Sunroom support post / columns

[Bruce Hutton]

Working on a pre-inspection report that has a 20 foot wide X 16 foot deep sunroom with a 4/12 pitched gable roof attached to the back of the back of a house......This is being supported with 4 by 4 pressure treated lumber for posting......How do I know if it should have been 6 by 6 pressure treated post?......There are 4 post along the 20 foot width & 2 post plus the ledger attachment along the 16 foot depth....What sizes should be used for support posting on a structure like this?.....Are there any charts to refer to for load bearing capacities?.....How would you report on this? Thanks for your help...Bruce

[Rick Cantrell]

Working on a pre-inspection report that has a 20 foot wide X 16 foot deep sunroom with a 4/12 pitched gable roof attached to the back of the back of a house......This is being supported with 4 by 4 pressure treated lumber for posting......How do I know if it should have been 6 by 6 pressure treated post?......There are 4 post along the 20 foot width & 2 post plus the ledger attachment along the 16 foot depth....What sizes should be used for support posting on a structure like this?.....Are there any charts to refer to for load bearing capacities?.....How would you report on this? Thanks for your help...Bruce


Check for permits and closed inspections.
If permitted and inspected, well, the inspections approved it.
If no permits or open inspection, report it and recommend an engineer/architect.
Do not give your approval or disapproval.
Remember, you are not and should not be expected to perform the work of an engineer/architect.
Don't fall into a trap trying to be something you are not.

[John Kogel]

The problem I see is not so much the 4 X 4 posts but the fact that there is no lateral bracing to keep them vertical. The support might not be adequate for the weight, but I would certainly call for bracing due to the height. Also check the attachment to the main structure.

(That looks like 8 in 12 roof pitch.)

[chris foley]

4x4 max is 8 ft in height , the use of 6x6 is standard building requirement for over 8ft. Also bracing is required when using 6x6 in excess of 10 ft at any point . The use of 4x4 and no bracing is sub standard for today but may have been ok when built . Unfortunately you have to check with your local codes at time of when it was built , but I would make comment to " todays building standards" and monitor for possible sagging etc. , Decks attached to structure require diagonal bracing only at outside girder line with structure

[Billy Stephens]

Looks Like an After thought Add On.
* as in not perminted

[Rick Cantrell]

Looks Like an After thought Add On.
* as in not perminted

My thoughts also.
That's why I said to check permits.

[Mark Reinmiller]

Working on a pre-inspection report that has a 20 foot wide X 16 foot deep sunroom with a 4/12 pitched gable roof attached to the back of the back of a house......This is being supported with 4 by 4 pressure treated lumber for posting......How do I know if it should have been 6 by 6 pressure treated post?......There are 4 post along the 20 foot width & 2 post plus the ledger attachment along the 16 foot depth....What sizes should be used for support posting on a structure like this?.....Are there any charts to refer to for load bearing capacities?.....How would you report on this? Thanks for your help...Bruce


There are too many variables for charts to be of much help. Am I correct to assume that the floor joists run front to rear? Also, I did not note your location. What is the design snow load? I can run a quick check with that info to give you an idea what is required. In general, 4x4s are not very efficient at about 8 feet in height. I would go with 6x6s. There is also the details of attachment. You cannot bolt a beam to the side of a 4x4. It would need to sit on top of the 4x4.

[H.G. Watson, Sr.]

The OP's stated location is Illinois.
As has been established earlier, more specifically in the central (mid) west-most edge of Illinois (i.e. Quincy in Adams County, just across the "Mighty Mississip" from legendary Hannibal, MO - a score or two miles south of the Iowa/Missouri line. (Cue off-camera voices "mark?" "Twain" -or not as the case may be), about two score south of Navoo (where Romney's cult/clan hung out for a bit before heading to Utah.

Where the subject property is exactly is anyone's guess - but I'm betting on the subject being a "river room". That's water to the right and beyond - the bridge in the background the bluff suggests that just might be the Mississippi in the far background to the right. That does not appear to be prescriptive addition/deck conversion construction full-height walk-out basement at the back; esp. for Illinois side (Seis = C or +) so suspecting (No licensing required for HI in MO) Missouri side. Sloped walk-out to a mud pond at waterway/floodway edge, not surprised areas of the back lawn appear to be silt-choked. Illinois has adopted IRC as default when no Home rule has elected otherwise.

