In last week’s post, we discussed some of the most common problems with manufactured home installations, today let’s talk about the problems that I think have the greatest impact. Truth be told, very few homeowners are ever going to know if their bonding wire is not attached or an anchor is not installed full depth. So listed below is a ranking of issues that have the greatest impact.
- Air Infiltration/Loss At The Marriage Line
In all of my years in talking with consumers and hearing about their concerns, excessive heating and cooling costs were consistently a top issue. While manufactured homes are very well insulated and tightly constructed, the weak link in the process is the marriage line gasket. Infrared imaging of several multi-section homes has proven this point time and time again.
During your next installation, pay close attention to the gasket and look for areas that might have been damaged by misplaced staples or shipping straps. These things can prevent the gasket from sealing as tightly as it should. More importantly, make sure the home sections are close enough to properly compress the gasket and prevent heat loss.
I would love to see some improvements in how we gasket the marriage line. How about double gaskets or maybe spray foam at this joint? Just a few things to consider.
- Site Grading
A close second to marriage line gasket issues is site grading. I fully understand that site grading is often difficult for the installer to address, especially if the installer is not involved in the site checks before the job is sold. But given the damage that can be caused as the result of poor site grading, I think installers should revisit their agreements with retailers and community owners to make it clear who is responsible for site grading. Bottom line, if the site is not graded properly, do not sign-off on the installation of the home.
The Pennsylvania Housing Research Center has produced a Builders Brief on site grading and what to do in situations where proper grading is difficult. Check it out: Site Design Considerations for Manufactured Housing
- Pier Failure
Now let me be clear, a concrete block used as a support pier is incredibly strong, and when properly spaced are rarely loaded beyond their capacity. While concrete block piers are strong, they are also fragile. Block piers must be evenly loaded at the top and fully supported by a smooth, flat and stable footing. Short of that, the block can crack, split and lead to failure.
While a typical single section home will have over 20 piers supporting it, a single pier failure might not seem like too big a deal. But that failed pier can have some significant impact on the walls, ceiling, floors, and window and door operation (see picture below). Not to mention, when a pier fails, the load is transferred to the adjacent piers, overloading those as well.
The vast majority of pier failures I have seen are the result of inadequate footings. Footing depth (frost protection) shape, size (as it relates to pier load and soil capacity) and the finishing of the surface are the keys to successful support of the homes.
- Added Structures
Almost every manufactured home producer states somewhere in their installation instructions or home-owner’s manual that “accessory structures must be independently supported”. They say that for one very simple reason: in order to keep the home affordable, they don’t over design or over build. The manufactured home, along with its foundation, is designed to completely support the weight of the home, 40 pounds per square foot (PSF) live load (furniture, people, etc.) and the weight of any snow that might be on the roof (in most of the country 20 PSF). Not the extra weight of any added structure.
We wouldn’t install a home with a 20 PSF roof snow load in Hancock Maine where the roof snow load is 40 PSF, because we know that the home can’t carry the extra weight. But we often don’t think twice about attaching a deck, patio cover room addition, or a garage and somehow expect the manufactured home to carry the added weight of the structure and any additional snow load.
Ad it is not just snow loading that is impacted by added structures, but wind loads as well! To illustrate this point, in July 2014, the Today Show aired a report on the performance of manufactured homes in wind storms. It clearly showed that a manufactured home could perform quite well in a wind storm and that most structural failure is the result of improperly supported added structures, such as car ports and awnings. You can see that short video HERE
What I really like is that they even provided a solution. They suggest adding support columns against the home and not expecting the house itself to absorb the extra load. This is one of several reports that clearly illustrate that added structures are the main cause of structural failure during a wind storm.
We all realize that other added structures, such as garages and decks can bring their own set of challenges, but we will save that entire issue for another post.
These are my personal top four problems with the greatest impact on manufactured homes. Do you disagree? Leave a comment, I would love to hear your thoughts.