I know that most professional installers are very conscientious when it comes to proper pier placement. But with all the variations in the installation instructions, some piers are often missed. Even while the manufacturers are required to identify “point load support areas” many areas are still overlooked.
One example of identifying point load locations.
Let’s take a quick look at some of manufacturers installation instructions to see where they do or do not require “point load” support piers.
I started with the new Clayton Installation Manual to see exactly where they require point load support. They want supports at each side of exterior doors in the side wall. No support is needed if the door is on the end wall supported by a “steel header”. So, do we need supports if the door is at the tail end of the home if it doesn’t have a header? They go further and say no support in needed for doors in the side wall if the chassis I-beam spacing is 112”.
A support pier may be needed at through-the-rim crossover locations.
Support is also required at locations where through-the-rim joist heat duct penetrate the floor rim-joist. I have seen this requirement in a few installation manuals, but not much further direction. I don’t know exactly where to position this pier, and I have never seen these areas identified as point load support areas on the underside of any home.
A support is needed at each side of a factory installed fireplace when located along the side wall or marriage wall, (again with the exception of fireplaces supported by the front chassis crossmember).
Adjustable outrigger at patio door location. Note the white paint marking the location.
The Clayton Installation Manual does allow adjustable outriggers to replace piers at the fireplace locations and door locations (less than 48”) along the marriage wall or side wall. The Clayton Manual doesn’t mention the use of an adjustable outrigger at the “through-the-rim” heat duct location. (check out page 21 on the Clayton Installation Manual).
So, just for fun, I decided to compare a few other installation manuals, starting with Champion.
Window configuration creates side wall opening greater than 4′.
When it comes to doors, Champion is pretty clear (page 16). They require a support at each point load including: both sides of doors in the side wall. If the door is less than 48”, adjustable outriggers may be used in place of door piers. “Blocking” is not required for doors in non-load bearing end-walls.
Here is an interesting one: Champion requires support “Under heavy (400 lbs or greater) items, such as heavy furniture, waterbeds, fireplaces and large fish tanks”. I better have a few extra blocks ready for the next visit from my mother-in-law!
Typical porch support.
What about Commodore/Colony you say? Ok, turn to page 15 in their installation manual. They want support at both sides of exterior doors at the side wall, but not at doors in the end walls. Porch posts always require support. They also want a support at through-the-rim heat crossover ducts, and under heavy items like waterbeds, fireplaces, and mothers-in-laws.
Here is the curve ball: “…where marriage line openings are greater than 10 feet, intermediate supports must be placed at maximum 10 feet on center”. Some other manufacturers have this same requirement. Others only want these intermediate supports if the home has perimeter supports (evenly spaced under the side walls).
T Brace (pier saver).
I think it’s only fair to say, that Commodore/Colony was the first manufacturer I was aware of to introduce “Pier Savers” for support of patio and other exterior doors! I am a big fan of pier savers. Look up their “Alternate T Brace” addendum A-7.
Skyline requires a support at exterior doors on side walls (not end walls), typical 4’ marriage line and side wall openings, through-the-rim crossover ducts, porch posts, heavy furniture, fireplaces, etc. BUT..Skyline utilizes the adjustable outriggers more liberally than most. Basically you can use an adjustable outrigger to replace a support with a load up to 1,700 lbs. Go to their charts on page 20 of their installation manual for span loads. Some Skyline plants provide the adjustable outriggers with the homes. Make sure you get a copy of the “Addendum to Installation Instructions for Installation of Adjustable Outriggers”
Shear wall strap needs pier support.
Finally, I checked out Fleetwood, pretty similar to the others, except they want support at “labeled G-2 strap locations” (see page 20 in their installation manual)
At this point you might be thinking, “just follow the pier print”. Well, I checked out a handful of “pier prints”, and most of the locations mentioned above are NOT identified on the pier prints. None showed the piers at the through-the-rim crossovers, or at any fireplaces. Also, the “intermediate” supports at the marriage line is missed by most. One pier print I noticed shows piers that defied any reasoning!
OK, here are the take-aways:
There is no “One Size Fits All”. Make sure you take 30 seconds, and open the installation manual and look under the heading “Install Footings” where you “Determine Locations”. Make sure you know each particular manufacturer’s variations.
Don’t trust the pier prints! Never, Ever! Follow only DAPIA stamped (approved) designs and instructions.
Investigate pier savers and adjustable outriggers! Some manufacturers already approve their use. If yours doesn’t, start asking for approval! The squeaky wheel always gets the grease.
And lastly, don’t invite my mother-in-law to your house!