In our last post we talked about how added structures, such as carports, patio covers and the like, add unintended vertical loads to a manufactured home. Today, let’s talk about how added structures subject the manufactured home to increased horizontal (wind) loads, and the possible damage that can occur as a result.
The biggest problem that I have seen is when an awning, carport or patio cover is attached directly to the fascia board of the manufactured home. Typically, the fascia board on a manufactured home is attached to the roof trusses without anticipation of a large attachment. Studies has shown that the manufactured home can easily withstand the required wind loads when the home is anchored according to the manufacturer’s installation instructions. But when a carport or patio cover is attached to the fascia board, it can subject the home to significantly higher loads than the home is designed for.
A quick review of the installation instructions for a few different awnings, carports or patio covers (common in the manufactured housing industry), shows that they agree that the awning should not be attached to the fascia board. However, there remains a concern as they suggest their products can be attached to the actual roof rafter or wall stud of the home (no mention of type of home, manufactured home or otherwise). I found no mention of fastening the mounting rail to a roof truss as opposed to a roof rafter. Nonetheless, I feel very safe in stating that the home manufacturer did not design the roof truss to support an awning, carport, porch canopy, or similar accessory.
Most critical is when the wind gets under these structures an they start to tear away from the home. As they break free, they create openings that allows the wind to get into the roof cavity, which can lead to catastrophic failure. Take a few minutes and watch these two videos. I think they make a pretty convincing case.
There are a few more things to discuss in regards adding structures to manufactured homes, but lets save those topics for yet one final post on this topic.