is a jacked patio cover blown into your neighbors family room window.

Appendix H is a good place to start for guidance. It may not be enforceable if not adopted, but it can certainly be cited as reference.

 

[ICE]

These patio covers come with factory engineering....lots of engineering....so much engineering that it is difficult to know what is required unless your particular detail drawings are highlighted. Years ago, a 4" slab was all that was needed.

I recently posted pictures of a massive footing for one of these. Had the builder read the footnote, he would have seen that the detail was for the planet Saturn.

 

[mtlogcabin]

Appendix H is a good place to start for guidance. It may not be enforceable if not adopted, but it can certainly be cited as reference.

Agree

but it may take more than a 1-1/2" tapcon at each column to make it work.

Agree again, That is why I stated connected to the original slab, I was thinking more along the lines of a 3/8" Titen anchor

http://www.strongtie.com/products/anchorsystems/mechanical/titen-hd/

 

[tbz]

Thank you for all the information, I am having a hard time wrapping my head around all the added re-work to replace what was originally there for over 40years without an issue.

We even did a removal permit for take down and now another permit for the replacement unit.

If there was going to be an issue you would have thought it would have showed up in the last 40 plus years. The slab and the unit never moved evident by the paint at the seams never splitting.

But thank you for all the input.

Tom

 

[mjesse]

If there was going to be an issue you would have thought it would have showed up in the last 40 plus years.

A sentiment I summed up in my first comment as "ick"

These are the types of things I struggle with as a Code Official, after working for, and as, a contractor for 25 years.

I know what the Code says, and what is required to comply. But occasionally there are things like patio covers that have worked just fine for generations without the requirements prescribed by Code.

It's a personal struggle to tell someone things have to be done a certain way because the Code "says so" despite having been real life tested since our grandfathers first installed them.

I think this is the reason I, and possibly others here, refuse to take the hard edged "No Mercy" code enforcement path. I try to look at things holistically, and apply the Code with some compassion and an understanding of what is really important. Fortunately, as the sole Code Official/building inspector for a small home-rule community, I have the ability to follow this path.

Good luck with your project, keep us posted.

mj

 

[mtlogcabin]

R104.11 Gives you the authority to "approve" alternate methods. Some fear this responsibility for a number of reasons, I for do not. The IRC is prescriptive and allows you to use other codes if what is being constructed is not covered prescriptively.

Hard edged "No Mercy" code enforcement is counter productive for a jurisdiction. We have to remember we work for the public and service should be a priority and if it means sitting down and coming up with alternative solutions in lieu of "Go get engineering" then that is what we should be doing. It is not hard it just takes effort on our part.

This patio is a perfect example of "finding a solution that works". I may have to get off my :butt and go out in the field to see what is there and listen to the proposed solution and make a rational decision based on the facts of what is existing and the proposed method of construction being proposed.

Been there 40 years with an existing awning, corners of the concrete are not cracked, no evidence of setteling or frost heave, proposed Titen will extend through the top slab to the original slab, that is sufficient to resist the uplift loads, approve as proposed

 

[fatboy]

In light of the additional info, I wouldn't have an issue with footings, but would like to see info on the anchorage.

 

[righter101]

R104.11 Gives you the authority to "approve" alternate methods. Some fear this responsibility for a number of reasons, I for do not. The IRC is prescriptive and allows you to use other codes if what is being constructed is not covered prescriptively. Hard edged "No Mercy" code enforcement is counter productive for a jurisdiction. We have to remember we work for the public and service should be a priority and if it means sitting down and coming up with alternative solutions in lieu of "Go get engineering" then that is what we should be doing. It is not hard it just takes effort on our part.

This patio is a perfect example of "finding a solution that works". I may have to get off my :butt and go out in the field to see what is there and listen to the proposed solution and make a rational decision based on the facts of what is existing and the proposed method of construction being proposed.

Been there 40 years with an existing awning, corners of the concrete are not cracked, no evidence of setteling or frost heave, proposed Titen will extend through the top slab to the original slab, that is sufficient to resist the uplift loads, approve as proposed

BRAVO!!!!

I have been trying to make this point to inspection and plan check staff but it gets met with resistance.

I have a fundamental problem with requiring engineering when the cost of the engineering either A) Doubles the cost of the project, or B) Exceeds the entire project cost.

Fences are another great example.

Thanks for the comments.

 

[Coder]

Is "common sense" allowed as a code enforcement official? I hope so.