[Billy Stephens]

The OP's stated location is Illinois.
As has been established earlier, more specifically in the central (mid) west-most edge of Illinois (i.e. Quincy in Adams County, just across the "Mighty Mississip" from legendary Hannibal, MO - a score or two miles south of the Iowa/Missouri line. (Cue off-camera voices "mark?" "Twain" -or not as the case may be), about two score south of Navoo (where Romney's cult/clan hung out for a bit before heading to Utah.

Where the subject property is exactly is anyone's guess - but I'm betting on the subject being a "river room". That's water to the right and beyond - the bridge in the background the bluff suggests that just might be the Mississippi in the far background to the right. That does not appear to be prescriptive addition/deck conversion construction full-height walk-out basement at the back; esp. for Illinois side (Seis = C or +) so suspecting (No licensing required for HI in MO) Missouri side. Sloped walk-out to a mud pond at waterway/floodway edge, not surprised areas of the back lawn appear to be silt-choked. Illinois has adopted IRC as default when no Home rule has elected otherwise.

Wow ,What an Imagination.

List of rivers of Illinois - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/List_of_rivers_of_Illinois)

[Raymond Wand]

Inform clients to have their lawyer check county/municipality/land title registry for building permit or permits that have not been signed-off/or permits not taken out from building department.

Personally if that where my house I would want 6x6, they really appear undersized given whats being supported.

[Mark Reinmiller]

Inform clients to have their lawyer check county/municipality/land title registry for building permit or permits that have not been signed-off/or permits not taken out from building department.

Personally if that where my house I would want 6x6, they really appear undersized given whats being supported.

Quite a few inspectors mention permits and inspections. That may indeed limit liability to the inspector, but it does not mean something is built correctly. A good part of my business is evaluating things that were built wrong, with permits and inspections.

I understand that inspectors cannot determine whether this is correct or not. I asked the OP for a little more info so that I could run a few quick number just as an example for others to see whether 4x4s can work. In some cases they can, but 6x6s would be better.

[H.G. Watson, Sr.]

Wow ,What an Imagination.

List of rivers of Illinois - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/List_of_rivers_of_Illinois)

The OP's base-of-operations is public record (license).

Can't see the 'forest for the trees' or in this case, the bridge, waterway(s), and bluff(s) Billy-boy?

Watershed plainly demonstrated. Its a sloped lot, walk out basement (and if you look at the long shot, the street, the front & side yards and the house across from this one are 'higher ground' then the back yard fashoned as a swale to the basement walk-out door then minor slope to the waterway.

News flash: It rains. Sometimes when it rains 'too much' &/or 'too long' or 'too fast'; it floods.

[Billy Stephens]

The OP's stated location is Illinois.
As has been established earlier, more specifically in the central (mid) west-most edge of Illinois (i.e. Quincy in Adams County, just across the "Mighty Mississip" from legendary Hannibal, MO - a score or two miles south of the Iowa/Missouri line. (Cue off-camera voices "mark?" "Twain" -or not as the case may be), about two score south of Navoo (where Romney's cult/clan hung out for a bit before heading to Utah.

Where the subject property is exactly is anyone's guess - but I'm betting on the subject being a "river room". That's water to the right and beyond - the bridge in the background the bluff suggests that just might be the Mississippi in the far background to the right. That does not appear to be prescriptive addition/deck conversion construction full-height walk-out basement at the back; esp. for Illinois side (Seis = C or +) so suspecting (No licensing required for HI in MO) Missouri side. Sloped walk-out to a mud pond at waterway/floodway edge, not surprised areas of the back lawn appear to be silt-choked. Illinois has adopted IRC as default when no Home rule has elected otherwise.


The OP's base-of-operations is public record (license).

Can't see the 'forest for the trees' or in this case, the bridge, waterway(s), and bluff(s) Billy-boy?

Watershed plainly demonstrated. Its a sloped lot, walk out basement (and if you look at the long shot, the street, the front & side yards and the house across from this one are 'higher ground' then the back yard fashoned as a swale to the basement walk-out door then minor slope to the waterway.

News flash: It rains. Sometimes when it rains 'too much' &/or 'too long' or 'too fast'; it floods.

Double News Flash just because this property is adjacent to a water source ( creek, drainage ditch , or other ) does not morph this screened in enclosure on stilts into a " River Room."

[Raymond Wand]

First picture, middle support closest to house looks like its two 2x4 sistered together? Blew picture up could not confirm, but there appears to be seam down the support as if 2x4's are sistered.

