Porch Column repair

[mpt1123]

Hi guys:
I have 2 columns supporting my front porch.  The columns are only 15 years old and sit on a porch which is concrete.  I suspect they columns are hollow, but they may be solid.  They're tapered with a flare out at the bottom.  The base of each column is surrounded by a decorative flange that's about 3 inches high. 

I noticed yesterday that the porch roof appears to be sagging on one end.  I suspect that one of the columns is rotted at the bottom.  The flange at the base is likely allowing water to penetrate and get to the base of the column.

I'd appreciate any tips to repairing rather than replacing the column.

Here's the plan.

Remove the flange at the base of the column.  I'll use my multimaster to make 2 cuts so that I can remove it - hopefully intact - and replace it when I'm done.
 
Using a bottle jack, raise the corner of the porch about an inch or two then support the porch with 2x4's.

Cut off the bottom inch (hopefully that's all that's rotted) of the column.
 
Repair any of the damaged wood with Conserve600 epoxy.

Build a round base for the column out of pressure treated wood.  Lower the porch on to the pressure treated wood. 

Fill in any crevices with Conserve60 epoxy.

Sand and finish the column.

Caulk the base with heavy duty waterproof marine caulk.

Reinstall the base around the column.

Paint.

Sound like a plan?

Thanks,
Mike
     

[Paul Marlowe]

Mike,
I'm with you until you mention supporting and cutting the shafts back.  I recommend the following:
1. Depending on how heavy the roof is you may need to double up 2x6's instead of using 2x4's for support.  I like to use wedges milled out of 2x4 or 2x3 stock to a demension of 1-1/2" > 0" over 16".  Wood shingles or similar tapered pieces could be used to lock in and adjust the height of your temporary posts which should be adjacent to the picking posts/jacking posts.  These are used for vertical support when you can rest on the deck as in your case with a concrete floor.  Make sure you spread the load at the top of the temporary posts with a 2x6x1-2' or similar size piece so you don't crush the trim/plate etc.
2. Cutting the bottom of the shaft is very aggressive and that should be done only as a last resort.  If the shaft is not going to be removed then you should securely brace it plumb and elevate it when the roof is picked up so it stays tight to the plate.  The damaged wood should be carefully picked and vacuumed away for a complete analysis of the soft wood.  If some of the shaft perimeter is sound this plane can be saved and used to help maintain the original shape.
3. The resulting damage is probably from wood decay fungi.  Therefore a treatment of borate preservative such as Board Defense or Bora-Care should be applied to the remaining affected area, then allowed to dry or force dried prior to applying epoxy.   
4. If the roof load is great the structural 600 epoxy can be used to consolidate then be thickened to cast the voids but stay short of the face.  This will allow room for 200 patch to be applied out to the face of the shaft.  The reason for this is because the patch is easily sanded once cured and the 600 which cures extremely hard is not.  The 200 can be made to blend into the surrounding wood and will paint smoothly as well.  If the load is less than substantial then epoxy 100 consolidant and epoxy 200 patch will be sufficient and my first choice.  If there are large voids greater than 2"-3" square you could fit a dry piece of consolidated wood and encapsulate it into the 200 patch if you wish.  Any of these three epoxies can be applied wet on wet if desired.
5. I feel pressure treated wood is a bad choice for most visible applications especially for column bases or plinths.  The wood species here would best be a kiln dried, rot resistant wood that has all the endgrain sealed with epoxy consolidant 100.  There should be an EPDM membrane below the plinth on the concrete to stop rising damp. 
6. Fill any voids/crevices with 200 rather than 600.  If any caulk is still needed after filling with 200 patch it should be neatly applied so it doesn't distract from the aesthetic appearance of the fabric.   

[mpt1123]

Paul:
Thanks for the quick response.
Since the porch roof is sagging, I assume that there is rot around the entire perimeter of the column. 

Keep in mind that I have a base (i.e cap) that surrounds the bottom of the column, so I have a little room to work where I can make repairs without anything showing.
 
If I can raise the column off the cement porch, say 1-2 inches, and assuming the column is hollow, would it be best to rebuild the bottom inch of the column using 600?  If I do that, will the newly rebuilt column likely take the load?  By the way, the porch is only 12 x 6, it's more of a portico, so the weight isn't too much.  How long does 600 take to cure?

Thanks,
Mike

[Paul Marlowe]

Mike,
You need to know if the shaft is solid or hollow.  You should be able to see if it is made up from staves which is indicated by a series of vertical joints.  This would mean there is a hollow shaft.  A smooth shaft without joints usually means a solid shaft but it could be bored hollow.
Yes you could use the 600 as you mentioned but cap it with 200 as I described earlier.  The 600 will cure in about 1-2 days at 75 degrees.

[mpt1123]

Paul:

I took some measurements and the porch roof is sagging about 1 1/2". 

The base of the column is surrounded by a collar made of what looks like a PVC resin material.  From what I can tell, the column is made of something similar (i.e. not wood ). 

What I found is that the column is in great shape.  However, whatever it was sitting on appears to have rotted away.  The area under and around the column, and under the collar, was damp with what looked like dart dirt.  I suspect it was actually rotted wood.  I didn't see any insects, although it was clear there were trails, similar to ants, through the dirt.  It's possible that the insects are up inside the column.  I'm guessing that since the sag is 1 1/2" that the column was sitting on a piece of pressure treated 2X.
 
Here's the plan.

Jack up the ceiling 1 1/2.  Replace the rotting 2X (not sure what I'll use at this time.  I'm looking for something stainless steel).  Lower the ceiling onto the new base.  Replace the collar.  Repeat for the other side since it was installed the same way it's just as likely to fail soon.

I'd like to drill a hole at the top of the column and inject it with your Board Defense to kill any insects. How do you use that product?  Is that appropriate for this situation?

Thanks again for all your help.
Mike     

[Paul Marlowe]

Mike,
Normally we would apply borate preservative directly on wood that was damaged by fungi, is going to be restored and is both visible and accessible.  You can also apply it to untreated, dry, rot resistant wood, allow it to dry then consolidate the ends prior to installing it under the column shaft.  No matter what your collar/base is made of, it would be practical to get a piece of EPDM (possibly from a commercial roofer) and install it as a brake below the base or plinth on top of the concrete.  This would stop moisture transfer between the fabric.