[John Kogel]

Any sign of Huckleberry Finn's dead pappy in that house? :D

[Kristi Silber]

The OP's base-of-operations is public record (license).

Can't see the 'forest for the trees' or in this case, the bridge, waterway(s), and bluff(s) Billy-boy?

Watershed plainly demonstrated. Its a sloped lot, walk out basement (and if you look at the long shot, the street, the front & side yards and the house across from this one are 'higher ground' then the back yard fashoned as a swale to the basement walk-out door then minor slope to the waterway.

News flash: It rains. Sometimes when it rains 'too much' &/or 'too long' or 'too fast'; it floods.

Oh, I just can't pass this up. You've outdone yourself this time! Silt-choked yard? The waterway that's actually a building? Watershed plainly demonstrated based on the landscaping? Mississippi?! Possible, but highly unlikely, considering the height of the sewer drainage and high water mark across the river.

Please, Bruce, come back and set the record straight!

[Billy Stephens]

Any sign of Huckleberry Finn's dead pappy in that house? :D

Hucks Pappy be Dead ??? :(

[Raymond Wand]

That supposed river looks like a pond.

[Scott Patterson]

My SWAG is that was once a deck that they put a roof and walls on! I'm not doing any permit searches, unless I'm paid to do it. If you don't like the 4x4 post then simple say that you recommend 6x6 or properly sized steel supports for increased safety. That is about all you really need to do.. Just recommend it!

[Rick Bunzel]

I never do permit searches. Let the client or Realtor do that.

If I were to see this I would state that the supports appear to be undersized for size of structure potential snow load, throw out the question on whether this is a permitted structure and recommend further evaluation by the appropriate licensed professional.

//Rick

[Rick Cantrell]

Like Scott and Rick B., I do not check permits.
In my earlier post I was describing a way that may help to answer the OP's question,
"How do I know if it should have been 6 by 6 pressure treated post?"
It may have been better if I said to recommend to check for permits.

[H.G. Watson, Sr.]

Double News Flash just because this property is adjacent to a water source ( creek, drainage ditch , or other ) does not morph this screened in enclosure on stilts into a " River Room."Breaking news for the bull-headded: that ain't no "screen porch" those are walls and windows.Simply plugging in 6x6's upon a slope subject to runnoff and errosion and a full 8' or more isn't going to stablixe.

[Billy Stephens]

Breaking news for the bull-headded: that ain't no "screen porch" those are walls and windows.

Now it is.

[Garry Sorrells]

Bruce,
I would question the joist used 2x10 or 2x12 and on what center??? 16 ft projection.

Bearing loads on on 4x4 supports may have been oked by local permit. Though 6x6 is what I would have used in addition to a beam with 2 additional 6x6 to beak the 16ft projection in half.

The exterior posts appear to break the loads into 8ft. Were they berried? Setting on footer?


If the water over flows the banks and flood the area, causing excessive runoff and erosion, just make the recommendation to not view it from the enclosed deck so as not to be in the "river room" as it floats down stream

- - - Updated - - -

General question : Is the term "river room" a local/regional term?

[Billy Stephens]

I'm betting on the subject being a "river room". That's water to the right and beyond - the bridge in the background the bluff suggests that just might be the Mississippi in the far background.




- - - Updated - - -

General question : Is the term "river room" a local/regional term?

Very Localized.

[Mark Reinmiller]

Working on a pre-inspection report that has a 20 foot wide X 16 foot deep sunroom with a 4/12 pitched gable roof attached to the back of the back of a house......This is being supported with 4 by 4 pressure treated lumber for posting......How do I know if it should have been 6 by 6 pressure treated post?......There are 4 post along the 20 foot width & 2 post plus the ledger attachment along the 16 foot depth....What sizes should be used for support posting on a structure like this?.....Are there any charts to refer to for load bearing capacities?.....How would you report on this? Thanks for your help...Bruce

I ran a quick calculation assuming the floor joists run front to rear and using a 30 psf snow load. The heaviest loaded columns would be the center side columns, Assuming a 4x4 SP standard grade at 8 feet length the load on the column is probably a bit under 4000 pounds. The allowable load is about 5900 pounds, assuming the 4x4s are straight and the load is relatively centered. So, it can work, but 4x4s often are not straight and the load is often not centered. Pretty much any porch like this should be designed by a licensed engineer because most municipalities do not have prescriptive requirements for lateral bracing. That is true whether there are 4x4s or 6x6s.